From 1cb2f900af100a9f92ab8b695b0fe3c62ca8e715 Mon Sep 17 00:00:00 2001
From: "Ryan X. Charles" <ryan@bitpay.com>
Date: Wed, 27 Aug 2014 17:15:10 -0700
Subject: [PATCH] symmetric encryption convenience class

---
 lib/expmt/encryption.js | 33 +++++++++++++++++++
 test/test.encryption.js | 73 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100644 lib/expmt/encryption.js
 create mode 100644 test/test.encryption.js

diff --git a/lib/expmt/encryption.js b/lib/expmt/encryption.js
new file mode 100644
index 0000000..dbb271c
--- /dev/null
+++ b/lib/expmt/encryption.js
@@ -0,0 +1,33 @@
+var AES = require('./aes');
+var CBC = require('./cbc');
+var Random = require('../random');
+var Hash = require('../hash');
+
+var Encryption = function Encryption() {
+};
+
+Encryption.encrypt = function(messagebuf, passwordstr) {
+  var cipherkeybuf = Hash.sha256(new Buffer(passwordstr));
+  return Encryption.encryptCipherkey(messagebuf, cipherkeybuf);
+};
+
+Encryption.decrypt = function(encbuf, passwordstr) {
+  var cipherkeybuf = Hash.sha256(new Buffer(passwordstr));
+  return Encryption.decryptCipherkey(encbuf, cipherkeybuf);
+};
+
+Encryption.encryptCipherkey = function(messagebuf, cipherkeybuf, ivbuf) {
+  ivbuf = ivbuf || Random.getRandomBuffer(128 / 8);
+  var ctbuf = CBC.encrypt(messagebuf, ivbuf, AES, cipherkeybuf);
+  var encbuf = Buffer.concat([ivbuf, ctbuf]);
+  return encbuf;
+};
+
+Encryption.decryptCipherkey = function(encbuf, cipherkeybuf) {
+  var ivbuf = encbuf.slice(0, 128 / 8);
+  var ctbuf = encbuf.slice(128 / 8);
+  var messagebuf = CBC.decrypt(ctbuf, ivbuf, AES, cipherkeybuf);
+  return messagebuf;
+};
+
+module.exports = Encryption;
diff --git a/test/test.encryption.js b/test/test.encryption.js
new file mode 100644
index 0000000..2c49fd1
--- /dev/null
+++ b/test/test.encryption.js
@@ -0,0 +1,73 @@
+var should = require('chai').should();
+var Encryption = require('../lib/expmt/encryption');
+
+describe('Encryption', function() {
+
+  describe('@encrypt', function() {
+
+    it('should return encrypt one block', function() {
+      var password = "password";
+      var messagebuf = new Buffer(128 / 8 - 1);
+      messagebuf.fill(0);
+      var encbuf = Encryption.encrypt(messagebuf, password);
+      encbuf.length.should.equal(128 / 8 + 128 / 8);
+    });
+
+  });
+
+  describe('@decrypt', function() {
+
+    it('should decrypt that which was encrypted', function() {
+      var password = "password";
+      var messagebuf = new Buffer(128 / 8 - 1);
+      messagebuf.fill(0);
+      var encbuf = Encryption.encrypt(messagebuf, password);
+      var messagebuf2 = Encryption.decrypt(encbuf, password);
+      messagebuf2.toString('hex').should.equal(messagebuf.toString('hex'));
+    });
+
+  });
+
+  describe('@encryptCipherkey', function() {
+
+    it('should return encrypt one block', function() {
+      var cipherkeybuf = new Buffer(256 / 8);
+      cipherkeybuf.fill(0x10);
+      var ivbuf = new Buffer(128 / 8);
+      ivbuf.fill(0);
+      var messagebuf = new Buffer(128 / 8 - 1);
+      messagebuf.fill(0);
+      var encbuf = Encryption.encryptCipherkey(messagebuf, cipherkeybuf, ivbuf);
+      encbuf.length.should.equal(128 / 8 + 128 / 8);
+    });
+
+    it('should return encrypt two blocks', function() {
+      var cipherkeybuf = new Buffer(256 / 8);
+      cipherkeybuf.fill(0x10);
+      var ivbuf = new Buffer(128 / 8);
+      ivbuf.fill(0);
+      var messagebuf = new Buffer(128 / 8);
+      messagebuf.fill(0);
+      var encbuf = Encryption.encryptCipherkey(messagebuf, cipherkeybuf, ivbuf);
+      encbuf.length.should.equal(128 / 8 + 128 / 8 + 128 / 8);
+    });
+
+  });
+
+  describe('@decryptCipherkey', function() {
+    
+    it('should decrypt that which was encrypted', function() {
+      var cipherkeybuf = new Buffer(256 / 8);
+      cipherkeybuf.fill(0x10);
+      var ivbuf = new Buffer(128 / 8);
+      ivbuf.fill(0);
+      var messagebuf = new Buffer(128 / 8);
+      messagebuf.fill(0);
+      var encbuf = Encryption.encryptCipherkey(messagebuf, cipherkeybuf, ivbuf);
+      var messagebuf2 = Encryption.decryptCipherkey(encbuf, cipherkeybuf);
+      messagebuf2.toString('hex').should.equal(messagebuf.toString('hex'));
+    });
+
+  });
+
+});