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Private/public key tweaking

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This commit is contained in:
Pieter Wuille 2013-05-27 01:18:48 +02:00
parent e3c5c26f54
commit 561b0e1044
1 changed files with 48 additions and 0 deletions
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48
src/secp256k1.c
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@ -146,6 +146,54 @@ int secp256k1_ecdsa_pubkey_decompress(unsigned char *pubkey, int *pubkeylen) {
return 1;
}
int secp256k1_ecdsa_privkey_tweak(unsigned char *seckey, const unsigned char *tweak) {
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);
if (ret) {
secp256k1_num_set_bin(&term, 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_free(&sec);
secp256k1_num_free(&term);
return ret;
}
int secp256k1_ecdsa_pubkey_tweak(unsigned char *pubkey, int pubkeylen, const unsigned char *tweak) {
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;
if (ret) {
if (!secp256k1_ecdsa_pubkey_parse(&p, pubkey, pubkeylen))
ret = 0;
}
if (ret) {
secp256k1_gej_t pt;
secp256k1_ecmult_gen(&pt, &term);
secp256k1_gej_add_ge(&pt, &pt, &p);
secp256k1_ge_set_gej(&p, &pt);
int oldlen = pubkeylen;
secp256k1_ecdsa_pubkey_serialize(&p, pubkey, &pubkeylen, oldlen <= 33);
assert(pubkeylen == oldlen);
}
secp256k1_num_free(&term);
return ret;
}
int secp256k1_ecdsa_privkey_export(const unsigned char *seckey, unsigned char *privkey, int *privkeylen, int compressed) {
secp256k1_num_t key;
secp256k1_num_init(&key);