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Add segwit support to SDK
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Reviewers: alex, john, mark

Reviewed By: alex, mark

Subscribers: ben

Differential Revision: https://phabricator.bitgo.com/D6233
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Arik Sosman committed Aug 23, 2017
1 parent 6d5bd40 commit 63b446b
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Showing 6 changed files with 132 additions and 72 deletions.
4 changes: 0 additions & 4 deletions .arclint
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Expand Up @@ -14,10 +14,6 @@
},
"spelling": {
"type": "spelling"
},
"eslint": {
"type": "eslint",
"include": "(\\.js$)"
}
}
}
2 changes: 1 addition & 1 deletion package.json
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
{
"name": "bitgo",
"version": "3.7.0",
"version": "3.8.0",
"description": "BitGo Javascript SDK",
"main": "./src/index.js",
"keywords": [
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130 changes: 85 additions & 45 deletions src/transactionBuilder.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,11 +7,13 @@

var Q = require('q');
var bitcoin = require('./bitcoin');
var bitcoinCash = require('./bitcoinCash');
var common = require('./common');
var Util = require('./util');
var _ = require('lodash');

const P2SH_INPUT_SIZE = 295;
const P2SH_P2WSH_INPUT_SIZE = 139;
const P2PKH_INPUT_SIZE = 160;
const OUTPUT_SIZE = 34;
const TX_OVERHEAD_SIZE = 10;
Expand Down Expand Up @@ -363,10 +365,14 @@ exports.createTransaction = function(params) {
unspents = _.filter(unspents, function(unspent) {
return unspent.value > minInputValue;
});
let segwitInputCount = 0;
unspents.every(function(unspent) {
if (unspent.witnessScript) {
segwitInputCount++;
}
inputAmount += unspent.value;
var script = new Buffer(unspent.script, 'hex');
transaction.addInput(unspent.tx_hash, unspent.tx_output_n, 0xffffffff, script);
transaction.addInput(unspent.tx_hash, unspent.tx_output_n, 0xffffffff);

return (inputAmount < (feeSingleKeySourceAddress ? totalOutputAmount : totalAmount));
});

Expand All @@ -386,7 +392,8 @@ exports.createTransaction = function(params) {
}

txInfo = {
nP2SHInputs: transaction.tx.ins.length - (feeSingleKeySourceAddress ? 1 : 0),
nP2SHInputs: transaction.tx.ins.length - (feeSingleKeySourceAddress ? 1 : 0) - segwitInputCount,
nP2SHP2WSHInputs: segwitInputCount,
nP2PKHInputs: feeSingleKeySourceAddress ? 1 : 0,
nOutputs: (
recipients.length + 1 + // recipients and change
Expand All @@ -398,6 +405,7 @@ exports.createTransaction = function(params) {

