diff options
Diffstat (limited to 'src/eckey_impl.h')
| -rw-r--r-- | src/eckey_impl.h | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/src/eckey_impl.h b/src/eckey_impl.h new file mode 100644 index 0000000000..290b1f0900 --- /dev/null +++ b/src/eckey_impl.h @@ -0,0 +1,200 @@ +/********************************************************************** + * Copyright (c) 2013, 2014 Pieter Wuille * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or http://www.opensource.org/licenses/mit-license.php.* + **********************************************************************/ + +#ifndef _SECP256K1_ECKEY_IMPL_H_ +#define _SECP256K1_ECKEY_IMPL_H_ + +#include "eckey.h" + +#include "num.h" +#include "field.h" +#include "group.h" +#include "ecmult_gen.h" + +static int secp256k1_eckey_pubkey_parse(secp256k1_ge_t *elem, const unsigned char *pub, int size) { + if (size == 33 && (pub[0] == 0x02 || pub[0] == 0x03)) { + secp256k1_fe_t x; + secp256k1_fe_set_b32(&x, pub+1); + return secp256k1_ge_set_xo(elem, &x, pub[0] == 0x03); + } else if (size == 65 && (pub[0] == 0x04 || pub[0] == 0x06 || pub[0] == 0x07)) { + secp256k1_fe_t x, y; + secp256k1_fe_set_b32(&x, pub+1); + secp256k1_fe_set_b32(&y, pub+33); + secp256k1_ge_set_xy(elem, &x, &y); + if ((pub[0] == 0x06 || pub[0] == 0x07) && secp256k1_fe_is_odd(&y) != (pub[0] == 0x07)) + return 0; + return secp256k1_ge_is_valid(elem); + } else { + return 0; + } +} + +static int secp256k1_eckey_pubkey_serialize(secp256k1_ge_t *elem, unsigned char *pub, int *size, int compressed) { + if (secp256k1_ge_is_infinity(elem)) { + return 0; + } + secp256k1_fe_normalize(&elem->x); + secp256k1_fe_normalize(&elem->y); + secp256k1_fe_get_b32(&pub[1], &elem->x); + if (compressed) { + *size = 33; + pub[0] = 0x02 | (secp256k1_fe_is_odd(&elem->y) ? 0x01 : 0x00); + } else { + *size = 65; + pub[0] = 0x04; + secp256k1_fe_get_b32(&pub[33], &elem->y); + } + return 1; +} + +static int secp256k1_eckey_privkey_parse(secp256k1_scalar_t *key, const unsigned char *privkey, int privkeylen) { + const unsigned char *end = privkey + privkeylen; + /* sequence header */ + if (end < privkey+1 || *privkey != 0x30) + return 0; + privkey++; + /* sequence length constructor */ + int lenb = 0; + if (end < privkey+1 || !(*privkey & 0x80)) + return 0; + lenb = *privkey & ~0x80; privkey++; + if (lenb < 1 || lenb > 2) + return 0; + if (end < privkey+lenb) + return 0; + /* sequence length */ + int len = 0; + len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0); + privkey += lenb; + if (end < privkey+len) + return 0; + /* sequence element 0: version number (=1) */ + if (end < privkey+3 || privkey[0] != 0x02 || privkey[1] != 0x01 || privkey[2] != 0x01) + return 0; + privkey += 3; + /* sequence element 1: octet string, up to 32 bytes */ + if (end < privkey+2 || privkey[0] != 0x04 || privkey[1] > 0x20 || end < privkey+2+privkey[1]) + return 0; + int overflow = 0; + unsigned char c[32] = {0}; + memcpy(c + 32 - privkey[1], privkey + 2, privkey[1]); + secp256k1_scalar_set_b32(key, c, &overflow); + memset(c, 0, 32); + return !overflow; +} + +static int secp256k1_eckey_privkey_serialize(unsigned char *privkey, int *privkeylen, const secp256k1_scalar_t *key, int compressed) { + secp256k1_gej_t rp; + secp256k1_ecmult_gen(&rp, key); + secp256k1_ge_t r; + secp256k1_ge_set_gej(&r, &rp); + if (compressed) { + static const unsigned char begin[] = { + 0x30,0x81,0xD3,0x02,0x01,0x01,0x04,0x20 + }; + static const unsigned char middle[] = { + 0xA0,0x81,0x85,0x30,0x81,0x82,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48, + 0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, + 0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, + 0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04, + 0x21,0x02,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87, + 0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8, + 0x17,0x98,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, + 0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E, + 0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x24,0x03,0x22,0x00 + }; + unsigned char *ptr = privkey; + memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin); + secp256k1_scalar_get_b32(ptr, key); ptr += 32; + memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle); + int pubkeylen = 0; + if (!secp256k1_eckey_pubkey_serialize(&r, ptr, &pubkeylen, 1)) { + return 0; + } + ptr += pubkeylen; + *privkeylen = ptr - privkey; + } else { + static const unsigned char begin[] = { + 0x30,0x82,0x01,0x13,0x02,0x01,0x01,0x04,0x20 + }; + static const unsigned char middle[] = { + 0xA0,0x81,0xA5,0x30,0x81,0xA2,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48, + 0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, + 0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, + 0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04, + 0x41,0x04,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87, + 0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8, + 0x17,0x98,0x48,0x3A,0xDA,0x77,0x26,0xA3,0xC4,0x65,0x5D,0xA4,0xFB,0xFC,0x0E,0x11, + 0x08,0xA8,0xFD,0x17,0xB4,0x48,0xA6,0x85,0x54,0x19,0x9C,0x47,0xD0,0x8F,0xFB,0x10, + 0xD4,0xB8,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, + 0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E, + 0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x44,0x03,0x42,0x00 + }; + unsigned char *ptr = privkey; + memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin); + secp256k1_scalar_get_b32(ptr, key); ptr += 32; + memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle); + int pubkeylen = 0; + if (!secp256k1_eckey_pubkey_serialize(&r, ptr, &pubkeylen, 0)) { + return 0; + } + ptr += pubkeylen; + *privkeylen = ptr - privkey; + } + return 1; +} + +static int secp256k1_eckey_privkey_tweak_add(secp256k1_scalar_t *key, const secp256k1_scalar_t *tweak) { + secp256k1_scalar_add(key, key, tweak); + if (secp256k1_scalar_is_zero(key)) + return 0; + return 1; +} + +static int 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; +} + +static int secp256k1_eckey_privkey_tweak_mul(secp256k1_scalar_t *key, const secp256k1_scalar_t *tweak) { + if (secp256k1_scalar_is_zero(tweak)) + return 0; + + secp256k1_scalar_mul(key, key, tweak); + return 1; +} + +static int 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 |