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Merge pull request #83

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7d681ac Add verification to 32bit field (Peter Dettman)
pull/11871/head
Pieter Wuille 10 years ago
parent 27aded3ccb 7d681ac636
commit 36abcf5510
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GPG Key ID: 57896D2FF8F0B657
2 changed files with 77 additions and 16 deletions
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82
src/field_10x26_impl.h
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@ -15,6 +15,36 @@
void static secp256k1_fe_inner_start(void) {}
void static secp256k1_fe_inner_stop(void) {}
#ifdef VERIFY
void static secp256k1_fe_verify(const secp256k1_fe_t *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);
r &= (a->magnitude >= 0);
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) {
r &= ((d[1] + 0x40UL + ((d[0] + 0x3D1UL) >> 26)) <= 0x3FFFFFFUL);
}
}
}
VERIFY_CHECK(r == 1);
}
#else
void static secp256k1_fe_verify(const secp256k1_fe_t *a) {}
#endif
void static secp256k1_fe_normalize(secp256k1_fe_t *r) {
uint32_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
@ -39,8 +69,8 @@ void static secp256k1_fe_normalize(secp256k1_fe_t *r) {
VERIFY_CHECK(t9 >> 23 == 0);
// At most a single final reduction is needed; check if the value is >= the field characteristic
x = (t9 >> 22) | ((t9 == 0x03FFFFFULL) & (m == 0x3FFFFFFULL)
& ((t1 + 0x40UL + ((t0 + 0x3D1UL) >> 26)) > 0x3FFFFFFULL));
x = (t9 >> 22) | ((t9 == 0x03FFFFFUL) & (m == 0x3FFFFFFUL)
& ((t1 + 0x40UL + ((t0 + 0x3D1UL) >> 26)) > 0x3FFFFFFUL));
// Apply the final reduction (for constant-time behaviour, we do it always)
t0 += x * 0x3D1UL; t1 += (x << 6);
@ -66,6 +96,7 @@ void static secp256k1_fe_normalize(secp256k1_fe_t *r) {
#ifdef VERIFY
r->magnitude = 1;
r->normalized = 1;
secp256k1_fe_verify(r);
#endif
}
@ -75,6 +106,7 @@ void static inline secp256k1_fe_set_int(secp256k1_fe_t *r, int a) {
#ifdef VERIFY
r->magnitude = 1;
r->normalized = 1;
secp256k1_fe_verify(r);
#endif
}
@ -82,6 +114,7 @@ void static inline secp256k1_fe_set_int(secp256k1_fe_t *r, int a) {
int static inline secp256k1_fe_is_zero(const secp256k1_fe_t *a) {
#ifdef VERIFY
VERIFY_CHECK(a->normalized);
secp256k1_fe_verify(a);
#endif
return (a->n[0] == 0 && a->n[1] == 0 && a->n[2] == 0 && a->n[3] == 0 && a->n[4] == 0 && a->n[5] == 0 && a->n[6] == 0 && a->n[7] == 0 && a->n[8] == 0 && a->n[9] == 0);
}
@ -89,14 +122,15 @@ int static inline secp256k1_fe_is_zero(const secp256k1_fe_t *a) {
int static inline secp256k1_fe_is_odd(const secp256k1_fe_t *a) {
#ifdef VERIFY
VERIFY_CHECK(a->normalized);
secp256k1_fe_verify(a);
#endif
return a->n[0] & 1;
}
void static inline secp256k1_fe_clear(secp256k1_fe_t *a) {
#ifdef VERIFY
a->normalized = 0;
a->magnitude = 0;
a->normalized = 1;
#endif
for (int i=0; i<10; i++) {
a->n[i] = 0;
@ -108,6 +142,8 @@ int static inline secp256k1_fe_equal(const secp256k1_fe_t *a, const secp256k1_fe
#ifdef VERIFY
VERIFY_CHECK(a->normalized);
VERIFY_CHECK(b->normalized);
secp256k1_fe_verify(a);
secp256k1_fe_verify(b);
#endif
return (a->n[0] == b->n[0] && a->n[1] == b->n[1] && a->n[2] == b->n[2] && a->n[3] == b->n[3] && a->n[4] == b->n[4] &&
a->n[5] == b->n[5] && a->n[6] == b->n[6] && a->n[7] == b->n[7] && a->n[8] == b->n[8] && a->n[9] == b->n[9]);
@ -126,6 +162,7 @@ void static secp256k1_fe_set_b32(secp256k1_fe_t *r, const unsigned char *a) {
#ifdef VERIFY
r->magnitude = 1;
r->normalized = 1;
secp256k1_fe_verify(r);
#endif
}
@ -133,6 +170,7 @@ void static secp256k1_fe_set_b32(secp256k1_fe_t *r, const unsigned char *a) {
void static secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe_t *a) {
#ifdef VERIFY
VERIFY_CHECK(a->normalized);
secp256k1_fe_verify(a);
#endif
for (int i=0; i<32; i++) {
int c = 0;
@ -148,8 +186,7 @@ void static secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe_t *a) {
void static inline secp256k1_fe_negate(secp256k1_fe_t *r, const secp256k1_fe_t *a, int m) {
#ifdef VERIFY
VERIFY_CHECK(a->magnitude <= m);
r->magnitude = m + 1;
r->normalized = 0;
secp256k1_fe_verify(a);
#endif
r->n[0] = 0x3FFFC2FUL * (m + 1) - a->n[0];
r->n[1] = 0x3FFFFBFUL * (m + 1) - a->n[1];
@ -161,13 +198,14 @@ void static inline secp256k1_fe_negate(secp256k1_fe_t *r, const secp256k1_fe_t *
r->n[7] = 0x3FFFFFFUL * (m + 1) - a->n[7];
r->n[8] = 0x3FFFFFFUL * (m + 1) - a->n[8];
r->n[9] = 0x03FFFFFUL * (m + 1) - a->n[9];
}
void static inline secp256k1_fe_mul_int(secp256k1_fe_t *r, int a) {
#ifdef VERIFY
r->magnitude *= a;
r->magnitude = m + 1;
r->normalized = 0;
secp256k1_fe_verify(r);
#endif
}
void static inline secp256k1_fe_mul_int(secp256k1_fe_t *r, int a) {
r->n[0] *= a;
r->n[1] *= a;
r->n[2] *= a;
@ -178,12 +216,16 @@ void static inline secp256k1_fe_mul_int(secp256k1_fe_t *r, int a) {
r->n[7] *= a;
r->n[8] *= a;
r->n[9] *= a;
#ifdef VERIFY
r->magnitude *= a;
r->normalized = 0;
secp256k1_fe_verify(r);
#endif
}
void static inline secp256k1_fe_add(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
#ifdef VERIFY
r->magnitude += a->magnitude;
r->normalized = 0;
secp256k1_fe_verify(a);
#endif
r->n[0] += a->n[0];
r->n[1] += a->n[1];
@ -195,6 +237,11 @@ void static inline secp256k1_fe_add(secp256k1_fe_t *r, const secp256k1_fe_t *a)
r->n[7] += a->n[7];
r->n[8] += a->n[8];
r->n[9] += a->n[9];
#ifdef VERIFY
r->magnitude += a->magnitude;
r->normalized = 0;
secp256k1_fe_verify(r);
#endif
}
void static inline secp256k1_fe_mul_inner(const uint32_t *a, const uint32_t *b, uint32_t *r) {
@ -455,19 +502,28 @@ void static secp256k1_fe_mul(secp256k1_fe_t *r, const secp256k1_fe_t *a, const s
#ifdef VERIFY
VERIFY_CHECK(a->magnitude <= 8);
VERIFY_CHECK(b->magnitude <= 8);
secp256k1_fe_verify(a);
secp256k1_fe_verify(b);
#endif
secp256k1_fe_mul_inner(a->n, b->n, r->n);
#ifdef VERIFY
r->magnitude = 1;
r->normalized = 0;
secp256k1_fe_verify(r);
#endif
secp256k1_fe_mul_inner(a->n, b->n, r->n);
}
void static secp256k1_fe_sqr(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
#ifdef VERIFY
VERIFY_CHECK(a->magnitude <= 8);
secp256k1_fe_verify(a);
#endif
secp256k1_fe_sqr_inner(a->n, r->n);
#ifdef VERIFY
r->magnitude = 1;
r->normalized = 0;
secp256k1_fe_verify(r);
#endif
secp256k1_fe_sqr_inner(a->n, r->n);
}
#endif

