Implement shielded addresses

package.json

@@ -24,6 +24,8 @@
     "standard": "10.0.2"
   },
   "dependencies": {
+    "bs58check": "2.0.2",
+    "libsodium-wrappers-sumo": "0.5.1",
     "typeforce": "1.11.1"
   }
 }

src/address.js

@@ -0,0 +1,144 @@
+'use strict'
+
+var bs58check = require('bs58check')
+var prf = require('./prf')
+var typeforce = require('typeforce')
+var types = require('./types')
+var util = require('./util')
+
+function fromBase58Check (address) {
+  var payload = bs58check.decode(address)
+  var version = payload.readUInt16BE(0)
+  var data = payload.slice(2)
+
+  return { data: data, version: version }
+}
+
+function toBase58Check (data, version) {
+  typeforce(types.tuple(types.Buffer, types.UInt16), arguments)
+
+  var payload = Buffer.alloc(data.length + 2)
+  payload.writeUInt16BE(version, 0)
+  data.copy(payload, 2)
+
+  return bs58check.encode(payload)
+}
+
+function PaymentAddress (aPk, pkEnc) {
+  typeforce(types.tuple(types.Buffer256bit, types.Buffer256bit), arguments)
+  this.a_pk = aPk
+  this.pk_enc = pkEnc
+}
+
+PaymentAddress.fromBuffer = function (buffer, __noStrict) {
+  var offset = 0
+  function readSlice (n) {
+    offset += n
+    return buffer.slice(offset - n, offset)
+  }
+
+  var aPk = readSlice(32)
+  var pkEnc = readSlice(32)
+  var addr = new PaymentAddress(aPk, pkEnc)
+
+  if (__noStrict) return addr
+  if (offset !== buffer.length) throw new Error('PaymentAddress has unexpected data')
+
+  return addr
+}
+
+PaymentAddress.prototype.byteLength = function () {
+  return 64
+}
+
+PaymentAddress.prototype.toBuffer = function () {
+  var buffer = Buffer.alloc(this.byteLength())
+
+  var offset = 0
+  function writeSlice (slice) {
+    slice.copy(buffer, offset)
+    offset += slice.length
+  }
+
+  writeSlice(this.a_pk)
+  writeSlice(this.pk_enc)
+
+  return buffer
+}
+
+PaymentAddress.prototype.toZAddress = function (version) {
+  return toBase58Check(this.toBuffer(), version)
+}
+
+function SpendingKey (aSk) {
+  typeforce(types.Buffer252bit, aSk)
+  this.a_sk = aSk
+}
+
+SpendingKey.random = function () {
+  return new SpendingKey(util.random_uint252())
+}
+
+SpendingKey.fromBuffer = function (buffer, __noStrict) {
+  var offset = 0
+  function readSlice (n) {
+    offset += n
+    return buffer.slice(offset - n, offset)
+  }
+
+  var aSk = readSlice(32)
+  var sk = new SpendingKey(aSk)
+
+  if (__noStrict) return sk
+  if (offset !== buffer.length) throw new Error('SpendingKey has unexpected data')
+
+  return sk
+}
+
+SpendingKey.prototype.byteLength = function () {
+  return 32
+}
+
+SpendingKey.prototype.toBuffer = function () {
+  var buffer = Buffer.alloc(this.byteLength())
+
+  var offset = 0
+  function writeSlice (slice) {
+    slice.copy(buffer, offset)
+    offset += slice.length
+  }
+
+  writeSlice(this.a_sk)
+
+  return buffer
+}
+
+SpendingKey.prototype.toZKey = function (version) {
+  return toBase58Check(this.toBuffer(), version)
+}
+
+SpendingKey.prototype.address = function () {
+  return new PaymentAddress(
+    prf.PRF_addr_a_pk(this.a_sk),
+    util.generate_pubkey(util.generate_privkey(this.a_sk))
+  )
+}
+
+function fromZAddress (address, versionMap) {
+  var decode = fromBase58Check(address)
+  if (decode.version in versionMap) return versionMap[decode.version].fromBuffer(decode.data)
+  throw new Error(address + ' has no matching z-address')
+}
+
+function fromZKey (key, versionMap) {
+  var decode = fromBase58Check(key)
+  if (decode.version in versionMap) return versionMap[decode.version].fromBuffer(decode.data)
+  throw new Error(key + ' has no matching z-key')
+}
+
+module.exports = {
+  PaymentAddress: PaymentAddress,
+  SpendingKey: SpendingKey,
+  fromZAddress: fromZAddress,
+  fromZKey: fromZKey
+}

