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Merge pull request #1228 from bitcoinjs/readme

README: add usage notes
v4
Jonathan Underwood 6 years ago
committed by GitHub
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96240b636d
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  1. 2
      CHANGELOG.md
  2. 40
      README.md
  3. 11
      test/integration/addresses.js
  4. 103
      test/integration/crypto.js
  5. 167
      test/integration/stealth.js

2
CHANGELOG.md

@ -19,7 +19,7 @@ __added__
__changed__
- `ECPair.prototype.sign` now returns a 64-byte signature `Buffer`, not an `ECSignature` object (#1084)
- `ECPair` (and all ECDSA code) now uses [`tiny-secp256k1`](http://github.com/bitcoinjs/tiny-secp256k1), which uses the [`libsecp256k1` library](https://github.com/bitcoin-core/secp256k1) (#1070)
- `ECPair` (and all ECDSA code) now uses [`tiny-secp256k1`](https://github.com/bitcoinjs/tiny-secp256k1), which uses the [`libsecp256k1` library](https://github.com/bitcoin-core/secp256k1) (#1070)
- `TransactionBuilder` internal variables are now `__` prefixed to discourage public usage (#1038)
- `TransactionBuilder` now defaults to version 2 transaction versions (#1036)
- `script.decompile` now returns `[Buffer]` or `null`, if decompilation failed (#1039)

