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trezor-firmware/firmware/signing.c

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/*
* This file is part of the TREZOR project.
*
* 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 "signing.h"
#include "fsm.h"
#include "layout2.h"
#include "messages.h"
#include "transaction.h"
#include "ecdsa.h"
#include "protect.h"
#include "crypto.h"
#include "secp256k1.h"
static uint32_t inputs_count;
static uint32_t outputs_count;
static const CoinType *coin;
static const HDNode *root;
static HDNode node;
static bool signing = false;
enum {
STAGE_REQUEST_1_INPUT,
STAGE_REQUEST_2_PREV_META,
STAGE_REQUEST_2_PREV_INPUT,
STAGE_REQUEST_2_PREV_OUTPUT,
STAGE_REQUEST_2_PREV_EXTRADATA,
STAGE_REQUEST_3_OUTPUT,
STAGE_REQUEST_4_INPUT,
STAGE_REQUEST_4_OUTPUT,
STAGE_REQUEST_5_OUTPUT
} signing_stage;
static uint32_t idx1, idx2;
static TxRequest resp;
static TxInputType input;
static TxOutputBinType bin_output;
static TxStruct to, tp, ti;
static SHA256_CTX tc;
static uint8_t hash[32], hash_check[32], privkey[32], pubkey[33], sig[64];
static uint64_t to_spend, spending, change_spend;
static uint32_t version = 1;
static uint32_t lock_time = 0;
static uint32_t progress, progress_step, progress_meta_step;
static bool multisig_fp_set, multisig_fp_mismatch;
static uint8_t multisig_fp[32];
/* progress_step/meta_step are fixed point numbers, giving the
* progress per input in permille with these many additional bits.
*/
#define PROGRESS_PRECISION 16
/*
Workflow of streamed signing
The STAGE_ constants describe the signing_stage when request is sent.
I - input
O - output
Phase1 - check inputs, previous transactions, and outputs
- ask for confirmations
- check fee
=========================================================
foreach I (idx1):
Request I STAGE_REQUEST_1_INPUT
Add I to TransactionChecksum
Calculate amount of I:
Request prevhash I, META STAGE_REQUEST_2_PREV_META
foreach prevhash I (idx2):
Request prevhash I STAGE_REQUEST_2_PREV_INPUT
foreach prevhash O (idx2):
Request prevhash O STAGE_REQUEST_2_PREV_OUTPUT
Add amount of prevhash O (which is amount of I)
Request prevhash extra data (if applicable) STAGE_REQUEST_2_PREV_EXTRADATA
Calculate hash of streamed tx, compare to prevhash I
foreach O (idx1):
Request O STAGE_REQUEST_3_OUTPUT
Add O to TransactionChecksum
Display output
Ask for confirmation
Check tx fee
Ask for confirmation
Phase2: sign inputs, check that nothing changed
===============================================
foreach I (idx1): // input to sign
foreach I (idx2):
Request I STAGE_REQUEST_4_INPUT
If idx1 == idx2
Remember key for signing
Fill scriptsig
Add I to StreamTransactionSign
Add I to TransactionChecksum
foreach O (idx2):
Request O STAGE_REQUEST_4_OUTPUT
Add O to StreamTransactionSign
Add O to TransactionChecksum
Compare TransactionChecksum with checksum computed in Phase 1
If different:
Failure
Sign StreamTransactionSign
Return signed chunk
foreach O (idx1):
Request O STAGE_REQUEST_5_OUTPUT
Rewrite change address
Return O
*/
void send_req_1_input(void)
{
signing_stage = STAGE_REQUEST_1_INPUT;
resp.has_request_type = true;
resp.request_type = RequestType_TXINPUT;
resp.has_details = true;
resp.details.has_request_index = true;
resp.details.request_index = idx1;
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_2_prev_meta(void)
{
signing_stage = STAGE_REQUEST_2_PREV_META;
resp.has_request_type = true;
resp.request_type = RequestType_TXMETA;
resp.has_details = true;
resp.details.has_tx_hash = true;
