What causes the error "java.security.InvalidKeyException: Parameters missing"?

Question

I'm trying to encrypt and decrypt a string using AES but getting an error I don't know how to resolve. This is the code:

public class EncryptionTest{

public static void main(String[] args) {        
    String encrypt = new String(encrypt("1234567890123456"));
    System.out.println("decrypted value:" + (decrypt("ThisIsASecretKey",encrypt)));
}

public static String encrypt(String value) {
    try {
        byte[] raw = new byte[]{'T', 'h', 'i', 's', 'I', 's', 'A', 'S', 'e', 'c', 'r', 'e', 't', 'K', 'e', 'y'};
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        byte[] encrypted = cipher.doFinal(value.getBytes());
        System.out.println("encrypted string:" + (new String(encrypted)));
        return new String(skeySpec.getEncoded());
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    return null;
}

public static String decrypt(String key, String encrypted) {
    try {
        SecretKeySpec skeySpec = new SecretKeySpec(Base64.decodeBase64(key), "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(skeySpec.getEncoded(),"AES"));
            (*)
        byte[] original = cipher.doFinal(Base64.decodeBase64(encrypted));
        original.toString();
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    return null;
}  
}

When I run it the "decription" values is null. It fails before the (***) !!

It gives me an exception:

java.security.InvalidKeyException: Parameters missing
    at com.sun.crypto.provider.CipherCore.init(CipherCore.java:388)
    at com.sun.crypto.provider.AESCipher.engineInit(AESCipher.java:186)
    at javax.crypto.Cipher.implInit(Cipher.java:787)
    at javax.crypto.Cipher.chooseProvider(Cipher.java:849)
    at javax.crypto.Cipher.init(Cipher.java:1213)
    at javax.crypto.Cipher.init(Cipher.java:1153)
    at firma.XmlEncryptionTest.decrypt(EncryptionTest.java:63)
    at firma.XmlEncryptionTest.main(EncryptionTest.java:41)

where the line 63 is the one before (***). I don't know what am I doing wrong and how to solve. I looked around on the internet but without finding out what coul be that missing parameter

Answer 1

The main issue in your code was caused by a failure to specify an IV value. You must specify an IV value when doing CBC-mode encryption and use that same value when performing the CBC-mode decryption.

Another problem is the mix and match of creating strings from byte arrays and base64-encoding. You also return null from your decrypt method every time. Even if you meant return original.toString();, that's still wrong (because toString() doesn't do what you wish it would on a byte array).

Below is an improved version of your code. It's far from optimal, but it compiles and works. You need to improve this to use a random IV. Also, if you plan to derive keys from passwords, don't just get the bytes, use a derivation function such as PBKDF2. You can see an example of using PBKDF2 in the JNCryptor source.

public class EncryptionTest {

  public static void main(String[] args) {
    try {

      String key = "ThisIsASecretKey";
      byte[] ciphertext = encrypt(key, "1234567890123456");
      System.out.println("decrypted value:" + (decrypt(key, ciphertext)));

    } catch (GeneralSecurityException e) {
      e.printStackTrace();
    }
  }

  public static byte[] encrypt(String key, String value)
      throws GeneralSecurityException {

    byte[] raw = key.getBytes(Charset.forName("UTF-8"));
    if (raw.length != 16) {
      throw new IllegalArgumentException("Invalid key size.");
    }

    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
    cipher.init(Cipher.ENCRYPT_MODE, skeySpec,
        new IvParameterSpec(new byte[16]));
    return cipher.doFinal(value.getBytes(Charset.forName("UTF-8")));
  }

  public static String decrypt(String key, byte[] encrypted)
      throws GeneralSecurityException {

    byte[] raw = key.getBytes(Charset.forName("UTF-8"));
    if (raw.length != 16) {
      throw new IllegalArgumentException("Invalid key size.");
    }
    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");

    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
    cipher.init(Cipher.DECRYPT_MODE, skeySpec,
        new IvParameterSpec(new byte[16]));
    byte[] original = cipher.doFinal(encrypted);

    return new String(original, Charset.forName("UTF-8"));
  }
}