frost trusted dealer: use set_int instead of clear

This commit adds a documentation file with instructions for how to use
the module.

.github/workflows/ci.yml

@@ -41,6 +41,7 @@ env:
   ECDSAADAPTOR: 'no'
   BPPP: 'no'
   SCHNORRSIG_HALFAGG: 'no'
+  FROST: 'no'
   ### test options
   SECP256K1_TEST_ITERS:
   BENCH: 'yes'
@@ -79,14 +80,14 @@ jobs:
       matrix:
         configuration:
           - env_vars: { WIDEMUL: 'int64',  RECOVERY: 'yes' }
-          - env_vars: { WIDEMUL: 'int64',                   ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes',  RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes'}
+          - env_vars: { WIDEMUL: 'int64',                   ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes',  RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes' }
           - env_vars: { WIDEMUL: 'int128' }
           - env_vars: { WIDEMUL: 'int128_struct',                                           ELLSWIFT: 'yes' }
           - env_vars: { WIDEMUL: 'int128', RECOVERY: 'yes',              SCHNORRSIG: 'yes', ELLSWIFT: 'yes' }
-          - env_vars: { WIDEMUL: 'int128',                  ECDH: 'yes', SCHNORRSIG: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes'}
+          - env_vars: { WIDEMUL: 'int128',                  ECDH: 'yes', SCHNORRSIG: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes' }
           - env_vars: { WIDEMUL: 'int128', ASM: 'x86_64',                                   ELLSWIFT: 'yes' }
-          - env_vars: {                    RECOVERY: 'yes',              SCHNORRSIG: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes'}
-          - env_vars: { CTIMETESTS: 'no',  RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', CPPFLAGS: '-DVERIFY' }
+          - env_vars: {                    RECOVERY: 'yes',              SCHNORRSIG: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes' }
+          - env_vars: { CTIMETESTS: 'no',  RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes', CPPFLAGS: '-DVERIFY' }
           - env_vars: { BUILD: 'distcheck', WITH_VALGRIND: 'no', CTIMETESTS: 'no', BENCH: 'no' }
           - env_vars: { CPPFLAGS: '-DDETERMINISTIC' }
           - env_vars: { CFLAGS: '-O0', CTIMETESTS: 'no' }
@@ -158,6 +159,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CC: ${{ matrix.cc }}
 
     steps:
@@ -211,6 +213,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CTIMETESTS: 'no'
 
     steps:
@@ -271,6 +274,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CTIMETESTS: 'no'
 
     steps:
@@ -325,6 +329,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CTIMETESTS: 'no'
 
     strategy:
@@ -389,6 +394,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CTIMETESTS: 'no'
 
     steps:
@@ -450,6 +456,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CTIMETESTS: 'no'
       SECP256K1_TEST_ITERS: 2
 
@@ -510,6 +517,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CTIMETESTS: 'no'
       CFLAGS: '-fsanitize=undefined,address -g'
       UBSAN_OPTIONS: 'print_stacktrace=1:halt_on_error=1'
@@ -576,6 +584,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CTIMETESTS: 'yes'
       CC: 'clang'
       SECP256K1_TEST_ITERS: 32
@@ -632,6 +641,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
       CTIMETESTS: 'no'
 
     strategy:
@@ -688,15 +698,15 @@ jobs:
       fail-fast: false
       matrix:
         env_vars:
-          - { WIDEMUL: 'int64',  RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes' }
+          - { WIDEMUL: 'int64',  RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes' }
           - { WIDEMUL: 'int128_struct', ECMULTGENPRECISION: 2, ECMULTWINDOW: 4 }
-          - { WIDEMUL: 'int128',                  ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes' }
+          - { WIDEMUL: 'int128',                  ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes' }
           - { WIDEMUL: 'int128', RECOVERY: 'yes' }
-          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes' }
-          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', CC: 'gcc' }
-          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes',           WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
-          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', CC: 'gcc', WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
-          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', CPPFLAGS: '-DVERIFY', CTIMETESTS: 'no' }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes' }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes', CC: 'gcc' }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes',           WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes', CC: 'gcc', WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes', CPPFLAGS: '-DVERIFY', CTIMETESTS: 'no' }
           - BUILD: 'distcheck'
 
     steps:
@@ -816,6 +826,7 @@ jobs:
       ECDSAADAPTOR: 'yes'
       BPPP: 'yes'
       SCHNORRSIG_HALFAGG: 'yes'
+      FROST: 'yes'
 
     steps:
       - name: Checkout

README.md

@@ -12,7 +12,7 @@ Added features:
 * Experimental module for Confidential Assets (Pedersen commitments, range proofs, and [surjection proofs](src/modules/surjection/surjection.md)).
 * Experimental module for Bulletproofs++ range proofs.
 * Experimental module for [address whitelisting](src/modules/whitelist/whitelist.md).
-* Experimental module for [FROST](src/modules/frost/frost.md).
+* Experimental module for FROST.
 
 Experimental features are made available for testing and review by the community. The APIs of these features should not be considered stable.
 

ci/ci.sh

@@ -14,7 +14,7 @@ print_environment() {
     for var in WERROR_CFLAGS MAKEFLAGS BUILD \
             ECMULTWINDOW ECMULTGENPRECISION ASM WIDEMUL WITH_VALGRIND EXTRAFLAGS \
             EXPERIMENTAL ECDH RECOVERY SCHNORRSIG SCHNORRSIG_HALFAGG ELLSWIFT \
-            ECDSA_S2C GENERATOR RANGEPROOF WHITELIST MUSIG ECDSAADAPTOR BPPP \
+            ECDSA_S2C GENERATOR RANGEPROOF WHITELIST MUSIG ECDSAADAPTOR BPPP FROST \
             SECP256K1_TEST_ITERS BENCH SECP256K1_BENCH_ITERS CTIMETESTS\
             EXAMPLES \
             HOST WRAPPER_CMD \
@@ -83,6 +83,7 @@ esac
     --enable-module-schnorrsig="$SCHNORRSIG"  --enable-module-musig="$MUSIG" --enable-module-ecdsa-adaptor="$ECDSAADAPTOR" \
     --enable-module-schnorrsig="$SCHNORRSIG" \
     --enable-module-schnorrsig-halfagg="$SCHNORRSIG_HALFAGG" \
+    --enable-module-frost="$FROST" \
     --enable-examples="$EXAMPLES" \
     --enable-ctime-tests="$CTIMETESTS" \
     --with-valgrind="$WITH_VALGRIND" \

configure.ac

@@ -236,15 +236,15 @@ AC_ARG_ENABLE(module_ecdsa-adaptor,
     [],
     [SECP_SET_DEFAULT([enable_module_ecdsa_adaptor], [no], [yes])])
 
+AC_ARG_ENABLE(module_frost,
+    AS_HELP_STRING([--enable-module-frost],[enable FROST module [default=no]]),
+    [],
+    [SECP_SET_DEFAULT([enable_module_frost], [no], [yes])])
+
 AC_ARG_ENABLE(external_default_callbacks,
     AS_HELP_STRING([--enable-external-default-callbacks],[enable external default callback functions [default=no]]), [],
     [SECP_SET_DEFAULT([enable_external_default_callbacks], [no], [no])])
 
-AC_ARG_ENABLE(module_frost,
-    AS_HELP_STRING([--enable-module-frost],[enable FROST module (experimental)]),
-    [],
-    [SECP_SET_DEFAULT([enable_module_frost], [no], [yes])])
-
 # Test-only override of the (autodetected by the C code) "widemul" setting.
 # Legal values are:
 #  * int64 (for [u]int64_t),
@@ -475,6 +475,14 @@ if test x"$enable_module_ecdsa_adaptor" = x"yes"; then
   SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ECDSA_ADAPTOR=1"
 fi
 
+if test x"$enable_module_frost" = x"yes"; then
+  if test x"$enable_module_schnorrsig" = x"no"; then
+    AC_MSG_ERROR([Module dependency error: You have disabled the schnorrsig module explicitly, but it is required by the musig module.])
+  fi
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_FROST=1"
+  enable_module_schnorrsig=yes
+fi
+
 if test x"$enable_module_musig" = x"yes"; then
   if test x"$enable_module_schnorrsig" = x"no"; then
     AC_MSG_ERROR([Module dependency error: You have disabled the schnorrsig module explicitly, but it is required by the musig module.])
@@ -535,14 +543,6 @@ if test x"$enable_module_ecdh" = x"yes"; then
   SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ECDH=1"
 fi
 
-if test x"$enable_module_frost" = x"yes"; then
-  if test x"$enable_module_schnorrsig" = x"no"; then
-    AC_MSG_ERROR([Module dependency error: You have disabled the schnorrsig module explicitly, but it is required by the frost module.])
-  fi
-  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_FROST=1"
-  enable_module_schnorrsig=yes
-fi
-
 if test x"$enable_external_default_callbacks" = x"yes"; then
   SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_EXTERNAL_DEFAULT_CALLBACKS=1"
 fi
@@ -592,12 +592,12 @@ else
   if test x"$enable_module_generator" = x"yes"; then
     AC_MSG_ERROR([NUMS generator module is experimental. Use --enable-experimental to allow.])
   fi
-  if test x"$set_asm" = x"arm32"; then
-    AC_MSG_ERROR([ARM32 assembly is experimental. Use --enable-experimental to allow.])
-  fi
   if test x"$enable_module_frost" = x"yes"; then
     AC_MSG_ERROR([FROST module is experimental. Use --enable-experimental to allow.])
   fi
+  if test x"$set_asm" = x"arm32"; then
+    AC_MSG_ERROR([ARM32 assembly is experimental. Use --enable-experimental to allow.])
+  fi
 fi
 
 ###
@@ -666,9 +666,9 @@ echo "  module whitelist        = $enable_module_whitelist"
 echo "  module musig            = $enable_module_musig"
 echo "  module ecdsa-s2c        = $enable_module_ecdsa_s2c"
 echo "  module ecdsa-adaptor    = $enable_module_ecdsa_adaptor"
+echo "  module frost            = $enable_module_frost"
 echo "  module bppp             = $enable_module_bppp"
 echo "  module schnorrsig-halfagg = $enable_module_schnorrsig_halfagg"
-echo "  module frost            = $enable_module_frost"
 echo
 echo "  asm                       = $set_asm"
 echo "  ecmult window size        = $set_ecmult_window"

examples/frost.c

@@ -25,10 +25,8 @@
 #define THRESHOLD 3
 
 struct signer_secrets {
-    secp256k1_keypair keypair;
-    secp256k1_frost_share agg_share;
+    secp256k1_frost_share share;
     secp256k1_frost_secnonce secnonce;
-    unsigned char seed[32];
 };
 
 struct signer {
@@ -36,86 +34,26 @@ struct signer {
     secp256k1_frost_pubnonce pubnonce;
     secp256k1_frost_session session;
     secp256k1_frost_partial_sig partial_sig;
-    secp256k1_pubkey vss_commitment[THRESHOLD];
-    unsigned char vss_hash[32];
-    unsigned char pok[64];
-    unsigned char id[33];
 };
 
-/* Create a key pair and store it in seckey and pubkey */
-int create_keypair_and_seed(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signer) {
-    unsigned char seckey[32];
-    secp256k1_pubkey pubkey_tmp;
-    size_t size = 33;
-
-    while (1) {
-        if (!fill_random(seckey, sizeof(seckey))) {
-            printf("Failed to generate randomness\n");
-            return 1;
-        }
-        if (secp256k1_keypair_create(ctx, &signer_secrets->keypair, seckey)) {
-            break;
-        }
-    }
-    if (!secp256k1_keypair_pub(ctx, &pubkey_tmp, &signer_secrets->keypair)) {
-        return 0;
-    }
-    if (!secp256k1_ec_pubkey_serialize(ctx, signer->id, &size, &pubkey_tmp, SECP256K1_EC_COMPRESSED)) {
-        return 0;
-    }
-    if (!fill_random(signer_secrets->seed, sizeof(signer_secrets->seed))) {
-        return 0;
-    }
-    return 1;
-}
-
 /* Create shares and coefficient commitments */
-int create_shares(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signer, secp256k1_xonly_pubkey *agg_pk) {
-    int i, j;
-    secp256k1_frost_share shares[N_SIGNERS][N_SIGNERS];
-    const secp256k1_pubkey *vss_commitments[N_SIGNERS];
-    const unsigned char *ids[N_SIGNERS];
+int create_shares(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signers, secp256k1_xonly_pubkey *pk) {
+    int i;
+    secp256k1_frost_share shares[N_SIGNERS];
+    secp256k1_pubkey pubshares[N_SIGNERS];
+    unsigned char seed[32];
 
-    for (i = 0; i < N_SIGNERS; i++) {
-        vss_commitments[i] = signer[i].vss_commitment;
-        ids[i] = signer[i].id;
+    if (!fill_random(seed, sizeof(seed))) {
+        return 0;
+    }
+
+    if (!secp256k1_frost_shares_trusted_gen(ctx, shares, pubshares, pk, seed, THRESHOLD, N_SIGNERS)) {
+        return 0;
     }
 
     for (i = 0; i < N_SIGNERS; i++) {
-        /* Generate a polynomial share for the participants */
-        if (!secp256k1_frost_shares_gen(ctx, shares[i], signer[i].vss_commitment, signer[i].pok, signer_secrets[i].seed, THRESHOLD, N_SIGNERS, ids)) {
-            return 0;
-        }
-    }
-
-    /* KeyGen communication round 1: exchange shares and coefficient
-     * commitments */
-    for (i = 0; i < N_SIGNERS; i++) {
-        const secp256k1_frost_share *assigned_shares[N_SIGNERS];
-
-        /* Each participant receives a share from each participant (including
-         * themselves) corresponding to their index. */
-        for (j = 0; j < N_SIGNERS; j++) {
-            assigned_shares[j] = &shares[j][i];
-        }
-        /* Each participant aggregates the shares they received. */
-        if (!secp256k1_frost_share_agg(ctx, &signer_secrets[i].agg_share, agg_pk, assigned_shares, vss_commitments, N_SIGNERS, THRESHOLD, signer[i].id)) {
-            return 0;
-        }
-        for (j = 0; j < N_SIGNERS; j++) {
-            /* Each participant verifies their shares. share_agg calls this
-             * internally, so it is only neccessary to call this function if
-             * share_agg returns an error, to determine which participant(s)
-             * submitted faulty data. */
-            if (!secp256k1_frost_share_verify(ctx, THRESHOLD, signer[i].id, assigned_shares[j], &vss_commitments[j])) {
-                return 0;
-            }
-            /* Each participant generates public verification shares that are
-             * used for verifying partial signatures. */
-            if (!secp256k1_frost_compute_pubshare(ctx, &signer[j].pubshare, THRESHOLD, signer[j].id, vss_commitments, N_SIGNERS)) {
-                return 0;
-            }
-        }
+        signer_secrets[i].share = shares[i];
+        signers[i].pubshare = pubshares[i];
     }
 
     return 1;
@@ -123,12 +61,12 @@ int create_shares(const secp256k1_context* ctx, struct signer_secrets *signer_se
 