40
README.md

@ -23,9 +23,10 @@ Mistakes and bugs happen, but with your help in resolving and reporting [issues]
- Easy to audit and verify,
- Tested, with test coverage >95%,
- Advanced and feature rich,
- Standardized, using [standard](http://github.com/standard/standard) and Node `Buffer`'s throughout, and
- Standardized, using [standard](https://github.com/standard/standard) and Node `Buffer`'s throughout, and
- Friendly, with a strong and helpful community, ready to answer questions.
## Documentation
Presently, we do not have any formal documentation other than our [examples](#examples), please [ask for help](https://github.com/bitcoinjs/bitcoinjs-lib/issues/new) if our examples aren't enough to guide you.
@ -42,12 +43,37 @@ If in doubt, see the [.travis.yml](.travis.yml) for what versions are used by ou
## Usage
Crypto is hard.
When working with private keys, the random number generator is fundamentally one of the most important parts of any software you write.
For random number generation, we *default* to the [`randombytes`](https://github.com/crypto-browserify/randombytes) module, which uses [`window.crypto.getRandomValues`](https://developer.mozilla.org/en-US/docs/Web/API/window.crypto.getRandomValues) in the browser, or Node js' [`crypto.randomBytes`](https://nodejs.org/api/crypto.html#crypto_crypto_randombytes_size_callback), depending on your build system.
Although this default is ~OK, there is no simple way to detect if the underlying RNG provided is good enough, or if it is **catastrophically bad**.
You should always verify this yourself to your own standards.
This library uses [tiny-secp256k1](https://github.com/bitcoinjs/tiny-secp256k1), which uses [RFC6979](https://tools.ietf.org/html/rfc6979) to help prevent `k` re-use and exploitation.
Unfortunately, this isn't a silver bullet.
Often, Javascript itself is working against us by bypassing these counter-measures.
Problems in [`Buffer (UInt8Array)`](https://github.com/feross/buffer), for example, can trivially result in **catastrophic fund loss** without any warning.
It can do this through undermining your random number generation, accidentally producing a [duplicate `k` value](https://www.nilsschneider.net/2013/01/28/recovering-bitcoin-private-keys.html), sending Bitcoin to a malformed output script, or any of a million different ways.
Running tests in your target environment is important and a recommended step to verify continuously.
Finally, **adhere to best practice**.
We are not an authorative source of best practice, but, at the very least:
* [Don't re-use addresses](https://en.bitcoin.it/wiki/Address_reuse).
* Don't share BIP32 extended public keys ('xpubs'). [They are a liability](https://bitcoin.stackexchange.com/questions/56916/derivation-of-parent-private-key-from-non-hardened-child), and it only takes 1 misplaced private key (or a buggy implementation!) and you are vulnerable to **catastrophic fund loss**.
* [Don't use `Math.random`](https://security.stackexchange.com/questions/181580/why-is-math-random-not-designed-to-be-cryptographically-secure) - in any way - don't.
* Enforce that users always verify (manually) a freshly-decoded human-readable version of their intended transaction before broadcast.
* Don't *ask* users to generate mnemonics, or 'brain wallets', humans are terrible random number generators.
* Lastly, if you can, use [Typescript](https://www.typescriptlang.org/) or similar.
### Browser
The recommended method of using `bitcoinjs-lib` in your browser is through [Browserify](https://github.com/substack/node-browserify).
If you're familiar with how to use browserify, ignore this and carry on, otherwise, it is recommended to read the tutorial at http://browserify.org/.
If you're familiar with how to use browserify, ignore this and carry on, otherwise, it is recommended to read the tutorial at https://browserify.org/.
**NOTE**: We use Node Maintenance LTS features, if you need strict ES5, use [`--transform babelify`](https://github.com/babel/babelify) in conjunction with your `browserify` step (using an [`es2015`](http://babeljs.io/docs/plugins/preset-es2015/) preset).
**NOTE**: We use Node Maintenance LTS features, if you need strict ES5, use [`--transform babelify`](https://github.com/babel/babelify) in conjunction with your `browserify` step (using an [`es2015`](https://babeljs.io/docs/plugins/preset-es2015/) preset).
**WARNING**: iOS devices have [problems](https://github.com/feross/buffer/issues/136), use atleast [buffer@5.0.5](https://github.com/feross/buffer/pull/155) or greater, and enforce the test suites (for `Buffer`, and any other dependency) pass before use.
@ -83,7 +109,6 @@ Otherwise, pull requests are appreciated.
Some examples interact (via HTTPS) with a 3rd Party Blockchain Provider (3PBP).
- [Generate a random address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L22)
- [Generate an address from a SHA256 hash](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L29)
- [Import an address via WIF](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L40)
- [Generate a 2-of-3 P2SH multisig address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L47)
- [Generate a SegWit address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L60)
@ -114,13 +139,6 @@ Some examples interact (via HTTPS) with a 3rd Party Blockchain Provider (3PBP).
- [Create (and broadcast via 3PBP) a Transaction where Alice can redeem the output after the expiry (in the future)](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/cltv.js#L88)
- [Create (and broadcast via 3PBP) a Transaction where Alice and Bob can redeem the output at any time](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/cltv.js#L144)
- [Create (but fail to broadcast via 3PBP) a Transaction where Alice attempts to redeem before the expiry](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/cltv.js#L190)
- [Recover a private key from duplicate R values](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/crypto.js#L14)
- [Recover a BIP32 parent private key from the parent public key, and a derived, non-hardened child private key](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/crypto.js#L68)
- [Generate a single-key stealth address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/stealth.js#L72)
- [Generate a single-key stealth address (randomly)](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/stealth.js#L91)
- [Recover parent recipient.d, if a derived private key is leaked (and nonce was revealed)](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/stealth.js#L107)
- [Generate a dual-key stealth address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/stealth.js#L124)
- [Generate a dual-key stealth address (randomly)](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/stealth.js#L147)
If you have a use case that you feel could be listed here, please [ask for it](https://github.com/bitcoinjs/bitcoinjs-lib/issues/new)!

11
test/integration/addresses.js

@ -25,17 +25,6 @@ describe('bitcoinjs-lib (addresses)', function () {
assert.strictEqual(address, '1F5VhMHukdnUES9kfXqzPzMeF1GPHKiF64')
})
it('can generate an address from a SHA256 hash', function () {
const hash = bitcoin.crypto.sha256(Buffer.from('correct horse battery staple'))
const keyPair = bitcoin.ECPair.fromPrivateKey(hash)
const { address } = bitcoin.payments.p2pkh({ pubkey: keyPair.publicKey })
// Generating addresses from SHA256 hashes is not secure if the input to the hash function is predictable
// Do not use with predictable inputs
assert.strictEqual(address, '1C7zdTfnkzmr13HfA2vNm5SJYRK6nEKyq8')
})
it('can import an address via WIF', function () {
const keyPair = bitcoin.ECPair.fromWIF('Kxr9tQED9H44gCmp6HAdmemAzU3n84H3dGkuWTKvE23JgHMW8gct')
const { address } = bitcoin.payments.p2pkh({ pubkey: keyPair.publicKey })

