basic stealth address support

Math only. Does not yet support transactions. Not yet compatible with Dark
Wallet.

index.js

@@ -18,8 +18,8 @@ privsec.Random = require('./lib/random');
 privsec.Signature = require('./lib/signature');
 
 //experimental
-//privsec.expmt = {};
-//privsec.expmt.Stealth = require('./lib/expmt/stealth');
+privsec.expmt = {};
+privsec.expmt.Stealth = require('./lib/expmt/stealth');
 
 //dependencies
 privsec.deps = {};

lib/expmt/stealth.js

@@ -0,0 +1,111 @@
+var Key = require('../key');
+var Privkey = require('../privkey');
+var Pubkey = require('../pubkey');
+var Hash = require('../hash');
+var KDF = require('../kdf');
+var base58check = require('../base58check');
+
+var Stealth = function Stealth(payloadKey, scanKey) {
+  if (!(this instanceof Stealth))
+    return new Stealth(payloadKey, scanKey);
+
+  this.payloadKey = payloadKey;
+  this.scanKey = scanKey;
+};
+
+Stealth.prototype.fromAddressBuffer = function(buf) {
+  if (!Buffer.isBuffer(buf) || buf.length !== 66)
+    throw new Error('stealth: A stealth address must have length 66');
+
+  var pPubBuf = buf.slice(0, 33);
+  var sPubBuf = buf.slice(33, 66);
+  
+  var payloadPubkey = Pubkey().fromDER(pPubBuf);
+  this.payloadKey = Key(undefined, payloadPubkey);
+  var scanPubkey = Pubkey().fromDER(sPubBuf);
+  this.scanKey = Key(undefined, scanPubkey);
+
+  return this;
+};
+
+Stealth.prototype.fromAddressString = function(str) {
+  var buf = base58check.decode(str);
+  this.fromAddressBuffer(buf);
+
+  return this;
+};
+
+Stealth.prototype.fromRandom = function() {
+  this.payloadKey = Key().fromRandom();
+  this.scanKey = Key().fromRandom();
+
+  return this;
+};
+
+Stealth.prototype.getSharedKeyAsReceiver = function(senderPubkey) {
+  var sharedSecretPoint = senderPubkey.point.mul(this.scanKey.privkey.bn);
+  var sharedSecretPubkey = Pubkey(sharedSecretPoint);
+  var buf = sharedSecretPubkey.toDER(true);
+  var sharedKey = KDF.sha256hmac2key(buf);
+
+  return sharedKey;
+};
+
+Stealth.prototype.getSharedKeyAsSender = function(senderKey) {
+  var sharedSecretPoint = this.scanKey.pubkey.point.mul(senderKey.privkey.bn);
+  var sharedSecretPubkey = Pubkey(sharedSecretPoint);
+  var buf = sharedSecretPubkey.toDER(true);
+  var sharedKey = KDF.sha256hmac2key(buf);
+
+  return sharedKey;
+};
+
+Stealth.prototype.getReceivePubkeyAsReceiver = function(senderPubkey) {
+  var sharedKey = this.getSharedKeyAsReceiver(senderPubkey);
+  var pubkey = Pubkey(this.payloadKey.pubkey.point.add(sharedKey.pubkey.point));
+
+  return pubkey;
+};
+
+Stealth.prototype.getReceivePubkeyAsSender = function(senderKey) {
+  var sharedKey = this.getSharedKeyAsSender(senderKey);
+  var pubkey = Pubkey(this.payloadKey.pubkey.point.add(sharedKey.pubkey.point));
+
+  return pubkey;
+};
+
+Stealth.prototype.getReceiveKey = function(senderPubkey) {
+  var sharedKey = this.getSharedKeyAsReceiver(senderPubkey);
+  var privkey = Privkey(this.payloadKey.privkey.bn.add(sharedKey.privkey.bn));
+  var key = Key(privkey);
+  key.privkey2pubkey();
+
+  return key;
+};
+
+Stealth.prototype.isForMe = function(senderPubkey, myPossiblePubkeyhash) {
+  var pubkey = this.getReceivePubkeyAsReceiver(senderPubkey);
+  var pubkeybuf = pubkey.toDER(true);
+  var pubkeyhash = Hash.sha256ripemd160(pubkeybuf);
+
+  if (pubkeyhash.toString('hex') === myPossiblePubkeyhash.toString('hex'))
+    return true;
+  else
+    return false;
+};
+
+Stealth.prototype.toAddressBuffer = function() {
+  var pBuf = this.payloadKey.pubkey.toDER(true);
+  var sBuf = this.scanKey.pubkey.toDER(true);
+
+  return Buffer.concat([pBuf, sBuf]);
+};
+
+Stealth.prototype.toAddressString = function() {
+  var buf = this.toAddressBuffer();
+  var b58 = base58check.encode(buf);
+
+  return b58;
+};
+
+module.exports = Stealth;

