javax.crypto.BadPaddingException：给定最终块解密时未正确填充错误 [英] javax.crypto.BadPaddingException: Given final block not properly padded error while decryption

问题描述

我正在对数据进行加密和解密，但是出现错误

I am doing encryption and decryption of data as follows but getting error

protected Cipher aes_Gen_with_Key(byte[] key)
    {
        Cipher cipher=null;
        try
        {
        byte[] key_hash = (key).toString().getBytes("UTF-8");
        key_hash = Arrays.copyOf(key_hash, 32); // use only first 256 bit
        SecretKeySpec secretKeySpec = new SecretKeySpec(key_hash, "AES"); 
        cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);

        } catch (Exception e) {
            System.out.println("Error Occured");
        }
        return cipher;
    }

    protected Cipher aes_Dec_with_Key(byte[] key,byte[] iv)
    {
        Cipher cipher=null;
        try
        {
        byte[] key_hash = (key).toString().getBytes("UTF-8");
        key_hash = Arrays.copyOf(key_hash, 32); // use only first 256 bit
        SecretKeySpec secretKeySpec = new SecretKeySpec(key_hash, "AES");
        cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE,secretKeySpec,new IvParameterSpec(iv));
        }
        catch (Exception e) {
            System.out.println(e);
        }

        return cipher;
    }

使用上述2个函数，我正在获取加密和解密的密码，但是获取javax.crypto.BadPaddingException：给定最终块未正确填充为错误。解密字节数组长度为752，解密长度为16字节长。可以有人建议吗？

With above 2 functions I am getting ciphers with which I am doing encryption and decryption, but getting javax.crypto.BadPaddingException: Given final block not properly padded as error. Length of decryption byte array is 752 and IV at decryption is 16 byte long. Can any one suggest?

这里是更少的相关代码块。
为无效使用java命名约定感到歉意

Here are few more relevant code blocks. Apologies for invalid use java naming conventions

   // Key Class
    import java.io.Serializable;
    @SuppressWarnings("serial")
    public class Key implements Serializable{
        byte[] gsmodp_hash=null;
        byte[] iv_pass=null;
        byte[] Nonce_Enc=null;
        byte[] iv_non=null;
        public Key() {
        }

        public Key(byte[] gsmodp_hash,byte[] iv_pass,byte[] Nonce_Enc,byte[] iv_non) {
            this.gsmodp_hash=gsmodp_hash;
            this.iv_pass=iv_pass;
            this.Nonce_Enc=Nonce_Enc;
            this.iv_non=iv_non;
        }
    }

    // Client side code

            JSONObject auth_step_obj=new JSONObject();
            try {

                BigInteger gsmodp=get_modu_frm_server(receivePacket);
                BigInteger R2=get_R2_frm_server(receivePacket);
                BigInteger N2=get_N2_frm_server(receivePacket);
                N2=crypto.dec_NonceG(N2);
                BigInteger a=crypto.get_RandLong();
                BigInteger gamodp= crypto.dh_GenerationG(a, crypto.g, crypto.p);
                BigInteger key=crypto.dh_GenerationG(a, gsmodp, crypto.p);

                // Got hash of g^abmodp

                byte[] dhkey=crypto.sha256G(key.toString());
                key=null;
                //Mixing passwords

                SecretKey secretkey=(SecretKey) userCredentials.get("password");
                byte[] mixed_hash=crypto.passwordMixerG(R2, secretkey.getEncoded());

                //Working Fine Till now
                // Getting Cipher for encrypting gsmodp using password and nonce
                Cipher cipher_password=crypto.aes_Gen_with_Key(mixed_hash);
                Cipher cipher_key=crypto.aes_Gen_with_Key(dhkey);

                // Generating quantities for JSON Object        
                byte[] gsmodp_hash=cipher_password.doFinal(gamodp.toString().getBytes());
                byte[] gsmodp_hash_iv=cipher_password.getIV();
                byte[] nonce_enc=cipher_key.doFinal(N2.toString().getBytes());
                byte[] nonce_enc_iv=cipher_key.getIV();
                Key authetication_parameters=new Key(gsmodp_hash,gsmodp_hash_iv,nonce_enc,nonce_enc_iv);
                auth_step_obj.put("obj",authetication_parameters);

            } catch (Exception e) {
                // TODO Auto-generated catch block
                System.out.println("Hi:sec_DH_Step");
            } 
            // This sends JSONObject to calling method which generates UDP packet and sends to server 
            return auth_step_obj;
        }

    // Server side code
    // Once packet received on server following happens
    ds.receive(receivePacket);
    SecretKey userKey=cryptoObj.get_from_KeyStoreG(user_name);
    // Adding R2 and userKey byte by byte
    byte[] mixed_hash=cryptoObj.passwordMixerG(R2, userKey.getEncoded());
    JSONObject authentication_nonce=new JSONObject();
    authentication_nonce=cryptoObj.readRecievedPacket(receivePacket);
    Key obj=(Key)authentication_nonce.get("obj");
    Cipher cipher=cryptoObj.aes_Dec_with_Key(mixed_hash,obj.iv_pass);
    // I am getting error on do final
    System.out.println(new String(cipher.doFinal(obj.gsmodp_hash)));

推荐答案

您提供的代码工作正常。错误必须在于您没有与我们共享的代码（即实际使用 Cipher 对象的代码）。

The code you presented works just fine. The error must lie in the code you haven't shared with us (i.e. the code that actually uses the Cipher objects).

我写下面的代码来测试你的问题代码：

I wrote the code below to test your question code:

public static void main(String[] args) throws Exception {

  Random random = new Random();
  byte[] key = new byte[32];
  random.nextBytes(key);

  byte[] plaintext = new byte[100];
  random.nextBytes(plaintext);

  Cipher enc = aes_Gen_with_Key(key);

  byte[] ciphertext = enc.doFinal(plaintext);
  byte[] iv = enc.getIV();

  Cipher dec = aes_Dec_with_Key(key, iv);

  byte[] recoveredPlaintext = dec.doFinal(ciphertext);

  System.out.println(Arrays.equals(plaintext, recoveredPlaintext));    
}

请注意，我使您的两个方法是静态的。你应该这样做，因为他们不使用任何实例变量。

Note, I made your two methods static. You should do the same, as they don't use any instance variables.

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