resp.details.tx_hash.size = input.prev_hash.size;
memcpy(resp.details.tx_hash.bytes, input.prev_hash.bytes, input.prev_hash.size);
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_2_prev_input(void)
{
signing_stage = STAGE_REQUEST_2_PREV_INPUT;
resp.has_request_type = true;
resp.request_type = RequestType_TXINPUT;
resp.has_details = true;
resp.details.has_request_index = true;
resp.details.request_index = idx2;
resp.details.has_tx_hash = true;
resp.details.tx_hash.size = input.prev_hash.size;
memcpy(resp.details.tx_hash.bytes, input.prev_hash.bytes, resp.details.tx_hash.size);
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_2_prev_output(void)
{
signing_stage = STAGE_REQUEST_2_PREV_OUTPUT;
resp.has_request_type = true;
resp.request_type = RequestType_TXOUTPUT;
resp.has_details = true;
resp.details.has_request_index = true;
resp.details.request_index = idx2;
resp.details.has_tx_hash = true;
resp.details.tx_hash.size = input.prev_hash.size;
memcpy(resp.details.tx_hash.bytes, input.prev_hash.bytes, resp.details.tx_hash.size);
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_2_prev_extradata(uint32_t chunk_offset, uint32_t chunk_len)
{
signing_stage = STAGE_REQUEST_2_PREV_EXTRADATA;
resp.has_request_type = true;
resp.request_type = RequestType_TXEXTRADATA;
resp.has_details = true;
resp.details.has_extra_data_offset = true;
resp.details.extra_data_offset = chunk_offset;
resp.details.has_extra_data_len = true;
resp.details.extra_data_len = chunk_len;
resp.details.has_tx_hash = true;
resp.details.tx_hash.size = input.prev_hash.size;
memcpy(resp.details.tx_hash.bytes, input.prev_hash.bytes, resp.details.tx_hash.size);
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_3_output(void)
{
signing_stage = STAGE_REQUEST_3_OUTPUT;
resp.has_request_type = true;
resp.request_type = RequestType_TXOUTPUT;
resp.has_details = true;
resp.details.has_request_index = true;
resp.details.request_index = idx1;
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_4_input(void)
{
signing_stage = STAGE_REQUEST_4_INPUT;
resp.has_request_type = true;
resp.request_type = RequestType_TXINPUT;
resp.has_details = true;
resp.details.has_request_index = true;
resp.details.request_index = idx2;
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_4_output(void)
{
signing_stage = STAGE_REQUEST_4_OUTPUT;
resp.has_request_type = true;
resp.request_type = RequestType_TXOUTPUT;
resp.has_details = true;
resp.details.has_request_index = true;
resp.details.request_index = idx2;
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_5_output(void)
{
signing_stage = STAGE_REQUEST_5_OUTPUT;
resp.has_request_type = true;
resp.request_type = RequestType_TXOUTPUT;
resp.has_details = true;
resp.details.has_request_index = true;
resp.details.request_index = idx1;
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void send_req_finished(void)
{
resp.has_request_type = true;
resp.request_type = RequestType_TXFINISHED;
msg_write(MessageType_MessageType_TxRequest, &resp);
}
void signing_init(uint32_t _inputs_count, uint32_t _outputs_count, const CoinType *_coin, const HDNode *_root, uint32_t _version, uint32_t _lock_time)
{
inputs_count = _inputs_count;
outputs_count = _outputs_count;
coin = _coin;
root = _root;
version = _version;
lock_time = _lock_time;
idx1 = 0;
to_spend = 0;
spending = 0;
change_spend = 0;
memset(&input, 0, sizeof(TxInputType));
memset(&resp, 0, sizeof(TxRequest));
signing = true;
progress = 0;
// we step by 500/inputs_count per input in phase1 and phase2
// this means 50 % per phase.
progress_step = (500 << PROGRESS_PRECISION) / inputs_count;
multisig_fp_set = false;
multisig_fp_mismatch = false;
tx_init(&to, inputs_count, outputs_count, version, lock_time, 0, false);
sha256_Init(&tc);
sha256_Update(&tc, (const uint8_t *)&inputs_count, sizeof(inputs_count));
sha256_Update(&tc, (const uint8_t *)&outputs_count, sizeof(outputs_count));
sha256_Update(&tc, (const uint8_t *)&version, sizeof(version));
sha256_Update(&tc, (const uint8_t *)&lock_time, sizeof(lock_time));
layoutProgressSwipe("Signing transaction", 0);
send_req_1_input();
}
#define MIN(a,b) (((a)<(b))?(a):(b))
void signing_txack(TransactionType *tx)
{
if (!signing) {
fsm_sendFailure(FailureType_Failure_UnexpectedMessage, "Not in Signing mode");
layoutHome();
return;
}
static int update_ctr = 0;
if (update_ctr++ == 20) {
layoutProgress("Signing transaction", progress);
update_ctr = 0;
}
int co;
memset(&resp, 0, sizeof(TxRequest));
switch (signing_stage) {
case STAGE_REQUEST_1_INPUT:
/* compute multisig fingerprint */
/* (if all input share the same fingerprint, outputs having the same fingerprint will be considered as change outputs) */
if (tx->inputs[0].script_type == InputScriptType_SPENDMULTISIG) {
if (tx->inputs[0].has_multisig && !multisig_fp_mismatch) {
if (multisig_fp_set) {
uint8_t h[32];
if (cryptoMultisigFingerprint(&(tx->inputs[0].multisig), h) == 0) {
fsm_sendFailure(FailureType_Failure_Other, "Error computing multisig fingeprint");
signing_abort();
return;
}
if (memcmp(multisig_fp, h, 32) != 0) {
multisig_fp_mismatch = true;
}
} else {
if (cryptoMultisigFingerprint(&(tx->inputs[0].multisig), multisig_fp) == 0) {
fsm_sendFailure(FailureType_Failure_Other, "Error computing multisig fingeprint");
signing_abort();
return;
}
multisig_fp_set = true;
}
}
} else { // InputScriptType_SPENDADDRESS
multisig_fp_mismatch = true;
}
sha256_Update(&tc, (const uint8_t *)tx->inputs, sizeof(TxInputType));
memcpy(&input, tx->inputs, sizeof(TxInputType));
send_req_2_prev_meta();
return;
case STAGE_REQUEST_2_PREV_META:
tx_init(&tp, tx->inputs_cnt, tx->outputs_cnt, tx->version, tx->lock_time, tx->extra_data_len, false);
progress_meta_step = progress_step / (tp.inputs_len + tp.outputs_len);
idx2 = 0;
if (tp.inputs_len > 0) {
send_req_2_prev_input();
} else {
tx_serialize_header_hash(&tp);
send_req_2_prev_output();
}
return;
case STAGE_REQUEST_2_PREV_INPUT:
progress = (idx1 * progress_step + idx2 * progress_meta_step) >> PROGRESS_PRECISION;
if (!tx_serialize_input_hash(&tp, tx->inputs)) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to serialize input");
signing_abort();
return;
}
if (idx2 < tp.inputs_len - 1) {
idx2++;
send_req_2_prev_input();
} else {
idx2 = 0;
send_req_2_prev_output();
}
return;
case STAGE_REQUEST_2_PREV_OUTPUT:
progress = (idx1 * progress_step + (tp.inputs_len + idx2) * progress_meta_step) >> PROGRESS_PRECISION;
if (!tx_serialize_output_hash(&tp, tx->bin_outputs)) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to serialize output");
signing_abort();
return;
}
if (idx2 == input.prev_index) {
to_spend += tx->bin_outputs[0].amount;
}
if (idx2 < tp.outputs_len - 1) {
/* Check prevtx of next input */
idx2++;
send_req_2_prev_output();
} else { // last output
if (tp.extra_data_len > 0) { // has extra data
send_req_2_prev_extradata(0, MIN(1024, tp.extra_data_len));
return;
}
tx_hash_final(&tp, hash, true);
if (memcmp(hash, input.prev_hash.bytes, 32) != 0) {
fsm_sendFailure(FailureType_Failure_Other, "Encountered invalid prevhash");
signing_abort();
return;
}
if (idx1 < inputs_count - 1) {
idx1++;
send_req_1_input();
} else {
idx1 = 0;
send_req_3_output();
}
}
return;
case STAGE_REQUEST_2_PREV_EXTRADATA:
if (!tx_serialize_extra_data_hash(&tp, tx->extra_data.bytes, tx->extra_data.size)) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to serialize extra data");
signing_abort();
return;
}
if (tp.extra_data_received < tp.extra_data_len) { // still some data remanining
send_req_2_prev_extradata(tp.extra_data_received, MIN(1024, tp.extra_data_len - tp.extra_data_received));
} else {
tx_hash_final(&tp, hash, true);
if (memcmp(hash, input.prev_hash.bytes, 32) != 0) {
fsm_sendFailure(FailureType_Failure_Other, "Encountered invalid prevhash");
signing_abort();
return;
}
if (idx1 < inputs_count - 1) {
idx1++;
send_req_1_input();
} else {
idx1 = 0;
send_req_3_output();
}
}
return;
case STAGE_REQUEST_3_OUTPUT:
{
/* Downloaded output idx1 the first time.
* Add it to transaction check
* Ask for permission.
