Implement address decoding

.jshintrc

@@ -7,7 +7,7 @@
     // Enforcing
     "bitwise"       : true,     // true: Prohibit bitwise operators (&, |, ^, etc.)
     "camelcase"     : false,    // true: Identifiers must be in camelCase
-    "curly"         : false,     // true: Require {} for every new block or scope
+    "curly"         : true,     // true: Require {} for every new block or scope
     "eqeqeq"        : true,     // true: Require triple equals (===) for comparison
     "freeze"        : true,     // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
     "forin"         : true,     // true: Require filtering for..in loops with obj.hasOwnProperty()

lib/address.js

@@ -0,0 +1,72 @@
+/**
+ * Working with Bitmessage addresses.
+ * @module bitmessage/address
+ */
+
+"use strict";
+
+var bufferEqual = require("buffer-equal");
+var bs58 = require("bs58");
+var varint = require("./varint");
+var bmcrypto = require("./crypto");
+var assert = require("./utils").assert;
+
+/**
+ * Parse Bitmessage Base58 encoded address (with or without `BM-`
+ * prefix) into address object.
+ */
+exports.decode = function(str) {
+  str = str.trim();
+  if (str.slice(0, 3) === "BM-") {
+    str = str.slice(3);
+  }
+
+  var bytes;
+  try {
+    bytes = bs58.decode(str);
+  } catch(e) {
+    return Promise.reject(e);
+  }
+
+  // Checksum validating.
+  var data = new Buffer(bytes.slice(0, -4));
+  var checksum = new Buffer(bytes.slice(-4));
+  return bmcrypto.sha512(data).then(bmcrypto.sha512).then(function(dhash) {
+    assert(bufferEqual(dhash.slice(0, 4), checksum), "Bad checkum");
+
+    var decoded = varint.decode(data);
+    var version = decoded.value;
+    assert(version <= 4, "Version too high");
+    assert(version >= 1, "Version too low");
+
+    data = decoded.rest;
+    decoded = varint.decode(data);
+    var stream = decoded.value;
+
+    var ripe = decoded.rest;
+    var ripelen = ripe.length;
+    switch (version) {
+      case 1:
+        assert(ripelen === 20);
+        break;
+      case 2:
+      case 3:
+        assert(ripelen >= 18, "Ripe too short");
+        assert(ripelen <= 20, "Ripe too long");
+        break;
+      case 4:
+        assert(ripelen >= 4, "Ripe too short");
+        assert(ripelen <= 20, "Ripe too long");
+        assert(ripe[0] !== 0, "Ripe encode error");
+        break;
+    }
+
+    // Prevent extra allocation. God, kill me please for premature
+    // optimizations.
+    if (ripelen < 20) {
+      var zeroes = new Buffer(Array(20 - ripelen));
+      ripe = Buffer.concat([zeroes, ripe]);
+    }
+    return {version: version, stream: stream, ripe: ripe};
+  });
+};

lib/crypto.browser.js

@@ -1,12 +1,28 @@
 /**
  * Browser version of the crypto for Bitmessage JS implementation.
- * @module bitmessage/lib/crypto.browser
+ *
+ * Documentation: <http://www.w3.org/TR/WebCryptoAPI/>
+ * Browsers support: <http://caniuse.com/#feat=cryptography>
+ * Blink implementation details: <https://sites.google.com/a/chromium.org/dev/blink/webcrypto>
+ *
+ * @module bitmessage/crypto.browser
  */
+// FIXME(Kagami): Support webkit subtle prefix!
+// TODO(Kagami): Try to support IE11.
 
 "use strict";
 
+require("es6-promise").polyfill();
+var ripemd160 = require("ripemd160");
+
 exports.sha512 = function(buf) {
   return window.crypto.subtle.digest({name: "SHA-512"}, buf).then(function(arr) {
     return new Buffer(new Uint8Array(arr));
   });
 };
+
+exports.ripemd160 = function(buf) {
+  // XXX(Kagami): No support in browsers via Web Crypto API currently,
+  // so use module.
+  return Promise.resolve(ripemd160(buf));
+};

lib/crypto.js

@@ -1,13 +1,11 @@
 /**
  * Node.js version of the crypto for Bitmessage JS implementation.
- * Wrap all crypto functions with promises because WebCryptoAPI uses it
- * throughout.
- * @module bitmessage/lib/crypto
+ * @module bitmessage/crypto
  */
 
 "use strict";
 
-var Promise = require("es6-promise").Promise;  // jshint ignore:line
+require("es6-promise").polyfill();
 var crypto = require("crypto");
 
 exports.sha512 = function(buf) {
@@ -15,3 +13,9 @@ exports.sha512 = function(buf) {
   hash.update(buf);
   return Promise.resolve(hash.digest());
 };
+
+exports.ripemd160 = function(buf) {
+  var hash = crypto.createHash("ripemd160");
+  hash.update(buf);
+  return Promise.resolve(hash.digest());
+};

lib/index.js

@@ -0,0 +1,8 @@
+/**
+ * Main Bitmessage module. Just reexports all public submodules.
+ * @module bitmessage
+ */
+
+"use strict";
+
+exports.Address = require("./address");

lib/utils.js

@@ -0,0 +1,7 @@
+"use strict";
+
+exports.assert = function(condition, message) {
+  if (!condition) {
+    throw new Error(message || "Assertion failed");
+  }
+};