src/index.js

@@ -1,3 +1,5 @@
 module.exports = {
-  JSDescription: require('./jsdescription')
+  JSDescription: require('./jsdescription'),
+
+  address: require('./address')
 }

src/types.js

@@ -10,11 +10,22 @@ function BoolNum (value) {
     value <= 1
 }
 
+// exposed, external API
+var PaymentAddress = typeforce.compile({
+  a_pk: typeforce.BufferN(32),
+  pk_enc: typeforce.BufferN(32)
+})
+var SpendingKey = typeforce.compile({
+  a_sk: Buffer252bit
+})
+
 // extend typeforce types with ours
 var types = {
   BoolNum: BoolNum,
   Buffer252bit: Buffer252bit,
-  Buffer256bit: typeforce.BufferN(32)
+  Buffer256bit: typeforce.BufferN(32),
+  PaymentAddress: PaymentAddress,
+  SpendingKey: SpendingKey
 }
 
 for (var typeName in typeforce) {

src/util.js

@@ -0,0 +1,40 @@
+'use strict'
+
+var prf = require('./prf')
+var sodium = require('libsodium-wrappers-sumo')
+var typeforce = require('typeforce')
+var types = require('./types')
+
+function randomUint256 () {
+  return Buffer.from(sodium.randombytes_buf(32))
+}
+
+function randomUint252 () {
+  var rand = Buffer.from(randomUint256())
+  rand[0] &= 0x0F
+  return rand
+}
+
+function generatePrivkey (aSk) {
+  var sk = prf.PRF_addr_sk_enc(aSk)
+
+  // Curve25519 clamping
+  sk[0] &= 248
+  sk[31] &= 127
+  sk[31] |= 64
+
+  return sk
+}
+
+function generatePubkey (skEnc) {
+  typeforce(types.Buffer256bit, skEnc)
+
+  return Buffer.from(sodium.crypto_scalarmult_base(skEnc))
+}
+
+module.exports = {
+  generate_privkey: generatePrivkey,
+  generate_pubkey: generatePubkey,
+  random_uint252: randomUint252,
+  random_uint256: randomUint256
+}

