des算法实现java

DES（Data Encryption Standard）是一种对称加密算法，它的实现可以使用Java提供的标准库中的javax.crypto包。

下面是一个简单的DES加密和解密的实例代码：

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

public class DESUtil {
    private static final String ALGORITHM = "DES";
    private static final String TRANSFORMATION = "DES/ECB/PKCS5Padding";

    public static String encrypt(String input, String key) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(StandardCharsets.UTF_8), ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, keySpec);
        byte[] encryptedBytes = cipher.doFinal(input.getBytes(StandardCharsets.UTF_8));
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }

    public static String decrypt(String input, String key) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(StandardCharsets.UTF_8), ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, keySpec);
        byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decode(input));
        return new String(decryptedBytes, StandardCharsets.UTF_8);
    }
}

使用示例：

public class Main {
    public static void main(String[] args) throws Exception {
        String input = "Hello, world!";
        String key = "my secret key";
        String encrypted = DESUtil.encrypt(input, key);
        System.out.println("Encrypted: " + encrypted);
        String decrypted = DESUtil.decrypt(encrypted, key);
        System.out.println("Decrypted: " + decrypted);
    }
}

输出：

Encrypted: QmYm8Bv6mJ2jMx0oUwW6Uw==
Decrypted: Hello, world!

注意：DES算法已经不安全，不推荐使用。可以使用更安全的AES算法代替。