How to fix Invalid AES key length?

Question

I am working on a text encryption and decryption project (following Struts 2)

Whenever I enter the password and the plain text I get a Invalid AES K

Answer 1

You can use this code, this code is for AES-256-CBC or you can use it for other AES encryption. Key length error mainly comes in 256-bit encryption.

This error comes due to the encoding or charset name we pass in the SecretKeySpec. Suppose, in my case, I have a key length of 44, but I am not able to encrypt my text using this long key; Java throws me an error of invalid key length. Therefore I pass my key as a BASE64 in the function, and it converts my 44 length key in the 32 bytes, which is must for the 256-bit encryption.

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.MessageDigest;
import java.security.Security;
import java.util.Base64;

public class Encrypt {

    static byte [] arr = {1,2,3,4,5,6,7,8,9};

    // static byte [] arr = new byte[16];

      public static void main(String...args) {
        try {
         //   System.out.println(Cipher.getMaxAllowedKeyLength("AES"));
            Base64.Decoder decoder = Base64.getDecoder();
            // static byte [] arr = new byte[16];
            Security.setProperty("crypto.policy", "unlimited");
            String key = "Your key";
       //     System.out.println("-------" + key);

            String value = "Hey, i am adnan";
            String IV = "0123456789abcdef";
       //     System.out.println(value);
            // log.info(value);
          IvParameterSpec iv = new IvParameterSpec(IV.getBytes());
            //    IvParameterSpec iv = new IvParameterSpec(arr);

        //    System.out.println(key);
            SecretKeySpec skeySpec = new SecretKeySpec(decoder.decode(key), "AES");
         //   System.out.println(skeySpec);
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        //    System.out.println("ffffdffffdffffd"+IV);
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
       //     System.out.println(cipher.getIV());

            byte[] encrypted = cipher.doFinal(value.getBytes());
            String encryptedString = Base64.getEncoder().encodeToString(encrypted);

            System.out.println("encrypted string,,,,,,,,,,,,,,,,,,,: " + encryptedString);
            // vars.put("input-1",encryptedString);
            //  log.info("beanshell");
        }catch (Exception e){
            System.out.println(e.getMessage());
        }
    }
}