trezor-firmware/firmware/crypto.c

/*
 * This file is part of the TREZOR project, https://trezor.io/
 *
 * Copyright (C) 2014 Pavol Rusnak <stick@satoshilabs.com>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <string.h>
#include "crypto.h"
#include "sha2.h"
#include "pbkdf2.h"
#include "aes/aes.h"
#include "hmac.h"
#include "bip32.h"
#include "layout.h"
#include "curves.h"
#include "secp256k1.h"
#include "address.h"
#include "coins.h"
#include "base58.h"
#include "segwit_addr.h"
#include "cash_addr.h"

uint32_t ser_length(uint32_t len, uint8_t *out)
{
	if (len < 253) {
		out[0] = len & 0xFF;
		return 1;
	}
	if (len < 0x10000) {
		out[0] = 253;
		out[1] = len & 0xFF;
		out[2] = (len >> 8) & 0xFF;
		return 3;
	}
	out[0] = 254;
	out[1] = len & 0xFF;
	out[2] = (len >> 8) & 0xFF;
	out[3] = (len >> 16) & 0xFF;
	out[4] = (len >> 24) & 0xFF;
	return 5;
}

uint32_t ser_length_hash(Hasher *hasher, uint32_t len)
{
	if (len < 253) {
		hasher_Update(hasher, (const uint8_t *)&len, 1);
		return 1;
	}
	if (len < 0x10000) {
		uint8_t d = 253;
		hasher_Update(hasher, &d, 1);
		hasher_Update(hasher, (const uint8_t *)&len, 2);
		return 3;
	}
	uint8_t d = 254;
	hasher_Update(hasher, &d, 1);
	hasher_Update(hasher, (const uint8_t *)&len, 4);
	return 5;
}

uint32_t deser_length(const uint8_t *in, uint32_t *out)
{
	if (in[0] < 253) {
		*out = in[0];
		return 1;
	}
	if (in[0] == 253) {
		*out = in[1] + (in[2] << 8);
		return 1 + 2;
	}
	if (in[0] == 254) {
		*out = in[1] + (in[2] << 8) + (in[3] << 16) + ((uint32_t) in[4] << 24);
		return 1 + 4;
	}
	*out = 0; // ignore 64 bit
	return 1 + 8;
}

int sshMessageSign(HDNode *node, const uint8_t *message, size_t message_len, uint8_t *signature)
{
	signature[0] = 0; // prefix: pad with zero, so all signatures are 65 bytes
	return hdnode_sign(node, message, message_len, HASHER_SHA2, signature + 1, NULL, NULL);
}

int gpgMessageSign(HDNode *node, const uint8_t *message, size_t message_len, uint8_t *signature)
{
	signature[0] = 0; // prefix: pad with zero, so all signatures are 65 bytes
	const curve_info *ed25519_curve_info = get_curve_by_name(ED25519_NAME);
	if (ed25519_curve_info && node->curve == ed25519_curve_info) {
		// GPG supports variable size digest for Ed25519 signatures
		return hdnode_sign(node, message, message_len, 0, signature + 1, NULL, NULL);
	} else {
		// Ensure 256-bit digest before proceeding
		if (message_len != 32) {
			return 1;
		}
		return hdnode_sign_digest(node, message, signature + 1, NULL, NULL);
	}
}

static void cryptoMessageHash(const CoinInfo *coin, const uint8_t *message, size_t message_len, uint8_t hash[HASHER_DIGEST_LENGTH]) {
	Hasher hasher;
	hasher_Init(&hasher, coin->curve->hasher_sign);
	hasher_Update(&hasher, (const uint8_t *)coin->signed_message_header, strlen(coin->signed_message_header));
	uint8_t varint[5];
	uint32_t l = ser_length(message_len, varint);
	hasher_Update(&hasher, varint, l);
	hasher_Update(&hasher, message, message_len);
	hasher_Final(&hasher, hash);
}

int cryptoMessageSign(const CoinInfo *coin, HDNode *node, InputScriptType script_type, const uint8_t *message, size_t message_len, uint8_t *signature)
{
	uint8_t hash[HASHER_DIGEST_LENGTH];
	cryptoMessageHash(coin, message, message_len, hash);

