InvalidKeyException java.security.InvalidKeyException: No installed provider supports this key: (null)

Question

I have two classes, one is main class and another is the implementation of AES.

However, in my AES class i have a method to decrypt a string, but whenever i run it, it gives an exception

My encryption method works just fine but my decryption method doesn't work as expected.

The code

private Cipher aesCipherForDecryption;
String strDecryptedText = new String();

public String decryptAES(final String ciphertext) {

    try {

        aesCipherForDecryption = Cipher.getInstance("AES/CBC/PKCS5PADDING");
        aesCipherForDecryption.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(iV));
        byte[] byteDecryptedText = aesCipherForDecryption.doFinal(byteCipherText);
        strDecryptedText = new String(byteDecryptedText);

    } catch (IllegalBlockSizeException e) {
        System.out.print("IllegalBlockSizeException " +e);
    } catch (BadPaddingException e) {
        System.out.print("BadPaddingException "+e);
    } catch (NoSuchAlgorithmException e) {
        System.out.print("NoSuchAlgorithmException "+ e);
    } catch (NoSuchPaddingException e) {
        System.out.print("NoSuchPaddingException "+e);
    } catch (InvalidKeyException e) {
        System.out.print("InvalidKeyException "+e);
    } catch (InvalidAlgorithmParameterException e) {
        System.out.print("InvalidAlgorithmParameterException "+e);
    }

    System.out.println("\nDecrypted Text message is " + strDecryptedText);
    return strDecryptedText;
}

The error this method outputs is

InvalidKeyException java.security.InvalidKeyException: No installed provider supports this key: (null)

UPDATE #1:

So i have updated the code as the following

public String decryptAES(byte[] ciphertext) {
    String strDecryptedText = new String();
        try {
            byte[] byteDecryptedText = aesCipherForDecryption.doFinal(ciphertext);

            strDecryptedText = new String(byteDecryptedText);

        } catch (IllegalBlockSizeException e) {
            System.out.print("IllegalBlockSizeException "+e);
            e.printStackTrace();
        } catch (BadPaddingException e) {
            System.out.print("BadPaddingException "+e);
            e.printStackTrace();
        }

    System.out.println("\nDecrypted Text message is " + strDecryptedText);
    return strDecryptedText;
}    

and in the main class i have this line

byte [] byteciphertext = ciphertext.getBytes();

just to convert the string to bytes

is it correct? i'm still having

IllegalBlockSizeException javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipherjavax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher

Could someone help me fix this issue?

Thank you.

Answer 1

secretKey is clearly null.

Other problems:

• You aren't using the input parameter cipherText.
• The input parameter cipherText should be a byte[], not a String: cipher text is binary, and String is not a container for binary data.
• The result string strDecryptedText should be a local variable, not a member variable.