refactoring of password change and preparations for server side encryption

services/password_encryption.js

@@ -0,0 +1,53 @@
+const options = require('./options');
+const my_scrypt = require('./my_scrypt');
+const utils = require('./utils');
+const crypto = require('crypto');
+const aesjs = require('./aes');
+
+async function verifyPassword(password) {
+    const givenPasswordHash = utils.toBase64(await my_scrypt.getVerificationHash(password));
+
+    const dbPasswordHash = await options.getOption('password_verification_hash');
+
+    return givenPasswordHash === dbPasswordHash;
+}
+
+function decryptDataKey(passwordDerivedKey, encryptedBase64) {
+    const encryptedBytes = utils.fromBase64(encryptedBase64);
+
+    const aes = getAes(passwordDerivedKey);
+    return aes.decrypt(encryptedBytes).slice(4);
+}
+
+function encryptDataKey(passwordDerivedKey, plainText) {
+    const aes = getAes(passwordDerivedKey);
+
+    const plainTextBuffer = Buffer.from(plainText, 'latin1');
+
+    const digest = crypto.createHash('sha256').update(plainTextBuffer).digest().slice(0, 4);
+
+    const encryptedBytes = aes.encrypt(Buffer.concat([digest, plainTextBuffer]));
+
+    return utils.toBase64(encryptedBytes);
+}
+
+async function getDecryptedDataKey(password) {
+    const passwordDerivedKey = await my_scrypt.getPasswordDerivedKey(password);
+
+    const encryptedDataKey = await options.getOption('encrypted_data_key');
+
+    const decryptedDataKey = decryptDataKey(passwordDerivedKey, encryptedDataKey);
+
+    return decryptedDataKey;
+}
+
+function getAes(key) {
+    return new aesjs.ModeOfOperation.ctr(key, new aesjs.Counter(5));
+}
+
+module.exports = {
+    verifyPassword,
+    decryptDataKey,
+    encryptDataKey,
+    getDecryptedDataKey
+};