RSA加密算法优化的java核心代码：DES算法加密明文，RSA加密DES初始密钥

以下是RSA加密算法优化的Java核心代码，包括DES算法加密明文和RSA加密DES初始密钥：

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;

public class RSAEncryption {
    
    private static final String RSA_ALGORITHM = "RSA";
    private static final String DES_ALGORITHM = "DES";

    // 生成DES密钥
    public static SecretKey generateDESKey() throws NoSuchAlgorithmException {
        KeyGenerator keyGenerator = KeyGenerator.getInstance(DES_ALGORITHM);
        keyGenerator.init(56);
        return keyGenerator.generateKey();
    }

    // 使用DES算法加密明文
    public static byte[] encrypt(byte[] plainText, Key key) throws Exception {
        Cipher cipher = Cipher.getInstance(DES_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(plainText);
    }

    // 使用RSA算法加密DES密钥
    public static byte[] encryptKey(Key key, Key publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(key.getEncoded());
    }

    // 使用RSA算法解密DES密钥
    public static Key decryptKey(byte[] encryptedKey, Key privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] decryptedKey = cipher.doFinal(encryptedKey);
        return new SecretKeySpec(decryptedKey, DES_ALGORITHM);
    }

    public static void main(String[] args) throws Exception {
        // 生成RSA密钥对
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(RSA_ALGORITHM);
        keyPairGenerator.initialize(1024);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        Key publicKey = keyPair.getPublic();
        Key privateKey = keyPair.getPrivate();

        // 生成DES密钥
        SecretKey desKey = generateDESKey();

        // 加密明文
        String plainText = "Hello world!";
        byte[] encryptedPlainText = encrypt(plainText.getBytes(), desKey);

        // 加密DES密钥
        byte[] encryptedKey = encryptKey(desKey, publicKey);

        // 解密DES密钥
        Key decryptedKey = decryptKey(encryptedKey, privateKey);

        // 解密明文
        byte[] decryptedPlainText = encrypt(encryptedPlainText, decryptedKey);

        System.out.println("Plain text: " + plainText);
        System.out.println("Encrypted plain text: " + new String(encryptedPlainText));
        System.out.println("Encrypted key: " + new String(encryptedKey));
        System.out.println("Decrypted key: " + new String(decryptedKey.getEncoded()));
        System.out.println("Decrypted plain text: " + new String(decryptedPlainText));
    }
}

在该代码中，我们首先使用`KeyGenerator`生成了一个56位的DES密钥，然后使用`Cipher`类实现了DES算法加密明文和RSA算法加密DES密钥的功能。其中，`Cipher.init()`方法用于初始化加密/解密模式和密钥，`Cipher.doFinal()`方法用于进行加密/解密操作，`Key.getEncoded()`方法用于将密钥编码为字节数组，`SecretKeySpec`类用于将字节数组转换为密钥对象。

最后，我们使用`KeyPairGenerator`生成了RSA密钥对，将公钥用于RSA加密DES密钥，将私钥用于RSA解密DES密钥，从而实现了RSA加密算法优化的Java代码。