mirror of
https://github.com/ElementsProject/lightning.git
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336 lines
9.5 KiB
C
336 lines
9.5 KiB
C
#include <ccan/cast/cast.h>
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#include "privkey.h"
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#include "pubkey.h"
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#include "script.h"
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#include "secp256k1.h"
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#include "shadouble.h"
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#include "signature.h"
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#include "tx.h"
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#include <assert.h>
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#undef DEBUG
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#ifdef DEBUG
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#include <ccan/err/err.h>
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#define SHA_FMT \
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"%02x%02x%02x%02x%02x%02x%02x%02x" \
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"%02x%02x%02x%02x%02x%02x%02x%02x" \
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"%02x%02x%02x%02x%02x%02x%02x%02x" \
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"%02x%02x%02x%02x%02x%02x%02x%02x"
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#define SHA_VALS(e) \
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e[0], e[1], e[2], e[3], e[4], e[5], e[6], e[7], \
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e[8], e[9], e[10], e[11], e[12], e[13], e[14], e[15], \
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e[16], e[17], e[18], e[19], e[20], e[21], e[22], e[23], \
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e[24], e[25], e[25], e[26], e[28], e[29], e[30], e[31]
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static void dump_tx(const char *msg,
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const struct bitcoin_tx *tx, size_t inputnum,
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const u8 *script, size_t script_len,
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const struct pubkey *key)
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{
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size_t i, j;
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warnx("%s tx version %u locktime %#x:",
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msg, tx->version, tx->lock_time);
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for (i = 0; i < tx->input_count; i++) {
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warnx("input[%zu].txid = "SHA_FMT, i,
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SHA_VALS(tx->input[i].txid.sha.u.u8));
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warnx("input[%zu].index = %u", i, tx->input[i].index);
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}
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for (i = 0; i < tx->output_count; i++) {
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warnx("output[%zu].amount = %llu",
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i, (long long)tx->output[i].amount);
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warnx("output[%zu].script = %llu",
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i, (long long)tx->output[i].script_length);
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for (j = 0; j < tx->output[i].script_length; j++)
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fprintf(stderr, "%02x", tx->output[i].script[j]);
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fprintf(stderr, "\n");
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}
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warnx("input[%zu].script = %zu", inputnum, script_len);
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for (i = 0; i < script_len; i++)
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fprintf(stderr, "%02x", script[i]);
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if (key) {
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fprintf(stderr, "\nPubkey: ");
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for (i = 0; i < pubkey_len(key); i++)
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fprintf(stderr, "%02x", key->key[i]);
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fprintf(stderr, "\n");
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}
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}
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#else
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static void dump_tx(const char *msg,
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const struct bitcoin_tx *tx, size_t inputnum,
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const u8 *script, size_t script_len,
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const struct pubkey *key)
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{
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}
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#endif
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bool sign_hash(const tal_t *ctx, const struct privkey *privkey,
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const struct sha256_double *h,
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struct signature *s)
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{
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secp256k1_context_t *secpctx;
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bool ok;
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secpctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
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if (!secpctx)
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return false;
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#ifdef USE_SCHNORR
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ok = secp256k1_schnorr_sign(secpctx, h->sha.u.u8,
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(unsigned char *)s,
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privkey->secret, NULL, NULL);
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#else
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ok = secp256k1_ecdsa_sign_compact(secpctx, h->sha.u.u8,
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(unsigned char *)s,
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privkey->secret, NULL, NULL, NULL);
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#endif
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secp256k1_context_destroy(secpctx);
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return ok;
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}
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/* Only does SIGHASH_ALL */
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static void sha256_tx_one_input(struct bitcoin_tx *tx,
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size_t input_num,
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const u8 *script, size_t script_len,
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struct sha256_double *hash)
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{
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struct sha256_ctx ctx = SHA256_INIT;
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size_t i;
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assert(input_num < tx->input_count);
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/* You must have all inputs zeroed to start. */
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for (i = 0; i < tx->input_count; i++)
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assert(tx->input[i].script_length == 0);
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tx->input[input_num].script_length = script_len;
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tx->input[input_num].script = cast_const(u8 *, script);
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sha256_init(&ctx);
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sha256_tx_for_sig(&ctx, tx);
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sha256_le32(&ctx, SIGHASH_ALL);
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sha256_double_done(&ctx, hash);
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/* Reset it for next time. */
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tx->input[input_num].script_length = 0;
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tx->input[input_num].script = NULL;
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}
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/* Only does SIGHASH_ALL */
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bool sign_tx_input(const tal_t *ctx, struct bitcoin_tx *tx,
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unsigned int in,
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const u8 *subscript, size_t subscript_len,
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const struct privkey *privkey, const struct pubkey *key,
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struct signature *sig)
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{
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struct sha256_double hash;
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sha256_tx_one_input(tx, in, subscript, subscript_len, &hash);
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dump_tx("Signing", tx, in, subscript, subscript_len, key);
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return sign_hash(ctx, privkey, &hash, sig);
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}
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static bool check_signed_hash(const struct sha256_double *hash,
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const struct signature *signature,
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const struct pubkey *key)
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{
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int ret;
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secp256k1_context_t *secpctx;
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secpctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY);
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if (!secpctx)
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return false;
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#ifdef USE_SCHNORR
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ret = secp256k1_schnorr_verify(secpctx, hash->sha.u.u8,
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(unsigned char *)signature,
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key->key, pubkey_len(key));
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#else
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{
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u8 der[72];
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size_t der_len;
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/* FIXME: secp256k1 missing secp256k1_ecdsa_verify_compact */
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der_len = signature_to_der(der, signature);
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ret = secp256k1_ecdsa_verify(secpctx, hash->sha.u.u8,
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der, der_len,
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key->key, pubkey_len(key));
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}
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#endif
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secp256k1_context_destroy(secpctx);
