From b2b660827c2f505b550176f7055af1018260212f Mon Sep 17 00:00:00 2001
From: Kagami Hiiragi <kagami@genshiken.org>
Date: Mon, 29 Dec 2014 22:59:18 +0300
Subject: [PATCH] WIF encode/decode

---
 README.md    |  6 +++---
 lib/index.js |  3 ++-
 lib/wif.js   | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 test.js      | 39 ++++++++++++++++++++++++++++++++++++
 4 files changed, 100 insertions(+), 4 deletions(-)
 create mode 100644 lib/wif.js

diff --git a/README.md b/README.md
index 0ab7325..c291aef 100644
--- a/README.md
+++ b/README.md
@@ -60,9 +60,9 @@ With the help of browserify `bitmessage` provides different implementations for
   - [ ] Message
     - [ ] encode
     - [ ] decode
-- [ ] WIF
-  - [ ] encode
-  - [ ] decode
+- [x] WIF
+  - [x] encode
+  - [x] decode
 - [ ] Parse PyBitmessage configs
   - [ ] decode keys.dat
   - [ ] decode knownnodes.dat
diff --git a/lib/index.js b/lib/index.js
index ac1e3f4..1045c2c 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,5 +1,5 @@
 /**
- * Main Bitmessage module. Just reexports all main submodules.
+ * Bitmessage library entry point. Just reexports common submodules.
  * @module bitmessage
  */
 
@@ -9,3 +9,4 @@
 // replace it with other library with the same API.
 exports.Int64 = require("int64-native");
 exports.Address = require("./address");
+exports.wif = require("./wif");
diff --git a/lib/wif.js b/lib/wif.js
new file mode 100644
index 0000000..9c62451
--- /dev/null
+++ b/lib/wif.js
@@ -0,0 +1,56 @@
+/**
+ * Implement WIF encoding/decoding.
+ * Reference: <https://en.bitcoin.it/wiki/Wallet_import_format>
+ * @module bitmessage/wif
+ */
+
+"use strict";
+
+require("es6-promise").polyfill();
+var assert = require("assert");
+var bufferEqual = require("buffer-equal");
+var bs58 = require("bs58");
+var bmcrypto = require("./crypto");
+
+// Compute the WIF checksum for the given data.
+function getchecksum(data) {
+  return bmcrypto.sha256(data).then(bmcrypto.sha256).then(function(dhash) {
+    return dhash.slice(0, 4);
+  });
+}
+
+/**
+ * Decode WIF encoded private key.
+ * @param {string} input - Input data
+ * @param {Promise.<Buffer,undefined>} A promise than contain private
+ * key when fulfilled
+ */
+exports.decode = function(input) {
+  var bytes;
+  try {
+    bytes = bs58.decode(input);
+    assert(bytes[0] === 0x80, "Bad WIF");
+  } catch(e) {
+    return Promise.reject(e);
+  }
+  var data = new Buffer(bytes.slice(0, -4));
+  var checksum = new Buffer(bytes.slice(-4));
+  return getchecksum(data).then(function(realchecksum) {
+    assert(bufferEqual(checksum, realchecksum), "Bad checkum");
+    return data.slice(1);
+  });
+};
+
+/**
+ * Convert private key to a WIF.
+ * @param {Buffer} privateKey - A private key to encode
+ * @return {Promise.<string,undefined>} A promise that contains the
+ * encoded key when fulfilled
+ */
+exports.encode = function(privateKey) {
+  var data = Buffer.concat([new Buffer([0x80]), privateKey]);
+  return getchecksum(data).then(function(checksum) {
+    var bytes = Buffer.concat([data, checksum]);
+    return bs58.encode(bytes);
+  });
+};
diff --git a/test.js b/test.js
index 7d176b8..a58148c 100644
--- a/test.js
+++ b/test.js
@@ -6,6 +6,7 @@ var allTests = typeof window === "undefined" ?
 var bitmessage = require("./lib");
 var Int64 = bitmessage.Int64;
 var Address = bitmessage.Address;
+var wif = bitmessage.wif;
 var varint = require("./lib/varint");
 var bmcrypto = require("./lib/crypto");
 
@@ -55,6 +56,44 @@ describe("var_int", function() {
   });
 });
 
+describe("WIF", function() {
+  var wifSign = "5JgQ79vTBusc61xYPtUEHYQ38AXKdDZgQ5rFp7Cbb4ZjXUKFZEV";
+  var wifEnc = "5K2aL8cnsEWHwHfHnUrPo8QdYyRfoYUBmhAnWY5GTpDLbeyusnE";
+  var signPrivateKey = Buffer("71c95d26c716a5e85e9af9efe26fb5f744dc98005a13d05d23ee92c77e038d9f", "hex");
+  var encPrivateKey = Buffer("9f9969c93c2d186787a7653f70e49be34c03c4a853e6ad0c867db0946bc433c6", "hex");
+
+  it("should decode", function() {
+    return wif.decode(wifSign)
+    .then(function(key1) {
+      expect(Buffer.isBuffer(key1)).to.be.true;
+      expect(key1.length).to.equal(32);
+      expect(key1.toString("hex")).to.equal(signPrivateKey.toString("hex"));
+      return wif.decode(wifEnc).then(function(key2) {
+        expect(Buffer.isBuffer(key2)).to.be.true;
+        expect(key2.length).to.equal(32);
+        expect(key2.toString("hex")).to.equal(encPrivateKey.toString("hex"));
+        return {
+          version: 4,
+          stream: 1,
+          signPrivateKey: key1,
+          encPrivateKey: key2,
+        };
+      });
+    }).then(Address.encode).then(function(str) {
+      expect(str).to.equal("BM-2cTux3PGRqHTEH6wyUP2sWeT4LrsGgy63z");
+    });
+  });
+
+  it("should encode", function() {
+    return wif.encode(signPrivateKey).then(function(wif1) {
+      expect(wif1).to.equal(wifSign);
+      return wif.encode(encPrivateKey);
+    }).then(function(wif2) {
+      expect(wif2).to.equal(wifEnc);
+    });
+  });
+});
+
 describe("Crypto", function() {
   it("should implement SHA-512 hash", function() {
     return bmcrypto.sha512(Buffer("test")).then(function(res) {