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Abstract out verify logic for fe_normalize_weak

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This commit is contained in:
Pieter Wuille 2022-01-28 17:54:22 -05:00
parent b6b6f9cb97
commit e28b51f522
4 changed files with 16 additions and 13 deletions
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7
src/field.h
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@ -76,6 +76,7 @@ static const secp256k1_fe secp256k1_const_beta = SECP256K1_FE_CONST(
* internal field implementation, to avoid the potential overhead of a
* function call (even though presumably inlinable). */
# define secp256k1_fe_normalize secp256k1_fe_impl_normalize
# define secp256k1_fe_normalize_weak secp256k1_fe_impl_normalize_weak
#endif /* !defined(VERIFY) */
/** Normalize a field element.
@ -85,7 +86,11 @@ static const secp256k1_fe secp256k1_const_beta = SECP256K1_FE_CONST(
*/
static void secp256k1_fe_normalize(secp256k1_fe *r);
/** Weakly normalize a field element: reduce its magnitude to 1, but don't fully normalize. */
/** Give a field element magnitude 1.
*
* On input, r must be a valid field element.
* On output, r represents the same value but has magnitude=1. Normalized is unchanged.
*/
static void secp256k1_fe_normalize_weak(secp256k1_fe *r);
/** Normalize a field element, without constant-time guarantee. */

7
src/field_10x26_impl.h
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@ -107,7 +107,7 @@ static void secp256k1_fe_impl_normalize(secp256k1_fe *r) {
r->n[5] = t5; r->n[6] = t6; r->n[7] = t7; r->n[8] = t8; r->n[9] = t9;
}
static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
static void secp256k1_fe_impl_normalize_weak(secp256k1_fe *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];
@ -131,11 +131,6 @@ static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
r->n[5] = t5; r->n[6] = t6; r->n[7] = t7; r->n[8] = t8; r->n[9] = t9;
#ifdef VERIFY
r->magnitude = 1;
secp256k1_fe_verify(r);
#endif
}
static void secp256k1_fe_normalize_var(secp256k1_fe *r) {

7
src/field_5x52_impl.h
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@ -89,7 +89,7 @@ static void secp256k1_fe_impl_normalize(secp256k1_fe *r) {
r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
}
static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
static void secp256k1_fe_impl_normalize_weak(secp256k1_fe *r) {
uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
/* Reduce t4 at the start so there will be at most a single carry from the first pass */
@ -106,11 +106,6 @@ static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
VERIFY_CHECK(t4 >> 49 == 0);
r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
#ifdef VERIFY
r->magnitude = 1;
secp256k1_fe_verify(r);
#endif
}
static void secp256k1_fe_normalize_var(secp256k1_fe *r) {

8
src/field_impl.h
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@ -156,6 +156,14 @@ SECP256K1_INLINE static void secp256k1_fe_normalize(secp256k1_fe *r) {
r->normalized = 1;
secp256k1_fe_verify(r);
}
static void secp256k1_fe_impl_normalize_weak(secp256k1_fe *r);
SECP256K1_INLINE static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
secp256k1_fe_verify(r);
secp256k1_fe_impl_normalize_weak(r);
r->magnitude = 1;
secp256k1_fe_verify(r);
}
#endif /* defined(VERIFY) */
#endif /* SECP256K1_FIELD_IMPL_H */