11
src/field_5x52_impl.h
Unescape View File

@ -43,8 +43,9 @@ void static secp256k1_fe_verify(const secp256k1_fe_t *a) {
r &= (d[2] <= 0xFFFFFFFFFFFFFULL * m);
r &= (d[3] <= 0xFFFFFFFFFFFFFULL * m);
r &= (d[4] <= 0x0FFFFFFFFFFFFULL * m);
r &= (a->magnitude >= 0);
if (a->normalized) {
r &= (m == 1);
r &= (a->magnitude <= 1);
if (r && (d[4] == 0x0FFFFFFFFFFFFULL) && ((d[3] & d[2] & d[1]) == 0xFFFFFFFFFFFFFULL)) {
r &= (d[0] < 0xFFFFEFFFFFC2FULL);
}
@ -128,7 +129,7 @@ int static inline secp256k1_fe_is_odd(const secp256k1_fe_t *a) {
void static inline secp256k1_fe_clear(secp256k1_fe_t *a) {
#ifdef VERIFY
a->magnitude = 0;
a->normalized = 0;
a->normalized = 1;
#endif
for (int i=0; i<5; i++) {
a->n[i] = 0;
@ -210,6 +211,9 @@ void static inline secp256k1_fe_mul_int(secp256k1_fe_t *r, int a) {
}
void static inline secp256k1_fe_add(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
#ifdef VERIFY
secp256k1_fe_verify(a);
#endif
r->n[0] += a->n[0];
r->n[1] += a->n[1];
r->n[2] += a->n[2];
@ -219,7 +223,6 @@ void static inline secp256k1_fe_add(secp256k1_fe_t *r, const secp256k1_fe_t *a)
r->magnitude += a->magnitude;
r->normalized = 0;
secp256k1_fe_verify(r);
secp256k1_fe_verify(a);
#endif
}
@ -241,11 +244,13 @@ void static secp256k1_fe_mul(secp256k1_fe_t *r, const secp256k1_fe_t *a, const s
void static secp256k1_fe_sqr(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
#ifdef VERIFY
VERIFY_CHECK(a->magnitude <= 8);
secp256k1_fe_verify(a);
#endif
secp256k1_fe_sqr_inner(a->n, r->n);
#ifdef VERIFY
r->magnitude = 1;
r->normalized = 0;
secp256k1_fe_verify(r);
#endif
}

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