diff options
Diffstat (limited to 'src/group.h')
| -rw-r--r-- | src/group.h | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/src/group.h b/src/group.h index 6185be052d..36e39ecf0f 100644 --- a/src/group.h +++ b/src/group.h @@ -59,6 +59,7 @@ static int secp256k1_ge_is_infinity(const secp256k1_ge *a); /** Check whether a group element is valid (i.e., on the curve). */ static int secp256k1_ge_is_valid_var(const secp256k1_ge *a); +/** Set r equal to the inverse of a (i.e., mirrored around the X axis) */ static void secp256k1_ge_neg(secp256k1_ge *r, const secp256k1_ge *a); /** Set a group element equal to another which is given in jacobian coordinates */ @@ -115,10 +116,8 @@ static void secp256k1_gej_add_ge_var(secp256k1_gej *r, const secp256k1_gej *a, c /** Set r equal to the sum of a and b (with the inverse of b's Z coordinate passed as bzinv). */ static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_ge *b, const secp256k1_fe *bzinv); -#ifdef USE_ENDOMORPHISM /** Set r to be equal to lambda times a, where lambda is chosen in a way such that this is very fast. */ static void secp256k1_ge_mul_lambda(secp256k1_ge *r, const secp256k1_ge *a); -#endif /** Clear a secp256k1_gej to prevent leaking sensitive information. */ static void secp256k1_gej_clear(secp256k1_gej *r); @@ -138,4 +137,15 @@ static void secp256k1_ge_storage_cmov(secp256k1_ge_storage *r, const secp256k1_g /** Rescale a jacobian point by b which must be non-zero. Constant-time. */ static void secp256k1_gej_rescale(secp256k1_gej *r, const secp256k1_fe *b); +/** Determine if a point (which is assumed to be on the curve) is in the correct (sub)group of the curve. + * + * In normal mode, the used group is secp256k1, which has cofactor=1 meaning that every point on the curve is in the + * group, and this function returns always true. + * + * When compiling in exhaustive test mode, a slightly different curve equation is used, leading to a group with a + * (very) small subgroup, and that subgroup is what is used for all cryptographic operations. In that mode, this + * function checks whether a point that is on the curve is in fact also in that subgroup. + */ +static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge* ge); + #endif /* SECP256K1_GROUP_H */ |