 /* Tweak the pubkey corresponding to the provided tweak cache, update the cache
  * and return the tweaked aggregate pk. */
-int tweak(const secp256k1_context* ctx, secp256k1_xonly_pubkey *agg_pk, secp256k1_frost_tweak_cache *cache) {
+int tweak(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pk, secp256k1_frost_tweak_cache *cache) {
     secp256k1_pubkey output_pk;
     unsigned char ordinary_tweak[32] = "this could be a BIP32 tweak....";
     unsigned char xonly_tweak[32] = "this could be a taproot tweak..";
 
-    if (!secp256k1_frost_pubkey_tweak(ctx, cache, agg_pk)) {
+    if (!secp256k1_frost_pubkey_tweak(ctx, cache, pk)) {
         return 0;
     }
 
@@ -154,7 +92,7 @@ int tweak(const secp256k1_context* ctx, secp256k1_xonly_pubkey *agg_pk, secp256k
      * the Schnorr signature against it. For this purpose we can ignore the
      * `pk_parity` output argument; we would need it if we would have to open
      * the taproot commitment. */
-    if (!secp256k1_xonly_pubkey_from_pubkey(ctx, agg_pk, NULL, &output_pk)) {
+    if (!secp256k1_xonly_pubkey_from_pubkey(ctx, pk, NULL, &output_pk)) {
         return 0;
     }
     return 1;
@@ -162,17 +100,18 @@ int tweak(const secp256k1_context* ctx, secp256k1_xonly_pubkey *agg_pk, secp256k
 
 /* Sign a message hash with the given threshold and aggregate shares and store
  * the result in sig */
-int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signer, const unsigned char* msg32, secp256k1_xonly_pubkey *agg_pk, unsigned char *sig64, const secp256k1_frost_tweak_cache *cache) {
+int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signer, const unsigned char* msg32, secp256k1_xonly_pubkey *pk, unsigned char *sig64, const secp256k1_frost_tweak_cache *cache) {
     int i;
-    int signer_id = 0;
+    size_t signer_id = 0;
     int signers[THRESHOLD];
     int is_signer[N_SIGNERS];
     const secp256k1_frost_pubnonce *pubnonces[THRESHOLD];
-    const unsigned char *ids[THRESHOLD];
+    size_t ids[THRESHOLD];
     const secp256k1_frost_partial_sig *partial_sigs[THRESHOLD];
 
     for (i = 0; i < N_SIGNERS; i++) {
         unsigned char session_id[32];
+
         /* Create random session ID. It is absolutely necessary that the session ID
          * is unique for every call of secp256k1_frost_nonce_gen. Otherwise
          * it's trivial for an attacker to extract the secret key! */
@@ -181,14 +120,14 @@ int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, st
         }
         /* Initialize session and create secret nonce for signing and public
          * nonce to send to the other signers. */
-        if (!secp256k1_frost_nonce_gen(ctx, &signer_secrets[i].secnonce, &signer[i].pubnonce, session_id, &signer_secrets[i].agg_share, msg32, agg_pk, NULL)) {
+        if (!secp256k1_frost_nonce_gen(ctx, &signer_secrets[i].secnonce, &signer[i].pubnonce, session_id, &signer_secrets[i].share, msg32, pk, NULL)) {
             return 0;
         }
         is_signer[i] = 0; /* Initialize is_signer */
     }
     /* Select a random subset of signers */
     for (i = 0; i < THRESHOLD; i++) {
-        unsigned int subset_seed;
+        size_t subset_seed;
 
         while (1) {
             if (!fill_random((unsigned char*)&subset_seed, sizeof(subset_seed))) {
@@ -205,19 +144,19 @@ int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, st
         /* Mark signer as assigned */
         pubnonces[i] = &signer[signer_id].pubnonce;
         /* pubkeys[i] = &signer[signer_id].pubkey; */
-        ids[i] = signer[signer_id].id;
+        ids[i] = signer_id + 1;
     }
     /* Signing communication round 1: Exchange nonces */
     for (i = 0; i < THRESHOLD; i++) {
         signer_id = signers[i];
-        if (!secp256k1_frost_nonce_process(ctx, &signer[signer_id].session, pubnonces, THRESHOLD, msg32, agg_pk, signer[signer_id].id, ids, cache, NULL)) {
+        if (!secp256k1_frost_nonce_process(ctx, &signer[signer_id].session, pubnonces, THRESHOLD, msg32, pk, signer_id + 1, ids, cache, NULL)) {
             return 0;
         }
         /* partial_sign will clear the secnonce by setting it to 0. That's because
          * you must _never_ reuse the secnonce (or use the same session_id to
          * create a secnonce). If you do, you effectively reuse the nonce and
          * leak the secret key. */
-        if (!secp256k1_frost_partial_sign(ctx, &signer[signer_id].partial_sig, &signer_secrets[signer_id].secnonce, &signer_secrets[signer_id].agg_share, &signer[signer_id].session, cache)) {
+        if (!secp256k1_frost_partial_sign(ctx, &signer[signer_id].partial_sig, &signer_secrets[signer_id].secnonce, &signer_secrets[signer_id].share, &signer[signer_id].session, cache)) {
             return 0;
         }
         partial_sigs[i] = &signer[signer_id].partial_sig;
@@ -246,45 +185,36 @@ int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, st
 
 int main(void) {
     secp256k1_context* ctx;
-    int i;
     struct signer_secrets signer_secrets[N_SIGNERS];
     struct signer signers[N_SIGNERS];
-    secp256k1_xonly_pubkey agg_pk;
+    secp256k1_xonly_pubkey pk;
     secp256k1_frost_tweak_cache cache;
     unsigned char msg[32] = "this_could_be_the_hash_of_a_msg!";
     unsigned char sig[64];
 
     /* Create a context for signing and verification */
     ctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
-    printf("Creating key pairs......");
-    for (i = 0; i < N_SIGNERS; i++) {
-        if (!create_keypair_and_seed(ctx, &signer_secrets[i], &signers[i])) {
-            printf("FAILED\n");
-            return 1;
-        }
-    }
-    printf("ok\n");
     printf("Creating shares.........");
-    if (!create_shares(ctx, signer_secrets, signers, &agg_pk)) {
+    if (!create_shares(ctx, signer_secrets, signers, &pk)) {
         printf("FAILED\n");
         return 1;
     }
     printf("ok\n");
     printf("Tweaking................");
-    /* Optionally tweak the aggregate key */
-    if (!tweak(ctx, &agg_pk, &cache)) {
+    /* Optionally tweak the key */
+    if (!tweak(ctx, &pk, &cache)) {
         printf("FAILED\n");
         return 1;
     }
     printf("ok\n");
     printf("Signing message.........");
-    if (!sign(ctx, signer_secrets, signers, msg, &agg_pk, sig, &cache)) {
+    if (!sign(ctx, signer_secrets, signers, msg, &pk, sig, &cache)) {
         printf("FAILED\n");
         return 1;
     }
     printf("ok\n");
     printf("Verifying signature.....");
-    if (!secp256k1_schnorrsig_verify(ctx, sig, msg, 32, &agg_pk)) {
+    if (!secp256k1_schnorrsig_verify(ctx, sig, msg, 32, &pk)) {
         printf("FAILED\n");
         return 1;
     }

include/secp256k1_frost.h

@@ -9,13 +9,14 @@ extern "C" {
 
 #include <stdint.h>
 
-/** This code is currently a work in progress. It's not secure nor stable.
- * IT IS EXTREMELY DANGEROUS AND RECKLESS TO USE THIS MODULE IN PRODUCTION!
- *
+/** This code is currently a work in progress. It's not secure nor stable.  IT
+ * IS EXTREMELY DANGEROUS AND RECKLESS TO USE THIS MODULE IN PRODUCTION!
+
  * This module implements a variant of Flexible Round-Optimized Schnorr
  * Threshold Signatures (FROST) by Chelsea Komlo and Ian Goldberg
  * (https://crysp.uwaterloo.ca/software/frost/). Signatures are compatible with
- * BIP-340 ("Schnorr").
+ * BIP-340 ("Schnorr"). There's an example C source file in the module's
+ * directory (examples/frost.c) that demonstrates how it can be used.
  *
  * The module also supports BIP-341 ("Taproot") and BIP-32 ("ordinary") public
  * key tweaking, and adaptor signatures.
@@ -182,14 +183,12 @@ SECP256K1_API int secp256k1_frost_share_parse(
 
 /** Creates key shares
  *
- *  To generate a key, each participant generates a share for each other
- *  participant. For example, in the case of 2 particpants, Alice and Bob, they
- *  each generate 2 shares, distribute 1 share to each other using a secure
- *  channel, and keep 1 for themselves.
- *
- *  Each participant must transmit shares over secure channels to each other
+ *  To generate a key, a trusted dealer generates a share for each other
  *  participant.
  *
+ *  The trusted dealer must transmit shares over secure channels to
+ *  participants.
+ *
  *  Each call to this function must have a UNIQUE and uniformly RANDOM seed32
  *  that must that must NOT BE REUSED in subsequent calls to this function and
  *  must be KEPT SECRET (even from other participants).
@@ -197,109 +196,25 @@ SECP256K1_API int secp256k1_frost_share_parse(
  *  Returns: 0 if the arguments are invalid, 1 otherwise
  *  Args:            ctx: pointer to a context object
  *  Out:          shares: pointer to the key shares
- *        vss_commitment: pointer to the VSS commitment
- *                 pok64: pointer to the proof of knowledge
- *   In:          seed32: 32-byte random seed as explained above. Must be
- *                        unique to this call to secp256k1_frost_shares_gen
- *                        and must be uniformly random.
+ *             pubshares: pointer to the public verification shares
+ *                    pk: pointer to the x-only public key
+ *   In:          seed32: a 32-byte random seed as explained above. Must be
+ *                        unique to this call to
+ *                        secp256k1_frost_shares_trusted_gen and must be
+ *                        uniformly random.
  *             threshold: the minimum number of signers required to produce a
  *                        signature
  *        n_participants: the total number of participants
- *                 ids33: array of 33-byte participant IDs
  */
-SECP256K1_API int secp256k1_frost_shares_gen(
+SECP256K1_API int secp256k1_frost_shares_trusted_gen(
     const secp256k1_context *ctx,
     secp256k1_frost_share *shares,
-    secp256k1_pubkey *vss_commitment,
-    unsigned char *pok64,
+    secp256k1_pubkey *pubshares,
+    secp256k1_xonly_pubkey *pk,
     const unsigned char *seed32,
     size_t threshold,
-    size_t n_participants,
-    const unsigned char * const* ids33
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(8);
-
-/** Aggregates shares
- *
- *  As part of the key generation protocol, each participant receives a share
- *  from each participant, including a share they "receive" from themselves.
- *  This function verifies those shares against their VSS commitments,
- *  aggregates the shares, and then aggregates the commitments to each
- *  participant's first polynomial coefficient to derive the aggregate public
- *  key.
- *
- *  If this function returns an error, `secp256k1_frost_share_verify` can be
- *  called on each share to determine which participants submitted faulty
- *  shares.
- *
- *  Returns: 0 if the arguments are invalid, 1 otherwise (which does NOT mean
- *           the resulting signature verifies).
- *  Args:         ctx: pointer to a context object
- *  Out:    agg_share: the aggregated share
- *             agg_pk: the aggregated x-only public key
- *  In:        shares: all key generation shares for the partcipant's index
- *    vss_commitments: coefficient commitments of all participants ordered by
- *                     the x-only pubkeys of the participants
- *           n_shares: the total number of shares
- *          threshold: the minimum number of shares required to produce a
- *                     signature
- *               id33: the 33-byte ID of the participant whose shares are being
- *                     aggregated
- */
-SECP256K1_API int secp256k1_frost_share_agg(
-    const secp256k1_context *ctx,
-    secp256k1_frost_share *agg_share,
-    secp256k1_xonly_pubkey *agg_pk,
-    const secp256k1_frost_share * const *shares,
-    const secp256k1_pubkey * const *vss_commitments,
-    size_t n_shares,
-    size_t threshold,
-    const unsigned char *id33
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(8);
-
-/** Verifies a share received during a key generation session
- *
- *  The signature is verified against the VSS commitment received with the
- *  share. This is only useful for purposes of determining which share(s) are
- *  invalid if share_agg returns an error.
- *
- *  Returns: 0 if the arguments are invalid or the share does not verify, 1
- *           otherwise
- *  Args         ctx: pointer to a context object
- *  In:    threshold: the minimum number of signers required to produce a
- *                    signature
- *              id33: the 33-byte participant ID of the share recipient
- *             share: pointer to a key generation share
- *    vss_commitment: the VSS commitment associated with the share
- */
-SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_share_verify(
-    const secp256k1_context *ctx,
-    size_t threshold,
-    const unsigned char *id33,
-    const secp256k1_frost_share *share,
-    const secp256k1_pubkey * const *vss_commitment
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
-
-/** Computes a public verification share used for verifying partial signatures
- *
- *  Returns: 0 if the arguments are invalid, 1 otherwise
- *  Args:        ctx: pointer to a context object
- *  In:     pubshare: pointer to a struct to store the public verification
- *                    share
- *         threshold: the minimum number of signers required to produce a
- *                    signature
- *              id33: the 33-byte participant ID of the participant whose
- *                    partial signature will be verified with the pubshare
- *   vss_commitments: coefficient commitments of all participants
- *    n_participants: the total number of participants
- */
-SECP256K1_API int secp256k1_frost_compute_pubshare(
-    const secp256k1_context *ctx,
-    secp256k1_pubkey *pubshare,
-    size_t threshold,
-    const unsigned char *id33,
-    const secp256k1_pubkey * const *vss_commitments,
     size_t n_participants
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
 