test/test.stealth.js

@@ -0,0 +1,177 @@
+var should = require('chai').should();
+var Stealth = require('../lib/expmt/stealth');
+var Key = require('../lib/key');
+var Privkey = require('../lib/privkey');
+var Pubkey = require('../lib/pubkey');
+var BN = require('../lib/bn');
+var Hash = require('../lib/hash');
+var base58check = require('../lib/base58check');
+
+describe('stealth', function() {
+  
+  var stealth = Stealth();
+  stealth.payloadKey = Key();
+  stealth.payloadKey.privkey = Privkey();
+  stealth.payloadKey.privkey.bn = BN().fromBuffer(Hash.sha256(new Buffer('test 1')));
+  stealth.payloadKey.privkey2pubkey();
+  stealth.scanKey = Key();
+  stealth.scanKey.privkey = Privkey();
+  stealth.scanKey.privkey.bn = BN().fromBuffer(Hash.sha256(new Buffer('test 2')));
+  stealth.scanKey.privkey2pubkey();
+
+  var senderKey = Key();
+  senderKey.privkey = Privkey();
+  senderKey.privkey.bn = BN().fromBuffer(Hash.sha256(new Buffer('test 3')));
+  senderKey.privkey2pubkey();
+
+  var addressString = '9dDbC9FzZ74r8njQkXD6W27gtrxLiWaeFPHxeo1fynQRXPicqxVt7u95ozbwoVVMXyrzaHKN9owsteg63FgwDfrxWx82SAW';
+
+  it('should create a new stealth', function() {
+    var stealth = new Stealth();
+    should.exist(stealth);
+  });
+
+  it('should create a new stealth without using "new"', function() {
+    var stealth = Stealth();
+    should.exist(stealth);
+  });
+
+  describe('#fromAddressBuffer', function() {
+
+    it('should give a stealth address with the right pubkeys', function() {
+      var stealth2 = new Stealth();
+      var buf = base58check.decode(addressString);
+      stealth2.fromAddressBuffer(buf);
+      stealth2.payloadKey.pubkey.toString().should.equal(stealth.payloadKey.pubkey.toString());
+      stealth2.scanKey.pubkey.toString().should.equal(stealth.scanKey.pubkey.toString());
+    });
+
+  });
+
+  describe('#fromAddressString', function() {
+
+    it('should give a stealth address with the right pubkeys', function() {
+      var stealth2 = new Stealth();
+      stealth2.fromAddressString(addressString);
+      stealth2.payloadKey.pubkey.toString().should.equal(stealth.payloadKey.pubkey.toString());
+      stealth2.scanKey.pubkey.toString().should.equal(stealth.scanKey.pubkey.toString());
+    });
+
+  });
+
+  describe('#fromRandom', function() {
+
+    it('should create a new stealth from random', function() {
+      var stealth = Stealth().fromRandom();
+      should.exist(stealth.payloadKey.privkey.bn.gt(0));
+      should.exist(stealth.scanKey.privkey.bn.gt(0));
+    });
+
+  });
+
+  describe('#getSharedKeyAsReceiver', function() {
+
+    it('should return a key', function() {
+      var key = stealth.getSharedKeyAsReceiver(senderKey.pubkey);
+      (key instanceof Key).should.equal(true);
+    });
+
+  });
+
+  describe('#getSharedKeyAsSender', function() {
+
+    it('should return a key', function() {
+      var stealth2 = new Stealth();
+      stealth2.payloadKey = new Key();
+      stealth2.payloadKey.pubkey = stealth.payloadKey.pubkey;
