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Abstract out tweak logic to secp256k1_eckey_* functions

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pull/11871/head
Pieter Wuille 10 years ago
parent ffffc87855
commit eb74c36bd2
3 changed files with 78 additions and 49 deletions
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6
src/eckey.h
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@ -10,7 +10,13 @@
int static secp256k1_eckey_pubkey_parse(secp256k1_ge_t *elem, const unsigned char *pub, int size);
void static secp256k1_eckey_pubkey_serialize(secp256k1_ge_t *elem, unsigned char *pub, int *size, int compressed);
int static secp256k1_eckey_privkey_parse(secp256k1_num_t *key, const unsigned char *privkey, int privkeylen);
int static secp256k1_eckey_privkey_serialize(unsigned char *privkey, int *privkeylen, const secp256k1_num_t *key, int compressed);
int static secp256k1_eckey_privkey_tweak_add(secp256k1_num_t *key, const secp256k1_num_t *tweak);
int static secp256k1_eckey_pubkey_tweak_add(secp256k1_ge_t *key, const secp256k1_num_t *tweak);
int static secp256k1_eckey_privkey_tweak_mul(secp256k1_num_t *key, const secp256k1_num_t *tweak);
int static secp256k1_eckey_pubkey_tweak_mul(secp256k1_ge_t *key, const secp256k1_num_t *tweak);
#endif

55
src/eckey_impl.h
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@ -131,4 +131,59 @@ int static secp256k1_eckey_privkey_serialize(unsigned char *privkey, int *privke
return 1;
}
int static secp256k1_eckey_privkey_tweak_add(secp256k1_num_t *key, const secp256k1_num_t *tweak) {
if (secp256k1_num_cmp(tweak, &secp256k1_ge_consts->order) >= 0)
return 0;
secp256k1_num_add(key, key, tweak);
secp256k1_num_mod(key, &secp256k1_ge_consts->order);
if (secp256k1_num_is_zero(key))
return 0;
return 1;
}
int static secp256k1_eckey_pubkey_tweak_add(secp256k1_ge_t *key, const secp256k1_num_t *tweak) {
if (secp256k1_num_cmp(tweak, &secp256k1_ge_consts->order) >= 0)
return 0;
secp256k1_gej_t pt;
secp256k1_gej_set_ge(&pt, key);
secp256k1_num_t one;
secp256k1_num_init(&one);
secp256k1_num_set_int(&one, 1);
secp256k1_ecmult(&pt, &pt, &one, tweak);
secp256k1_num_free(&one);
if (secp256k1_gej_is_infinity(&pt))
return 0;
secp256k1_ge_set_gej(key, &pt);
return 1;
}
int static secp256k1_eckey_privkey_tweak_mul(secp256k1_num_t *key, const secp256k1_num_t *tweak) {
if (secp256k1_num_is_zero(tweak))
return 0;
if (secp256k1_num_cmp(tweak, &secp256k1_ge_consts->order) >= 0)
return 0;
secp256k1_num_mod_mul(key, key, tweak, &secp256k1_ge_consts->order);
return 1;
}
int static secp256k1_eckey_pubkey_tweak_mul(secp256k1_ge_t *key, const secp256k1_num_t *tweak) {
if (secp256k1_num_is_zero(tweak))
return 0;
if (secp256k1_num_cmp(tweak, &secp256k1_ge_consts->order) >= 0)
return 0;
secp256k1_num_t zero;
secp256k1_num_init(&zero);
secp256k1_num_set_int(&zero, 0);
secp256k1_gej_t pt;
secp256k1_gej_set_ge(&pt, key);
secp256k1_ecmult(&pt, &pt, tweak, &zero);
secp256k1_num_free(&zero);
secp256k1_ge_set_gej(key, &pt);
return 1;
}
#endif

66
src/secp256k1.c
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@ -220,23 +220,18 @@ int secp256k1_ec_privkey_tweak_add(unsigned char *seckey, const unsigned char *t
DEBUG_CHECK(seckey != NULL);
DEBUG_CHECK(tweak != NULL);
int ret = 1;
secp256k1_num_t term;
secp256k1_num_init(&term);
secp256k1_num_set_bin(&term, tweak, 32);
if (secp256k1_num_cmp(&term, &secp256k1_ge_consts->order) >= 0)
ret = 0;
secp256k1_num_t sec;
secp256k1_num_init(&sec);
secp256k1_num_set_bin(&sec, seckey, 32);
int ret = secp256k1_eckey_privkey_tweak_add(&sec, &term);
if (ret) {
secp256k1_num_set_bin(&sec, seckey, 32);
secp256k1_num_add(&sec, &sec, &term);
secp256k1_num_mod(&sec, &secp256k1_ge_consts->order);
if (secp256k1_num_is_zero(&sec))
ret = 0;
}
if (ret)
secp256k1_num_get_bin(seckey, 32, &sec);
}
secp256k1_num_clear(&sec);
secp256k1_num_clear(&term);
secp256k1_num_free(&sec);
@ -249,32 +244,20 @@ int secp256k1_ec_pubkey_tweak_add(unsigned char *pubkey, int pubkeylen, const un
DEBUG_CHECK(pubkey != NULL);
DEBUG_CHECK(tweak != NULL);
int ret = 1;
secp256k1_num_t term;
secp256k1_num_init(&term);
secp256k1_num_set_bin(&term, tweak, 32);
if (secp256k1_num_cmp(&term, &secp256k1_ge_consts->order) >= 0)
ret = 0;
secp256k1_ge_t p;
int ret = secp256k1_eckey_pubkey_parse(&p, pubkey, pubkeylen);
if (ret) {
if (!secp256k1_eckey_pubkey_parse(&p, pubkey, pubkeylen))
ret = 0;
ret = secp256k1_eckey_pubkey_tweak_add(&p, &term);
}
if (ret) {
secp256k1_gej_t pt;
secp256k1_gej_set_ge(&pt, &p);
secp256k1_num_t one;
secp256k1_num_init(&one);
secp256k1_num_set_int(&one, 1);
secp256k1_ecmult(&pt, &pt, &one, &term);
secp256k1_num_free(&one);
if (secp256k1_gej_is_infinity(&pt))
ret = 0;
secp256k1_ge_set_gej(&p, &pt);
int oldlen = pubkeylen;
secp256k1_eckey_pubkey_serialize(&p, pubkey, &pubkeylen, oldlen <= 33);
VERIFY_CHECK(pubkeylen == oldlen);
}
secp256k1_num_free(&term);
return ret;
}
@ -283,22 +266,19 @@ int secp256k1_ec_privkey_tweak_mul(unsigned char *seckey, const unsigned char *t
DEBUG_CHECK(seckey != NULL);
DEBUG_CHECK(tweak != NULL);
int ret = 1;
secp256k1_num_t factor;
secp256k1_num_init(&factor);
secp256k1_num_set_bin(&factor, tweak, 32);
if (secp256k1_num_is_zero(&factor))
ret = 0;
if (secp256k1_num_cmp(&factor, &secp256k1_ge_consts->order) >= 0)
ret = 0;
secp256k1_num_t sec;
secp256k1_num_init(&sec);
secp256k1_num_set_bin(&sec, seckey, 32);
int ret = secp256k1_eckey_privkey_tweak_mul(&sec, &factor);
if (ret) {
secp256k1_num_set_bin(&sec, seckey, 32);
secp256k1_num_mod_mul(&sec, &sec, &factor, &secp256k1_ge_consts->order);
}
if (ret)
secp256k1_num_get_bin(seckey, 32, &sec);
}
secp256k1_num_clear(&sec);
secp256k1_num_clear(&factor);
secp256k1_num_free(&sec);
secp256k1_num_free(&factor);
return ret;
@ -309,32 +289,20 @@ int secp256k1_ec_pubkey_tweak_mul(unsigned char *pubkey, int pubkeylen, const un
DEBUG_CHECK(pubkey != NULL);
DEBUG_CHECK(tweak != NULL);
int ret = 1;
secp256k1_num_t factor;
secp256k1_num_init(&factor);
secp256k1_num_set_bin(&factor, tweak, 32);
if (secp256k1_num_is_zero(&factor))
ret = 0;
if (secp256k1_num_cmp(&factor, &secp256k1_ge_consts->order) >= 0)
ret = 0;
secp256k1_ge_t p;
int ret = secp256k1_eckey_pubkey_parse(&p, pubkey, pubkeylen);
if (ret) {
if (!secp256k1_eckey_pubkey_parse(&p, pubkey, pubkeylen))
ret = 0;
ret = secp256k1_eckey_pubkey_tweak_mul(&p, &factor);
}
if (ret) {
secp256k1_num_t zero;
secp256k1_num_init(&zero);
secp256k1_num_set_int(&zero, 0);
secp256k1_gej_t pt;
secp256k1_gej_set_ge(&pt, &p);
secp256k1_ecmult(&pt, &pt, &factor, &zero);
secp256k1_num_free(&zero);
secp256k1_ge_set_gej(&p, &pt);
int oldlen = pubkeylen;
secp256k1_eckey_pubkey_serialize(&p, pubkey, &pubkeylen, oldlen <= 33);
VERIFY_CHECK(pubkeylen == oldlen);
}
secp256k1_num_free(&factor);
return ret;
}

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