53 lines
1.8 KiB
JavaScript
53 lines
1.8 KiB
JavaScript
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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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describe('bitcoinjs-lib (crypto)', function() {
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it('can recover a parent private key from the parent\'s 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.privKey, 'You already have the parent private key')
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assert(child.privKey, 'Missing child private key')
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var curve = bitcoin.ECKey.curve
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var QP = master.pubKey.toBuffer()
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var QP64 = QP.toString('base64')
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var d1 = child.privKey.d
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var d2
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var indexBuffer = new Buffer(4)
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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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indexBuffer.writeUInt32BE(i, 0)
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// calculate I
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var data = Buffer.concat([QP, indexBuffer])
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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.ECKey(d2, true).pub.toBuffer()
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if (Qp.toString('base64') === QP64) break
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}
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var node = new bitcoin.HDNode(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.equal(recovered.toBase58(), master.toBase58())
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})
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})
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