103
test/integration/crypto.js

@ -1,103 +0,0 @@
const { describe, it } = require('mocha')
const assert = require('assert')
const BN = require('bn.js')
const bitcoin = require('../../')
const bip32 = require('bip32')
const crypto = require('crypto')
const tinysecp = require('tiny-secp256k1')
describe('bitcoinjs-lib (crypto)', function () {
it('can recover a private key from duplicate R values', function () {
// https://blockchain.info/tx/f4c16475f2a6e9c602e4a287f9db3040e319eb9ece74761a4b84bc820fbeef50
const tx = bitcoin.Transaction.fromHex('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')
tx.ins.forEach(function (input, vin) {
const { output: prevOutput, pubkey, signature } = bitcoin.payments.p2pkh({ input: input.script })
const scriptSignature = bitcoin.script.signature.decode(signature)
const m = tx.hashForSignature(vin, prevOutput, scriptSignature.hashType)
assert(bitcoin.ECPair.fromPublicKey(pubkey).verify(m, scriptSignature.signature), 'Invalid m')
// store the required information
input.signature = scriptSignature.signature
input.z = new BN(m)
})
const n = new BN('fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141', 16)
for (var i = 0; i < tx.ins.length; ++i) {
for (var j = i + 1; j < tx.ins.length; ++j) {
const inputA = tx.ins[i]
const inputB = tx.ins[j]
// enforce matching r values
const r = inputA.signature.slice(0, 32)
const rB = inputB.signature.slice(0, 32)
assert.strictEqual(r.toString('hex'), rB.toString('hex'))
const rInv = new BN(r).invm(n)
const s1 = new BN(inputA.signature.slice(32, 64))
const s2 = new BN(inputB.signature.slice(32, 64))
const z1 = inputA.z
const z2 = inputB.z
const zz = z1.sub(z2).mod(n)
const ss = s1.sub(s2).mod(n)
// k = (z1 - z2) / (s1 - s2)
// d1 = (s1 * k - z1) / r
// d2 = (s2 * k - z2) / r
const k = zz.mul(ss.invm(n)).mod(n)
const d1 = ((s1.mul(k).mod(n)).sub(z1).mod(n)).mul(rInv).mod(n)
const d2 = ((s2.mul(k).mod(n)).sub(z2).mod(n)).mul(rInv).mod(n)
// enforce matching private keys
assert.strictEqual(d1.toString(), d2.toString())
}
}
})
it('can recover a BIP32 parent private key from the parent public key, and a derived, non-hardened child private key', function () {
function recoverParent (master, child) {
assert(master.isNeutered(), 'You already have the parent private key')
assert(!child.isNeutered(), 'Missing child private key')
const serQP = master.publicKey
const d1 = child.privateKey
const data = Buffer.alloc(37)
serQP.copy(data, 0)
// search index space until we find it
let d2
for (var i = 0; i < 0x80000000; ++i) {
data.writeUInt32BE(i, 33)
// calculate I
const I = crypto.createHmac('sha512', master.chainCode).update(data).digest()
const IL = I.slice(0, 32)
// See bip32.js:273 to understand
d2 = tinysecp.privateSub(d1, IL)
const Qp = bip32.fromPrivateKey(d2, Buffer.alloc(32, 0)).publicKey
if (Qp.equals(serQP)) break
}
const node = bip32.fromPrivateKey(d2, master.chainCode, master.network)
node.depth = master.depth
node.index = master.index
node.masterFingerprint = master.masterFingerprint
return node
}
const seed = crypto.randomBytes(32)
const master = bip32.fromSeed(seed)
const child = master.derive(6) // m/6
// now for the recovery
const neuteredMaster = master.neutered()
const recovered = recoverParent(neuteredMaster, child)
assert.strictEqual(recovered.toBase58(), master.toBase58())
})
})