 /** Obtain the aggregate public key from a FROST x-only aggregate public key.
  *
@@ -311,7 +226,7 @@ SECP256K1_API int secp256k1_frost_compute_pubshare(
  *  Args:        ctx: pointer to a context object
  *  Out:   ec_agg_pk: the FROST-aggregated public key.
  *  In: xonly_agg_pk: the aggregated x-only public key that is the output of
- *                    `secp256k1_frost_share_agg`
+ *                    `secp256k1_frost_shares_gen`
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_get(
     const secp256k1_context *ctx,
@@ -326,7 +241,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_get(
  *  Out: tweak_cache: pointer to a frost_tweak_cache struct that is required
  *                    for key tweaking
  *  In:       agg_pk: the aggregated x-only public key that is the output of
- *                    `secp256k1_frost_share_agg`
+ *                    `secp256k1_frost_shares_gen`
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_tweak(
     const secp256k1_context *ctx,
@@ -342,7 +257,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_tweak(
  *  the following pseudocode buf and buf2 have identical contents (absent
  *  earlier failures).
  *
- *  secp256k1_frost_share_agg(..., xonly_agg_pk, ...)
+ *  secp256k1_frost_shares_gen(..., xonly_agg_pk, ...)
  *  secp256k1_frost_pubkey_tweak(..., tweak_cache, xonly_agg_pk)
  *  secp256k1_frost_pubkey_ec_tweak_add(..., output_pk, tweak_cache, tweak32)
  *  secp256k1_ec_pubkey_serialize(..., buf, output_pk)
@@ -385,7 +300,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_ec_tweak_a
  *  the following pseudocode xonly_pubkey_tweak_add_check (absent earlier
  *  failures) returns 1.
  *
- *  secp256k1_frost_share_agg(..., agg_pk, ...)
+ *  secp256k1_frost_shares_gen(..., agg_pk, ...)
  *  secp256k1_frost_pubkey_tweak(..., tweak_cache, agg_pk)
  *  secp256k1_frost_pubkey_xonly_tweak_add(..., output_pk, tweak_cache, tweak32)
  *  secp256k1_xonly_pubkey_serialize(..., buf, output_pk)
@@ -486,9 +401,9 @@ SECP256K1_API int secp256k1_frost_nonce_gen(
  *                      greater than 0.
  *               msg32: the 32-byte message to sign
  *              agg_pk: the FROST-aggregated public key
- *            myd_id33: the 33-byte ID of the participant who will use the
- *                      session for signing
- *               ids33: array of the 33-byte participant IDs of the signers
+ *               my_id: the ID of the participant who will use the session for
+ *                      signing
+*                  ids: array of the IDs of the signers
  *         tweak_cache: pointer to frost_tweak_cache struct (can be NULL)
  *             adaptor: optional pointer to an adaptor point encoded as a
  *                      public key if this signing session is part of an
@@ -501,11 +416,11 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_nonce_process(
     size_t n_pubnonces,
     const unsigned char *msg32,
     const secp256k1_xonly_pubkey *agg_pk,
-    const unsigned char *my_id33,
-    const unsigned char * const* ids33,
+    size_t my_id,
+    const size_t *ids,
     const secp256k1_frost_tweak_cache *tweak_cache,
     const secp256k1_pubkey *adaptor
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(6) SECP256K1_ARG_NONNULL(7) SECP256K1_ARG_NONNULL(8);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(6) SECP256K1_ARG_NONNULL(8);
 
 /** Produces a partial signature
  *

src/ctime_tests.c

@@ -47,6 +47,10 @@
 #include "../include/secp256k1_musig.h"
 #endif
 
+#ifdef ENABLE_MODULE_FROST
+#include "include/secp256k1_frost.h"
+#endif
+
 static void run_tests(secp256k1_context *ctx, unsigned char *key);
 
 int main(void) {
@@ -349,4 +353,79 @@ static void run_tests(secp256k1_context *ctx, unsigned char *key) {
         CHECK(ret == 1);
     }
 #endif
+
+#ifdef ENABLE_MODULE_FROST
+    {
+        secp256k1_xonly_pubkey pk;
+        unsigned char session_id[32];
+        secp256k1_frost_secnonce secnonce[2];
+        secp256k1_frost_pubnonce pubnonce[2];
+        const secp256k1_frost_pubnonce *pubnonce_ptr[2];
+        secp256k1_frost_tweak_cache cache;
+        secp256k1_frost_session session;
+        secp256k1_frost_partial_sig partial_sig;
+        const secp256k1_frost_partial_sig *partial_sig_ptr[1];
+        unsigned char extra_input[32];
+        unsigned char sec_adaptor[32];
+        secp256k1_pubkey adaptor;
+        unsigned char pre_sig[64];
+        int nonce_parity;
+        secp256k1_frost_share shares[2];
+        secp256k1_pubkey pubshares[2];
+        size_t ids[2];
+
+        pubnonce_ptr[0] = &pubnonce[0];
+        pubnonce_ptr[1] = &pubnonce[1];
+        SECP256K1_CHECKMEM_DEFINE(key, 32);
+        memcpy(extra_input, key, sizeof(extra_input));
+        extra_input[0] = extra_input[0] + 1;
+        memcpy(sec_adaptor, key, sizeof(sec_adaptor));
+        sec_adaptor[0] = extra_input[0] + 2;
+        memcpy(session_id, key, sizeof(session_id));
+        session_id[0] = session_id[0] + 3;
+        partial_sig_ptr[0] = &partial_sig;
+        ids[0] = 1;
+        ids[1] = 2;
+
+        /* shares_gen */
+        SECP256K1_CHECKMEM_UNDEFINE(key, 32);
+        ret = secp256k1_frost_shares_trusted_gen(ctx, shares, pubshares, &pk, key, 2, 2);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+        SECP256K1_CHECKMEM_UNDEFINE(&shares[0], sizeof(shares[0]));
+        SECP256K1_CHECKMEM_UNDEFINE(&shares[1], sizeof(shares[1]));
+        /* nonce_gen */
+        SECP256K1_CHECKMEM_UNDEFINE(session_id, sizeof(session_id));
+        CHECK(secp256k1_ec_pubkey_create(ctx, &adaptor, sec_adaptor));
+        SECP256K1_CHECKMEM_UNDEFINE(extra_input, sizeof(extra_input));
+        SECP256K1_CHECKMEM_UNDEFINE(sec_adaptor, sizeof(sec_adaptor));
+        CHECK(secp256k1_frost_pubkey_tweak(ctx, &cache, &pk) == 1);
+        ret = secp256k1_frost_nonce_gen(ctx, &secnonce[0], &pubnonce[0], session_id, &shares[0], msg, &pk, extra_input);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+        ret = secp256k1_frost_nonce_gen(ctx, &secnonce[1], &pubnonce[1], session_id, &shares[1], msg, &pk, extra_input);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+        /* partial_sign */
+        CHECK(secp256k1_frost_nonce_process(ctx, &session, pubnonce_ptr, 2, msg, &pk, 1, ids, &cache, &adaptor) == 1);
+        ret = secp256k1_keypair_create(ctx, &keypair, key);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+        ret = secp256k1_frost_partial_sign(ctx, &partial_sig, &secnonce[0], &shares[0], &session, &cache);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+        /* adapt */
+        SECP256K1_CHECKMEM_DEFINE(&partial_sig, sizeof(partial_sig));
+        CHECK(secp256k1_frost_partial_sig_agg(ctx, pre_sig, &session, partial_sig_ptr, 1));
+        SECP256K1_CHECKMEM_DEFINE(pre_sig, sizeof(pre_sig));
+        CHECK(secp256k1_frost_nonce_parity(ctx, &nonce_parity, &session));
+        ret = secp256k1_frost_adapt(ctx, sig, pre_sig, sec_adaptor, nonce_parity);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+        /* extract_adaptor */
+        ret = secp256k1_frost_extract_adaptor(ctx, sec_adaptor, sig, pre_sig, nonce_parity);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+    }
+#endif
 }

src/modules/frost/Makefile.am.include

@@ -5,3 +5,4 @@ noinst_HEADERS += src/modules/frost/keygen_impl.h
 noinst_HEADERS += src/modules/frost/session.h
 noinst_HEADERS += src/modules/frost/session_impl.h
 noinst_HEADERS += src/modules/frost/adaptor_impl.h
+noinst_HEADERS += src/modules/frost/tests_impl.h

src/modules/frost/adaptor_impl.h

@@ -1,5 +1,5 @@
 /***********************************************************************
- * Copyright (c) 2022-2024 Jesse Posner                                *
+ * Copyright (c) 2022-2023 Jesse Posner                                *
  * Distributed under the MIT software license, see the accompanying    *
  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
  ***********************************************************************/

src/modules/frost/frost.md

@@ -0,0 +1,78 @@
+Notes on the frost module API
+===========================
+
+The following sections contain additional notes on the API of the frost module
+(`include/secp256k1_frost.h`). A usage example can be found in
+`examples/frost.c`.
+
+# API misuse
+
+Users of the frost module must take great care to make sure of the following:
+
+1. The dealer establishes a secure communications channel with each participant
+   and uses that channel to transmit shares during key generation.
+2. A unique set of coefficients per key generation session is generated in
+   `secp256k1_frost_share_gen`. See the corresponding comment in
+   `include/secp256k1_frost.h` for how to ensure that.
+3. The `pubnonces` provided to `secp256k1_frost_nonce_process` are sorted by
+   the corresponding lexicographic ordering of the x-only pubkey of each
+   participant, and the `pubkeys` provided to `secp256k1_frost_nonce_process`
+   are sorted lexicographically.
+4. A unique nonce per signing session is generated in
+   `secp256k1_frost_nonce_gen`. See the corresponding comment in
+   `include/secp256k1_frost.h` for how to ensure that.
+5. The `secp256k1_frost_secnonce` structure is never copied or serialized. See
+   also the comment on `secp256k1_frost_secnonce` in
+   `include/secp256k1_frost.h`.
+6. Opaque data structures are never written to or read from directly. Instead,
+   only the provided accessor functions are used.
+7. If adaptor signatures are used, all partial signatures are verified.
+
+# Key Generation
+
+1. A trusted dealer generates shares with `secp256k1_frost_shares_trusted_gen`
+   and distributes a share and the public key to each participant using a
+   secure channel.
+
+# Tweaking
+
+A (Taproot) tweak can be added to the resulting public key with
+`secp256k1_xonly_pubkey_tweak_add`, after converting it to an xonly pubkey if
+necessary with `secp256k1_xonly_pubkey_from_pubkey`.
+
+An ordinary tweak can be added to the resulting public key with
+`secp256k1_ec_pubkey_tweak_add`, after converting it to an ordinary pubkey if
+necessary with `secp256k1_frost_pubkey_get`.
+
+Tweaks can also be chained together by tweaking an already tweaked key.
+
+# Signing
+
+1. Optionally add a tweak by calling `secp256k1_frost_pubkey_tweak` and then
+   `secp256k1_frost_pubkey_xonly_tweak_add` for a Taproot tweak and
+   `secp256k1_frost_pubkey_ec_tweak_add` for an ordinary tweak.
+2. Generate a pair of secret and public nonce with `secp256k1_frost_nonce_gen`
+   and send the public nonce to the other signers.
+3. Process the aggregate nonce with `secp256k1_frost_nonce_process`.
+4. Create a partial signature with `secp256k1_frost_partial_sign`.
+5. Verify the partial signatures (optional in some scenarios) with
+   `secp256k1_frost_partial_sig_verify`.
+6. Someone (not necessarily the signer) obtains all partial signatures and
+   aggregates them into the final Schnorr signature using
+   `secp256k1_frost_partial_sig_agg`.
+
+The aggregate signature can be verified with `secp256k1_schnorrsig_verify`.
+
+Note that steps 1 to 3 can happen before the message to be signed is known to
+the signers. Therefore, the communication round to exchange nonces can be
+viewed as a pre-processing step that is run whenever convenient to the signers.
+This disables some of the defense-in-depth measures that may protect against
+API misuse in some cases. Similarly, the API supports an alternative protocol
+flow where generating the key (see Key Generation above) is allowed to happen
+after exchanging nonces (step 2).
+
+# Verification
+
+A participant who wants to verify the partial signatures, but does not sign
+itself may do so using the above instructions except that the verifier skips
+steps 2 and 4.

src/modules/frost/keygen.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2024 Jesse Posner                               *
+ * Copyright (c) 2021-2023 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/

src/modules/frost/keygen_impl.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2024 Jesse Posner                               *
+ * Copyright (c) 2021-2023 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/
@@ -53,24 +53,6 @@ static int secp256k1_tweak_cache_load(const secp256k1_context* ctx, secp256k1_tw
     return 1;
 }
 
-/* Computes indexhash = tagged_hash(pk) */
-static int secp256k1_frost_compute_indexhash(secp256k1_scalar *indexhash, const unsigned char *id33) {
-    secp256k1_sha256 sha;
-    unsigned char buf[32];
-
-    secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/index", sizeof("FROST/index") - 1);
-    secp256k1_sha256_write(&sha, id33, 33);
-    secp256k1_sha256_finalize(&sha, buf);
-    secp256k1_scalar_set_b32(indexhash, buf, NULL);
-    /* The x-coordinate must not be zero (see
-     * draft-irtf-cfrg-frost-08#section-4.2.2) */
-    if (secp256k1_scalar_is_zero(indexhash)) {
-        return 0;
-    }
-
-    return 1;
-}
-
 static const unsigned char secp256k1_frost_share_magic[4] = { 0xa1, 0x6a, 0x42, 0x03 };
 
 static void secp256k1_frost_share_save(secp256k1_frost_share* share, secp256k1_scalar *s) {
@@ -81,6 +63,8 @@ static void secp256k1_frost_share_save(secp256k1_frost_share* share, secp256k1_s
 static int secp256k1_frost_share_load(const secp256k1_context* ctx, secp256k1_scalar *s, const secp256k1_frost_share* share) {
     int overflow;
 
