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const asmcrypto = require('asmcrypto.js')
const Unibabel = require('browserify-unibabel')
/**
* A Microsoft Edge-specific encryption class that exposes
* the interface expected by eth-keykeyring-controller
*/
class EdgeEncryptor {
/**
* Encrypts an arbitrary object to ciphertext
*
* @param {string} password Used to generate a key to encrypt the data
* @param {Object} dataObject Data to encrypt
* @returns {Promise<string>} Promise resolving to an object with ciphertext
*/
encrypt (password, dataObject) {
var salt = this._generateSalt()
return this._keyFromPassword(password, salt)
.then(function (key) {
var data = JSON.stringify(dataObject)
var dataBuffer = Unibabel.utf8ToBuffer(data)
var vector = global.crypto.getRandomValues(new Uint8Array(16))
var resultbuffer = asmcrypto.AES_GCM.encrypt(dataBuffer, key, vector)
var buffer = new Uint8Array(resultbuffer)
var vectorStr = Unibabel.bufferToBase64(vector)
var vaultStr = Unibabel.bufferToBase64(buffer)
return JSON.stringify({
data: vaultStr,
iv: vectorStr,
salt: salt,
})
})
}
/**
* Decrypts an arbitrary object from ciphertext
*
* @param {string} password Used to generate a key to decrypt the data
* @param {string} text Ciphertext of an encrypted object
* @returns {Promise<Object>} Promise resolving to copy of decrypted object
*/
decrypt (password, text) {
const payload = JSON.parse(text)
const salt = payload.salt
return this._keyFromPassword(password, salt)
.then(function (key) {
const encryptedData = Unibabel.base64ToBuffer(payload.data)
const vector = Unibabel.base64ToBuffer(payload.iv)
return new Promise((resolve, reject) => {
var result
try {
result = asmcrypto.AES_GCM.decrypt(encryptedData, key, vector)
} catch (err) {
return reject(new Error('Incorrect password'))
}
const decryptedData = new Uint8Array(result)
const decryptedStr = Unibabel.bufferToUtf8(decryptedData)
const decryptedObj = JSON.parse(decryptedStr)
resolve(decryptedObj)
})
})
}
/**
* Retrieves a cryptographic key using a password
*
* @private
* @param {string} password Password used to unlock a cryptographic key
* @param {string} salt Random base64 data
* @returns {Promise<Object>} Promise resolving to a derived key
*/
_keyFromPassword (password, salt) {
var passBuffer = Unibabel.utf8ToBuffer(password)
var saltBuffer = Unibabel.base64ToBuffer(salt)
const iterations = 10000
const length = 32 // SHA256 hash size
return new Promise((resolve) => {
var key = asmcrypto.Pbkdf2HmacSha256(passBuffer, saltBuffer, iterations, length)
resolve(key)
})
}
/**
* Generates random base64 encoded data
*
* @private
* @returns {string} Randomized base64 encoded data
*/
_generateSalt (byteCount = 32) {
var view = new Uint8Array(byteCount)
global.crypto.getRandomValues(view)
var b64encoded = btoa(String.fromCharCode.apply(null, view))
return b64encoded
}
}
module.exports = EdgeEncryptor
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