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Diffstat (limited to 'vendor/github.com/ethereum/go-ethereum/crypto/secp256k1/ext.h')
-rw-r--r-- | vendor/github.com/ethereum/go-ethereum/crypto/secp256k1/ext.h | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/vendor/github.com/ethereum/go-ethereum/crypto/secp256k1/ext.h b/vendor/github.com/ethereum/go-ethereum/crypto/secp256k1/ext.h new file mode 100644 index 000000000..e422fe4b4 --- /dev/null +++ b/vendor/github.com/ethereum/go-ethereum/crypto/secp256k1/ext.h @@ -0,0 +1,130 @@ +// Copyright 2015 Jeffrey Wilcke, Felix Lange, Gustav Simonsson. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be found in +// the LICENSE file. + +// secp256k1_context_create_sign_verify creates a context for signing and signature verification. +static secp256k1_context* secp256k1_context_create_sign_verify() { + return secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY); +} + +// secp256k1_ext_ecdsa_recover recovers the public key of an encoded compact signature. +// +// Returns: 1: recovery was successful +// 0: recovery was not successful +// Args: ctx: pointer to a context object (cannot be NULL) +// Out: pubkey_out: the serialized 65-byte public key of the signer (cannot be NULL) +// In: sigdata: pointer to a 65-byte signature with the recovery id at the end (cannot be NULL) +// msgdata: pointer to a 32-byte message (cannot be NULL) +static int secp256k1_ext_ecdsa_recover( + const secp256k1_context* ctx, + unsigned char *pubkey_out, + const unsigned char *sigdata, + const unsigned char *msgdata +) { + secp256k1_ecdsa_recoverable_signature sig; + secp256k1_pubkey pubkey; + + if (!secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &sig, sigdata, (int)sigdata[64])) { + return 0; + } + if (!secp256k1_ecdsa_recover(ctx, &pubkey, &sig, msgdata)) { + return 0; + } + size_t outputlen = 65; + return secp256k1_ec_pubkey_serialize(ctx, pubkey_out, &outputlen, &pubkey, SECP256K1_EC_UNCOMPRESSED); +} + +// secp256k1_ext_ecdsa_verify verifies an encoded compact signature. +// +// Returns: 1: signature is valid +// 0: signature is invalid +// Args: ctx: pointer to a context object (cannot be NULL) +// In: sigdata: pointer to a 64-byte signature (cannot be NULL) +// msgdata: pointer to a 32-byte message (cannot be NULL) +// pubkeydata: pointer to public key data (cannot be NULL) +// pubkeylen: length of pubkeydata +static int secp256k1_ext_ecdsa_verify( + const secp256k1_context* ctx, + const unsigned char *sigdata, + const unsigned char *msgdata, + const unsigned char *pubkeydata, + size_t pubkeylen +) { + secp256k1_ecdsa_signature sig; + secp256k1_pubkey pubkey; + + if (!secp256k1_ecdsa_signature_parse_compact(ctx, &sig, sigdata)) { + return 0; + } + if (!secp256k1_ec_pubkey_parse(ctx, &pubkey, pubkeydata, pubkeylen)) { + return 0; + } + return secp256k1_ecdsa_verify(ctx, &sig, msgdata, &pubkey); +} + +// secp256k1_ext_reencode_pubkey decodes then encodes a public key. It can be used to +// convert between public key formats. The input/output formats are chosen depending on the +// length of the input/output buffers. +// +// Returns: 1: conversion successful +// 0: conversion unsuccessful +// Args: ctx: pointer to a context object (cannot be NULL) +// Out: out: output buffer that will contain the reencoded key (cannot be NULL) +// In: outlen: length of out (33 for compressed keys, 65 for uncompressed keys) +// pubkeydata: the input public key (cannot be NULL) +// pubkeylen: length of pubkeydata +static int secp256k1_ext_reencode_pubkey( + const secp256k1_context* ctx, + unsigned char *out, + size_t outlen, + const unsigned char *pubkeydata, + size_t pubkeylen +) { + secp256k1_pubkey pubkey; + + if (!secp256k1_ec_pubkey_parse(ctx, &pubkey, pubkeydata, pubkeylen)) { + return 0; + } + unsigned int flag = (outlen == 33) ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED; + return secp256k1_ec_pubkey_serialize(ctx, out, &outlen, &pubkey, flag); +} + +// secp256k1_ext_scalar_mul multiplies a point by a scalar in constant time. +// +// Returns: 1: multiplication was successful +// 0: scalar was invalid (zero or overflow) +// Args: ctx: pointer to a context object (cannot be NULL) +// Out: point: the multiplied point (usually secret) +// In: point: pointer to a 64-byte public point, +// encoded as two 256bit big-endian numbers. +// scalar: a 32-byte scalar with which to multiply the point +int secp256k1_ext_scalar_mul(const secp256k1_context* ctx, unsigned char *point, const unsigned char *scalar) { + int ret = 0; + int overflow = 0; + secp256k1_fe feX, feY; + secp256k1_gej res; + secp256k1_ge ge; + secp256k1_scalar s; + ARG_CHECK(point != NULL); + ARG_CHECK(scalar != NULL); + (void)ctx; + + secp256k1_fe_set_b32(&feX, point); + secp256k1_fe_set_b32(&feY, point+32); + secp256k1_ge_set_xy(&ge, &feX, &feY); + secp256k1_scalar_set_b32(&s, scalar, &overflow); + if (overflow || secp256k1_scalar_is_zero(&s)) { + ret = 0; + } else { + secp256k1_ecmult_const(&res, &ge, &s); + secp256k1_ge_set_gej(&ge, &res); + /* Note: can't use secp256k1_pubkey_save here because it is not constant time. */ + secp256k1_fe_normalize(&ge.x); + secp256k1_fe_normalize(&ge.y); + secp256k1_fe_get_b32(point, &ge.x); + secp256k1_fe_get_b32(point+32, &ge.y); + ret = 1; + } + secp256k1_scalar_clear(&s); + return ret; +} |