*/
bool is_change = false;
if (tx->outputs[0].script_type == OutputScriptType_PAYTOMULTISIG &&
tx->outputs[0].has_multisig &&
multisig_fp_set && !multisig_fp_mismatch) {
uint8_t h[32];
if (cryptoMultisigFingerprint(&(tx->outputs[0].multisig), h) == 0) {
fsm_sendFailure(FailureType_Failure_Other, "Error computing multisig fingeprint");
signing_abort();
return;
}
if (memcmp(multisig_fp, h, 32) == 0) {
is_change = true;
}
} else
if (tx->outputs[0].script_type == OutputScriptType_PAYTOADDRESS &&
tx->outputs[0].address_n_count > 0) {
is_change = true;
}
if (is_change) {
if (change_spend == 0) { // not set
change_spend = tx->outputs[0].amount;
} else {
fsm_sendFailure(FailureType_Failure_Other, "Only one change output allowed");
signing_abort();
return;
}
}
spending += tx->outputs[0].amount;
co = compile_output(coin, root, tx->outputs, &bin_output, !is_change);
if (!is_change) {
layoutProgress("Signing transaction", progress);
}
if (co < 0) {
fsm_sendFailure(FailureType_Failure_Other, "Signing cancelled by user");
signing_abort();
return;
} else if (co == 0) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to compile output");
signing_abort();
return;
}
sha256_Update(&tc, (const uint8_t *)&bin_output, sizeof(TxOutputBinType));
if (idx1 < outputs_count - 1) {
idx1++;
send_req_3_output();
} else {
sha256_Final(&tc, hash_check);
// check fees
if (spending > to_spend) {
fsm_sendFailure(FailureType_Failure_NotEnoughFunds, "Not enough funds");
layoutHome();
return;
}
uint64_t fee = to_spend - spending;
uint32_t tx_est_size = transactionEstimateSizeKb(inputs_count, outputs_count);
if (fee > (uint64_t)tx_est_size * coin->maxfee_kb) {
layoutFeeOverThreshold(coin, fee, tx_est_size);
if (!protectButton(ButtonRequestType_ButtonRequest_FeeOverThreshold, false)) {
fsm_sendFailure(FailureType_Failure_ActionCancelled, "Fee over threshold. Signing cancelled.");
layoutHome();
return;
}
layoutProgress("Signing transaction", progress);
}
// last confirmation
layoutConfirmTx(coin, to_spend - change_spend, fee);
if (!protectButton(ButtonRequestType_ButtonRequest_SignTx, false)) {
fsm_sendFailure(FailureType_Failure_ActionCancelled, "Signing cancelled by user");
signing_abort();
return;
}
// Everything was checked, now phase 2 begins and the transaction is signed.
progress_meta_step = progress_step / (inputs_count + outputs_count);
layoutProgress("Signing transaction", progress);
idx1 = 0;
idx2 = 0;
send_req_4_input();
}
return;
}
case STAGE_REQUEST_4_INPUT:
progress = 500 + ((idx1 * progress_step + idx2 * progress_meta_step) >> PROGRESS_PRECISION);
if (idx2 == 0) {
tx_init(&ti, inputs_count, outputs_count, version, lock_time, 0, true);
sha256_Init(&tc);
sha256_Update(&tc, (const uint8_t *)&inputs_count, sizeof(inputs_count));
sha256_Update(&tc, (const uint8_t *)&outputs_count, sizeof(outputs_count));
sha256_Update(&tc, (const uint8_t *)&version, sizeof(version));
sha256_Update(&tc, (const uint8_t *)&lock_time, sizeof(lock_time));
memset(privkey, 0, 32);
memset(pubkey, 0, 33);
}
sha256_Update(&tc, (const uint8_t *)tx->inputs, sizeof(TxInputType));
if (idx2 == idx1) {
memcpy(&input, tx->inputs, sizeof(TxInputType));
memcpy(&node, root, sizeof(HDNode));
if (hdnode_private_ckd_cached(&node, tx->inputs[0].address_n, tx->inputs[0].address_n_count, NULL) == 0) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to derive private key");
signing_abort();
return;
}
hdnode_fill_public_key(&node);
if (tx->inputs[0].script_type == InputScriptType_SPENDMULTISIG) {
if (!tx->inputs[0].has_multisig) {
fsm_sendFailure(FailureType_Failure_Other, "Multisig info not provided");
signing_abort();
return;
}
tx->inputs[0].script_sig.size = compile_script_multisig(&(tx->inputs[0].multisig), tx->inputs[0].script_sig.bytes);
} else { // SPENDADDRESS
ecdsa_get_pubkeyhash(node.public_key, hash);
tx->inputs[0].script_sig.size = compile_script_sig(coin->address_type, hash, tx->inputs[0].script_sig.bytes);
}