estTxSize = estimateTransactionSize({
nP2SHInputs: txInfo.nP2SHInputs,
nP2SHP2WSHInputs: txInfo.nP2SHP2WSHInputs,
nP2PKHInputs: txInfo.nP2PKHInputs,
nOutputs: txInfo.nOutputs
});
Expand All @@ -407,6 +415,7 @@ exports.createTransaction = function(params) {
bitgo: params.wallet.bitgo,
feeRate: feeRate,
nP2SHInputs: txInfo.nP2SHInputs,
nP2SHP2WSHInputs: txInfo.nP2SHP2WSHInputs,
nP2PKHInputs: txInfo.nP2PKHInputs,
nOutputs: txInfo.nOutputs
});
Expand Down Expand Up @@ -559,7 +568,10 @@ exports.createTransaction = function(params) {
return params.changeAddress;
} else {
// Otherwise create a new address per output, for privacy
return params.wallet.createAddress({chain: 1, validate: validate})
// determine if segwit or not
const isSegwit = bitgo.getConstants().enableSegwit;
const changeChain = isSegwit ? 11 : 1;
return params.wallet.createAddress({ chain: changeChain, validate: validate })
.then(function(result) {
return result.address;
});
Expand Down Expand Up @@ -614,7 +626,7 @@ exports.createTransaction = function(params) {
var serialize = function() {
// only need to return the unspents that were used and just the chainPath, redeemScript, and instant flag
var pickedUnspents = _.map(unspents, function(unspent) {
return _.pick(unspent, ['chainPath', 'redeemScript', 'instant']);
return _.pick(unspent, ['chainPath', 'redeemScript', 'instant', 'witnessScript', 'value']);
});
var prunedUnspents = _.slice(pickedUnspents, 0, transaction.tx.ins.length - feeSingleKeyUnspentsUsed.length);
_.each(feeSingleKeyUnspentsUsed, function(feeUnspent) {
Expand Down Expand Up @@ -669,20 +681,30 @@ exports.createTransaction = function(params) {
* @returns size: estimated size of the transaction in bytes
*/
var estimateTransactionSize = function(params) {
if (typeof(params.nP2SHInputs) !== 'number' || params.nP2SHInputs < 1) {
if (!_.isInteger(params.nP2SHInputs) || params.nP2SHInputs < 0) {
throw new Error('expecting positive nP2SHInputs');
}
if ((params.nP2PKHInputs) && (typeof(params.nP2PKHInputs) !== 'number')) {
if (!_.isInteger(params.nP2PKHInputs) || params.nP2PKHInputs < 0) {
throw new Error('expecting positive nP2PKHInputs to be numeric');
}
if (typeof(params.nOutputs) !== 'number' || params.nOutputs < 1) {
if (!_.isInteger(params.nP2SHP2WSHInputs) || params.nP2SHP2WSHInputs < 0) {
throw new Error('expecting positive nP2SHP2WSHInputs to be numeric');
}
if ((params.nP2SHInputs + params.nP2SHP2WSHInputs) < 1) {
throw new Error('expecting at least one nP2SHInputs or nP2SHP2WSHInputs');
}
if (!_.isInteger(params.nOutputs) || params.nOutputs < 1) {
throw new Error('expecting positive nOutputs');
}



var estimatedSize = P2SH_INPUT_SIZE * params.nP2SHInputs +
P2SH_P2WSH_INPUT_SIZE * (params.nP2SHP2WSHInputs || 0) +
P2PKH_INPUT_SIZE * (params.nP2PKHInputs || 0) +
OUTPUT_SIZE * params.nOutputs +
TX_OVERHEAD_SIZE;
// if the tx contains at least one segwit input, the tx overhead is increased by 1
TX_OVERHEAD_SIZE + (params.nP2SHP2WSHInputs > 0 ? 1 : 0);

return estimatedSize;
};
Expand Down Expand Up @@ -736,16 +758,16 @@ exports.signTransaction = function(params) {

var validate = (params.validate === undefined) ? true : params.validate;
var privKey;
if (typeof(params.transactionHex) != 'string') {
if (typeof(params.transactionHex) !== 'string') {
throw new Error('expecting the transaction hex as a string');
}
if (!Array.isArray(params.unspents)) {
throw new Error('expecting the unspents array');
}
if (typeof(validate) != 'boolean') {
if (typeof(validate) !== 'boolean') {
throw new Error('expecting validate to be a boolean');
}
if (typeof(keychain) != 'object' || typeof(keychain.xprv) != 'string') {
if (typeof(keychain) !== 'object' || typeof(keychain.xprv) !== 'string') {
if (typeof(params.signingKey) === 'string') {
privKey = bitcoin.ECPair.fromWIF(params.signingKey, bitcoin.getNetwork());
keychain = undefined;
Expand All @@ -759,7 +781,7 @@ exports.signTransaction = function(params) {
feeSingleKey = bitcoin.ECPair.fromWIF(params.feeSingleKeyWIF, bitcoin.getNetwork());
}

var transaction = bitcoin.Transaction.fromHex(params.transactionHex);
var transaction = bitcoinCash.Transaction.fromHex(params.transactionHex);
if (transaction.ins.length !== params.unspents.length) {
throw new Error('length of unspents array should equal to the number of transaction inputs');
}
Expand All @@ -769,47 +791,57 @@ exports.signTransaction = function(params) {
var rootExtKey = bitcoin.HDNode.fromBase58(keychain.xprv);
hdPath = bitcoin.hdPath(rootExtKey);
}
var txb;

for (var index = 0; index < transaction.ins.length; ++index) {
if (params.unspents[index].redeemScript === false) {
var txb = bitcoinCash.TransactionBuilder.fromTransaction(transaction, rootExtKey.keyPair.network);

for (let index = 0; index < txb.tx.ins.length; ++index) {
const currentUnspent = params.unspents[index];
if (currentUnspent.redeemScript === false) {
// this is the input from a single key fee address
if (!feeSingleKey) {
throw new Error('single key address used in input but feeSingleKeyWIF not provided');
}

