用java写一段加密函数

我可以为你提供一段示例代码，可以帮助你使用Java语言来编写加密函数：import javax.crypto.Cipher;import javax.crypto.spec.SecretKeySpec;public class AESEncryption {public static byte[] encrypt(String key, String data) throws Exception {byte[] keyBytes = key.getBytes();SecretKeySpec secretKey = new SecretKeySpec(keyBytes, "AES");Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");cipher.init(Cipher.ENCRYPT_MODE, secretKey);byte[] encryptedData = cipher.doFinal(data.getBytes());return encryptedData;}}

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用Java 写段 RSA 加密算法

以下是使用Java实现RSA加密算法的示例代码：

import java.math.BigInteger;
import java.util.Random;

public class RSA {

    private BigInteger n, d, e;

    private int bitlen = 1024;

    public RSA() {
        Random r = new Random();
        BigInteger p = BigInteger.probablePrime(bitlen / 2, r);
        BigInteger q = BigInteger.probablePrime(bitlen / 2, r);
        n = p.multiply(q);
        BigInteger m = (p.subtract(BigInteger.ONE)).multiply(q.subtract(BigInteger.ONE));
        e = BigInteger.probablePrime(bitlen / 2, r);
        while (m.gcd(e).intValue() > 1) {
            e = BigInteger.probablePrime(bitlen / 2, r);
        }
        d = e.modInverse(m);
    }

    public RSA(BigInteger e, BigInteger d, BigInteger n) {
        this.e = e;
        this.d = d;
        this.n = n;
    }

    public synchronized BigInteger[] encrypt(byte[] message) {
        BigInteger[] cipher = new BigInteger[message.length];
        for (int i = 0; i < message.length; i++) {
            cipher[i] = BigInteger.valueOf(message[i]).modPow(e, n);
        }
        return cipher;
    }

    public synchronized byte[] decrypt(BigInteger[] cipher) {
        byte[] message = new byte[cipher.length];
        for (int i = 0; i < message.length; i++) {
            message[i] = cipher[i].modPow(d, n).byteValue();
        }
        return message;
    }

    public static void main(String[] args) {
        RSA rsa = new RSA();

        String text1 = "Hello World";
        System.out.println("Original Text 1: " + text1);

        //加密
        byte[] plaintext1 = text1.getBytes();
        BigInteger[] ciphertext1 = rsa.encrypt(plaintext1);
        System.out.print("Ciphertext 1: ");
        for (int i = 0; i < ciphertext1.length; i++) {
            System.out.print(ciphertext1[i].toString() + " ");
        }
        System.out.println();

        //解密
        byte[] decrypted1 = rsa.decrypt(ciphertext1);
        System.out.println("Decrypted Text 1: " + new String(decrypted1));

        String text2 = "RSA is an asymmetric cryptographic algorithm";
        System.out.println("Original Text 2: " + text2);

        //加密
        byte[] plaintext2 = text2.getBytes();
        BigInteger[] ciphertext2 = rsa.encrypt(plaintext2);
        System.out.print("Ciphertext 2: ");
        for (int i = 0; i < ciphertext2.length; i++) {
            System.out.print(ciphertext2[i].toString() + " ");
        }
        System.out.println();

        //解密
        byte[] decrypted2 = rsa.decrypt(ciphertext2);
        System.out.println("Decrypted Text 2: " + new String(decrypted2));
    }
}

上述代码实现了一个简单的RSA加密算法，包括密钥生成、加密和解密功能。在main函数中，我们加密了两个字符串并进行了解密。

麻烦写一段RSA加密PKCS1 JAVA代码

好的，以下是一个使用RSA加密PKCS1的JAVA代码示例，其中使用了Bouncy Castle库：

import org.bouncycastle.crypto.AsymmetricBlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.engines.RSAEngine;
import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
import org.bouncycastle.crypto.params.RSAKeyParameters;
import org.bouncycastle.crypto.util.PublicKeyFactory;
import org.bouncycastle.crypto.util.PrivateKeyFactory;
import org.bouncycastle.crypto.util.PKCS1Encoding;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import java.security.Security;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import java.security.interfaces.RSAPublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;

public class RSAPKCS1Example {

    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());

        // 生成RSA密钥对
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA", "BC");
        keyPairGenerator.initialize(2048, new SecureRandom());
        KeyPair keyPair = keyPairGenerator.generateKeyPair();

        // 获取公钥和私钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

        // 加密数据
        byte[] data = "Hello, World!".getBytes("UTF-8");
        byte[] encryptedData = encrypt(data, publicKey);

        // 解密数据
        byte[] decryptedData = decrypt(encryptedData, privateKey);
        String decryptedText = new String(decryptedData, "UTF-8");

        // 输出结果
        System.out.println("原始数据：" + new String(data, "UTF-8"));
        System.out.println("加密后数据：" + bytesToHex(encryptedData));
        System.out.println("解密后数据：" + decryptedText);
    }

    public static byte[] encrypt(byte[] data, RSAPublicKey publicKey) throws Exception {
        AsymmetricKeyParameter keyParameters = PublicKeyFactory.createKey(publicKey.getEncoded());
        AsymmetricBlockCipher cipher = new PKCS1Encoding(new RSAEngine());
        cipher.init(true, keyParameters);
        return cipher.processBlock(data, 0, data.length);
    }

    public static byte[] decrypt(byte[] encryptedData, RSAPrivateKey privateKey) throws Exception {
        AsymmetricKeyParameter keyParameters = PrivateKeyFactory.createKey(privateKey.getEncoded());
        AsymmetricBlockCipher cipher = new PKCS1Encoding(new RSAEngine());
        cipher.init(false, keyParameters);
        return cipher.processBlock(encryptedData, 0, encryptedData.length);
    }

    public static String bytesToHex(byte[] data) {
        StringBuilder builder = new StringBuilder();
        for (byte b : data) {
            builder.append(String.format("%02X", b));
        }
        return builder.toString();
    }

}

在上面的示例中，我们使用了Bouncy Castle库来进行RSA加密和解密，并使用了PKCS1编码方式。首先，我们使用`KeyPairGenerator`生成一个2048位的RSA密钥对，并从中获取公钥和私钥。然后，我们将原始数据进行加密，并将加密后的数据存储在`encryptedData`数组中。最后，我们使用私钥对加密后的数据进行解密，并将解密后的数据存储在`decryptedData`数组中。注意，我们使用了一个辅助函数`bytesToHex`将字节数组转换为十六进制字符串，以便于输出结果。