test/address.js

@@ -0,0 +1,114 @@
+/* global describe, it */
+
+var assert = require('assert')
+
+var address = require('../src/address')
+
+var fixtures = require('./fixtures/address')
+
+describe('PaymentAddress', function () {
+  function fromRaw (raw) {
+    var aPk = Buffer.from(raw.a_pk, 'hex')
+    var pkEnc = Buffer.from(raw.pk_enc, 'hex')
+    return new address.PaymentAddress(aPk, pkEnc)
+  }
+
+  describe('fromZAddress', function () {
+    fixtures.valid.forEach(function (f) {
+      var versionMap = {}
+      versionMap[f.addressVersion] = address.PaymentAddress
+
+      it('imports ' + f.address, function () {
+        var actual = address.fromZAddress(f.address, versionMap)
+        assert.strictEqual(
+          actual.toZAddress(f.addressVersion),
+          f.address,
+          actual.toZAddress(f.addressVersion))
+      })
+    })
+
+    fixtures.invalid.fromZAddress.forEach(function (f) {
+      var versionMap = {}
+      versionMap[f.addressVersion] = address.PaymentAddress
+
+      it('throws on ' + f.exception, function () {
+        assert.throws(function () {
+          address.fromZAddress(f.address, versionMap)
+        }, f.exception)
+      })
+    })
+  })
+
+  describe('toZAddress', function () {
+    fixtures.valid.forEach(function (f) {
+      it('exports ' + f.address, function () {
+        var actual = fromRaw(f.raw)
+        assert.strictEqual(
+          actual.toZAddress(f.addressVersion),
+          f.address,
+          actual.toZAddress(f.addressVersion))
+      })
+    })
+  })
+})
+
+describe('SpendingKey', function () {
+  function fromRaw (raw) {
+    var aSk = Buffer.from(raw.a_sk, 'hex')
+    return new address.SpendingKey(aSk)
+  }
+
+  describe('fromZKey', function () {
+    fixtures.valid.forEach(function (f) {
+      var versionMap = {}
+      versionMap[f.keyVersion] = address.SpendingKey
+
+      it('imports ' + f.key, function () {
+        var actual = address.fromZKey(f.key, versionMap)
+        assert.strictEqual(
+          actual.toZKey(f.keyVersion),
+          f.key,
+          actual.toZKey(f.keyVersion))
+      })
+    })
+
+    fixtures.invalid.fromZKey.forEach(function (f) {
+      var versionMap = {}
+      versionMap[f.keyVersion] = address.SpendingKey
+
+      it('throws on ' + f.exception, function () {
+        assert.throws(function () {
+          address.fromZKey(f.key, versionMap)
+        }, f.exception)
+      })
+    })
+  })
+
+  describe('toZKey', function () {
+    fixtures.valid.forEach(function (f) {
+      it('exports ' + f.key, function () {
+        var actual = fromRaw(f.raw)
+        assert.strictEqual(
+          actual.toZKey(f.keyVersion),
+          f.key,
+          actual.toZKey(f.keyVersion))
+      })
+    })
+  })
+
+  describe('address', function () {
+    fixtures.valid.forEach(function (f) {
+      var versionMap = {}
+      versionMap[f.keyVersion] = address.SpendingKey
+
+      it('correctly derives for ' + f.key, function () {
+        var key = address.fromZKey(f.key, versionMap)
+        var actual = key.address()
+        assert.strictEqual(
+          actual.toZAddress(f.addressVersion),
+          f.address,
+          actual.toZAddress(f.addressVersion))
+      })
+    })
+  })
+})