txb = bitcoin.TransactionBuilder.fromTransaction(transaction);
txb.sign(index, feeSingleKey);
transaction = txb.buildIncomplete();
continue;
}

const chainPath = currentUnspent.chainPath;
if (hdPath) {
var subPath = keychain.walletSubPath || '/0/0';
var path = keychain.path + subPath + params.unspents[index].chainPath;
var path = keychain.path + subPath + chainPath;
privKey = hdPath.deriveKey(path);
}

const isSegwitInput = !!currentUnspent.witnessScript;

// subscript is the part of the output script after the OP_CODESEPARATOR.
// Since we are only ever signing p2sh outputs, which do not have
// OP_CODESEPARATORS, it is always the output script.
var subscript = new Buffer(params.unspents[index].redeemScript, 'hex');
let subscript = new Buffer(currentUnspent.redeemScript, 'hex');
currentUnspent.validationScript = subscript;

// In order to sign with bitcoinjs-lib, we must use its transaction
// builder, confusingly named the same exact thing as our transaction
// builder, but with inequivalent behavior.
txb = bitcoin.TransactionBuilder.fromTransaction(transaction);
try {
txb.sign(index, privKey, subscript, bitcoin.Transaction.SIGHASH_ALL);
if (isSegwitInput) {
const witnessScript = new Buffer(currentUnspent.witnessScript, 'hex');
currentUnspent.validationScript = witnessScript;
txb.sign(index, privKey, subscript, bitcoin.Transaction.SIGHASH_ALL, currentUnspent.value, witnessScript);
} else {
txb.sign(index, privKey, subscript, bitcoin.Transaction.SIGHASH_ALL);
}
} catch (e) {
return Q.reject('Failed to sign input #' + index);
}

// Build the "incomplete" transaction, i.e. one that does not have all
// the signatures (since we are only signing the first of 2 signatures in
// a 2-of-3 multisig).
transaction = txb.buildIncomplete();
}

// reserialize transaction
transaction = txb.build();

for (let index = 0; index < transaction.ins.length; ++index) {
// bitcoinjs-lib adds one more OP_0 than we need. It creates one OP_0 for
// every n public keys in an m-of-n multisig, and replaces the OP_0s with
// the signature of the nth public key, then removes any remaining OP_0s
Expand All @@ -819,30 +851,21 @@ exports.signTransaction = function(params) {
// chronological order, but is not compatible with the BitGo API, which
// assumes m OP_0s for m-of-n multisig (or m-1 after the first signature
// is created). Thus we need to remove the superfluous OP_0.
var chunks = bitcoin.script.decompile(transaction.ins[index].script);
if (chunks.length !== 5) {
throw new Error('unexpected number of chunks in the OP_CHECKMULTISIG script after signing');
}
if (chunks[1]) {
chunks.splice(2, 1); // The extra OP_0 is the third chunk
} else if (chunks[2]) {
chunks.splice(1, 1); // The extra OP_0 is the second chunk
}

transaction.ins[index].script = bitcoin.script.compile(chunks);
const currentUnspent = params.unspents[index];

// The signatures are validated server side and on the bitcoin network, so
// the signature validation is optional and can be disabled by setting:
// validate = false
if (validate) {
if (exports.verifyInputSignatures(transaction, index, subscript) !== -1) {
if (exports.verifyInputSignatures(transaction, index, currentUnspent.validationScript, false, currentUnspent.value) !== -1) {
throw new Error('number of signatures is invalid - something went wrong when signing');
}
}
}

return Q.when({
transactionHex: transaction.toBuffer().toString('hex')
transactionHex: transaction.toHex()
});
};

