58 lines
1.8 KiB
JavaScript
58 lines
1.8 KiB
JavaScript
/* global describe, it */
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var assert = require('assert')
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var bigi = require('bigi')
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var bitcoin = require('../../')
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var crypto = require('crypto')
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var ecurve = require('ecurve')
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var secp256k1 = ecurve.getCurveByName('secp256k1')
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describe('bitcoinjs-lib (BIP32)', function () {
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it('can recover a BIP32 parent private key from the parent public key, and a derived, non-hardened child private key', function () {
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function recoverParent (master, child) {
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assert(!master.keyPair.d, 'You already have the parent private key')
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assert(child.keyPair.d, 'Missing child private key')
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var curve = secp256k1
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var QP = master.keyPair.Q
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var serQP = master.keyPair.getPublicKeyBuffer()
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var d1 = child.keyPair.d
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var d2
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var data = new Buffer(37)
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serQP.copy(data, 0)
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// search index space until we find it
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for (var i = 0; i < bitcoin.HDNode.HIGHEST_BIT; ++i) {
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data.writeUInt32BE(i, 33)
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// calculate I
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var I = crypto.createHmac('sha512', master.chainCode).update(data).digest()
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var IL = I.slice(0, 32)
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var pIL = bigi.fromBuffer(IL)
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// See hdnode.js:273 to understand
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d2 = d1.subtract(pIL).mod(curve.n)
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var Qp = new bitcoin.ECPair(d2).Q
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if (Qp.equals(QP)) break
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}
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var node = new bitcoin.HDNode(new bitcoin.ECPair(d2), master.chainCode, master.network)
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node.depth = master.depth
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node.index = master.index
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node.masterFingerprint = master.masterFingerprint
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return node
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}
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var seed = crypto.randomBytes(32)
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var master = bitcoin.HDNode.fromSeedBuffer(seed)
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var child = master.derive(6) // m/6
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// now for the recovery
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var neuteredMaster = master.neutered()
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var recovered = recoverParent(neuteredMaster, child)
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assert.strictEqual(recovered.toBase58(), master.toBase58())
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})
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})
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