/*

* Copyright 2014-2023 The GmSSL Project. All Rights Reserved.

*

* Licensed under the Apache License, Version 2.0 (the License); you may

* not use this file except in compliance with the License.

*

* http://www.apache.org/licenses/LICENSE-2.0

*/

import org.gmssl.Sm4Cbc;

import org.gmssl.Random;

public class Sm4CbcExample {

public static void main(String[] args) {

Random rng = new Random();

byte[] key = rng.randBytes(Sm4Cbc.KEY_SIZE);

byte[] iv = rng.randBytes(Sm4Cbc.IV_SIZE);

// Encrypted plaintext is "110101200106032443"

byte[] plaintext = "ID:110101200106032443".getBytes();

int plaintextOffset = "ID:".length();

int plaintextLen = plaintext.length - plaintextOffset;

boolean encrypt = true;

boolean decrypt = false;

int i;

System.out.println("SM4-CBC Example");

Sm4Cbc sm4cbc = new Sm4Cbc();

// Encrypt

byte[] ciphertext = new byte[plaintextLen + Sm4Cbc.BLOCK_SIZE]; // Prepare large enough ciphertext buffer

int ciphertextOffset = 0;

int ciphertextLen;

sm4cbc.init(key, iv, encrypt);

ciphertextLen = sm4cbc.update(plaintext, plaintextOffset, plaintextLen, ciphertext, ciphertextOffset);

ciphertextOffset += ciphertextLen;

ciphertextLen += sm4cbc.doFinal(ciphertext, ciphertextOffset);

System.out.print("ciphertext : ");

for (i = 0; i < ciphertextLen; i++) {

System.out.printf("%02x", ciphertext[i]);

}

System.out.print("\n");

// Decrypt

sm4cbc.init(key, iv, decrypt);

byte[] decrypted = new byte[ciphertextLen + Sm4Cbc.BLOCK_SIZE]; // prepare large enough plaintext buffer

int decryptedOffset = 0;

int decryptedLen;

ciphertextOffset = 0;

decryptedLen = sm4cbc.update(ciphertext, ciphertextOffset, ciphertextLen, decrypted, decryptedOffset);

decryptedOffset += decryptedLen;

decryptedLen += sm4cbc.doFinal(decrypted, decryptedOffset);

System.out.print("decrypted : ");

for (i = 0; i < decryptedLen; i++) {

System.out.printf("%02x", decrypted[i]);

}

System.out.print("\n");

}

}