frost/secp256k1-zkp
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Merge magnitude/normalized fields, move/improve comments

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Also split secp256k1_fe_verify into a generic and an implementation
specific part.
This commit is contained in:
Pieter Wuille
2022-01-28 17:39:30 -05:00
parent 341cc19726
commit b29566c51b
6 changed files with 96 additions and 61 deletions
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17
src/field_10x26_impl.h
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@@ -12,17 +12,8 @@
#include "field.h"
#include "modinv32_impl.h"
/** See the comment at the top of field_5x52_impl.h for more details.
*
* Here, we represent field elements as 10 uint32_t's in base 2^26, least significant first,
* where limbs can contain >26 bits.
* A magnitude M means:
* - 2*M*(2^22-1) is the max (inclusive) of the most significant limb
* - 2*M*(2^26-1) is the max (inclusive) of the remaining limbs
*/
static void secp256k1_fe_verify(const secp256k1_fe *a) {
#ifdef VERIFY
static void secp256k1_fe_impl_verify(const secp256k1_fe *a) {
const uint32_t *d = a->n;
int m = a->normalized ? 1 : 2 * a->magnitude, r = 1;
r &= (d[0] <= 0x3FFFFFFUL * m);
@@ -35,10 +26,7 @@ static void secp256k1_fe_verify(const secp256k1_fe *a) {
r &= (d[7] <= 0x3FFFFFFUL * m);
r &= (d[8] <= 0x3FFFFFFUL * m);
r &= (d[9] <= 0x03FFFFFUL * m);
r &= (a->magnitude >= 0);
r &= (a->magnitude <= 32);
if (a->normalized) {
r &= (a->magnitude <= 1);
if (r && (d[9] == 0x03FFFFFUL)) {
uint32_t mid = d[8] & d[7] & d[6] & d[5] & d[4] & d[3] & d[2];
if (mid == 0x3FFFFFFUL) {
@@ -47,9 +35,8 @@ static void secp256k1_fe_verify(const secp256k1_fe *a) {
}
}
VERIFY_CHECK(r == 1);
#endif
(void)a;
}
#endif
static void secp256k1_fe_get_bounds(secp256k1_fe *r, int m) {
VERIFY_CHECK(m >= 0);