+    /* The magic is non-secret so it can be declassified to allow branching. */
+    secp256k1_declassify(ctx, &share->data[0], 4);
     ARG_CHECK(secp256k1_memcmp_var(&share->data[0], secp256k1_frost_share_magic, 4) == 0);
     secp256k1_scalar_set_b32(s, &share->data[4], &overflow);
     /* Parsed shares cannot overflow */
@@ -111,82 +95,14 @@ int secp256k1_frost_share_parse(const secp256k1_context* ctx, secp256k1_frost_sh
     return 1;
 }
 
-static void secp256k1_frost_derive_coeff(secp256k1_scalar *coeff, const unsigned char *polygen32, size_t i) {
+int secp256k1_frost_shares_trusted_gen(const secp256k1_context *ctx, secp256k1_frost_share *shares, secp256k1_pubkey *pubshares, secp256k1_xonly_pubkey *pk, const unsigned char *seed32, size_t threshold, size_t n_participants) {
     secp256k1_sha256 sha;
-    unsigned char buf[32];
-
-    secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/coeffgen", sizeof("FROST/coeffgen") - 1);
-    secp256k1_sha256_write(&sha, polygen32, 32);
-    secp256k1_write_be64(&buf[0], i);
-    secp256k1_sha256_write(&sha, buf, 8);
-    secp256k1_sha256_finalize(&sha, buf);
-    secp256k1_scalar_set_b32(coeff, buf, NULL);
-}
-
-static int secp256k1_frost_vss_gen(const secp256k1_context *ctx, secp256k1_pubkey *vss_commitment, unsigned char *pok64, const unsigned char *polygen32, size_t threshold) {
-    secp256k1_sha256 sha;
-    unsigned char buf[32];
-    secp256k1_keypair keypair;
     secp256k1_gej rj;
     secp256k1_ge rp;
-    size_t i;
-    int ret = 1;
-
-    for (i = 0; i < threshold; i++) {
-        secp256k1_scalar coeff_i;
-
-        secp256k1_frost_derive_coeff(&coeff_i, polygen32, i);
-        /* Compute proof-of-knowledge for constant term */
-        if (i == threshold - 1) {
-            secp256k1_scalar_get_b32(buf, &coeff_i);
-            ret &= secp256k1_keypair_create(ctx, &keypair, buf);
-
-            secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/KeygenPoK", sizeof("FROST/KeygenPoK") - 1);
-            secp256k1_sha256_finalize(&sha, buf);
-
-            ret &= secp256k1_schnorrsig_sign32(ctx, pok64, buf, &keypair, NULL);
-        }
-
-        /* Compute commitment to each coefficient */
-        secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &rj, &coeff_i);
-        secp256k1_ge_set_gej(&rp, &rj);
-        secp256k1_pubkey_save(&vss_commitment[threshold - i - 1], &rp);
-    }
-    return ret;
-}
-
-static int secp256k1_frost_share_gen(secp256k1_frost_share *share, const unsigned char *polygen32, size_t threshold, const unsigned char *id33) {
-    secp256k1_scalar idx;
-    secp256k1_scalar share_i;
-    size_t i;
-    int ret = 1;
-
-    /* Derive share */
-    /* See draft-irtf-cfrg-frost-08#appendix-C.1 */
-    secp256k1_scalar_set_int(&share_i, 0);
-    if (!secp256k1_frost_compute_indexhash(&idx, id33)) {
-        return 0;
-    }
-    for (i = 0; i < threshold; i++) {
-        secp256k1_scalar coeff_i;
-
-        secp256k1_frost_derive_coeff(&coeff_i, polygen32, i);
-        /* Horner's method to evaluate polynomial to derive shares */
-        secp256k1_scalar_add(&share_i, &share_i, &coeff_i);
-        if (i < threshold - 1) {
-            secp256k1_scalar_mul(&share_i, &share_i, &idx);
-        }
-    }
-    secp256k1_frost_share_save(share, &share_i);
-
-    return ret;
-}
-
-int secp256k1_frost_shares_gen(const secp256k1_context *ctx, secp256k1_frost_share *shares, secp256k1_pubkey *vss_commitment, unsigned char *pok64, const unsigned char *seed32, size_t threshold, size_t n_participants, const unsigned char * const* ids33) {
-    secp256k1_sha256 sha;
     unsigned char polygen[32];
-    size_t i;
+    size_t i, j;
     int ret = 1;
+    int pk_parity = 0;
 
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
@@ -194,254 +110,69 @@ int secp256k1_frost_shares_gen(const secp256k1_context *ctx, secp256k1_frost_sha
     for (i = 0; i < n_participants; i++) {
         memset(&shares[i], 0, sizeof(shares[i]));
     }
-    ARG_CHECK(vss_commitment != NULL);
-    ARG_CHECK(pok64 != NULL);
+    ARG_CHECK(pubshares != NULL);
+    ARG_CHECK(pk != NULL);
     ARG_CHECK(seed32 != NULL);
-    ARG_CHECK(ids33 != NULL);
     ARG_CHECK(threshold > 1);
     ARG_CHECK(n_participants >= threshold);
 
-    /* Commit to all inputs */
-    secp256k1_sha256_initialize(&sha);
+    /* Commit to threshold, n_participants, and seed */
+    secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/trusted-shares-polygen", sizeof("FROST/trusted-shares-polygen") - 1);
     secp256k1_sha256_write(&sha, seed32, 32);
     secp256k1_write_be64(&polygen[0], threshold);
     secp256k1_write_be64(&polygen[8], n_participants);
     secp256k1_sha256_write(&sha, polygen, 16);
-    for (i = 0; i < n_participants; i++) {
-        secp256k1_sha256_write(&sha, ids33[i], 33);
-    }
     secp256k1_sha256_finalize(&sha, polygen);
 
-    ret &= secp256k1_frost_vss_gen(ctx, vss_commitment, pok64, polygen, threshold);
-
+    /* Derive shares */
+    /* See draft-irtf-cfrg-frost-08#appendix-C.1 */
     for (i = 0; i < n_participants; i++) {
-        ret &= secp256k1_frost_share_gen(&shares[i], polygen, threshold, ids33[i]);
-    }
+        secp256k1_scalar share_i, idx;
 
-    return ret;
-}
+        secp256k1_scalar_set_int(&share_i, 0);
 
-typedef struct {
-    const secp256k1_context *ctx;
-    secp256k1_scalar idx;
-    secp256k1_scalar idxn;
-    const secp256k1_pubkey * const* vss_commitment;
-} secp256k1_frost_verify_share_ecmult_data;
+        for (j = 0; j < threshold; j++) {
+            unsigned char buf[32];
+            secp256k1_scalar coeff_i;
 
-typedef struct {
-    const secp256k1_context *ctx;
-    secp256k1_scalar idx;
-    secp256k1_scalar idxn;
-    const secp256k1_pubkey * const* vss_commitments;
-    size_t threshold;
-} secp256k1_frost_compute_pubshare_ecmult_data;
+            secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/trusted-shares-coeffgen", sizeof("FROST/trusted-shares-coeffgen") - 1);
+            secp256k1_sha256_write(&sha, polygen, 32);
+            secp256k1_write_be64(&buf[0], j);
+            secp256k1_sha256_write(&sha, buf, 8);
+            secp256k1_sha256_finalize(&sha, buf);
+            secp256k1_scalar_set_b32(&coeff_i, buf, NULL);
 
-typedef struct {
-    const secp256k1_context *ctx;
-    const secp256k1_pubkey * const* pks;
-    size_t threshold;
-} secp256k1_frost_pubkey_combine_ecmult_data;
+            /* Horner's method to evaluate polynomial to derive shares */
+            secp256k1_scalar_add(&share_i, &share_i, &coeff_i);
+            if (j < threshold - 1) {
+                secp256k1_scalar_set_int(&idx, i + 1);
+                secp256k1_scalar_mul(&share_i, &share_i, &idx);
+            }
 
-static int secp256k1_frost_verify_share_ecmult_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data) {
-    secp256k1_frost_verify_share_ecmult_data *ctx = (secp256k1_frost_verify_share_ecmult_data *) data;
-    if (!secp256k1_pubkey_load(ctx->ctx, pt, *(ctx->vss_commitment)+idx)) {
-        return 0;
-    }
-    *sc = ctx->idxn;
-    secp256k1_scalar_mul(&ctx->idxn, &ctx->idxn, &ctx->idx);
-
-    return 1;
-}
-
-static int secp256k1_frost_compute_pubshare_ecmult_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data) {
-    secp256k1_frost_compute_pubshare_ecmult_data *ctx = (secp256k1_frost_compute_pubshare_ecmult_data *) data;
-
-    if (!secp256k1_pubkey_load(ctx->ctx, pt, &ctx->vss_commitments[idx/ctx->threshold][idx % ctx->threshold])) {
-        return 0;
-    }
-    if (idx != 0 && idx % ctx->threshold == 0) {
-        secp256k1_scalar_set_int(&ctx->idxn, 1);
-    }
-    *sc = ctx->idxn;
-    secp256k1_scalar_mul(&ctx->idxn, &ctx->idxn, &ctx->idx);
-
-    return 1;
-}
-
-static int secp256k1_frost_pubkey_combine_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data) {
-    secp256k1_frost_pubkey_combine_ecmult_data *ctx = (secp256k1_frost_pubkey_combine_ecmult_data *) data;
-
-    secp256k1_scalar_set_int(sc, 1);
-    /* the public key is the first index of each set of coefficients */
-    return secp256k1_pubkey_load(ctx->ctx, pt, &ctx->pks[idx][0]);
-}
-
-/* See draft-irtf-cfrg-frost-08#appendix-C.2 */
-static int secp256k1_frost_vss_verify_internal(const secp256k1_context* ctx, size_t threshold, const unsigned char *id33, const secp256k1_scalar *share, const secp256k1_pubkey * const* vss_commitment) {
-    secp256k1_scalar share_neg;
-    secp256k1_gej tmpj, snj;
-    secp256k1_ge sng;
-    secp256k1_frost_verify_share_ecmult_data verify_share_ecmult_data;
-
-    ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
-
-    /* Use an EC multi-multiplication to verify the following equation:
-     *   0 = - share_i*G + idx^0*vss_commitment[0]
-     *                   + ...
-     *                   + idx^(threshold - 1)*vss_commitment[threshold - 1]*/
-    verify_share_ecmult_data.ctx = ctx;
-    verify_share_ecmult_data.vss_commitment = vss_commitment;
-    /* Evaluate the public polynomial at the idx */
-    if (!secp256k1_frost_compute_indexhash(&verify_share_ecmult_data.idx, id33)) {
-        return 0;
-    }
-    secp256k1_scalar_set_int(&verify_share_ecmult_data.idxn, 1);
-    /* TODO: add scratch */
-    if (!secp256k1_ecmult_multi_var(&ctx->error_callback, NULL, &tmpj, NULL, secp256k1_frost_verify_share_ecmult_callback, (void *) &verify_share_ecmult_data, threshold)) {
-        return 0;
-    }
-    secp256k1_scalar_negate(&share_neg, share);
-    secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &snj, &share_neg);
-    secp256k1_ge_set_gej(&sng, &snj);
-    secp256k1_gej_add_ge(&tmpj, &tmpj, &sng);
-    return secp256k1_gej_is_infinity(&tmpj);
-}
-
-/* See draft-irtf-cfrg-frost-08#appendix-C.2 */
-int secp256k1_frost_share_verify(const secp256k1_context* ctx, size_t threshold, const unsigned char *id33, const secp256k1_frost_share *share, const secp256k1_pubkey * const* vss_commitment) {
-    secp256k1_scalar share_i;
-
-    VERIFY_CHECK(ctx != NULL);
-    ARG_CHECK(id33 != NULL);
-    ARG_CHECK(share != NULL);
-    ARG_CHECK(vss_commitment != NULL);
-    ARG_CHECK(threshold > 1);
-
-    if (!secp256k1_frost_share_load(ctx, &share_i, share)) {
-        return 0;
-    }
-
-    return secp256k1_frost_vss_verify_internal(ctx, threshold, id33, &share_i, vss_commitment);
-}
-
-int secp256k1_frost_compute_pubshare(const secp256k1_context* ctx, secp256k1_pubkey *pubshare, size_t threshold, const unsigned char *id33, const secp256k1_pubkey * const* vss_commitments, size_t n_participants) {
-    secp256k1_gej pkj;
-    secp256k1_ge pkp, tmp;
-    secp256k1_frost_compute_pubshare_ecmult_data compute_pubshare_ecmult_data;
-    secp256k1_frost_pubkey_combine_ecmult_data pubkey_combine_ecmult_data;
-
-    VERIFY_CHECK(ctx != NULL);
-    ARG_CHECK(pubshare != NULL);
-    memset(pubshare, 0, sizeof(*pubshare));
-    ARG_CHECK(id33 != NULL);
-    ARG_CHECK(vss_commitments != NULL);
-    ARG_CHECK(n_participants > 1);
-    ARG_CHECK(threshold > 1);
-
-    if (threshold > n_participants) {
-        return 0;
-    }
-
-    /* Use an EC multi-multiplication to compute the following equation:
-     *   agg_share_i*G = (
-     *      idx^0*vss_commitment[0][0] + ...
-     *                                 + idx^(t - 1)*vss_commitment[0][t - 1]
-     *   )                             + ...
-     *                                 + (
-     *      idx^0*vss_commitment[n - 1][0] + ...
-     *                                     + idx^(t - 1)*vss_commitment[n - 1][t - 1]
-     *   )*/
-    compute_pubshare_ecmult_data.ctx = ctx;
-    compute_pubshare_ecmult_data.vss_commitments = vss_commitments;
-    compute_pubshare_ecmult_data.threshold = threshold;
-    /* Evaluate the public polynomial at the idx */
-    if (!secp256k1_frost_compute_indexhash(&compute_pubshare_ecmult_data.idx, id33)) {
-        return 0;
-    }
-    secp256k1_scalar_set_int(&compute_pubshare_ecmult_data.idxn, 1);
-    /* TODO: add scratch */
-    if (!secp256k1_ecmult_multi_var(&ctx->error_callback, NULL, &pkj, NULL, secp256k1_frost_compute_pubshare_ecmult_callback, (void *) &compute_pubshare_ecmult_data, n_participants*threshold)) {
-        return 0;
-    }
-    secp256k1_ge_set_gej(&tmp, &pkj);
-
-    /* Combine pubkeys */
-    pubkey_combine_ecmult_data.ctx = ctx;
-    pubkey_combine_ecmult_data.pks = vss_commitments;
-    pubkey_combine_ecmult_data.threshold = threshold;
-
-    /* TODO: add scratch */
-    if (!secp256k1_ecmult_multi_var(&ctx->error_callback, NULL, &pkj, NULL, secp256k1_frost_pubkey_combine_callback, (void *) &pubkey_combine_ecmult_data, n_participants)) {
-        return 0;
-    }
-    secp256k1_ge_set_gej(&pkp, &pkj);
-    secp256k1_fe_normalize_var(&pkp.y);
-    if (secp256k1_fe_is_odd(&pkp.y)) {
-        secp256k1_ge_neg(&tmp, &tmp);
-    }
-
-    secp256k1_pubkey_save(pubshare, &tmp);
-
-    return 1;
-}
-
-int secp256k1_frost_share_agg(const secp256k1_context* ctx, secp256k1_frost_share *agg_share, secp256k1_xonly_pubkey *agg_pk, const secp256k1_frost_share * const* shares, const secp256k1_pubkey * const* vss_commitments, size_t n_shares, size_t threshold, const unsigned char *id33) {
-    secp256k1_frost_pubkey_combine_ecmult_data pubkey_combine_ecmult_data;
-    secp256k1_gej pkj;
-    secp256k1_ge pkp;
-    int pk_parity;
-    secp256k1_scalar acc;
-    size_t i;
-    int ret = 1;
-
-    VERIFY_CHECK(ctx != NULL);
-    ARG_CHECK(agg_share != NULL);
-    memset(agg_share, 0, sizeof(*agg_share));
-    ARG_CHECK(agg_pk != NULL);
-    memset(agg_pk, 0, sizeof(*agg_pk));
-    ARG_CHECK(shares != NULL);
-    ARG_CHECK(vss_commitments != NULL);
-    ARG_CHECK(id33 != NULL);
-    ARG_CHECK(n_shares > 1);
-    ARG_CHECK(threshold > 1);
-
-    if (threshold > n_shares) {
-        return 0;
-    }
-
-    secp256k1_scalar_clear(&acc);
-    for (i = 0; i < n_shares; i++) {
-        secp256k1_scalar share_i;
-
-        if (!secp256k1_frost_share_load(ctx, &share_i, shares[i])) {
-            return 0;
+            /* Compute x-only public key for constant term */
+            if (i == 0 && j == threshold - 1) {
+                /* Compute commitment to constant term */
+                secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &rj, &coeff_i);
+                secp256k1_ge_set_gej(&rp, &rj);
+                /* The commitment is non-secret so it can be declassified to
+                 * allow branching. */
+                secp256k1_declassify(ctx, &rp, sizeof(rp));
+                secp256k1_fe_normalize_var(&rp.y);
+                pk_parity = secp256k1_extrakeys_ge_even_y(&rp);
+                secp256k1_xonly_pubkey_save(pk, &rp);
+            }
         }
-        /* Verify share against commitments */
-        ret &= secp256k1_frost_vss_verify_internal(ctx, threshold, id33, &share_i, &vss_commitments[i]);
-        secp256k1_scalar_add(&acc, &acc, &share_i);
+
+        if (pk_parity == 1) {
+            secp256k1_scalar_negate(&share_i, &share_i);
+        }
+        secp256k1_frost_share_save(&shares[i], &share_i);
+        /* Compute pubshare */
+        secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &rj, &share_i);
+        secp256k1_ge_set_gej(&rp, &rj);
+        secp256k1_pubkey_save(&pubshares[i], &rp);
     }
 
