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Simplify secp256k1_fe_{impl_,}verify

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This commit is contained in:
Pieter Wuille 2023-05-11 04:42:09 -04:00
parent 4e176ad5b9
commit 7fc642fa25
3 changed files with 24 additions and 27 deletions
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27
src/field_10x26_impl.h
View File

@ -15,26 +15,25 @@
#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);
r &= (d[1] <= 0x3FFFFFFUL * m);
r &= (d[2] <= 0x3FFFFFFUL * m);
r &= (d[3] <= 0x3FFFFFFUL * m);
r &= (d[4] <= 0x3FFFFFFUL * m);
r &= (d[5] <= 0x3FFFFFFUL * m);
r &= (d[6] <= 0x3FFFFFFUL * m);
r &= (d[7] <= 0x3FFFFFFUL * m);
r &= (d[8] <= 0x3FFFFFFUL * m);
r &= (d[9] <= 0x03FFFFFUL * m);
int m = a->normalized ? 1 : 2 * a->magnitude;
VERIFY_CHECK(d[0] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[1] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[2] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[3] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[4] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[5] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[6] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[7] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[8] <= 0x3FFFFFFUL * m);
VERIFY_CHECK(d[9] <= 0x03FFFFFUL * m);
if (a->normalized) {
if (r && (d[9] == 0x03FFFFFUL)) {
if (d[9] == 0x03FFFFFUL) {
uint32_t mid = d[8] & d[7] & d[6] & d[5] & d[4] & d[3] & d[2];
if (mid == 0x3FFFFFFUL) {
r &= ((d[1] + 0x40UL + ((d[0] + 0x3D1UL) >> 26)) <= 0x3FFFFFFUL);
VERIFY_CHECK((d[1] + 0x40UL + ((d[0] + 0x3D1UL) >> 26)) <= 0x3FFFFFFUL);
}
}
}
VERIFY_CHECK(r == 1);
}
#endif

17
src/field_5x52_impl.h
View File

@ -21,19 +21,18 @@
#ifdef VERIFY
static void secp256k1_fe_impl_verify(const secp256k1_fe *a) {
const uint64_t *d = a->n;
int m = a->normalized ? 1 : 2 * a->magnitude, r = 1;
int m = a->normalized ? 1 : 2 * a->magnitude;
/* secp256k1 'p' value defined in "Standards for Efficient Cryptography" (SEC2) 2.7.1. */
r &= (d[0] <= 0xFFFFFFFFFFFFFULL * m);
r &= (d[1] <= 0xFFFFFFFFFFFFFULL * m);
r &= (d[2] <= 0xFFFFFFFFFFFFFULL * m);
r &= (d[3] <= 0xFFFFFFFFFFFFFULL * m);
r &= (d[4] <= 0x0FFFFFFFFFFFFULL * m);
VERIFY_CHECK(d[0] <= 0xFFFFFFFFFFFFFULL * m);
VERIFY_CHECK(d[1] <= 0xFFFFFFFFFFFFFULL * m);
VERIFY_CHECK(d[2] <= 0xFFFFFFFFFFFFFULL * m);
VERIFY_CHECK(d[3] <= 0xFFFFFFFFFFFFFULL * m);
VERIFY_CHECK(d[4] <= 0x0FFFFFFFFFFFFULL * m);
if (a->normalized) {
if (r && (d[4] == 0x0FFFFFFFFFFFFULL) && ((d[3] & d[2] & d[1]) == 0xFFFFFFFFFFFFFULL)) {
r &= (d[0] < 0xFFFFEFFFFFC2FULL);
if ((d[4] == 0x0FFFFFFFFFFFFULL) && ((d[3] & d[2] & d[1]) == 0xFFFFFFFFFFFFFULL)) {
VERIFY_CHECK(d[0] < 0xFFFFEFFFFFC2FULL);
}
}
VERIFY_CHECK(r == 1);
}
#endif

7
src/field_impl.h
View File

@ -163,12 +163,11 @@ static void secp256k1_fe_verify(const secp256k1_fe *a) { (void)a; }
static void secp256k1_fe_impl_verify(const secp256k1_fe *a);
static void secp256k1_fe_verify(const secp256k1_fe *a) {
/* Magnitude between 0 and 32. */
int r = (a->magnitude >= 0) & (a->magnitude <= 32);
VERIFY_CHECK((a->magnitude >= 0) && (a->magnitude <= 32));
/* Normalized is 0 or 1. */
r &= (a->normalized == 0) | (a->normalized == 1);
VERIFY_CHECK((a->normalized == 0) || (a->normalized == 1));
/* If normalized, magnitude must be 0 or 1. */
if (a->normalized) r &= (a->magnitude <= 1);
VERIFY_CHECK(r == 1);
if (a->normalized) VERIFY_CHECK(a->magnitude <= 1);
/* Invoke implementation-specific checks. */
secp256k1_fe_impl_verify(a);
}