167
test/integration/stealth.js

@ -1,167 +0,0 @@
const { describe, it } = require('mocha')
const assert = require('assert')
const bitcoin = require('../../')
const ecc = require('tiny-secp256k1')
function getAddress (node, network) {
return bitcoin.payments.p2pkh({ pubkey: node.publicKey, network }).address
}
// vG = (dG \+ sha256(e * dG)G)
function stealthSend (e, Q) {
const eQ = ecc.pointMultiply(Q, e, true) // shared secret
const c = bitcoin.crypto.sha256(eQ)
const Qc = ecc.pointAddScalar(Q, c)
const vG = bitcoin.ECPair.fromPublicKey(Qc)
return vG
}
// v = (d + sha256(eG * d))
function stealthReceive (d, eG) {
const eQ = ecc.pointMultiply(eG, d) // shared secret
const c = bitcoin.crypto.sha256(eQ)
const dc = ecc.privateAdd(d, c)
const v = bitcoin.ECPair.fromPrivateKey(dc)
return v
}
// d = (v - sha256(e * dG))
function stealthRecoverLeaked (v, e, Q) {
const eQ = ecc.pointMultiply(Q, e) // shared secret
const c = bitcoin.crypto.sha256(eQ)
const vc = ecc.privateSub(v, c)
const d = bitcoin.ECPair.fromPrivateKey(vc)
return d
}
// vG = (rG \+ sha256(e * dG)G)
function stealthDualSend (e, R, Q) {
const eQ = ecc.pointMultiply(Q, e) // shared secret
const c = bitcoin.crypto.sha256(eQ)
const Rc = ecc.pointAddScalar(R, c)
const vG = bitcoin.ECPair.fromPublicKey(Rc)
return vG
}
// vG = (rG \+ sha256(eG * d)G)
function stealthDualScan (d, R, eG) {
const eQ = ecc.pointMultiply(eG, d) // shared secret
const c = bitcoin.crypto.sha256(eQ)
const Rc = ecc.pointAddScalar(R, c)
const vG = bitcoin.ECPair.fromPublicKey(Rc)
return vG
}
// v = (r + sha256(eG * d))
function stealthDualReceive (d, r, eG) {
const eQ = ecc.pointMultiply(eG, d) // shared secret
const c = bitcoin.crypto.sha256(eQ)
const rc = ecc.privateAdd(r, c)
const v = bitcoin.ECPair.fromPrivateKey(rc)
return v
}
describe('bitcoinjs-lib (crypto)', function () {
it('can generate a single-key stealth address', function () {
// XXX: should be randomly generated, see next test for example
const recipient = bitcoin.ECPair.fromWIF('5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss') // private to recipient
const nonce = bitcoin.ECPair.fromWIF('KxVqB96pxbw1pokzQrZkQbLfVBjjHFfp2mFfEp8wuEyGenLFJhM9') // private to sender
// ... recipient reveals public key (recipient.Q) to sender
const forSender = stealthSend(nonce.privateKey, recipient.publicKey)
assert.equal(getAddress(forSender), '1CcZWwCpACJL3AxqoDbwEt4JgDFuTHUspE')
assert.throws(function () { forSender.toWIF() }, /Error: Missing private key/)
// ... sender reveals nonce public key (nonce.Q) to recipient
const forRecipient = stealthReceive(recipient.privateKey, nonce.publicKey)
assert.equal(getAddress(forRecipient), '1CcZWwCpACJL3AxqoDbwEt4JgDFuTHUspE')
assert.equal(forRecipient.toWIF(), 'L1yjUN3oYyCXV3LcsBrmxCNTa62bZKWCybxVJMvqjMmmfDE8yk7n')
// sender and recipient, both derived same address
assert.equal(getAddress(forSender), getAddress(forRecipient))
})
it('can generate a single-key stealth address (randomly)', function () {
const recipient = bitcoin.ECPair.makeRandom() // private to recipient
const nonce = bitcoin.ECPair.makeRandom() // private to sender
// ... recipient reveals public key (recipient.Q) to sender
const forSender = stealthSend(nonce.privateKey, recipient.publicKey)
assert.throws(function () { forSender.toWIF() }, /Error: Missing private key/)
// ... sender reveals nonce public key (nonce.Q) to recipient
const forRecipient = stealthReceive(recipient.privateKey, nonce.publicKey)
assert.doesNotThrow(function () { forRecipient.toWIF() })
// sender and recipient, both derived same address
