From 17506fe14f84680bc6b5421eff4c797154a513bd Mon Sep 17 00:00:00 2001
From: Kevin Serrano <kevgagser@gmail.com>
Date: Wed, 19 Oct 2016 11:17:29 -0700
Subject: Merge in crypto.

---
 app/scripts/lib/encryptor.js | 119 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 app/scripts/lib/encryptor.js

(limited to 'app/scripts')

diff --git a/app/scripts/lib/encryptor.js b/app/scripts/lib/encryptor.js
new file mode 100644
index 000000000..91d6ed5ce
--- /dev/null
+++ b/app/scripts/lib/encryptor.js
@@ -0,0 +1,119 @@
+var ethUtil = require('ethereumjs-util')
+
+module.exports = {
+
+  // Simple encryption methods:
+  encrypt,
+  decrypt,
+
+  // More advanced encryption methods:
+  keyFromPassword,
+  encryptWithKey,
+  decryptWithKey,
+
+  // Buffer <-> String methods
+  convertArrayBufferViewtoString,
+  convertStringToArrayBufferView,
+
+  // Buffer <-> Hex string methods
+  serializeBufferForStorage,
+  serializeBufferFromStorage,
+}
+
+// Takes a Pojo, returns encrypted text.
+function encrypt (password, dataObj) {
+  return keyFromPassword(password)
+  .then(function (passwordDerivedKey) {
+    return encryptWithKey(passwordDerivedKey, dataObj)
+  })
+}
+
+function encryptWithKey (key, dataObj) {
+  var data = JSON.stringify(dataObj)
+  var dataBuffer = convertStringToArrayBufferView(data)
+  var vector = global.crypto.getRandomValues(new Uint8Array(16))
+
+  return global.crypto.subtle.encrypt({
+    name: 'AES-GCM',
+    iv: vector,
+  }, key, dataBuffer).then(function(buf){
+    var buffer = new Uint8Array(buf)
+    var vectorStr = serializeBufferForStorage(vector)
+    return serializeBufferForStorage(buffer) + vectorStr
+  })
+}
+
+// Takes encrypted text, returns the restored Pojo.
+function decrypt (password, text) {
+  return keyFromPassword(password)
+  .then(function (key) {
+    return decryptWithKey(key, text)
+  })
+}
+
+function decryptWithKey (key, text) {
+  const parts = text.split('0x')
+  const encryptedData = serializeBufferFromStorage(parts[1])
+  const vector = serializeBufferFromStorage(parts[2])
+  return crypto.subtle.decrypt({name: 'AES-GCM', iv: vector}, key, encryptedData)
+  .then(function(result){
+    const decryptedData = new Uint8Array(result)
+    const decryptedStr = convertArrayBufferViewtoString(decryptedData)
+    const decryptedObj = JSON.parse(decryptedStr)
+    return decryptedObj
+  })
+}
+
+function convertStringToArrayBufferView (str) {
+  var bytes = new Uint8Array(str.length)
+  for (var i = 0; i < str.length; i++) {
+    bytes[i] = str.charCodeAt(i)
+  }
+
+  return bytes
+}
+
+function convertArrayBufferViewtoString (buffer) {
+  var str = ''
+  for (var i = 0; i < buffer.byteLength; i++) {
+    str += String.fromCharCode(buffer[i])
+  }
+
+  return str
+}
+
+function keyFromPassword (password) {
+  var passBuffer = convertStringToArrayBufferView(password)
+  return global.crypto.subtle.digest('SHA-256', passBuffer)
+  .then(function (passHash){
+    return global.crypto.subtle.importKey('raw', passHash, {name: 'AES-GCM'}, false, ['encrypt', 'decrypt'])
+  })
+}
+
+function serializeBufferFromStorage (str) {
+  str = ethUtil.stripHexPrefix(str)
+  var buf = new Uint8Array(str.length / 2)
+  for (var i = 0; i < str.length; i += 2) {
+    var seg = str.substr(i, 2)
+    buf[i / 2] = parseInt(seg, 16)
+  }
+  return buf
+}
+
+// Should return a string, ready for storage, in hex format.
+function serializeBufferForStorage (buffer) {
+  var result = '0x'
+  var len = buffer.length || buffer.byteLength
+  for (var i = 0; i < len; i++) {
+    result += unprefixedHex(buffer[i])
+  }
+  return result
+}
+
+function unprefixedHex (num) {
+  var hex = num.toString(16)
+  while (hex.length < 2) {
+    hex = '0' + hex
+  }
+  return hex
+}
-- 
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