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return ret == 1;
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}
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bool check_tx_sig(struct bitcoin_tx *tx, size_t input_num,
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const u8 *redeemscript, size_t redeemscript_len,
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const struct pubkey *key,
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const struct bitcoin_signature *sig)
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{
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struct sha256_double hash;
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bool ret;
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assert(input_num < tx->input_count);
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sha256_tx_one_input(tx, input_num, redeemscript, redeemscript_len,
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&hash);
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/* We only use SIGHASH_ALL for the moment. */
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if (sig->stype != SIGHASH_ALL)
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return false;
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ret = check_signed_hash(&hash, &sig->sig, key);
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if (!ret)
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dump_tx("Sig failed", tx, input_num,
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redeemscript, redeemscript_len, key);
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return ret;
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}
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bool check_2of2_sig(struct bitcoin_tx *tx, size_t input_num,
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const u8 *redeemscript, size_t redeemscript_len,
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const struct pubkey *key1, const struct pubkey *key2,
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const struct bitcoin_signature *sig1,
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const struct bitcoin_signature *sig2)
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{
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struct sha256_double hash;
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assert(input_num < tx->input_count);
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sha256_tx_one_input(tx, input_num, redeemscript, redeemscript_len,
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&hash);
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/* We only use SIGHASH_ALL for the moment. */
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if (sig1->stype != SIGHASH_ALL || sig2->stype != SIGHASH_ALL)
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return false;
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return check_signed_hash(&hash, &sig1->sig, key1)
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&& check_signed_hash(&hash, &sig2->sig, key2);
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}
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/* Stolen direct from bitcoin/src/script/sign.cpp:
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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2014 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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*/
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static bool IsValidSignatureEncoding(const unsigned char sig[], size_t len)
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{
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// Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S] [sighash]
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// * total-length: 1-byte length descriptor of everything that follows,
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// excluding the sighash byte.
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// * R-length: 1-byte length descriptor of the R value that follows.
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// * R: arbitrary-length big-endian encoded R value. It must use the shortest
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// possible encoding for a positive integers (which means no null bytes at
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// the start, except a single one when the next byte has its highest bit set).
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// * S-length: 1-byte length descriptor of the S value that follows.
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// * S: arbitrary-length big-endian encoded S value. The same rules apply.
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// * sighash: 1-byte value indicating what data is hashed (not part of the DER
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// signature)
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// Minimum and maximum size constraints.
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if (len < 9) return false;
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if (len > 73) return false;
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// A signature is of type 0x30 (compound).
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if (sig[0] != 0x30) return false;
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// Make sure the length covers the entire signature.
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if (sig[1] != len - 3) return false;
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// Extract the length of the R element.
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unsigned int lenR = sig[3];
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// Make sure the length of the S element is still inside the signature.
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if (5 + lenR >= len) return false;
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// Extract the length of the S element.
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unsigned int lenS = sig[5 + lenR];
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// Verify that the length of the signature matches the sum of the length
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// of the elements.
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if ((size_t)(lenR + lenS + 7) != len) return false;
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// Check whether the R element is an integer.
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if (sig[2] != 0x02) return false;
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// Zero-length integers are not allowed for R.
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if (lenR == 0) return false;
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// Negative numbers are not allowed for R.
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if (sig[4] & 0x80) return false;
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// Null bytes at the start of R are not allowed, unless R would
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// otherwise be interpreted as a negative number.
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if (lenR > 1 && (sig[4] == 0x00) && !(sig[5] & 0x80)) return false;
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// Check whether the S element is an integer.
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if (sig[lenR + 4] != 0x02) return false;
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// Zero-length integers are not allowed for S.
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if (lenS == 0) return false;
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// Negative numbers are not allowed for S.
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if (sig[lenR + 6] & 0x80) return false;
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// Null bytes at the start of S are not allowed, unless S would otherwise be
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// interpreted as a negative number.
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if (lenS > 1 && (sig[lenR + 6] == 0x00) && !(sig[lenR + 7] & 0x80)) return false;
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return true;
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}
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/* DER encode a value, return length used. */
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static size_t der_encode_val(const u8 *val, u8 *der)
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{
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size_t len = 0, val_len = 32;
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der[len++] = 0x2; /* value type. */
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/* Strip leading zeroes. */
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while (val_len && val[0] == 0) {
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val++;
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val_len--;
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}
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/* Add zero byte if it would otherwise be signed. */
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if (val[0] & 0x80) {
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der[len++] = 1 + val_len; /* value length */
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der[len++] = 0;
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} else
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der[len++] = val_len; /* value length */
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memcpy(der + len, val, val_len);
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return len + val_len;
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}
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size_t signature_to_der(u8 der[72], const struct signature *sig)
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{
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size_t len = 0;
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der[len++] = 0x30; /* Type */
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der[len++] = 0; /* Total length after this: fill it at end. */
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len += der_encode_val(sig->r, der + len);
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len += der_encode_val(sig->s, der + len);
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/* Fix up total length */
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der[1] = len - 2;
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/* IsValidSignatureEncoding() expect extra byte for sighash */
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assert(IsValidSignatureEncoding(der, len + 1));
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return len;
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}
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/* Signature must have low S value. */
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bool sig_valid(const struct signature *sig)
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{
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#ifdef USE_SCHNORR
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/* FIXME: Is there some sanity check we can do here? */
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return true;
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#else
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return (sig->s[0] & 0x80) == 0;
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#endif
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}
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