Expand All @@ -855,22 +878,34 @@ exports.signTransaction = function(params) {
* @param inputIndex the input index to verify
* @param pubScript the redeem script to verify with
* @param ignoreKeyIndices array of multisig keys indexes (in order of keychains on the wallet). e.g. [1] to ignore backup keys
* @param amount
* @returns {number}
*/
exports.verifyInputSignatures = function(transaction, inputIndex, pubScript, ignoreKeyIndices) {
exports.verifyInputSignatures = function(transaction, inputIndex, pubScript, ignoreKeyIndices, amount) {
if (inputIndex < 0 || inputIndex >= transaction.ins.length) {
throw new Error('illegal index');
}

ignoreKeyIndices = ignoreKeyIndices || [];
var sigScript = transaction.ins[inputIndex].script;
const currentTransactionInput = transaction.ins[inputIndex];
var sigScript = currentTransactionInput.script;
var sigsNeeded = 1;
var sigs = [];
var pubKeys = [];
var decompiledSigScript = bitcoin.script.decompile(sigScript);

const isSegwitInput = currentTransactionInput.witness.length > 0;
if (isSegwitInput) {
decompiledSigScript = currentTransactionInput.witness;
sigScript = bitcoin.script.compile(decompiledSigScript);
if (!amount) {
return 0;
}
}

// Check the script type to determine number of signatures, the pub keys, and the script to hash.
switch (bitcoin.script.classifyInput(sigScript, true)) {
const inputClassification = bitcoinCash.script.classifyInput(sigScript, true);
switch (inputClassification) {
case 'scripthash':
// Replace the pubScript with the P2SH Script.
pubScript = decompiledSigScript[decompiledSigScript.length - 1];
Expand All @@ -897,16 +932,21 @@ exports.verifyInputSignatures = function(transaction, inputIndex, pubScript, ign
return 0;
}

var numVerifiedSignatures = 0;
for (var sigIndex = 0; sigIndex < sigs.length; ++sigIndex) {
let numVerifiedSignatures = 0;
for (let sigIndex = 0; sigIndex < sigs.length; ++sigIndex) {
// If this is an OP_0, then its been left as a placeholder for a future sig.
if (sigs[sigIndex] == bitcoin.opcodes.OP_0) {
if (sigs[sigIndex] === bitcoin.opcodes.OP_0) {
continue;
}

var hashType = sigs[sigIndex][sigs[sigIndex].length - 1];
sigs[sigIndex] = sigs[sigIndex].slice(0, sigs[sigIndex].length - 1); // pop hash type from end
var signatureHash = transaction.hashForSignature(inputIndex, pubScript, hashType);
let signatureHash;
if (isSegwitInput) {
signatureHash = transaction.hashForWitnessV0(inputIndex, pubScript, amount, hashType);
} else {
signatureHash = transaction.hashForSignature(inputIndex, pubScript, hashType);
}

var validSig = false;

Expand Down
5 changes: 4 additions & 1 deletion src/v2/wallet.js
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Original file line number Diff line number Diff line change
Expand Up @@ -257,6 +257,7 @@ Wallet.prototype.createAddress = function(params, callback) {
params = params || {};
common.validateParams(params, [], [], callback);

// TODO: verify address generation
params.chain = params.chain || 0;
return this.bitgo.post(this.baseCoin.url('/wallet/' + this._wallet.id + '/address'))
.send(params)
Expand Down Expand Up @@ -543,6 +544,7 @@ Wallet.prototype.signTransaction = function(params, callback) {
}
userPrv = this.bitgo.decrypt({ input: userEncryptedPrv, password: params.walletPassphrase });
}

var self = this;
return Q.fcall(function() {
const signingParams = _.extend({}, params, { txPrebuild: txPrebuild, prv: userPrv });
Expand Down Expand Up @@ -617,6 +619,7 @@ Wallet.prototype.sendMany = function(params, callback) {
throw new Error('Only one of prebuildTx and recipients may be specified');
}

// TODO: use Array.isArray
if (params.recipients && !(params.recipients instanceof Array)) {
throw new Error('expecting recipients array');
}
Expand All @@ -633,8 +636,8 @@ Wallet.prototype.sendMany = function(params, callback) {

// pass in either the prebuild promise or, if undefined, the actual prebuild
return Q.all([txPrebuildPromise || txPrebuild, userKeychainPromise])
// preserve the "this"-reference in signTransaction
.spread(function(txPrebuild, userKeychain) {
// TODO: fix blob for
var signingParams = _.extend({}, params, { txPrebuild: txPrebuild, keychain: userKeychain });
return self.signTransaction(signingParams);
})
Expand Down
1 change: 1 addition & 0 deletions src/v2/wallets.js
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,7 @@ Wallets.prototype.add = function(params, callback) {
keys: params.keys
};

// TODO: replace all IFs with single pick line
if (params.enterprise) {
walletParams.enterprise = params.enterprise;
}
Expand Down
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