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var ethUtil = require('ethereumjs-util')
var vector = global.crypto.getRandomValues(new Uint8Array(16))
module.exports = {
encrypt,
decrypt,
convertArrayBufferViewtoString,
keyFromPassword,
encryptWithKey,
decryptWithKey,
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)
return global.crypto.subtle.encrypt({
name: 'AES-GCM',
iv: vector
}, key, dataBuffer).then(function(buf){
var buffer = new Uint8Array(buf)
return serializeBufferForStorage(buffer)
})
}
// Takes encrypted text, returns the restored Pojo.
function decrypt (password, text) {
return keyFromPassword(password)
.then(function (key) {
return decryptWithKey(key, text)
})
}
// AUDIT: See if this still works when generating a fresh vector
function decryptWithKey (key, text) {
const encryptedData = serializeBufferFromStorage(text)
return crypto.subtle.decrypt({name: "AES-GCM", iv: vector}, key, encryptedData)
.then(function(result){
const decryptedData = new Uint8Array(result)
const decryptedStr = convertArrayBufferViewtoString(decryptedData)
const numArr = decryptedStr.split(',')
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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