	uint8_t pby;
	int result = hdnode_sign_digest(node, hash, signature + 1, &pby, NULL);
	if (result == 0) {
		switch (script_type) {
			case InputScriptType_SPENDP2SHWITNESS:
				// segwit-in-p2sh
				signature[0] = 35 + pby;
				break;
			case InputScriptType_SPENDWITNESS:
				// segwit
				signature[0] = 39 + pby;
				break;
			default:
				// p2pkh
				signature[0] = 31 + pby;
				break;
		}
	}
	return result;
}

int cryptoMessageVerify(const CoinInfo *coin, const uint8_t *message, size_t message_len, const char *address, const uint8_t *signature)
{
	// check for invalid signature prefix
	if (signature[0] < 27 || signature[0] > 43) {
		return 1;
	}

	uint8_t hash[HASHER_DIGEST_LENGTH];
	cryptoMessageHash(coin, message, message_len, hash);

	uint8_t recid = (signature[0] - 27) % 4;
	bool compressed = signature[0] >= 31;

	// check if signature verifies the digest and recover the public key
	uint8_t pubkey[65];
	if (ecdsa_recover_pub_from_sig(coin->curve->params, pubkey, signature + 1, hash, recid) != 0) {
		return 3;
	}
	// convert public key to compressed pubkey if necessary
	if (compressed) {
		pubkey[0] = 0x02 | (pubkey[64] & 1);
	}

	// check if the address is correct
	uint8_t addr_raw[MAX_ADDR_RAW_SIZE];
	uint8_t recovered_raw[MAX_ADDR_RAW_SIZE];

	// p2pkh
	if (signature[0] >= 27 && signature[0] <= 34) {
		size_t len;
		if (coin->cashaddr_prefix) {
			if (!cash_addr_decode(addr_raw, &len, coin->cashaddr_prefix, address)) {
				return 2;
			}
		} else {
			len = base58_decode_check(address, coin->curve->hasher_base58, addr_raw, MAX_ADDR_RAW_SIZE);
		}
		ecdsa_get_address_raw(pubkey, coin->address_type, coin->curve->hasher_pubkey, recovered_raw);
		if (memcmp(recovered_raw, addr_raw, len) != 0
			|| len != address_prefix_bytes_len(coin->address_type) + 20) {
			return 2;
		}
	} else
	// segwit-in-p2sh
	if (signature[0] >= 35 && signature[0] <= 38) {
		size_t len = base58_decode_check(address, coin->curve->hasher_base58, addr_raw, MAX_ADDR_RAW_SIZE);
		ecdsa_get_address_segwit_p2sh_raw(pubkey, coin->address_type_p2sh, coin->curve->hasher_pubkey, recovered_raw);
		if (memcmp(recovered_raw, addr_raw, len) != 0
			|| len != address_prefix_bytes_len(coin->address_type_p2sh) + 20) {
			return 2;
		}
	} else
	// segwit
	if (signature[0] >= 39 && signature[0] <= 42) {
		int witver;
		size_t len;
		if (!coin->bech32_prefix
			|| !segwit_addr_decode(&witver, recovered_raw, &len, coin->bech32_prefix, address)) {
			return 4;
		}
		ecdsa_get_pubkeyhash(pubkey, coin->curve->hasher_pubkey, addr_raw);
		if (memcmp(recovered_raw, addr_raw, len) != 0
			|| witver != 0 || len != 20) {
			return 2;
		}
	} else {
		return 4;
	}