test/fixtures/address.json

@@ -0,0 +1,94 @@
+{
+  "valid": [
+    {
+      "raw": {
+        "a_sk": "0d05ff283bfb519619b4ad0a2a417fcf3e0782de56e7ebd508cfbf365401d18f",
+        "a_pk": "c47235aa758c7fffaa12726e7c3c11b48e116db5373215dabadbaaa6a6d5cde4",
+        "pk_enc": "58230f1e86b26bd34c383e7503e28a195c5f4016f4ed8020b8e642c0b36baf08"
+      },
+      "keyVersion": 43830,
+      "addressVersion": 5786,
+      "key": "SKxthnmAMPWVea6ganJZzPjvFauoLDvgyHHbZy54qMpuFFh2L3nP",
+      "address": "zcZviziuUB45WMY4jnV5Vmx6ZKDLyXzb12QbnWyDofTqZEbeJZF49vVNi75UgiuzXFytgJ6bJoq22gUsANBS4BjUfFudBMu"
+    },
+    {
+      "raw": {
+        "a_sk": "0fcdb3870de951df0fee40a35380127c4dcb7c964dab356faa4b43b0da4602fa",
+        "a_pk": "0658e1ea67b8adf24b706c54949b35d8cf385080a84f06a318eeb195b04a1a35",
+        "pk_enc": "d00fdb5cbf7c57c0df14ee44e24653debf3e7e3ae446cf29ffd9e1d59a74303a"
+      },
+      "keyVersion": 43830,
+      "addressVersion": 5786,
+      "key": "SKxuvoZevPsBHMhQ96wEN8rU4BCR3vwNFyA1W1AbsMMe2Ts4E2BC",
+      "address": "zc94F8QLFHXR4unq4njynUGcQ3cpyC9CNeoZhrPq5VsKrwKDGea79mZPTuCmzixF5wFi9zNaXpRS2fPYaz4bNTUCkPMfgG1"
+    },
+    {
+      "raw": {
+        "a_sk": "0473fcb81c85f84f15b6449bb678500c4e675f26e8b47d3380a08442bd28a541",
+        "a_pk": "141687f6df6c101be90517243281fe70f02bba59ab0a24bc804c49567d077450",
+        "pk_enc": "40e2e2663801419181b5bd00d7e72e1e03f6aaab701726aa1363ebd1a27a250e"
+      },
+      "keyVersion": 44040,
+      "addressVersion": 5814,
+      "key": "ST13FvCzYJWFmDATmpVgeG14HXgHPSaNMkiU4ynyuNADq11xUEq1",
+      "address": "ztLdfP3bNQ8kHeuxyZyoDHN79KKrpVJq9yMAZ4pKYup76sAG1oUH98egwYXFRjFWmUXHuuX2ypLtZE6k7ycYShJhMpw3g8K"
+    },
+    {
+      "raw": {
+        "a_sk": "0888cd0d3d859403f3243e0e3261ec1f0ef3145c1a5e8a382a26e1e3c8ae452b",
+        "a_pk": "f74f556fd6fd8e73963875f6d825502dabe802c1a3ff9bca76b121549cb0e505",
+        "pk_enc": "39bbc4529383d4e65b75658628521d5691ad30731ef503577752d45e36d63905"
+      },
+      "keyVersion": 44040,
+      "addressVersion": 5814,
+      "key": "ST154AnoeTzvZ1UqbumkGwvVaq1jds3FNEPxDgTuogYkKgPkGZwj",
+      "address": "ztrMqKR8HndoCoGmPxFA7Yq2YjjyBXCzDWd5MGc9px6Uz5r8LDYvHtnQH7n7QQmZxVJTfWdCYbDqaf9yWLXn74AophUVxZZ"
+    }
+  ],
+  "invalid": {
+    "fromZAddress": [
+      {
+        "exception": "Invalid checksum",
+        "addressVersion": 5786,
+        "address": "zcZviziuUB45WMY4jnV5Vmx6ZKDLyXzb12QbnWyDofTqZEbeJZF49vVNi75UgiuzXFytgJ6bJoq22gUsANBS4BjUfFudBMv"
+      },
+      {
+        "exception": "Expected property \"1\" of type Buffer(Length: 32), got Buffer(Length: 31)",
+        "addressVersion": 5786,
+        "address": "E45HhnFUkK8wwgYWPqNKEmd3csM1uENCnKSjmkVbcww7UExRmJj9sWLa1hoKxfx44geMmhaSSnW1EXF1wggyRjm4cX3fiw"
+      },
+      {
+        "exception": "PaymentAddress has unexpected data",
+        "addressVersion": 5786,
+        "address": "5PHzL8MmxawNatZe7Vqkvr1QBXdPVAXoB57DAXuH9WxmTKH1ueVK2vP6EpRpmCKzttZ876STgRbgwYRFzQLV3b4NV5X29CmcE"
+      },
+      {
+        "exception": "ztLdfP3bNQ8kHeuxyZyoDHN79KKrpVJq9yMAZ4pKYup76sAG1oUH98egwYXFRjFWmUXHuuX2ypLtZE6k7ycYShJhMpw3g8K has no matching z-address",
+        "addressVersion": 5786,
+        "address": "ztLdfP3bNQ8kHeuxyZyoDHN79KKrpVJq9yMAZ4pKYup76sAG1oUH98egwYXFRjFWmUXHuuX2ypLtZE6k7ycYShJhMpw3g8K"
+      }
+    ],
+    "fromZKey": [
+      {
+        "exception": "Invalid checksum",
+        "keyVersion": 43830,
+        "key": "SKxthnmAMPWVea6ganJZzPjvFauoLDvgyHHbZy54qMpuFFh2L3nQ"
+      },
+      {
+        "exception": "Expected property \"1\" of type Buffer(Length: 32), got Buffer(Length: 31)",
+        "keyVersion": 43830,
+        "key": "6jp6pku9TphDP795tcBn5r76ipZMU1fSpeDpi11vS1BrSpiiqCx"
+      },
+      {
+        "exception": "SpendingKey has unexpected data",
+        "keyVersion": 43830,
+        "key": "2vnhhD2yvGzMBSq65i6xYcKNS3Ng3Vr3yRQtFaWUwvSvRbuSSqg77N"
+      },
+      {
+        "exception": "ST13FvCzYJWFmDATmpVgeG14HXgHPSaNMkiU4ynyuNADq11xUEq1 has no matching z-key",
+        "keyVersion": 43830,
+        "key": "ST13FvCzYJWFmDATmpVgeG14HXgHPSaNMkiU4ynyuNADq11xUEq1"
+      }
+    ]
+  }
+}