github.com/annchain/OG@v0.0.9/deprecated/ogcrypto/secp256k1/ext.h (about) 1 // Copyright 2015 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 // secp256k1_context_create_sign_verify creates a context for signing and signature verification. 18 static secp256k1_context* secp256k1_context_create_sign_verify() { 19 return secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY); 20 } 21 22 // secp256k1_ext_ecdsa_recover recovers the public key of an encoded compact signature. 23 // 24 // Returns: 1: recovery was successful 25 // 0: recovery was not successful 26 // Args: ctx: pointer to a context object (cannot be NULL) 27 // Out: pubkey_out: the serialized 65-byte public key of the signer (cannot be NULL) 28 // In: sigdata: pointer to a 65-byte signature with the recovery id at the end (cannot be NULL) 29 // msgdata: pointer to a 32-byte message (cannot be NULL) 30 static int secp256k1_ext_ecdsa_recover( 31 const secp256k1_context* ctx, 32 unsigned char *pubkey_out, 33 const unsigned char *sigdata, 34 const unsigned char *msgdata 35 ) { 36 secp256k1_ecdsa_recoverable_signature sig; 37 secp256k1_pubkey pubkey; 38 39 if (!secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &sig, sigdata, (int)sigdata[64])) { 40 return 0; 41 } 42 if (!secp256k1_ecdsa_recover(ctx, &pubkey, &sig, msgdata)) { 43 return 0; 44 } 45 size_t outputlen = 65; 46 return secp256k1_ec_pubkey_serialize(ctx, pubkey_out, &outputlen, &pubkey, SECP256K1_EC_UNCOMPRESSED); 47 } 48 49 // secp256k1_ext_ecdsa_verify verifies an encoded compact signature. 50 // 51 // Returns: 1: signature is valid 52 // 0: signature is invalid 53 // Args: ctx: pointer to a context object (cannot be NULL) 54 // In: sigdata: pointer to a 64-byte signature (cannot be NULL) 55 // msgdata: pointer to a 32-byte message (cannot be NULL) 56 // pubkeydata: pointer to public key data (cannot be NULL) 57 // pubkeylen: length of pubkeydata 58 static int secp256k1_ext_ecdsa_verify( 59 const secp256k1_context* ctx, 60 const unsigned char *sigdata, 61 const unsigned char *msgdata, 62 const unsigned char *pubkeydata, 63 size_t pubkeylen 64 ) { 65 secp256k1_ecdsa_signature sig; 66 secp256k1_pubkey pubkey; 67 68 if (!secp256k1_ecdsa_signature_parse_compact(ctx, &sig, sigdata)) { 69 return 0; 70 } 71 if (!secp256k1_ec_pubkey_parse(ctx, &pubkey, pubkeydata, pubkeylen)) { 72 return 0; 73 } 74 return secp256k1_ecdsa_verify(ctx, &sig, msgdata, &pubkey); 75 } 76 77 // secp256k1_ext_reencode_pubkey decodes then encodes a public key. It can be used to 78 // convert between public key formats. The input/output formats are chosen depending on the 79 // length of the input/output buffers. 80 // 81 // Returns: 1: conversion successful 82 // 0: conversion unsuccessful 83 // Args: ctx: pointer to a context object (cannot be NULL) 84 // Out: out: output buffer that will contain the reencoded key (cannot be NULL) 85 // In: outlen: length of out (33 for compressed keys, 65 for uncompressed keys) 86 // pubkeydata: the input public key (cannot be NULL) 87 // pubkeylen: length of pubkeydata 88 static int secp256k1_ext_reencode_pubkey( 89 const secp256k1_context* ctx, 90 unsigned char *out, 91 size_t outlen, 92 const unsigned char *pubkeydata, 93 size_t pubkeylen 94 ) { 95 secp256k1_pubkey pubkey; 96 97 if (!secp256k1_ec_pubkey_parse(ctx, &pubkey, pubkeydata, pubkeylen)) { 98 return 0; 99 } 100 unsigned int flag = (outlen == 33) ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED; 101 return secp256k1_ec_pubkey_serialize(ctx, out, &outlen, &pubkey, flag); 102 } 103 104 // secp256k1_ext_scalar_mul multiplies a point by a scalar in constant time. 105 // 106 // Returns: 1: multiplication was successful 107 // 0: scalar was invalid (zero or overflow) 108 // Args: ctx: pointer to a context object (cannot be NULL) 109 // Out: point: the multiplied point (usually secret) 110 // In: point: pointer to a 64-byte public point, 111 // encoded as two 256bit big-endian numbers. 112 // scalar: a 32-byte scalar with which to multiply the point 113 int secp256k1_ext_scalar_mul(const secp256k1_context* ctx, unsigned char *point, const unsigned char *scalar) { 114 int ret = 0; 115 int overflow = 0; 116 secp256k1_fe feX, feY; 117 secp256k1_gej res; 118 secp256k1_ge ge; 119 secp256k1_scalar s; 120 ARG_CHECK(point != NULL); 121 ARG_CHECK(scalar != NULL); 122 (void)ctx; 123 124 secp256k1_fe_set_b32(&feX, point); 125 secp256k1_fe_set_b32(&feY, point+32); 126 secp256k1_ge_set_xy(&ge, &feX, &feY); 127 secp256k1_scalar_set_b32(&s, scalar, &overflow); 128 if (overflow || secp256k1_scalar_is_zero(&s)) { 129 ret = 0; 130 } else { 131 secp256k1_ecmult_const(&res, &ge, &s); 132 secp256k1_ge_set_gej(&ge, &res); 133 /* Note: can't use secp256k1_pubkey_save here because it is not constant time. */ 134 secp256k1_fe_normalize(&ge.x); 135 secp256k1_fe_normalize(&ge.y); 136 secp256k1_fe_get_b32(point, &ge.x); 137 secp256k1_fe_get_b32(point+32, &ge.y); 138 ret = 1; 139 } 140 secp256k1_scalar_clear(&s); 141 return ret; 142 }