if (tx->inputs[0].script_sig.size == 0) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to compile input");
signing_abort();
return;
}
memcpy(privkey, node.private_key, 32);
memcpy(pubkey, node.public_key, 33);
} else {
tx->inputs[0].script_sig.size = 0;
}
if (!tx_serialize_input_hash(&ti, tx->inputs)) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to serialize input");
signing_abort();
return;
}
if (idx2 < inputs_count - 1) {
idx2++;
send_req_4_input();
} else {
idx2 = 0;
send_req_4_output();
}
return;
case STAGE_REQUEST_4_OUTPUT:
progress = 500 + ((idx1 * progress_step + (inputs_count + idx2) * progress_meta_step) >> PROGRESS_PRECISION);
co = compile_output(coin, root, tx->outputs, &bin_output, false);
if (co < 0) {
fsm_sendFailure(FailureType_Failure_Other, "Signing cancelled by user");
signing_abort();
return;
} else if (co == 0) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to compile output");
signing_abort();
return;
}
sha256_Update(&tc, (const uint8_t *)&bin_output, sizeof(TxOutputBinType));
if (!tx_serialize_output_hash(&ti, &bin_output)) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to serialize output");
signing_abort();
return;
}
if (idx2 < outputs_count - 1) {
idx2++;
send_req_4_output();
} else {
sha256_Final(&tc, hash);
if (memcmp(hash, hash_check, 32) != 0) {
fsm_sendFailure(FailureType_Failure_Other, "Transaction has changed during signing");
signing_abort();
return;
}
tx_hash_final(&ti, hash, false);
resp.has_serialized = true;
resp.serialized.has_signature_index = true;
resp.serialized.signature_index = idx1;
resp.serialized.has_signature = true;
resp.serialized.has_serialized_tx = true;
if (ecdsa_sign_digest(&secp256k1, privkey, hash, sig, NULL, NULL) != 0) {
fsm_sendFailure(FailureType_Failure_Other, "Signing failed");
signing_abort();
return;
}
resp.serialized.signature.size = ecdsa_sig_to_der(sig, resp.serialized.signature.bytes);
if (input.script_type == InputScriptType_SPENDMULTISIG) {
if (!input.has_multisig) {
fsm_sendFailure(FailureType_Failure_Other, "Multisig info not provided");
signing_abort();
return;
}
// fill in the signature
int pubkey_idx = cryptoMultisigPubkeyIndex(&(input.multisig), pubkey);
if (pubkey_idx < 0) {
fsm_sendFailure(FailureType_Failure_Other, "Pubkey not found in multisig script");
signing_abort();
return;
}
memcpy(input.multisig.signatures[pubkey_idx].bytes, resp.serialized.signature.bytes, resp.serialized.signature.size);
input.multisig.signatures[pubkey_idx].size = resp.serialized.signature.size;
input.script_sig.size = serialize_script_multisig(&(input.multisig), input.script_sig.bytes);
if (input.script_sig.size == 0) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to serialize multisig script");
signing_abort();
return;
}
} else { // SPENDADDRESS
input.script_sig.size = serialize_script_sig(resp.serialized.signature.bytes, resp.serialized.signature.size, pubkey, 33, input.script_sig.bytes);
}
resp.serialized.serialized_tx.size = tx_serialize_input(&to, &input, resp.serialized.serialized_tx.bytes);
// since this took a longer time, update progress
layoutProgress("Signing transaction", progress);
update_ctr = 0;
if (idx1 < inputs_count - 1) {
idx1++;
idx2 = 0;
send_req_4_input();
} else {
idx1 = 0;
send_req_5_output();
}
}
return;
case STAGE_REQUEST_5_OUTPUT:
if (compile_output(coin, root, tx->outputs, &bin_output,false) <= 0) {
fsm_sendFailure(FailureType_Failure_Other, "Failed to compile output");
signing_abort();
return;
}
resp.has_serialized = true;
resp.serialized.has_serialized_tx = true;
resp.serialized.serialized_tx.size = tx_serialize_output(&to, &bin_output, resp.serialized.serialized_tx.bytes);
if (idx1 < outputs_count - 1) {
idx1++;
send_req_5_output();
} else {
send_req_finished();
signing_abort();
}
return;
}
fsm_sendFailure(FailureType_Failure_Other, "Signing error");
signing_abort();
}
void signing_abort(void)
{
if (signing) {
layoutHome();
signing = false;
}
}
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