-    /* Combine pubkeys */
-    pubkey_combine_ecmult_data.ctx = ctx;
-    pubkey_combine_ecmult_data.pks = vss_commitments;
-    pubkey_combine_ecmult_data.threshold = threshold;
-
-    /* TODO: add scratch */
-    if (!secp256k1_ecmult_multi_var(&ctx->error_callback, NULL, &pkj, NULL, secp256k1_frost_pubkey_combine_callback, (void *) &pubkey_combine_ecmult_data, n_shares)) {
-        return 0;
-    }
-
-    secp256k1_ge_set_gej(&pkp, &pkj);
-    secp256k1_fe_normalize_var(&pkp.y);
-    pk_parity = secp256k1_extrakeys_ge_even_y(&pkp);
-    secp256k1_xonly_pubkey_save(agg_pk, &pkp);
-
-    /* Invert the aggregate share if the combined pubkey has an odd Y coordinate. */
-    if (pk_parity == 1) {
-        secp256k1_scalar_negate(&acc, &acc);
-    }
-    secp256k1_frost_share_save(agg_share, &acc);
-
     return ret;
 }
 

src/modules/frost/main_impl.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2024 Jesse Posner                               *
+ * Copyright (c) 2021-2023 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/

src/modules/frost/session.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2024 Jesse Posner                               *
+ * Copyright (c) 2021-2023 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/

src/modules/frost/session_impl.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2024 Jesse Posner                               *
+ * Copyright (c) 2021-2023 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/
@@ -313,7 +313,7 @@ int secp256k1_frost_nonce_gen(const secp256k1_context* ctx, secp256k1_frost_secn
     return ret;
 }
 
-static int secp256k1_frost_sum_nonces(const secp256k1_context* ctx, secp256k1_gej *summed_nonces, const secp256k1_frost_pubnonce * const *pubnonces, size_t n_pubnonces) {
+static int secp256k1_frost_sum_nonces(const secp256k1_context* ctx, secp256k1_gej *summed_nonces, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces) {
     size_t i;
     int j;
 
@@ -334,19 +334,16 @@ static int secp256k1_frost_sum_nonces(const secp256k1_context* ctx, secp256k1_ge
 
 /* TODO: consider updating to frost-08 to address maleability at the cost of performance */
 /* See https://github.com/cfrg/draft-irtf-cfrg-frost/pull/217 */
-static int secp256k1_frost_compute_noncehash(const secp256k1_context* ctx, unsigned char *noncehash, const unsigned char *msg, const secp256k1_frost_pubnonce * const *pubnonces, size_t n_pubnonces, const unsigned char *pk32, const unsigned char * const *ids33) {
+static int secp256k1_frost_compute_noncehash(const secp256k1_context* ctx, unsigned char *noncehash, const unsigned char *msg, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces, const unsigned char *pk32, const size_t *ids) {
     unsigned char buf[66];
     secp256k1_sha256 sha;
     size_t i;
 
     secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/noncecoef", sizeof("FROST/noncecoef") - 1);
-    /* TODO: sort by index */
     for (i = 0; i < n_pubnonces; i++) {
         secp256k1_scalar idx;
 
-        if (!secp256k1_frost_compute_indexhash(&idx, ids33[i])) {
-            return 0;
-        }
+        secp256k1_scalar_set_int(&idx, ids[i]);
         secp256k1_scalar_get_b32(buf, &idx);
         secp256k1_sha256_write(&sha, buf, 32);
         if (!secp256k1_frost_pubnonce_serialize(ctx, buf, pubnonces[i])) {
@@ -360,7 +357,7 @@ static int secp256k1_frost_compute_noncehash(const secp256k1_context* ctx, unsig
     return 1;
 }
 
-static int secp256k1_frost_nonce_process_internal(const secp256k1_context* ctx, int *fin_nonce_parity, unsigned char *fin_nonce, secp256k1_scalar *b, secp256k1_gej *aggnoncej, const unsigned char *msg, const secp256k1_frost_pubnonce * const *pubnonces, size_t n_pubnonces, const unsigned char *pk32, const unsigned char * const *ids33) {
+static int secp256k1_frost_nonce_process_internal(const secp256k1_context* ctx, int *fin_nonce_parity, unsigned char *fin_nonce, secp256k1_scalar *b, secp256k1_gej *aggnoncej, const unsigned char *msg, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces, const unsigned char *pk32, const size_t *ids) {
     unsigned char noncehash[32];
     secp256k1_ge fin_nonce_pt;
     secp256k1_gej fin_nonce_ptj;
@@ -368,7 +365,7 @@ static int secp256k1_frost_nonce_process_internal(const secp256k1_context* ctx,
 
     secp256k1_ge_set_gej(&aggnonce[0], &aggnoncej[0]);
     secp256k1_ge_set_gej(&aggnonce[1], &aggnoncej[1]);
-    if (!secp256k1_frost_compute_noncehash(ctx, noncehash, msg, pubnonces, n_pubnonces, pk32, ids33)) {
+    if (!secp256k1_frost_compute_noncehash(ctx, noncehash, msg, pubnonces, n_pubnonces, pk32, ids)) {
         return 0;
     }
     /* fin_nonce = aggnonce[0] + b*aggnonce[1] */
@@ -389,7 +386,7 @@ static int secp256k1_frost_nonce_process_internal(const secp256k1_context* ctx,
     return 1;
 }
 
-static int secp256k1_frost_lagrange_coefficient(secp256k1_scalar *r, const unsigned char * const *ids33, size_t n_participants, const unsigned char *my_id33) {
+static int secp256k1_frost_lagrange_coefficient(secp256k1_scalar *r, const size_t *ids, size_t n_participants, size_t my_id) {
     size_t i;
     secp256k1_scalar num;
     secp256k1_scalar den;
@@ -397,15 +394,11 @@ static int secp256k1_frost_lagrange_coefficient(secp256k1_scalar *r, const unsig
 
     secp256k1_scalar_set_int(&num, 1);
     secp256k1_scalar_set_int(&den, 1);
-    if (!secp256k1_frost_compute_indexhash(&party_idx, my_id33)) {
-        return 0;
-    }
+    secp256k1_scalar_set_int(&party_idx, my_id);
     for (i = 0; i < n_participants; i++) {
         secp256k1_scalar mul;
 
-        if (!secp256k1_frost_compute_indexhash(&mul, ids33[i])) {
-            return 0;
-        }
+        secp256k1_scalar_set_int(&mul, ids[i]);
         if (secp256k1_scalar_eq(&mul, &party_idx)) {
             continue;
         }
@@ -422,7 +415,7 @@ static int secp256k1_frost_lagrange_coefficient(secp256k1_scalar *r, const unsig
     return 1;
 }
 
-int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_session *session, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces, const unsigned char *msg32, const secp256k1_xonly_pubkey *pk, const unsigned char *my_id33, const unsigned char * const *ids33, const secp256k1_frost_tweak_cache *tweak_cache, const secp256k1_pubkey *adaptor) {
+int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_session *session, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces, const unsigned char *msg32, const secp256k1_xonly_pubkey *pk, size_t my_id, const size_t *ids, const secp256k1_frost_tweak_cache *tweak_cache, const secp256k1_pubkey *adaptor) {
     secp256k1_ge aggnonce_pt[2];
     secp256k1_gej aggnonce_ptj[2];
     unsigned char fin_nonce[32];
@@ -435,10 +428,12 @@ int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_
     ARG_CHECK(session != NULL);
     ARG_CHECK(msg32 != NULL);
     ARG_CHECK(pubnonces != NULL);
-    ARG_CHECK(ids33 != NULL);
-    ARG_CHECK(my_id33 != NULL);
-    ARG_CHECK(pk != NULL);
+    ARG_CHECK(ids != NULL);
     ARG_CHECK(n_pubnonces > 1);
+    ARG_CHECK(my_id != 0);
+    for (i = 0; i < n_pubnonces; i++) {
+        ARG_CHECK(ids[i] != 0);
+    }
 
     if (!secp256k1_xonly_pubkey_serialize(ctx, pk32, pk)) {
         return 0;
@@ -453,6 +448,7 @@ int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_
                here, we will never be able to determine who it is. Therefore, we
                should continue such that the culprit is revealed when collecting
                and verifying partial signatures.
+
                However, dealing with the point at infinity (loading,
                de-/serializing) would require a lot of extra code complexity.
                Instead, we set the aggregate nonce to some arbitrary point (the
@@ -476,7 +472,7 @@ int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_
         }
         secp256k1_gej_add_ge_var(&aggnonce_ptj[0], &aggnonce_ptj[0], &adaptorp, NULL);
     }
-    if (!secp256k1_frost_nonce_process_internal(ctx, &session_i.fin_nonce_parity, fin_nonce, &session_i.noncecoef, aggnonce_ptj, msg32, pubnonces, n_pubnonces, pk32, ids33)) {
+    if (!secp256k1_frost_nonce_process_internal(ctx, &session_i.fin_nonce_parity, fin_nonce, &session_i.noncecoef, aggnonce_ptj, msg32, pubnonces, n_pubnonces, pk32, ids)) {
         return 0;
     }
 