+      stealth2.scanKey = new Key();
+      stealth2.scanKey.pubkey = stealth.scanKey.pubkey;
+      var key = stealth2.getSharedKeyAsSender(senderKey);
+      (key instanceof Key).should.equal(true);
+    });
+
+    it('should return the same key as getSharedKeyAsReceiver', function() {
+      var stealth2 = new Stealth();
+      stealth2.payloadKey = new Key();
+      stealth2.payloadKey.pubkey = stealth.payloadKey.pubkey;
+      stealth2.scanKey = new Key();
+      stealth2.scanKey.pubkey = stealth.scanKey.pubkey;
+      var key = stealth2.getSharedKeyAsSender(senderKey);
+
+      var key2 = stealth.getSharedKeyAsReceiver(senderKey.pubkey);
+      key.toString().should.equal(key2.toString());
+    });
+
+  });
+
+  describe('#getReceivePubkeyAsReceiver', function() {
+    
+    it('should return a pubkey', function() {
+      var pubkey = stealth.getReceivePubkeyAsReceiver(senderKey.pubkey);
+      (pubkey instanceof Pubkey).should.equal(true);
+    });
+
+  });
+
+  describe('#getReceivePubkeyAsSender', function() {
+    
+    it('should return a pubkey', function() {
+      var pubkey = stealth.getReceivePubkeyAsSender(senderKey);
+      (pubkey instanceof Pubkey).should.equal(true);
+    });
+
+    it('should return the same pubkey as getReceivePubkeyAsReceiver', function() {
+      var pubkey = stealth.getReceivePubkeyAsSender(senderKey);
+      var pubkey2 = stealth.getReceivePubkeyAsReceiver(senderKey.pubkey);
+      pubkey2.toString().should.equal(pubkey.toString());
+    });
+
+  });
+
+  describe('#getReceiveKey', function() {
+
+    it('should return a key', function() {
+      var key = stealth.getReceiveKey(senderKey.pubkey);
+      (key instanceof Key).should.equal(true);
+    });
+
+    it('should return a key with the same pubkey as getReceivePubkeyAsReceiver', function() {
+      var key = stealth.getReceiveKey(senderKey.pubkey);
+      var pubkey = stealth.getReceivePubkeyAsReceiver(senderKey.pubkey);
+      key.pubkey.toString().should.equal(pubkey.toString());
+    });
+
+  });
+
+  describe('#isForMe', function() {
+
+    it('should return true if it (the transaction or message) is for me', function() {
+      var pubkeyhash = new Buffer('3cb64fa6ee9b3e8754e3e2bd033bf61048604a99', 'hex');
+      stealth.isForMe(senderKey.pubkey, pubkeyhash).should.equal(true);
+    });
+
+    it('should return false if it (the transaction or message) is not for me', function() {
+      var pubkeyhash = new Buffer('00b64fa6ee9b3e8754e3e2bd033bf61048604a99', 'hex');
+      stealth.isForMe(senderKey.pubkey, pubkeyhash).should.equal(false);
+    });
+
+  });
+
+  describe('#toAddressBuffer', function() {
+    
+    it('should return this known address buffer', function() {
+      var buf = stealth.toAddressBuffer();
+      base58check.encode(buf).should.equal(addressString);
+    });
+
+  });
+
+  describe('#toAddressString', function() {
+    
+    it('should return this known address string', function() {
+      stealth.toAddressString().should.equal(addressString);
+    });
+
+  });
+
+});