AES Cipher Check

jjs_aes_cipher_check.js

// please run with jjs

var Cipher = javax.crypto.Cipher;
var KeyGenerator = javax.crypto.KeyGenerator;
var String = java.lang.String;
var Arrays = java.util.Arrays;
var SecureRandom = java.security.SecureRandom;
var SecretKeySpec = javax.crypto.spec.SecretKeySpec;

var share_secret_seed = "share_secret_seed";
var raw_text = "no man is an island";
var raw_bytes = raw_text.getBytes("UTF-8");

function get_key(seed) {
    // https://docs.oracle.com/javase/8/docs/technotes/guides/security/SunProviders.html#SecureRandomImp
    // you must set the algorithm as 'SHA1PRNG', because the different platform have different impl
    var random = SecureRandom.getInstance("SHA1PRNG");
    random.setSeed(seed.getBytes());
    var keyGenerator = KeyGenerator.getInstance("AES");
    keyGenerator.init(256, random);
    var hashed_key = keyGenerator.generateKey().getEncoded()
    return new SecretKeySpec(hashed_key, "AES");
}

function encrypt(bytes, secret) {
    var cipher = Cipher.getInstance("AES");
    var key = get_key(secret)
    cipher.init(Cipher.ENCRYPT_MODE, key);
    return cipher.doFinal(bytes);
}

function decrypt(bytes, secret) {
    var cipher = Cipher.getInstance("AES");
    var key = get_key(secret)
    cipher.init(Cipher.DECRYPT_MODE, key);
    return cipher.doFinal(bytes);
}


var encrypted_bytes = encrypt(raw_bytes, share_secret_seed)
var decrypted_bytes = decrypt(encrypted_bytes, share_secret_seed)

print("raw text:\t" + Arrays.toString(raw_bytes));
print("encrypted:\t" + Arrays.toString(encrypted_bytes));
print("decrypted:\t" + Arrays.toString(decrypted_bytes));