@@ -500,7 +496,7 @@ int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_
     }
     /* Update the challenge by multiplying the Lagrange coefficient to prepare
      * for signing. */
-    if (!secp256k1_frost_lagrange_coefficient(&l, ids33, n_pubnonces, my_id33)) {
+    if (!secp256k1_frost_lagrange_coefficient(&l, ids, n_pubnonces, my_id)) {
         return 0;
     }
     secp256k1_scalar_mul(&session_i.challenge, &session_i.challenge, &l);

src/modules/frost/tests_impl.h

@@ -0,0 +1,738 @@
+/***********************************************************************
+ * Copyright (c) 2022, 2023 Jesse Posner                               *
+ * Distributed under the MIT software license, see the accompanying    *
+ * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
+ ***********************************************************************/
+
+#ifndef SECP256K1_MODULE_FROST_TESTS_IMPL_H
+#define SECP256K1_MODULE_FROST_TESTS_IMPL_H
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "../../../include/secp256k1.h"
+#include "../../../include/secp256k1_extrakeys.h"
+#include "../../../include/secp256k1_frost.h"
+
+#include "session.h"
+#include "keygen.h"
+#include "../../scalar.h"
+#include "../../scratch.h"
+#include "../../field.h"
+#include "../../group.h"
+#include "../../hash.h"
+#include "../../util.h"
+
+/* Simple (non-adaptor, non-tweaked) 3-of-5 FROST aggregate, sign, verify
+ * test. */
+void frost_simple_test(void) {
+    secp256k1_frost_pubnonce pubnonce[5];
+    const secp256k1_frost_pubnonce *pubnonce_ptr[5];
+    unsigned char msg[32];
+    secp256k1_xonly_pubkey pk;
+    unsigned char seed[32];
+    secp256k1_frost_share shares[5];
+    secp256k1_frost_secnonce secnonce[5];
+    secp256k1_pubkey pubshares[5];
+    secp256k1_frost_partial_sig partial_sig[5];
+    const secp256k1_frost_partial_sig *partial_sig_ptr[5];
+    unsigned char final_sig[64];
+    secp256k1_frost_session session;
+    int i;
+    size_t ids[5];
+
+    secp256k1_testrand256(seed);
+
+    for (i = 0; i < 5; i++) {
+        pubnonce_ptr[i] = &pubnonce[i];
+        partial_sig_ptr[i] = &partial_sig[i];
+        ids[i] = i + 1;
+    }
+
+    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 5) == 1);
+
+    secp256k1_testrand256(msg);
+    for (i = 0; i < 3; i++) {
+        unsigned char session_id[32];
+
+        secp256k1_testrand256(session_id);
+
+        CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[i], &pubnonce[i], session_id, &shares[i], NULL, NULL, NULL) == 1);
+    }
+    for (i = 0; i < 3; i++) {
+        CHECK(secp256k1_frost_nonce_process(CTX, &session, pubnonce_ptr, 3, msg, &pk, ids[i], ids, NULL, NULL) == 1);
+        CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[i], &secnonce[i], &shares[i], &session, NULL) == 1);
+        CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[i], &pubnonce[i], &pubshares[i], &session, NULL) == 1);
+    }
+    CHECK(secp256k1_frost_partial_sig_agg(CTX, final_sig, &session, partial_sig_ptr, 3) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &pk) == 1);
+}
+
+void frost_pubnonce_summing_to_inf(secp256k1_frost_pubnonce *pubnonce) {
+    secp256k1_ge ge[2];
+    int i;
+    secp256k1_gej summed_nonces[2];
+    const secp256k1_frost_pubnonce *pubnonce_ptr[2];
+
+    ge[0] = secp256k1_ge_const_g;
+    ge[1] = secp256k1_ge_const_g;
+
+    for (i = 0; i < 2; i++) {
+        secp256k1_frost_pubnonce_save(&pubnonce[i], ge);
+        pubnonce_ptr[i] = &pubnonce[i];
+        secp256k1_ge_neg(&ge[0], &ge[0]);
+        secp256k1_ge_neg(&ge[1], &ge[1]);
+    }
+
+    secp256k1_frost_sum_nonces(CTX, summed_nonces, pubnonce_ptr, 2);
+    CHECK(secp256k1_gej_is_infinity(&summed_nonces[0]));
+    CHECK(secp256k1_gej_is_infinity(&summed_nonces[1]));
+}
+
+int frost_memcmp_and_randomize(unsigned char *value, const unsigned char *expected, size_t len) {
+    int ret;
+    size_t i;
+    ret = secp256k1_memcmp_var(value, expected, len);
+    for (i = 0; i < len; i++) {
+        value[i] = secp256k1_testrand_bits(8);
+    }
+    return ret;
+}
+
+void frost_api_tests(void) {
+    secp256k1_frost_partial_sig partial_sig[5];
+    const secp256k1_frost_partial_sig *partial_sig_ptr[5];
+    secp256k1_frost_partial_sig invalid_partial_sig;
+    const secp256k1_frost_partial_sig *invalid_partial_sig_ptr[5];
+    unsigned char final_sig[64];
+    unsigned char pre_sig[64];
+    unsigned char buf[32];
+    /* unsigned char sk[5][32]; */
+    unsigned char max64[64];
+    unsigned char zeros68[68] = { 0 };
+    unsigned char session_id[5][32];
+    unsigned char seed[32];
+    secp256k1_frost_secnonce secnonce[5];
+    secp256k1_frost_secnonce secnonce_tmp;
+    secp256k1_frost_secnonce invalid_secnonce;
+    secp256k1_frost_pubnonce pubnonce[5];
+    const secp256k1_frost_pubnonce *pubnonce_ptr[5];
+    unsigned char pubnonce_ser[66];
+    secp256k1_frost_pubnonce inf_pubnonce[5];
+    secp256k1_frost_pubnonce invalid_pubnonce;
+    const secp256k1_frost_pubnonce *invalid_pubnonce_ptr[5];
+    unsigned char msg[32];
+    secp256k1_xonly_pubkey pk;
+    secp256k1_pubkey full_pk;
+    secp256k1_frost_tweak_cache tweak_cache;
+    secp256k1_frost_tweak_cache invalid_tweak_cache;
+    secp256k1_frost_session session[5];
+    secp256k1_frost_session invalid_session;
+    secp256k1_xonly_pubkey invalid_pk;
+    unsigned char tweak[32];
+    int nonce_parity;
+    unsigned char sec_adaptor[32];
+    unsigned char sec_adaptor1[32];
+    secp256k1_pubkey adaptor;
+    secp256k1_pubkey invalid_vss_pk;
+    secp256k1_frost_share invalid_share;
+    secp256k1_frost_share shares[5];
+    secp256k1_pubkey pubshares[5];
+    int i;
+    size_t ids[5];
+    size_t invalid_ids[5];
+
+    /** setup **/
+    memset(max64, 0xff, sizeof(max64));
+    memset(&invalid_share, 0xff, sizeof(invalid_share));
+    /* Simulate structs being uninitialized by setting it to 0s. We don't want
+     * to produce undefined behavior by actually providing uninitialized
+     * structs. */
+    memset(&invalid_pk, 0, sizeof(invalid_pk));
+    memset(&invalid_secnonce, 0, sizeof(invalid_secnonce));
+    memset(&invalid_partial_sig, 0, sizeof(invalid_partial_sig));
+    memset(&invalid_pubnonce, 0, sizeof(invalid_pubnonce));
+    memset(&invalid_vss_pk, 0, sizeof(invalid_vss_pk));
+    memset(&invalid_tweak_cache, 0, sizeof(invalid_tweak_cache));
+    memset(&invalid_session, 0, sizeof(invalid_session));
+    frost_pubnonce_summing_to_inf(inf_pubnonce);
+
+    secp256k1_testrand256(sec_adaptor);
+    secp256k1_testrand256(msg);
+    secp256k1_testrand256(tweak);
+    secp256k1_testrand256(seed);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &adaptor, sec_adaptor) == 1);
+    for (i = 0; i < 5; i++) {
+        pubnonce_ptr[i] = &pubnonce[i];
+        partial_sig_ptr[i] = &partial_sig[i];
+        invalid_partial_sig_ptr[i] = &partial_sig[i];
+        ids[i] = i + 1;
+        invalid_ids[i] = i + 1;
+        secp256k1_testrand256(session_id[i]);
+    }
+    invalid_pubnonce_ptr[0] = &invalid_pubnonce;
+    invalid_partial_sig_ptr[0] = &invalid_partial_sig;
+    invalid_ids[2] = 0;
+
+    /** main test body **/
+
+    /** Key generation **/
+    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 5) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, NULL, pubshares, &pk, seed, 3, 5));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, NULL, &pk, seed, 3, 5));
+    for (i = 0; i < 5; i++) {
+        CHECK(frost_memcmp_and_randomize(shares[i].data, zeros68, sizeof(shares[i].data)) == 0);
+    }
+    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, NULL, seed, 3, 5));
+    for (i = 0; i < 5; i++) {
+        CHECK(frost_memcmp_and_randomize(shares[i].data, zeros68, sizeof(shares[i].data)) == 0);
+    }
+    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, NULL, 3, 5));
+    for (i = 0; i < 5; i++) {
+        CHECK(frost_memcmp_and_randomize(shares[i].data, zeros68, sizeof(shares[i].data)) == 0);
+    }
+    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 0, 5));
+    for (i = 0; i < 5; i++) {
+        CHECK(frost_memcmp_and_randomize(shares[i].data, zeros68, sizeof(shares[i].data)) == 0);
+    }
+    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 0));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 2));
+
+    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 5) == 1);
+
+    /* pubkey_get */
+    CHECK(secp256k1_frost_pubkey_get(CTX, &full_pk, &pk) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_get(CTX, NULL, &pk));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_get(CTX, &full_pk, NULL));
+    CHECK(secp256k1_memcmp_var(&full_pk, zeros68, sizeof(full_pk)) == 0);
+
+    /** Tweaking **/
+
+    /* pubkey_tweak */
+    CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &pk) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_tweak(CTX, NULL, &pk));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &invalid_pk));
+
+    CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &pk) == 1);
+
+    /* tweak_add */
+    {
+        int (*tweak_func[2]) (const secp256k1_context* ctx, secp256k1_pubkey *output_pubkey, secp256k1_frost_tweak_cache *tweak_cache, const unsigned char *tweak32);
+        tweak_func[0] = secp256k1_frost_pubkey_ec_tweak_add;
+        tweak_func[1] = secp256k1_frost_pubkey_xonly_tweak_add;
+        CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &pk) == 1);
+        for (i = 0; i < 2; i++) {
+            secp256k1_pubkey tmp_output_pk;
+            secp256k1_frost_tweak_cache tmp_tweak_cache = tweak_cache;
+            CHECK((*tweak_func[i])(CTX, &tmp_output_pk, &tmp_tweak_cache, tweak) == 1);
+            /* Reset tweak_cache */
+            tmp_tweak_cache = tweak_cache;
+            CHECK((*tweak_func[i])(CTX, &tmp_output_pk, &tmp_tweak_cache, tweak) == 1);
+            tmp_tweak_cache = tweak_cache;
+            CHECK((*tweak_func[i])(CTX, NULL, &tmp_tweak_cache, tweak) == 1);
+            tmp_tweak_cache = tweak_cache;
+            CHECK_ILLEGAL(CTX, (*tweak_func[i])(CTX, &tmp_output_pk, NULL, tweak));
+            CHECK(frost_memcmp_and_randomize(tmp_output_pk.data, zeros68, sizeof(tmp_output_pk.data)) == 0);
+            tmp_tweak_cache = tweak_cache;
+            CHECK_ILLEGAL(CTX, (*tweak_func[i])(CTX, &tmp_output_pk, &tmp_tweak_cache, NULL));
+            CHECK(frost_memcmp_and_randomize(tmp_output_pk.data, zeros68, sizeof(tmp_output_pk.data)) == 0);
+            tmp_tweak_cache = tweak_cache;
+            CHECK((*tweak_func[i])(CTX, &tmp_output_pk, &tmp_tweak_cache, max64) == 0);
+            CHECK(frost_memcmp_and_randomize(tmp_output_pk.data, zeros68, sizeof(tmp_output_pk.data)) == 0);
+            tmp_tweak_cache = tweak_cache;
+            /* Uninitialized tweak_cache */
+            CHECK_ILLEGAL(CTX, (*tweak_func[i])(CTX, &tmp_output_pk, &invalid_tweak_cache, tweak));
+            CHECK(frost_memcmp_and_randomize(tmp_output_pk.data, zeros68, sizeof(tmp_output_pk.data)) == 0);
+        }
+    }
+
+    /** Session creation **/
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, &pk, max64) == 1);
+    CHECK_ILLEGAL(STATIC_CTX, secp256k1_frost_nonce_gen(STATIC_CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, &pk, max64));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, NULL, &pubnonce[0], session_id[0], &shares[0], msg, &pk, max64));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], NULL, session_id[0], &shares[0], msg, &pk, max64));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], NULL, &shares[0], msg, &pk, max64));
+    CHECK(frost_memcmp_and_randomize(secnonce[0].data, zeros68, sizeof(secnonce[0].data)) == 0);
+    /* no seckey and session_id is 0 */
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], zeros68, NULL, msg, &pk, max64) == 0);
+    CHECK(frost_memcmp_and_randomize(secnonce[0].data, zeros68, sizeof(secnonce[0].data)) == 0);
+    /* session_id 0 is fine when a seckey is provided */
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], zeros68, &shares[0], msg, &pk, max64) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], NULL, msg, &pk, max64) == 1);
+    /* invalid share */
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &invalid_share, msg, &pk, max64));
+    CHECK(frost_memcmp_and_randomize(secnonce[0].data, zeros68, sizeof(secnonce[0].data)) == 0);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], NULL, &pk, max64) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, NULL, max64) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, &invalid_pk, max64));
+    CHECK(frost_memcmp_and_randomize(secnonce[0].data, zeros68, sizeof(secnonce[0].data)) == 0);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, &pk, NULL) == 1);
+
+    /* Every in-argument except session_id can be NULL */
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], NULL, NULL, NULL, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[1], &pubnonce[1], session_id[1], &shares[1], NULL, NULL, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[2], &pubnonce[2], session_id[2], &shares[2], NULL, NULL, NULL) == 1);
+
+    /** Serialize and parse public nonces **/
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubnonce_serialize(CTX, NULL, &pubnonce[0]));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubnonce_serialize(CTX, pubnonce_ser, NULL));
+    CHECK(frost_memcmp_and_randomize(pubnonce_ser, zeros68, sizeof(pubnonce_ser)) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubnonce_serialize(CTX, pubnonce_ser, &invalid_pubnonce));
+    CHECK(frost_memcmp_and_randomize(pubnonce_ser, zeros68, sizeof(pubnonce_ser)) == 0);
+    CHECK(secp256k1_frost_pubnonce_serialize(CTX, pubnonce_ser, &pubnonce[0]) == 1);
+
+    CHECK(secp256k1_frost_pubnonce_parse(CTX, &pubnonce[0], pubnonce_ser) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubnonce_parse(CTX, NULL, pubnonce_ser));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubnonce_parse(CTX, &pubnonce[0], NULL));
+    CHECK(secp256k1_frost_pubnonce_parse(CTX, &pubnonce[0], zeros68) == 0);
+    CHECK(secp256k1_frost_pubnonce_parse(CTX, &pubnonce[0], pubnonce_ser) == 1);
+
+    {
+        /* Check that serialize and parse results in the same value */
+        secp256k1_frost_pubnonce tmp;
+        CHECK(secp256k1_frost_pubnonce_serialize(CTX, pubnonce_ser, &pubnonce[0]) == 1);
+        CHECK(secp256k1_frost_pubnonce_parse(CTX, &tmp, pubnonce_ser) == 1);
+        CHECK(secp256k1_memcmp_var(&tmp, &pubnonce[0], sizeof(tmp)) == 0);
+    }
+
+    /** Process nonces **/
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, NULL, pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], NULL, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 0, msg, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], invalid_pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, NULL, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, NULL, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, 0, ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], invalid_ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], NULL, &tweak_cache, &adaptor));
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, NULL, &adaptor) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &invalid_tweak_cache, &adaptor));
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, (secp256k1_pubkey *)&invalid_pk));
+
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[1], pubnonce_ptr, 3, msg, &pk, ids[1], ids, &tweak_cache, &adaptor) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[2], pubnonce_ptr, 3, msg, &pk, ids[2], ids, &tweak_cache, &adaptor) == 1);
+
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &session[0], &tweak_cache) == 1);
+    /* The secnonce is set to 0 and subsequent signing attempts fail */
+    CHECK(secp256k1_memcmp_var(&secnonce_tmp, zeros68, sizeof(secnonce_tmp)) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &session[0], &tweak_cache));
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, NULL, &secnonce_tmp, &shares[0], &session[0], &tweak_cache));
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], NULL, &shares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &invalid_secnonce, &shares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, NULL, &session[0], &tweak_cache));
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &invalid_share, &session[0], &tweak_cache));
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], NULL, &tweak_cache));
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &invalid_session, &tweak_cache));
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &session[0], NULL) == 1);
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &session[0], &invalid_tweak_cache));
+    memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
+
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce[0], &shares[0], &session[0], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[1], &secnonce[1], &shares[1], &session[1], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[2], &secnonce[2], &shares[2], &session[2], &tweak_cache) == 1);
+
+    CHECK(secp256k1_frost_partial_sig_serialize(CTX, buf, &partial_sig[0]) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_serialize(CTX, NULL, &partial_sig[0]));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_serialize(CTX, buf, NULL));
+    CHECK(secp256k1_frost_partial_sig_parse(CTX, &partial_sig[0], buf) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_parse(CTX, NULL, buf));
+    CHECK(secp256k1_frost_partial_sig_parse(CTX, &partial_sig[0], max64) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_parse(CTX, &partial_sig[0], NULL));
+
+    {
+        /* Check that serialize and parse results in the same value */
+        secp256k1_frost_partial_sig tmp;
+        CHECK(secp256k1_frost_partial_sig_serialize(CTX, buf, &partial_sig[0]) == 1);
+        CHECK(secp256k1_frost_partial_sig_parse(CTX, &tmp, buf) == 1);
+        CHECK(secp256k1_memcmp_var(&tmp, &partial_sig[0], sizeof(tmp)) == 0);
+    }
+
+    /** Partial signature verification */
