text: 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())
    })
  })
  