lib/varint.js

@@ -0,0 +1,39 @@
+/**
+ * Implement `var_int` encoding/decoding.
+ * @module bitmessage/varint
+ */
+
+"use strict";
+
+// TODO(Kagami): Since `node-int64` and `int64-native` APIs are slightly
+// differ, there might be need in platform-dependent wrapper. Also think
+// that to do with 64bit arithmetic since `node-int64` doesn't implement
+// it.
+var Int64 = require("int64-native");
+var assert = require("./utils").assert;
+
+exports.decode = function(buf) {
+  assert(buf.length > 0, "Empty buffer");
+  var value, length;
+  switch (buf[0]) {
+    case 253:
+      value = buf.readUInt16BE(1);
+      length = 3;
+      break;
+    case 254:
+      value = buf.readUInt32BE(1);
+      length = 5;
+      break;
+    case 255:
+      var hi = buf.readUInt32BE(1);
+      var lo = buf.readUInt32BE(5);
+      value = new Int64(hi, lo);
+      length = 9;
+      break;
+    default:
+      value = buf[0];
+      length = 1;
+  }
+  var rest = buf.slice(length);
+  return {value: value, length: length, rest: rest};
+};

package.json

@@ -4,6 +4,7 @@
   "description": "JavaScript Bitmessage library",
   "main": "./lib/index.js",
   "browser": {
+    "int64-native": "node-int64",
     "./lib/crypto.js": "./lib/crypto.browser.js"
   },
   "scripts": {
@@ -38,6 +39,11 @@
     "mocha": "*"
   },
   "dependencies": {
-    "es6-promise": "^2.0.1"
+    "bs58": "^2.0.0",
+    "buffer-equal": "~0.0.1",
+    "es6-promise": "^2.0.1",
+    "int64-native": "^0.3.2",
+    "node-int64": "^0.3.2",
+    "ripemd160": "^0.2.0"
   }
 }

test.js

@@ -1,11 +1,68 @@
 var expect = require("chai").expect;
 
+var bufferEqual = require("buffer-equal");
+var bitmessage = require("./lib");
+var Address = bitmessage.Address;
+var varint = require("./lib/varint");
 var bmcrypto = require("./lib/crypto");
 
-describe("Bitmessage crypto", function() {
-  it("should calculate sha512 hash", function() {
-    return bmcrypto.sha512(new Buffer("test")).then(function(res) {
+describe("var_int", function() {
+  it("should decode", function() {
+    var res;
+    expect(varint.decode.bind(Buffer([]))).to.throw(Error);
+
+    res = varint.decode(Buffer([123]));
+    expect(res.value).to.equal(123);
+    expect(res.length).to.equal(1);
+    expect(bufferEqual(res.rest, Buffer([]))).to.be.true;
+
+    res = varint.decode(Buffer("fd123456", "hex"));
+    expect(res.value).to.equal(0x1234);
+    expect(res.length).to.equal(3);
+    expect(bufferEqual(res.rest, Buffer("56", "hex"))).to.be.true;
+
+    res = varint.decode(Buffer("fe1234567890", "hex"));
+    expect(res.value).to.equal(0x12345678);
+    expect(res.length).to.equal(5);
+    expect(bufferEqual(res.rest, Buffer("90", "hex"))).to.be.true;
+
+    res = varint.decode(Buffer("ff0000001234567890", "hex"));
+    expect(res.value == 0x1234567890).to.be.true;
+    expect(res.length).to.equal(9);
+    expect(res.rest.length).to.equal(0);
+  });
+});
+
+describe("Crypto", function() {
+  it("should implement SHA-512 hash", function() {
+    return bmcrypto.sha512(Buffer("test")).then(function(res) {
       expect(res.toString("hex")).to.equal("ee26b0dd4af7e749aa1a8ee3c10ae9923f618980772e473f8819a5d4940e0db27ac185f8a0e1d5f84f88bc887fd67b143732c304cc5fa9ad8e6f57f50028a8ff");
     });
   });
+
+  it("should implement RIPEMD-160 hash", function() {
+    return bmcrypto.ripemd160(Buffer("test")).then(function(res) {
+      expect(res.toString("hex")).to.equal("5e52fee47e6b070565f74372468cdc699de89107");
+    });
+  });
+});
+
+describe("Address", function() {
+  it("should decode Bitmessage address", function() {
+    return Address.decode("BM-2cTux3PGRqHTEH6wyUP2sWeT4LrsGgy63z")
+      .then(function(addr) {
+        expect(addr.version).to.equal(4);
+        expect(addr.stream).to.equal(1);
+        expect(bufferEqual(addr.ripe, Buffer("003ab6655de4bd8c603eba9b00dd5970725fdd56", "hex"))).to.be.true;
+      });
+  });
+
+  it("should decode Bitmessage address badly formatted", function() {
+    return Address.decode("  2cTux3PGRqHTEH6wyUP2sWeT4LrsGgy63z ")
+      .then(function(addr) {
+        expect(addr.version).to.equal(4);
+        expect(addr.stream).to.equal(1);
+        expect(bufferEqual(addr.ripe, Buffer("003ab6655de4bd8c603eba9b00dd5970725fdd56", "hex"))).to.be.true;
+      });
+  });
 });