!7

import java.security.*;

import java.security.spec.*;

import javax.crypto.*;

import javax.crypto.spec.*;

p {

  S original = "hello";

  byte[] data = original.getBytes("UTF-8");

  printHex(data);

  Random ranGen = new SecureRandom();

  byte[] salt = new byte[8]; // 8 grains of salt

  ranGen.nextBytes(salt);

  String pw = "pw";

  byte[] enc = encrypt(data, pw, salt);

  printHex(enc);

  System.out.println("enc length: " + enc.length);

  byte[] dec = decrypt(enc, pw, salt);

  S decoded = fromUtf8(dec);

  System.out.println("decrypted: " + decoded);

  assertEquals(original, decoded);

  print("OK!!!!");

}

static IvParameterSpec makeIV() {

  ret new IvParameterSpec(new byte[16]);

}

static SecretKey makeKey(S password, byte[] salt) throws Exception {

  /* Derive the key, given password and salt. */

  SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");

  // only with unlimited strength:

  //KeySpec spec = new PBEKeySpec(password, salt, 65536, 256);

  // Let's try this:

  KeySpec spec = new PBEKeySpec(toCharArray(password), salt, 65536, 128);

  SecretKey tmp = factory.generateSecret(spec);

  SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

  return secret;

}

public static byte[] encrypt(byte[] data, S password, byte[] salt) {

  try {

    SecretKey secret = makeKey(password, salt);

    /* Encrypt the message. */

    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

    cipher.init(Cipher.ENCRYPT_MODE, secret, makeIV());

    ByteArrayOutputStream baos = new ByteArrayOutputStream();

    baos.write(cipher.update(data));

    baos.write(cipher.doFinal());

    byte[] ciphertext = baos.toByteArray();

    return ciphertext;

  } catch (Exception e) {

    throw new RuntimeException(e);

  }

}

static byte[] decrypt(byte[] ciphertext, S password, byte[] salt) {

  try {

    SecretKey secret = makeKey(password, salt);

    /* Decrypt the message, given derived key and initialization vector. */

    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

    ByteArrayOutputStream baos = new ByteArrayOutputStream();

    cipher.init(Cipher.DECRYPT_MODE, secret, makeIV());

    baos.write(cipher.update(ciphertext));

    baos.write(cipher.doFinal());

    return baos.toByteArray(); 

  } catch (Exception e) {

    throw new RuntimeException(e);

  }

}