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383 lines
11 KiB
383 lines
11 KiB
/**
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* Copyright (c) SatoshiLabs
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
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* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <assert.h>
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#include <stdbool.h>
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#include <string.h>
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#include "memzero.h"
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#include "secp256k1.h"
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#include "zkp_context.h"
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#include "vendor/secp256k1-zkp/include/secp256k1.h"
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#include "vendor/secp256k1-zkp/include/secp256k1_extrakeys.h"
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#include "vendor/secp256k1-zkp/include/secp256k1_preallocated.h"
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#include "vendor/secp256k1-zkp/include/secp256k1_recovery.h"
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#include "zkp_ecdsa.h"
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static bool is_zero_digest(const uint8_t *digest) {
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const uint8_t zeroes[32] = {0};
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return memcmp(digest, zeroes, 32) == 0;
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}
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// ECDSA compressed public key derivation
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// curve has to be &secp256k1
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// private_key_bytes has 32 bytes
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// public_key_bytes has 33 bytes
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// returns 0 on success
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int zkp_ecdsa_get_public_key33(const ecdsa_curve *curve,
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const uint8_t *private_key_bytes,
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uint8_t *public_key_bytes) {
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assert(curve == &secp256k1);
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if (curve != &secp256k1) {
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return 1;
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}
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int result = 0;
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secp256k1_context *context_writable = NULL;
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if (result == 0) {
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context_writable = zkp_context_acquire_writable();
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if (context_writable == NULL) {
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result = 1;
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}
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}
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if (result == 0) {
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if (secp256k1_context_writable_randomize(context_writable) != 0) {
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result = 1;
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}
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}
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secp256k1_pubkey public_key = {0};
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if (result == 0) {
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if (secp256k1_ec_pubkey_create(context_writable, &public_key,
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private_key_bytes) != 1) {
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result = 1;
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}
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}
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if (context_writable) {
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zkp_context_release_writable();
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context_writable = NULL;
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}
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if (result == 0) {
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size_t written = 33;
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const secp256k1_context *context_read_only = zkp_context_get_read_only();
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int returned = secp256k1_ec_pubkey_serialize(
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context_read_only, public_key_bytes, &written, &public_key,
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SECP256K1_EC_COMPRESSED);
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if (returned != 1 || written != 33) {
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result = 1;
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}
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}
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memzero(&public_key, sizeof(public_key));
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return result;
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}
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// ECDSA uncompressed public key derivation
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// curve has to be &secp256k1
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// private_key_bytes has 32 bytes
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// public_key_bytes has 65 bytes
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// returns 0 on success
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int zkp_ecdsa_get_public_key65(const ecdsa_curve *curve,
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const uint8_t *private_key_bytes,
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uint8_t *public_key_bytes) {
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assert(curve == &secp256k1);
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if (curve != &secp256k1) {
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return 1;
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}
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int result = 0;
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secp256k1_context *context_writable = NULL;
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if (result == 0) {
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context_writable = zkp_context_acquire_writable();
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if (context_writable == NULL) {
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result = 1;
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}
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}
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if (result == 0) {
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if (secp256k1_context_writable_randomize(context_writable) != 0) {
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result = 1;
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}
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}
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secp256k1_pubkey public_key = {0};
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if (result == 0) {
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if (secp256k1_ec_pubkey_create(context_writable, &public_key,
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private_key_bytes) != 1) {
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result = 1;
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}
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}
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if (context_writable) {
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zkp_context_release_writable();
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context_writable = NULL;
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}
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if (result == 0) {
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size_t written = 65;
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const secp256k1_context *context_read_only = zkp_context_get_read_only();
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int returned = secp256k1_ec_pubkey_serialize(
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context_read_only, public_key_bytes, &written, &public_key,
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SECP256K1_EC_UNCOMPRESSED);
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if (returned != 1 || written != 65) {
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result = 1;
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}
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}
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memzero(&public_key, sizeof(public_key));
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return result;
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}
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// ECDSA signing
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// curve has to be &secp256k1
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// private_key_bytes has 32 bytes
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// digest has 32 bytes
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// signature_bytes has 64 bytes
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// pby is one byte
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// is_canonical has to be NULL
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// returns 0 on success
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int zkp_ecdsa_sign_digest(
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const ecdsa_curve *curve, const uint8_t *private_key_bytes,
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const uint8_t *digest, uint8_t *signature_bytes, uint8_t *pby,
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int (*is_canonical)(uint8_t by, uint8_t signature_bytes[64])) {
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assert(curve == &secp256k1);
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assert(is_canonical == NULL);
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if (curve != &secp256k1 || is_canonical != NULL) {
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return 1;
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}
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int result = 0;
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if (result == 0) {
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if (is_zero_digest(digest)) {
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// The probability of the digest being all-zero by chance is
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// infinitesimal, so this is most likely an indication of a bug.
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// Furthermore, the signature has no value, because in this case it can be
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// easily forged for any public key, see zkp_ecdsa_verify_digest().
