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Use secp256k1_memclear() to clear stack memory instead of memset()

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All of the invocations of secp256k1_memclear() operate on stack
memory and happen after the function is done with the memory object.
This commit replaces existing memset() invocations and also adds
secp256k1_memclear() to code locations where clearing was missing;
there is no guarantee that this commit covers all code locations
where clearing is necessary.

Co-Authored-By: isle2983 <isle2983@yahoo.com>
This commit is contained in:
Tim Ruffing
2019-06-08 13:54:14 +02:00
committed by Sebastian Falbesoner
parent e3497bbf00
commit 9bb368d146
8 changed files with 23 additions and 21 deletions
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4
src/secp256k1.c
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@@ -494,7 +494,7 @@ static int nonce_function_rfc6979(unsigned char *nonce32, const unsigned char *m
buffer_append(keydata, &offset, algo16, 16);
}
secp256k1_rfc6979_hmac_sha256_initialize(&rng, keydata, offset);
memset(keydata, 0, sizeof(keydata));
secp256k1_memclear(keydata, sizeof(keydata));
for (i = 0; i <= counter; i++) {
secp256k1_rfc6979_hmac_sha256_generate(&rng, nonce32, 32);
}
@@ -548,7 +548,7 @@ static int secp256k1_ecdsa_sign_inner(const secp256k1_context* ctx, secp256k1_sc
* seckey. As a result is_sec_valid is included in ret only after ret was
* used as a branching variable. */
ret &= is_sec_valid;
memset(nonce32, 0, 32);
secp256k1_memclear(nonce32, sizeof(nonce32));
secp256k1_scalar_clear(&msg);
secp256k1_scalar_clear(&non);
secp256k1_scalar_clear(&sec);