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &session[0], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[1], &pubnonce[0], &pubshares[0], &session[0], &tweak_cache) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, NULL, &pubnonce[0], &pubshares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &invalid_partial_sig, &pubnonce[0], &pubshares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], NULL, &pubshares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &invalid_pubnonce, &pubshares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], NULL, &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &invalid_vss_pk, &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], NULL, &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &invalid_session, &tweak_cache));
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &session[0], NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &session[0], &invalid_tweak_cache));
+
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &session[0], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[1], &pubnonce[1], &pubshares[1], &session[1], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[2], &pubnonce[2], &pubshares[2], &session[2], &tweak_cache) == 1);
+
+    /** Signature aggregation and verification */
+    CHECK(secp256k1_frost_partial_sig_agg(CTX, pre_sig, &session[0], partial_sig_ptr, 3) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_agg(CTX, NULL, &session[0], partial_sig_ptr, 3));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_agg(CTX, pre_sig, NULL, partial_sig_ptr, 3));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_agg(CTX, pre_sig, &invalid_session, partial_sig_ptr, 3));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_agg(CTX, pre_sig, &session[0], NULL, 3));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_agg(CTX, pre_sig, &session[0], invalid_partial_sig_ptr, 3));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_agg(CTX, pre_sig, &session[0], partial_sig_ptr, 0));
+    CHECK(secp256k1_frost_partial_sig_agg(CTX, pre_sig, &session[0], partial_sig_ptr, 1) == 1);
+    CHECK(secp256k1_frost_partial_sig_agg(CTX, pre_sig, &session[1], partial_sig_ptr, 2) == 1);
+    CHECK(secp256k1_frost_partial_sig_agg(CTX, pre_sig, &session[2], partial_sig_ptr, 3) == 1);
+
+    /** Adaptor signature verification */
+    CHECK(secp256k1_frost_nonce_parity(CTX, &nonce_parity, &session[0]) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_parity(CTX, NULL, &session[0]));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_parity(CTX, &nonce_parity, NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_parity(CTX, &nonce_parity, &invalid_session));
+
+    CHECK(secp256k1_frost_adapt(CTX, final_sig, pre_sig, sec_adaptor, nonce_parity) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_adapt(CTX, NULL, pre_sig, sec_adaptor, 0));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_adapt(CTX, final_sig, NULL, sec_adaptor, 0));
+    CHECK(secp256k1_frost_adapt(CTX, final_sig, max64, sec_adaptor, 0) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_adapt(CTX, final_sig, pre_sig, NULL, 0));
+    CHECK(secp256k1_frost_adapt(CTX, final_sig, pre_sig, max64, 0) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_adapt(CTX, final_sig, pre_sig, sec_adaptor, 2));
+    /* sig and pre_sig argument point to the same location */
+    memcpy(final_sig, pre_sig, sizeof(final_sig));
+    CHECK(secp256k1_frost_adapt(CTX, final_sig, final_sig, sec_adaptor, nonce_parity) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &pk) == 1);
+
+    CHECK(secp256k1_frost_adapt(CTX, final_sig, pre_sig, sec_adaptor, nonce_parity) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &pk) == 1);
+
+    /** Secret adaptor can be extracted from signature */
+    CHECK(secp256k1_frost_extract_adaptor(CTX, sec_adaptor1, final_sig, pre_sig, nonce_parity) == 1);
+    CHECK(secp256k1_memcmp_var(sec_adaptor, sec_adaptor1, 32) == 0);
+    /* wrong nonce parity */
+    CHECK(secp256k1_frost_extract_adaptor(CTX, sec_adaptor1, final_sig, pre_sig, !nonce_parity) == 1);
+    CHECK(secp256k1_memcmp_var(sec_adaptor, sec_adaptor1, 32) != 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_extract_adaptor(CTX, NULL, final_sig, pre_sig, 0));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_extract_adaptor(CTX, sec_adaptor1, NULL, pre_sig, 0));
+    CHECK(secp256k1_frost_extract_adaptor(CTX, sec_adaptor1, max64, pre_sig, 0) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_extract_adaptor(CTX, sec_adaptor1, final_sig, NULL, 0));
+    CHECK(secp256k1_frost_extract_adaptor(CTX, sec_adaptor1, final_sig, max64, 0) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_extract_adaptor(CTX, sec_adaptor1, final_sig, pre_sig, 2));
+}
+
+void frost_nonce_bitflip(unsigned char **args, size_t n_flip, size_t n_bytes) {
+    secp256k1_scalar k1[2], k2[2];
+
+    secp256k1_nonce_function_frost(k1, args[0], args[1], args[2], args[3], args[4]);
+    secp256k1_testrand_flip(args[n_flip], n_bytes);
+    secp256k1_nonce_function_frost(k2, args[0], args[1], args[2], args[3], args[4]);
+    CHECK(secp256k1_scalar_eq(&k1[0], &k2[0]) == 0);
+    CHECK(secp256k1_scalar_eq(&k1[1], &k2[1]) == 0);
+}
+
+void frost_nonce_test(void) {
+    unsigned char *args[5];
+    unsigned char session_id[32];
+    unsigned char sk[32];
+    unsigned char msg[32];
+    unsigned char agg_pk[32];
+    unsigned char extra_input[32];
+    int i, j;
+    secp256k1_scalar k[5][2];
+
+    secp256k1_testrand_bytes_test(session_id, sizeof(session_id));
+    secp256k1_testrand_bytes_test(sk, sizeof(sk));
+    secp256k1_testrand_bytes_test(msg, sizeof(msg));
+    secp256k1_testrand_bytes_test(agg_pk, sizeof(agg_pk));
+    secp256k1_testrand_bytes_test(extra_input, sizeof(extra_input));
+
+    /* Check that a bitflip in an argument results in different nonces. */
+    args[0] = session_id;
+    args[1] = msg;
+    args[2] = sk;
+    args[3] = agg_pk;
+    args[4] = extra_input;
+    for (i = 0; i < COUNT; i++) {
+        frost_nonce_bitflip(args, 0, sizeof(session_id));
+        frost_nonce_bitflip(args, 1, sizeof(msg));
+        frost_nonce_bitflip(args, 2, sizeof(sk));
+        frost_nonce_bitflip(args, 3, sizeof(agg_pk));
+        frost_nonce_bitflip(args, 4, sizeof(extra_input));
+    }
+    /* Check that if any argument is NULL, a different nonce is produced than if
+     * any other argument is NULL. */
+    memcpy(msg, session_id, sizeof(msg));
+    memcpy(sk, session_id, sizeof(sk));
+    memcpy(agg_pk, session_id, sizeof(agg_pk));
+    memcpy(extra_input, session_id, sizeof(extra_input));
+    secp256k1_nonce_function_frost(k[0], args[0], args[1], args[2], args[3], args[4]);
+    secp256k1_nonce_function_frost(k[1], args[0], NULL, args[2], args[3], args[4]);
+    secp256k1_nonce_function_frost(k[2], args[0], args[1], NULL, args[3], args[4]);
+    secp256k1_nonce_function_frost(k[3], args[0], args[1], args[2], NULL, args[4]);
+    secp256k1_nonce_function_frost(k[4], args[0], args[1], args[2], args[3], NULL);
+    for (i = 0; i < 4; i++) {
+        for (j = i+1; j < 5; j++) {
+            CHECK(secp256k1_scalar_eq(&k[i][0], &k[j][0]) == 0);
+            CHECK(secp256k1_scalar_eq(&k[i][1], &k[j][1]) == 0);
+        }
+    }
+}
+
+/* Attempts to create a signature for the aggregate public key using given secret
+ * keys and tweak_cache. */
+void frost_tweak_test_helper(const secp256k1_xonly_pubkey* pk, const secp256k1_frost_share *sr0, const secp256k1_frost_share *sr1, const secp256k1_frost_share *sr2, secp256k1_frost_tweak_cache *tweak_cache, const size_t *ids, const secp256k1_pubkey *sr_pk0, const secp256k1_pubkey *sr_pk1, const secp256k1_pubkey *sr_pk2) {
+    unsigned char session_id[3][32];
+    unsigned char msg[32];
+    secp256k1_frost_secnonce secnonce[3];
+    secp256k1_frost_pubnonce pubnonce[3];
+    const secp256k1_frost_pubnonce *pubnonce_ptr[3];
+    secp256k1_frost_session session[5];
+    secp256k1_frost_partial_sig partial_sig[3];
+    const secp256k1_frost_partial_sig *partial_sig_ptr[3];
+    unsigned char final_sig[64];
+    int i;
+
+    for (i = 0; i < 3; i++) {
+        pubnonce_ptr[i] = &pubnonce[i];
+        partial_sig_ptr[i] = &partial_sig[i];
+
+        secp256k1_testrand256(session_id[i]);
+    }
+    secp256k1_testrand256(msg);
+
+
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], sr0, NULL, NULL, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[1], &pubnonce[1], session_id[1], sr1, NULL, NULL, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[2], &pubnonce[2], session_id[2], sr2, NULL, NULL, NULL) == 1);
+
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, pk, ids[0], ids, tweak_cache, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[1], pubnonce_ptr, 3, msg, pk, ids[1], ids, tweak_cache, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[2], pubnonce_ptr, 3, msg, pk, ids[2], ids, tweak_cache, NULL) == 1);
+
+
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce[0], sr0, &session[0], tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[1], &secnonce[1], sr1, &session[1], tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[2], &secnonce[2], sr2, &session[2], tweak_cache) == 1);
+
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], sr_pk0, &session[0], tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[1], &pubnonce[1], sr_pk1, &session[1], tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[2], &pubnonce[2], sr_pk2, &session[2], tweak_cache) == 1);
+
+    CHECK(secp256k1_frost_partial_sig_agg(CTX, final_sig, &session[0], partial_sig_ptr, 3) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), pk) == 1);
+}
+
+/* Create aggregate public key P[0], tweak multiple times (using xonly and
+ * ordinary tweaking) and test signing. */
+void frost_tweak_test(void) {
+    secp256k1_pubkey pubshares[5];
+    secp256k1_frost_tweak_cache tweak_cache;
+    enum { N_TWEAKS = 8 };
+    secp256k1_pubkey P[N_TWEAKS + 1];
+    secp256k1_xonly_pubkey P_xonly[N_TWEAKS + 1];
+    unsigned char seed[32];
+    secp256k1_frost_share shares[5];
+    int i;
+    size_t ids[5];
+
+    secp256k1_testrand256(seed);
+
+    /* Key Setup */
+    for (i = 0; i < 5; i++) {
+        ids[i] = i + 1;
+    }
+    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &P_xonly[0], seed, 3, 5) == 1);
+
+    frost_tweak_test_helper(&P_xonly[0], &shares[0], &shares[1], &shares[2], NULL, ids, &pubshares[0], &pubshares[1], &pubshares[2]);
+    CHECK(secp256k1_frost_pubkey_get(CTX, &P[0], &P_xonly[0]));
+    CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &P_xonly[0]) == 1);
+
+    /* Compute Pi = f(Pj) + tweaki*G where where j = i-1 and try signing for */
+    /* that key. If xonly is set to true, the function f is normalizes the input */
+    /* point to have an even X-coordinate ("xonly-tweaking"). */
+    /* Otherwise, the function f is the identity function.  */
+    for (i = 1; i <= N_TWEAKS; i++) {
+        unsigned char tweak[32];
+        int P_parity;
+        int xonly = secp256k1_testrand_bits(1);
+
+        secp256k1_testrand256(tweak);
+        if (xonly) {
+            CHECK(secp256k1_frost_pubkey_xonly_tweak_add(CTX, &P[i], &tweak_cache, tweak) == 1);
+        } else {
+            CHECK(secp256k1_frost_pubkey_ec_tweak_add(CTX, &P[i], &tweak_cache, tweak) == 1);
+        }
+        CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &P_xonly[i], &P_parity, &P[i]));
+        /* Check that frost_pubkey_tweak_add produces same result as */
+        /* xonly_pubkey_tweak_add or ec_pubkey_tweak_add.  */
+        if (xonly) {
+            unsigned char P_serialized[32];
+            CHECK(secp256k1_xonly_pubkey_serialize(CTX, P_serialized, &P_xonly[i]));
+            CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, P_serialized, P_parity, &P_xonly[i-1], tweak) == 1);
+        } else {
+            secp256k1_pubkey tmp_key = P[i-1];
+            CHECK(secp256k1_ec_pubkey_tweak_add(CTX, &tmp_key, tweak));
+            CHECK(secp256k1_memcmp_var(&tmp_key, &P[i], sizeof(tmp_key)) == 0);
+        }
+        /* Test signing for P[i] */
+        frost_tweak_test_helper(&P_xonly[i], &shares[0], &shares[1], &shares[2], &tweak_cache, ids, &pubshares[0], &pubshares[1], &pubshares[2]);
+    }
+}
+
+/* Performs a FROST DKG */
+void frost_dkg_test_helper(secp256k1_frost_share *shares, secp256k1_xonly_pubkey *pk) {
+    unsigned char seed[32];
+    secp256k1_pubkey pubshares[5];
+
+    secp256k1_testrand256(seed);
+
+    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, pk, seed, 3, 5) == 1);
+}
+
+/* Signs a message with a FROST keypair */
+int frost_sign_test_helper(unsigned char *final_sig, const secp256k1_frost_share *share, const secp256k1_xonly_pubkey *pk, const unsigned char *msg, const secp256k1_pubkey *adaptor) {
+    unsigned char session_id[3][32];
+    secp256k1_frost_secnonce secnonce[3];
+    secp256k1_frost_pubnonce pubnonce[3];
+    const secp256k1_frost_pubnonce *pubnonce_ptr[3];
+    secp256k1_frost_partial_sig partial_sig[5];
+    const secp256k1_frost_partial_sig *partial_sig_ptr[5];
+    secp256k1_frost_session session;
+    int i;
+    int nonce_parity;
+    secp256k1_frost_session_internal session_i;
+    size_t ids[5];
+
+    for (i = 0; i < 3; i++) {
+        pubnonce_ptr[i] = &pubnonce[i];
+        partial_sig_ptr[i] = &partial_sig[i];
+        ids[i] = i + 1;
+    }
+
+    for (i = 0; i < 3; i++) {
+        secp256k1_testrand256(session_id[i]);
+
+        CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[i], &pubnonce[i], session_id[i], &share[i], NULL, NULL, NULL) == 1);
+    }
+    for (i = 0; i < 3; i++) {
+        CHECK(secp256k1_frost_nonce_process(CTX, &session, pubnonce_ptr, 3, msg, pk, i + 1, ids, NULL, adaptor) == 1);
+        CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[i], &secnonce[i], &share[i], &session, NULL) == 1);
+    }
+    CHECK(secp256k1_frost_partial_sig_agg(CTX, final_sig, &session, partial_sig_ptr, 3) == 1);
+
+    CHECK(secp256k1_frost_nonce_parity(CTX, &nonce_parity, &session));
+
+    secp256k1_frost_session_load(CTX, &session_i, &session);
+
+    return nonce_parity;
+}
+
+void frost_rand_scalar(secp256k1_scalar *scalar) {
+    unsigned char buf32[32];
+    secp256k1_testrand256(buf32);
+    secp256k1_scalar_set_b32(scalar, buf32, NULL);
+}
+
+void frost_multi_hop_lock_tests(void) {
+    secp256k1_frost_share share_a[5];
+    secp256k1_frost_share share_b[5];
+    secp256k1_xonly_pubkey agg_pk_a;
+    secp256k1_xonly_pubkey agg_pk_b;
+    unsigned char asig_ab[64];
+    unsigned char asig_bc[64];
+    unsigned char pop[32];
+    secp256k1_pubkey pubkey_pop;
+    unsigned char tx_ab[32];
+    unsigned char tx_bc[32];
+    unsigned char buf[32];
+    secp256k1_scalar t1, t2, tp;
+    secp256k1_pubkey l, r;
+    secp256k1_ge l_ge, r_ge;
+    secp256k1_scalar deckey;
+    unsigned char sig_ab[64];
+    unsigned char sig_bc[64];
+    int nonce_parity_ab;
+    int nonce_parity_bc;
+
+    /* Alice DKG */
+    frost_dkg_test_helper(share_a, &agg_pk_a);
+
+    /* Bob DKG */
+    frost_dkg_test_helper(share_b, &agg_pk_b);
+
+    /* Carol setup */
+    /* Proof of payment */
+    secp256k1_testrand256(pop);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pubkey_pop, pop));
+
+    /* Alice setup */
+    secp256k1_testrand256(tx_ab);
+    frost_rand_scalar(&t1);
+    frost_rand_scalar(&t2);
+    secp256k1_scalar_add(&tp, &t1, &t2);
+    /* Left lock */
+    secp256k1_pubkey_load(CTX, &l_ge, &pubkey_pop);
+    CHECK(secp256k1_eckey_pubkey_tweak_add(&l_ge, &t1));
+    secp256k1_pubkey_save(&l, &l_ge);
+    /* Right lock */
+    secp256k1_pubkey_load(CTX, &r_ge, &pubkey_pop);
+    CHECK(secp256k1_eckey_pubkey_tweak_add(&r_ge, &tp));
+    secp256k1_pubkey_save(&r, &r_ge);
+    /* Encrypt Alice's signature with the left lock as the encryption key */
+    nonce_parity_ab = frost_sign_test_helper(asig_ab, share_a, &agg_pk_a, tx_ab, &l);
+
+    /* Bob setup */
+    CHECK(secp256k1_frost_verify_adaptor(CTX, asig_ab, tx_ab, &agg_pk_a, &l, nonce_parity_ab) == 1);
+    secp256k1_testrand256(tx_bc);
+    /* Encrypt Bob's signature with the right lock as the encryption key */
+    nonce_parity_bc = frost_sign_test_helper(asig_bc, share_b, &agg_pk_b, tx_bc, &r);
+
+    /* Carol decrypt */
+    CHECK(secp256k1_frost_verify_adaptor(CTX, asig_bc, tx_bc, &agg_pk_b, &r, nonce_parity_bc) == 1);
+    secp256k1_scalar_set_b32(&deckey, pop, NULL);
+    secp256k1_scalar_add(&deckey, &deckey, &tp);
+    secp256k1_scalar_get_b32(buf, &deckey);
+    CHECK(secp256k1_frost_adapt(CTX, sig_bc, asig_bc, buf, nonce_parity_bc));
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig_bc, tx_bc, sizeof(tx_bc), &agg_pk_b) == 1);
+
+    /* Bob recover and decrypt */
+    CHECK(secp256k1_frost_extract_adaptor(CTX, buf, sig_bc, asig_bc, nonce_parity_bc));
+    secp256k1_scalar_set_b32(&deckey, buf, NULL);
+    secp256k1_scalar_negate(&t2, &t2);
+    secp256k1_scalar_add(&deckey, &deckey, &t2);
+    secp256k1_scalar_get_b32(buf, &deckey);
+    CHECK(secp256k1_frost_adapt(CTX, sig_ab, asig_ab, buf, nonce_parity_ab));
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig_ab, tx_ab, sizeof(tx_ab), &agg_pk_a) == 1);
+
+    /* Alice recover and derive proof of payment */
+    CHECK(secp256k1_frost_extract_adaptor(CTX, buf, sig_ab, asig_ab, nonce_parity_ab));
+    secp256k1_scalar_set_b32(&deckey, buf, NULL);
+    secp256k1_scalar_negate(&t1, &t1);
+    secp256k1_scalar_add(&deckey, &deckey, &t1);
+    secp256k1_scalar_get_b32(buf, &deckey);
+    CHECK(secp256k1_memcmp_var(buf, pop, 32) == 0);
+}
+
+void run_frost_tests(void) {
+    int i;
+
+    for (i = 0; i < COUNT; i++) {
+        frost_simple_test();
+    }
+    frost_api_tests();
+    frost_nonce_test();
+    for (i = 0; i < COUNT; i++) {
+        /* Run multiple times to ensure that pk and nonce have different y
+         * parities */
+        frost_tweak_test();
+    }
+    for (i = 0; i < COUNT; i++) {
+        frost_multi_hop_lock_tests();
+    }
+}
+
+#endif