	return 0;
}

/* ECIES disabled
int cryptoMessageEncrypt(curve_point *pubkey, const uint8_t *msg, size_t msg_size, bool display_only, uint8_t *nonce, size_t *nonce_len, uint8_t *payload, size_t *payload_len, uint8_t *hmac, size_t *hmac_len, const uint8_t *privkey, const uint8_t *address_raw)
{
	if (privkey && address_raw) { // signing == true
		HDNode node;
		payload[0] = display_only ? 0x81 : 0x01;
		uint32_t l = ser_length(msg_size, payload + 1);
		memcpy(payload + 1 + l, msg, msg_size);
		memcpy(payload + 1 + l + msg_size, address_raw, 21);
		hdnode_from_xprv(0, 0, 0, privkey, privkey, SECP256K1_NAME, &node);
		if (cryptoMessageSign(&node, msg, msg_size, payload + 1 + l + msg_size + 21) != 0) {
			return 1;
		}
		*payload_len = 1 + l + msg_size + 21 + 65;
	} else {
		payload[0] = display_only ? 0x80 : 0x00;
		uint32_t l = ser_length(msg_size, payload + 1);
		memcpy(payload + 1 + l, msg, msg_size);
		*payload_len = 1 + l + msg_size;
	}
	// generate random nonce
	curve_point R;
	bignum256 k;
	if (generate_k_random(&secp256k1, &k) != 0) {
		return 2;
	}
	// compute k*G
	scalar_multiply(&secp256k1, &k, &R);
	nonce[0] = 0x02 | (R.y.val[0] & 0x01);
	bn_write_be(&R.x, nonce + 1);
	*nonce_len = 33;
	// compute shared secret
	point_multiply(&secp256k1, &k, pubkey, &R);
	uint8_t shared_secret[33];
	shared_secret[0] = 0x02 | (R.y.val[0] & 0x01);
	bn_write_be(&R.x, shared_secret + 1);
	// generate keying bytes
	uint8_t keying_bytes[80];
	uint8_t salt[22 + 33];
	memcpy(salt, "Bitcoin Secure Message", 22);
	memcpy(salt + 22, nonce, 33);
	pbkdf2_hmac_sha256(shared_secret, 33, salt, 22 + 33, 2048, keying_bytes, 80);
	// encrypt payload
	aes_encrypt_ctx ctx;
	aes_encrypt_key256(keying_bytes, &ctx);
	aes_cfb_encrypt(payload, payload, *payload_len, keying_bytes + 64, &ctx);
	// compute hmac
	uint8_t out[32];
	hmac_sha256(keying_bytes + 32, 32, payload, *payload_len, out);
	memcpy(hmac, out, 8);
	*hmac_len = 8;

	return 0;
}

int cryptoMessageDecrypt(curve_point *nonce, uint8_t *payload, size_t payload_len, const uint8_t *hmac, size_t hmac_len, const uint8_t *privkey, uint8_t *msg, size_t *msg_len, bool *display_only, bool *signing, uint8_t *address_raw)
{
	if (hmac_len != 8) {
		return 1;
	}
	// compute shared secret
	curve_point R;
	bignum256 k;
	bn_read_be(privkey, &k);
	point_multiply(&secp256k1, &k, nonce, &R);
	uint8_t shared_secret[33];
	shared_secret[0] = 0x02 | (R.y.val[0] & 0x01);
	bn_write_be(&R.x, shared_secret + 1);
	// generate keying bytes
	uint8_t keying_bytes[80];
	uint8_t salt[22 + 33];
	memcpy(salt, "Bitcoin Secure Message", 22);
	salt[22] = 0x02 | (nonce->y.val[0] & 0x01);
	bn_write_be(&(nonce->x), salt + 23);
	pbkdf2_hmac_sha256(shared_secret, 33, salt, 22 + 33, 2048, keying_bytes, 80);
	// compute hmac
	uint8_t out[32];
	hmac_sha256(keying_bytes + 32, 32, payload, payload_len, out);
	if (memcmp(hmac, out, 8) != 0) {
		return 2;
	}
	// decrypt payload
	aes_encrypt_ctx ctx;
	aes_encrypt_key256(keying_bytes, &ctx);
	aes_cfb_decrypt(payload, payload, payload_len, keying_bytes + 64, &ctx);
	// check first byte
	if (payload[0] != 0x00 && payload[0] != 0x01 && payload[0] != 0x80 && payload[0] != 0x81) {
		return 3;
	}
	*signing = payload[0] & 0x01;
	*display_only = payload[0] & 0x80;
	uint32_t l, o;
	l = deser_length(payload + 1, &o);
	if (*signing) {
		// FIXME: assumes a raw address is 21 bytes (also below).
		if (1 + l + o + 21 + 65 != payload_len) {
			return 4;
		}
		// FIXME: cryptoMessageVerify changed to take the address_type as a parameter.
		if (cryptoMessageVerify(payload + 1 + l, o, payload + 1 + l + o, payload + 1 + l + o + 21) != 0) {
			return 5;
		}
		memcpy(address_raw, payload + 1 + l + o, 21);
	} else {
		if (1 + l + o != payload_len) {
			return 4;
		}
	}
	memcpy(msg, payload + 1 + l, o);
	*msg_len = o;
	return 0;
}
*/

