Java AES 128 ECB 到 AES 256 ECB 转换

Question

I have an issue to upgrade an AES 128 bit encryption to AES 256 in ECB mode. But I'm unable to find any solution for that. Mostly solutions are there for AES 256 CBC mode. Any help is highly appreciated.

The exception that I got was due to bad padding

PS: I'm aware of the vulnerability of ECB mode in AES but this is what I need to implement at the moment.

import org.apache.tomcat.util.codec.binary.Base64;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.security.GeneralSecurityException;

public class Decrypt {
    public static String decryptPayload(String payload) throws Exception {
        byte[] keyBytes = {
                0x74, 0x68, 0x69, 0x73, 0x49, 0x73, 0x43, 0x53, 0x75, 0x63, 0x72, 0x65, 0x44, 0x4b, 0x55, 0x79
        };
        try {
            payload = payload.replace(' ', '+');
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
            final SecretKeySpec secretKey = new SecretKeySpec(keyBytes, "AES");
            cipher.init(Cipher.DECRYPT_MODE, secretKey);
            return new String(cipher.doFinal(
                    Base64.decodeBase64(payload)));
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        }
        return null;
    }
}

The implementation of AES 256 ECB I tried was as follows:

    public static String decrypt(String strToDecrypt, String secretKey) {
        try
        {
            IvParameterSpec ivspec = new IvParameterSpec(iv);

            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
            KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), salt.getBytes(), 65536, 256);
            SecretKey tmp = factory.generateSecret(spec);
            SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");

            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
            cipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec);
            return new String(cipher.doFinal(Base64.getDecoder().decode(strToDecrypt)));
        }
        catch (Exception e) {
            System.out.println("Error while decrypting: " + e.toString());
        }
        return null;
    }

Answer 1

The entire solution which worked for me, thanks to @MichaelFehr

public void tester() {
        System.out.println("Program starts");
        String key = "5u7x!A%D*G-KaPdSgVkYp3s6v9y/B?E(";
        String payload = "Test string to test AES 256 ECB";
        String encrypted = "";
        String decrypted = "";
        // Encryption
        try{
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
            final SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), "AES");
            cipher.init(Cipher.ENCRYPT_MODE, secretKey);
            final String encryptedString = Base64.encodeBase64String(cipher.doFinal(payload.getBytes()));
            System.out.println("The encrypted string is\n"+encryptedString);
            encrypted = encryptedString;
        }
        catch(Exception e){
            e.printStackTrace();
        }


        // Decryption
        try
        {
            decrypted = encrypted.replace(' ', '+');
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
            final SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), "AES");
            cipher.init(Cipher.DECRYPT_MODE, secretKey);
            final String decryptedString = new String(cipher.doFinal(Base64.decodeBase64(encrypted)));
            System.out.println("The decrypted string is\n"+decryptedString);
            decrypted=decryptedString;
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }