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277 lines
7.9 KiB
277 lines
7.9 KiB
/*
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* This file is part of the TREZOR project.
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*
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* Copyright (C) 2014 Pavol Rusnak <stick@satoshilabs.com>
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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#include "crypto.h"
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#include "sha2.h"
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#include "ecdsa.h"
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#include "pbkdf2.h"
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#include "aes.h"
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#include "hmac.h"
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#include "bip32.h"
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uint32_t ser_length(uint32_t len, uint8_t *out)
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{
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if (len < 253) {
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out[0] = len & 0xFF;
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return 1;
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}
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if (len < 0x10000) {
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out[0] = 253;
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out[1] = len & 0xFF;
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out[2] = (len >> 8) & 0xFF;
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return 3;
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}
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out[0] = 254;
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out[1] = len & 0xFF;
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out[2] = (len >> 8) & 0xFF;
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out[3] = (len >> 16) & 0xFF;
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out[4] = (len >> 24) & 0xFF;
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return 5;
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}
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uint32_t deser_length(const uint8_t *in, uint32_t *out)
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{
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if (in[0] < 253) {
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*out = in[0];
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return 1;
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}
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if (in[0] == 253) {
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*out = in[1] + (in[2] << 8);
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return 1 + 2;
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}
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if (in[0] == 254) {
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*out = in[1] + (in[2] << 8) + (in[3] << 16) + (in[4] << 24);
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return 1 + 4;
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}
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*out = 0; // ignore 64 bit
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return 1 + 8;
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}
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int cryptoMessageSign(const uint8_t *message, pb_size_t message_len, const uint8_t *privkey, uint8_t *signature)
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{
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SHA256_CTX ctx;
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sha256_Init(&ctx);
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sha256_Update(&ctx, (const uint8_t *)"\x18" "Bitcoin Signed Message:" "\n", 25);
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uint8_t varint[5];
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uint32_t l = ser_length(message_len, varint);
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sha256_Update(&ctx, varint, l);
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sha256_Update(&ctx, message, message_len);
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uint8_t hash[32];
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sha256_Final(hash, &ctx);
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sha256_Raw(hash, 32, hash);
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uint8_t pby;
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ecdsa_sign_digest(privkey, hash, signature + 1, &pby);
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signature[0] = 27 + pby + 4;
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return 0;
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}
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int cryptoMessageVerify(const uint8_t *message, pb_size_t message_len, const uint8_t *address_raw, const uint8_t *signature)
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{
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bignum256 r, s, e;
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curve_point cp, cp2;
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SHA256_CTX ctx;
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uint8_t pubkey[65], addr_raw[21], hash[32];
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uint8_t nV = signature[0];
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if (nV < 27 || nV >= 35) {
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return 1;
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}
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bool compressed;
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compressed = (nV >= 31);
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if (compressed) {
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nV -= 4;
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}
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uint8_t recid = nV - 27;
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// read r and s
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bn_read_be(signature + 1, &r);
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bn_read_be(signature + 33, &s);
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// x = r
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memcpy(&cp.x, &r, sizeof(bignum256));
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// compute y from x
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uncompress_coords(recid % 2, &cp.x, &cp.y);
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// calculate hash
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sha256_Init(&ctx);
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sha256_Update(&ctx, (const uint8_t *)"\x18" "Bitcoin Signed Message:" "\n", 25);
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uint8_t varint[5];
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uint32_t l = ser_length(message_len, varint);
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sha256_Update(&ctx, varint, l);
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sha256_Update(&ctx, message, message_len);
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sha256_Final(hash, &ctx);
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sha256_Raw(hash, 32, hash);
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// e = -hash
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bn_read_be(hash, &e);
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bn_substract_noprime(&order256k1, &e, &e);
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// r = r^-1
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bn_inverse(&r, &order256k1);
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point_multiply(&s, &cp, &cp);
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scalar_multiply(&e, &cp2);
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point_add(&cp2, &cp);
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point_multiply(&r, &cp, &cp);
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pubkey[0] = 0x04;
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bn_write_be(&cp.x, pubkey + 1);
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bn_write_be(&cp.y, pubkey + 33);
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// check if the address is correct
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if (compressed) {
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pubkey[0] = 0x02 | (cp.y.val[0] & 0x01);
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}
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ecdsa_get_address_raw(pubkey, address_raw[0], addr_raw);
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if (memcmp(addr_raw, address_raw, 21) != 0) {
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return 2;
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}
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// check if signature verifies the digest
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if (ecdsa_verify_digest(pubkey, signature + 1, hash) != 0) {
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return 3;
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}
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return 0;
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}
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// internal from ecdsa.c
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int generate_k_random(bignum256 *k);
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int cryptoMessageEncrypt(curve_point *pubkey, const uint8_t *msg, pb_size_t msg_size, bool display_only, uint8_t *nonce, pb_size_t *nonce_len, uint8_t *payload, pb_size_t *payload_len, uint8_t *hmac, pb_size_t *hmac_len, const uint8_t *privkey, const uint8_t *address_raw)
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{
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if (privkey && address_raw) { // signing == true
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payload[0] = display_only ? 0x81 : 0x01;