uint8_t *cryptoHDNodePathToPubkey(const CoinInfo *coin, const HDNodePathType *hdnodepath)
{
	if (!hdnodepath->node.has_public_key || hdnodepath->node.public_key.size != 33) return 0;
	static HDNode node;
	if (hdnode_from_xpub(hdnodepath->node.depth, hdnodepath->node.child_num, hdnodepath->node.chain_code.bytes, hdnodepath->node.public_key.bytes, coin->curve_name, &node) == 0) {
		return 0;
	}
	layoutProgressUpdate(true);
	for (uint32_t i = 0; i < hdnodepath->address_n_count; i++) {
		if (hdnode_public_ckd(&node, hdnodepath->address_n[i]) == 0) {
			return 0;
		}
		layoutProgressUpdate(true);
	}
	return node.public_key;
}

int cryptoMultisigPubkeyIndex(const CoinInfo *coin, const MultisigRedeemScriptType *multisig, const uint8_t *pubkey)
{
	for (size_t i = 0; i < multisig->pubkeys_count; i++) {
		const uint8_t *node_pubkey = cryptoHDNodePathToPubkey(coin, &(multisig->pubkeys[i]));
		if (node_pubkey && memcmp(node_pubkey, pubkey, 33) == 0) {
			return i;
		}
	}
	return -1;
}

int cryptoMultisigFingerprint(const MultisigRedeemScriptType *multisig, uint8_t *hash)
{
	static const HDNodePathType *ptr[15], *swap;
	const uint32_t n = multisig->pubkeys_count;
	if (n < 1 || n > 15) {
		return 0;
	}
	// check sanity
	if (!multisig->has_m || multisig->m < 1 || multisig->m > 15) return 0;
	for (uint32_t i = 0; i < n; i++) {
		ptr[i] = &(multisig->pubkeys[i]);
		if (!ptr[i]->node.has_public_key || ptr[i]->node.public_key.size != 33) return 0;
		if (ptr[i]->node.chain_code.size != 32) return 0;
	}
	// minsort according to pubkey
	for (uint32_t i = 0; i < n - 1; i++) {
		for (uint32_t j = n - 1; j > i; j--) {
			if (memcmp(ptr[i]->node.public_key.bytes, ptr[j]->node.public_key.bytes, 33) > 0) {
				swap = ptr[i];
				ptr[i] = ptr[j];
				ptr[j] = swap;
			}
		}
	}
	// hash sorted nodes
	SHA256_CTX ctx;
	sha256_Init(&ctx);
	sha256_Update(&ctx, (const uint8_t *)&(multisig->m), sizeof(uint32_t));
	for (uint32_t i = 0; i < n; i++) {
		sha256_Update(&ctx, (const uint8_t *)&(ptr[i]->node.depth), sizeof(uint32_t));
		sha256_Update(&ctx, (const uint8_t *)&(ptr[i]->node.fingerprint), sizeof(uint32_t));
		sha256_Update(&ctx, (const uint8_t *)&(ptr[i]->node.child_num), sizeof(uint32_t));
		sha256_Update(&ctx, ptr[i]->node.chain_code.bytes, 32);
		sha256_Update(&ctx, ptr[i]->node.public_key.bytes, 33);
	}
	sha256_Update(&ctx, (const uint8_t *)&n, sizeof(uint32_t));
	sha256_Final(&ctx, hash);
	layoutProgressUpdate(true);
	return 1;
}

int cryptoIdentityFingerprint(const IdentityType *identity, uint8_t *hash)
{
	SHA256_CTX ctx;
	sha256_Init(&ctx);
	sha256_Update(&ctx, (const uint8_t *)&(identity->index), sizeof(uint32_t));
	if (identity->has_proto && identity->proto[0]) {
		sha256_Update(&ctx, (const uint8_t *)(identity->proto), strlen(identity->proto));
		sha256_Update(&ctx, (const uint8_t *)"://", 3);
	}
	if (identity->has_user && identity->user[0]) {
		sha256_Update(&ctx, (const uint8_t *)(identity->user), strlen(identity->user));
		sha256_Update(&ctx, (const uint8_t *)"@", 1);
	}
	if (identity->has_host && identity->host[0]) {
		sha256_Update(&ctx, (const uint8_t *)(identity->host), strlen(identity->host));
	}
	if (identity->has_port && identity->port[0]) {
		sha256_Update(&ctx, (const uint8_t *)":", 1);
		sha256_Update(&ctx, (const uint8_t *)(identity->port), strlen(identity->port));
	}
	if (identity->has_path && identity->path[0]) {
		sha256_Update(&ctx, (const uint8_t *)(identity->path), strlen(identity->path));
	}
	sha256_Final(&ctx, hash);
	return 1;
}