assert.equal(getAddress(forSender), getAddress(forRecipient))
})
it('can recover parent recipient.d, if a derived private key is leaked [and nonce was revealed]', function () {
const recipient = bitcoin.ECPair.makeRandom() // private to recipient
const nonce = bitcoin.ECPair.makeRandom() // private to sender
// ... recipient reveals public key (recipient.Q) to sender
const forSender = stealthSend(nonce.privateKey, recipient.publicKey)
assert.throws(function () { forSender.toWIF() }, /Error: Missing private key/)
// ... sender reveals nonce public key (nonce.Q) to recipient
const forRecipient = stealthReceive(recipient.privateKey, nonce.publicKey)
assert.doesNotThrow(function () { forRecipient.toWIF() })
// ... recipient accidentally leaks forRecipient.d on the blockchain
const leaked = stealthRecoverLeaked(forRecipient.privateKey, nonce.privateKey, recipient.publicKey)
assert.equal(leaked.toWIF(), recipient.toWIF())
})
it('can generate a dual-key stealth address', function () {
// XXX: should be randomly generated, see next test for example
const recipient = bitcoin.ECPair.fromWIF('5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss') // private to recipient
const scan = bitcoin.ECPair.fromWIF('L5DkCk3xLLoGKncqKsWQTdaPSR4V8gzc14WVghysQGkdryRudjBM') // private to scanner/recipient
const nonce = bitcoin.ECPair.fromWIF('KxVqB96pxbw1pokzQrZkQbLfVBjjHFfp2mFfEp8wuEyGenLFJhM9') // private to sender
// ... recipient reveals public key(s) (recipient.Q, scan.Q) to sender
const forSender = stealthDualSend(nonce.privateKey, recipient.publicKey, scan.publicKey)
assert.throws(function () { forSender.toWIF() }, /Error: Missing private key/)
// ... sender reveals nonce public key (nonce.Q) to scanner
const forScanner = stealthDualScan(scan.privateKey, recipient.publicKey, nonce.publicKey)
assert.throws(function () { forScanner.toWIF() }, /Error: Missing private key/)
// ... scanner reveals relevant transaction + nonce public key (nonce.Q) to recipient
const forRecipient = stealthDualReceive(scan.privateKey, recipient.privateKey, nonce.publicKey)
assert.doesNotThrow(function () { forRecipient.toWIF() })
// scanner, sender and recipient, all derived same address
assert.equal(getAddress(forSender), getAddress(forScanner))
assert.equal(getAddress(forSender), getAddress(forRecipient))
})
it('can generate a dual-key stealth address (randomly)', function () {
const recipient = bitcoin.ECPair.makeRandom() // private to recipient
const scan = bitcoin.ECPair.makeRandom() // private to scanner/recipient
const nonce = bitcoin.ECPair.makeRandom() // private to sender
// ... recipient reveals public key(s) (recipient.Q, scan.Q) to sender
const forSender = stealthDualSend(nonce.privateKey, recipient.publicKey, scan.publicKey)
assert.throws(function () { forSender.toWIF() }, /Error: Missing private key/)
// ... sender reveals nonce public key (nonce.Q) to scanner
const forScanner = stealthDualScan(scan.privateKey, recipient.publicKey, nonce.publicKey)
assert.throws(function () { forScanner.toWIF() }, /Error: Missing private key/)
// ... scanner reveals relevant transaction + nonce public key (nonce.Q) to recipient
const forRecipient = stealthDualReceive(scan.privateKey, recipient.privateKey, nonce.publicKey)
assert.doesNotThrow(function () { forRecipient.toWIF() })
// scanner, sender and recipient, all derived same address
assert.equal(getAddress(forSender), getAddress(forScanner))
assert.equal(getAddress(forSender), getAddress(forRecipient))
})
})
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