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uint32_t l = ser_length(msg_size, payload + 1);
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memcpy(payload + 1 + l, msg, msg_size);
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memcpy(payload + 1 + l + msg_size, address_raw, 21);
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if (cryptoMessageSign(msg, msg_size, privkey, payload + 1 + l + msg_size + 21) != 0) {
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return 1;
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}
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*payload_len = 1 + l + msg_size + 21 + 65;
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} else {
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payload[0] = display_only ? 0x80 : 0x00;
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uint32_t l = ser_length(msg_size, payload + 1);
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memcpy(payload + 1 + l, msg, msg_size);
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*payload_len = 1 + l + msg_size;
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}
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// generate random nonce
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curve_point R;
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bignum256 k;
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if (generate_k_random(&k) != 0) {
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return 2;
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}
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// compute k*G
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scalar_multiply(&k, &R);
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nonce[0] = 0x02 | (R.y.val[0] & 0x01);
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bn_write_be(&R.x, nonce + 1);
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*nonce_len = 33;
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// compute shared secret
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point_multiply(&k, pubkey, &R);
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uint8_t shared_secret[33];
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shared_secret[0] = 0x02 | (R.y.val[0] & 0x01);
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bn_write_be(&R.x, shared_secret + 1);
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// generate keying bytes
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uint8_t keying_bytes[80];
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uint8_t salt[22 + 33 + 4];
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memcpy(salt, "Bitcoin Secure Message", 22);
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memcpy(salt + 22, nonce, 33);
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pbkdf2_hmac_sha256(shared_secret, 33, salt, 22 + 33, 2048, keying_bytes, 80, NULL);
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// encrypt payload
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aes_encrypt_ctx ctx;
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aes_encrypt_key256(keying_bytes, &ctx);
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aes_cfb_encrypt(payload, payload, *payload_len, keying_bytes + 64, &ctx);
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// compute hmac
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uint8_t out[32];
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hmac_sha256(keying_bytes + 32, 32, payload, *payload_len, out);
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memcpy(hmac, out, 8);
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*hmac_len = 8;
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return 0;
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}
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int cryptoMessageDecrypt(curve_point *nonce, uint8_t *payload, pb_size_t payload_len, const uint8_t *hmac, pb_size_t hmac_len, const uint8_t *privkey, uint8_t *msg, pb_size_t *msg_len, bool *display_only, bool *signing, uint8_t *address_raw)
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{
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if (hmac_len != 8) {
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return 1;
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}
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// compute shared secret
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curve_point R;
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bignum256 k;
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bn_read_be(privkey, &k);
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point_multiply(&k, nonce, &R);
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uint8_t shared_secret[33];
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shared_secret[0] = 0x02 | (R.y.val[0] & 0x01);
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bn_write_be(&R.x, shared_secret + 1);
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// generate keying bytes
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uint8_t keying_bytes[80];
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uint8_t salt[22 + 33 + 4];
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memcpy(salt, "Bitcoin Secure Message", 22);
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salt[22] = 0x02 | (nonce->y.val[0] & 0x01);
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bn_write_be(&(nonce->x), salt + 23);
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pbkdf2_hmac_sha256(shared_secret, 33, salt, 22 + 33, 2048, keying_bytes, 80, NULL);
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// compute hmac
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uint8_t out[32];
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hmac_sha256(keying_bytes + 32, 32, payload, payload_len, out);
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if (memcmp(hmac, out, 8) != 0) {
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return 2;
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}
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// decrypt payload
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aes_encrypt_ctx ctx;
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aes_encrypt_key256(keying_bytes, &ctx);
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aes_cfb_decrypt(payload, payload, payload_len, keying_bytes + 64, &ctx);
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// check first byte
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if (payload[0] != 0x00 && payload[0] != 0x01 && payload[0] != 0x80 && payload[0] != 0x81) {
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return 3;
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}
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*signing = payload[0] & 0x01;
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*display_only = payload[0] & 0x80;
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uint32_t l, o;
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l = deser_length(payload + 1, &o);
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if (*signing) {
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if (1 + l + o + 21 + 65 != payload_len) {
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return 4;
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}
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if (cryptoMessageVerify(payload + 1 + l, o, payload + 1 + l + o, payload + 1 + l + o + 21) != 0) {
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return 5;
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}
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memcpy(address_raw, payload + 1 + l + o, 21);
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} else {
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if (1 + l + o != payload_len) {
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return 4;
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}
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}
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memcpy(msg, payload + 1 + l, o);
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*msg_len = o;
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return 0;
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}
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uint8_t *cryptoHDNodePathToPubkey(const HDNodePathType *hdnodepath)
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{
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static HDNode node;
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hdnode_from_xpub(hdnodepath->node.depth, hdnodepath->node.fingerprint, hdnodepath->node.child_num, hdnodepath->node.chain_code.bytes, hdnodepath->node.public_key.bytes, &node);
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uint32_t i;
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for (i = 0; i < hdnodepath->address_n_count; i++) {
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hdnode_public_ckd(&node, hdnodepath->address_n[i]);
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}
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return node.public_key;
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}
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int cryptoMultisigPubkeyIndex(const MultisigRedeemScriptType *multisig, const uint8_t *pubkey)
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{
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int i;
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for (i = 0; i < multisig->pubkeys_count; i++) {
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if (memcmp(cryptoHDNodePathToPubkey(&(multisig->pubkeys[i])), pubkey, 33) == 0) {
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return i;
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}
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}
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return -1;
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}
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