src/modules/generator/main_impl.h

@@ -276,6 +276,7 @@ static void secp256k1_pedersen_commitment_save(secp256k1_pedersen_commitment* co
 
 int secp256k1_pedersen_commitment_parse(const secp256k1_context* ctx, secp256k1_pedersen_commitment* commit, const unsigned char *input) {
     secp256k1_fe x;
+    secp256k1_ge ge;
 
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(commit != NULL);
@@ -284,20 +285,28 @@ int secp256k1_pedersen_commitment_parse(const secp256k1_context* ctx, secp256k1_
 
     if ((input[0] & 0xFE) != 8 ||
         !secp256k1_fe_set_b32_limit(&x, &input[1]) ||
-        !secp256k1_ge_x_on_curve_var(&x)) {
+        !secp256k1_ge_set_xquad(&ge, &x)) {
         return 0;
     }
-
-    memcpy(commit->data, input, 33);
+    if (input[0] & 1) {
+        secp256k1_ge_neg(&ge, &ge);
+    }
+    secp256k1_pedersen_commitment_save(commit, &ge);
     return 1;
 }
 
 int secp256k1_pedersen_commitment_serialize(const secp256k1_context* ctx, unsigned char *output, const secp256k1_pedersen_commitment* commit) {
+    secp256k1_ge ge;
+
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(output != NULL);
     ARG_CHECK(commit != NULL);
 
-    memcpy(output, commit->data, 33);
+    secp256k1_pedersen_commitment_load(&ge, commit);
+
+    output[0] = 9 ^ secp256k1_fe_is_square_var(&ge.y);
+    secp256k1_fe_normalize_var(&ge.x);
+    secp256k1_fe_get_b32(&output[1], &ge.x);
     return 1;
 }
 

src/modules/generator/tests_impl.h

@@ -264,13 +264,7 @@ static void test_pedersen(void) {
     }
     CHECK(secp256k1_pedersen_blind_sum(CTX, &blinds[(total - 1) * 32], bptr, total - 1, inputs));
     for (i = 0; i < total; i++) {
-        unsigned char result[33];
-        secp256k1_pedersen_commitment parse;
-
         CHECK(secp256k1_pedersen_commit(CTX, &commits[i], &blinds[i * 32], values[i], secp256k1_generator_h));
-        CHECK(secp256k1_pedersen_commitment_serialize(CTX, result, &commits[i]));
-        CHECK(secp256k1_pedersen_commitment_parse(CTX, &parse, result));
-        CHECK(secp256k1_memcmp_var(&commits[i], &parse, 33) == 0);
     }
     CHECK(secp256k1_pedersen_verify_tally(CTX, cptr, inputs, &cptr[inputs], outputs));
     CHECK(secp256k1_pedersen_verify_tally(CTX, &cptr[inputs], outputs, cptr, inputs));

src/secp256k1.c

@@ -889,6 +889,10 @@ static int secp256k1_ge_parse_ext(secp256k1_ge* ge, const unsigned char *in33) {
 # include "modules/ecdsa_adaptor/main_impl.h"
 #endif
 
+#ifdef ENABLE_MODULE_FROST
+# include "modules/frost/main_impl.h"
+#endif
+
 #ifdef ENABLE_MODULE_MUSIG
 # include "modules/musig/main_impl.h"
 #endif
@@ -908,7 +912,3 @@ static int secp256k1_ge_parse_ext(secp256k1_ge* ge, const unsigned char *in33) {
 #ifdef ENABLE_MODULE_SURJECTIONPROOF
 # include "modules/surjection/main_impl.h"
 #endif
-
-#ifdef ENABLE_MODULE_FROST
-# include "modules/frost/main_impl.h"
-#endif

src/tests.c

@@ -7502,6 +7502,10 @@ static void run_ecdsa_wycheproof(void) {
 # include "modules/ecdsa_adaptor/tests_impl.h"
 #endif
 
+#ifdef ENABLE_MODULE_FROST
+# include "modules/frost/tests_impl.h"
+#endif
+
 static void run_secp256k1_memczero_test(void) {
     unsigned char buf1[6] = {1, 2, 3, 4, 5, 6};
     unsigned char buf2[sizeof(buf1)];
@@ -7892,6 +7896,10 @@ int main(int argc, char **argv) {
     run_ecdsa_adaptor_tests();
 #endif
 
+#ifdef ENABLE_MODULE_FROST
+    run_frost_tests();
+#endif
+
     /* util tests */
     run_secp256k1_memczero_test();
     run_secp256k1_byteorder_tests();