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result = 1;
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}
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}
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secp256k1_context *context_writable = NULL;
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if (result == 0) {
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context_writable = zkp_context_acquire_writable();
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if (context_writable == NULL) {
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result = 1;
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}
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}
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if (result == 0) {
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if (secp256k1_context_writable_randomize(context_writable) != 0) {
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result = 1;
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}
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}
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secp256k1_ecdsa_recoverable_signature recoverable_signature = {0};
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if (result == 0) {
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if (secp256k1_ecdsa_sign_recoverable(context_writable,
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&recoverable_signature, digest,
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private_key_bytes, NULL, NULL) != 1) {
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result = 1;
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}
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}
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if (context_writable) {
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zkp_context_release_writable();
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context_writable = NULL;
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}
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if (result == 0) {
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int recid = 0;
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const secp256k1_context *context_read_only = zkp_context_get_read_only();
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if (secp256k1_ecdsa_recoverable_signature_serialize_compact(
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context_read_only, signature_bytes, &recid,
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&recoverable_signature) != 1) {
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result = 1;
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}
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if (pby != NULL) {
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*pby = (uint8_t)recid;
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}
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}
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memzero(&recoverable_signature, sizeof(recoverable_signature));
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return result;
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}
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// ECDSA public key recovery
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// public_key_bytes has 65 bytes
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// signature_bytes has 64 bytes
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// digest has 32 bytes
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// recid is 0, 1, 2 or 3
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// returns 0 on success
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int zkp_ecdsa_recover_pub_from_sig(const ecdsa_curve *curve,
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uint8_t *public_key_bytes,
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const uint8_t *signature_bytes,
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const uint8_t *digest, int recid) {
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assert(curve == &secp256k1);
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if (curve != &secp256k1) {
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return 1;
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}
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int result = 0;
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const secp256k1_context *context_read_only = zkp_context_get_read_only();
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secp256k1_ecdsa_recoverable_signature recoverable_signature = {0};
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if (result == 0) {
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if (secp256k1_ecdsa_recoverable_signature_parse_compact(
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context_read_only, &recoverable_signature, signature_bytes,
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recid) != 1) {
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result = 1;
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}
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}
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secp256k1_pubkey public_key = {0};
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if (result == 0) {
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if (secp256k1_ecdsa_recover(context_read_only, &public_key,
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&recoverable_signature, digest) != 1) {
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result = 1;
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}
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}
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memzero(&recoverable_signature, sizeof(recoverable_signature));
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if (result == 0) {
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size_t written = 65;
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int returned = secp256k1_ec_pubkey_serialize(
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context_read_only, public_key_bytes, &written, &public_key,
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SECP256K1_EC_UNCOMPRESSED);
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if (returned != 1 || written != 65) {
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result = 1;
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}
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}
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memzero(&public_key, sizeof(public_key));
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return result;
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}
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// ECDSA verification
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// curve has to be &secp256k1
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// public_key_bytes has 33 or 65 bytes
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// signature_bytes has 64 bytes
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// digest has 32 bytes
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// returns 0 if verification succeeded
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int zkp_ecdsa_verify_digest(const ecdsa_curve *curve,
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const uint8_t *public_key_bytes,
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const uint8_t *signature_bytes,
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const uint8_t *digest) {
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assert(curve == &secp256k1);
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if (curve != &secp256k1) {
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return 1;
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}
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int result = 0;
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int public_key_length = 0;
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if (result == 0) {
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if (public_key_bytes[0] == 0x04) {
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public_key_length = 65;
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} else if (public_key_bytes[0] == 0x02 || public_key_bytes[0] == 0x03) {
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public_key_length = 33;
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} else {
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result = 1;
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}
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}
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if (result == 0) {
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if (is_zero_digest(digest)) {
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// The digest was all-zero. The probability of this happening by chance is
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// infinitesimal, but it could be induced by a fault injection. In this
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// case the signature (r,s) can be forged by taking r := (t * Q).x mod n
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// and s := r * t^-1 mod n for any t in [1, n-1]. We fail verification,
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// because there is no guarantee that the signature was created by the
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// owner of the private key.
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result = 3;
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}
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}
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const secp256k1_context *context_read_only = zkp_context_get_read_only();
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secp256k1_pubkey public_key = {0};
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if (result == 0) {
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if (secp256k1_ec_pubkey_parse(context_read_only, &public_key,
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public_key_bytes, public_key_length) != 1) {
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result = 1;
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}
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}
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secp256k1_ecdsa_signature signature = {0};
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if (result == 0) {
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if (secp256k1_ecdsa_signature_parse_compact(context_read_only, &signature,
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signature_bytes) != 1) {
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result = 2;
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}
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}
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if (result == 0) {
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secp256k1_ecdsa_signature_normalize(context_read_only, &signature,
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&signature);
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if (secp256k1_ecdsa_verify(context_read_only, &signature, digest,
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&public_key) != 1) {
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result = 5;
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}
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}
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memzero(&public_key, sizeof(public_key));
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memzero(&signature, sizeof(signature));
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return result;
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}
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// ECDSA verification
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// curve has to be &secp256k1
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// public_key_bytes has 33 or 65 bytes
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// signature_bytes has 64 bytes
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// returns 0 if verification succeeded
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int zkp_ecdsa_verify(const ecdsa_curve *curve, HasherType hasher_type,
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const uint8_t *public_key_bytes,
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const uint8_t *signature_bytes, const uint8_t *message,
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uint32_t message_length) {
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assert(curve == &secp256k1);
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if (curve != &secp256k1) {
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return 1;
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}
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uint8_t hash[32] = {0};
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hasher_Raw(hasher_type, message, message_length, hash);
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int result =
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zkp_ecdsa_verify_digest(curve, public_key_bytes, signature_bytes, hash);
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memzero(hash, sizeof(hash));
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return result;
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}
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