Java中的加密函数，实现数据的安全传输和存储

在Java中，可以使用各种加密函数来实现数据的安全传输和存储。下面介绍一些常用的加密函数和用法。

1. 对称加密算法：

对称加密算法使用相同的密钥进行加密和解密，常见的对称加密算法有DES、3DES、AES等。

使用AES算法示例代码如下：

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class AESEncryption {
    private static final String AES_ALGORITHM = "AES";
    private static final String AES_MODE = "AES/ECB/PKCS5Padding";

    public static String encrypt(String data, String key) {
        try {
            SecretKeySpec secretKeySpec = new SecretKeySpec(key.getBytes(), AES_ALGORITHM);
            Cipher cipher = Cipher.getInstance(AES_MODE);
            cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
            byte[] encryptedBytes = cipher.doFinal(data.getBytes());
            return Base64.getEncoder().encodeToString(encryptedBytes);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String decrypt(String encryptedData, String key) {
        try {
            SecretKeySpec secretKeySpec = new SecretKeySpec(key.getBytes(), AES_ALGORITHM);
            Cipher cipher = Cipher.getInstance(AES_MODE);
            cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
            byte[] encryptedBytes = Base64.getDecoder().decode(encryptedData);
            byte[] decryptedBytes = cipher.doFinal(encryptedBytes);
            return new String(decryptedBytes);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static void main(String[] args) {
        String data = "Hello, world!";
        String key = "0123456789ABCDEF0123456789ABCDEF";
        String encryptedData = encrypt(data, key);
        System.out.println("Encrypted data: " + encryptedData);
        String decryptedData = decrypt(encryptedData, key);
        System.out.println("Decrypted data: " + decryptedData);
    }
}

2. 非对称加密算法：

非对称加密算法使用一对密钥（公钥和私钥）进行加密和解密，常见的非对称加密算法有RSA、DSA等。

使用RSA算法示例代码如下：

import javax.crypto.Cipher;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.Base64;

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

    public static KeyPair generateKeyPair() {
        try {
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(RSA_ALGORITHM);
            keyPairGenerator.initialize(2048);
            return keyPairGenerator.generateKeyPair();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String encrypt(String data, PublicKey publicKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            byte[] encryptedBytes = cipher.doFinal(data.getBytes());
            return Base64.getEncoder().encodeToString(encryptedBytes);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String decrypt(String encryptedData, PrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] encryptedBytes = Base64.getDecoder().decode(encryptedData);
            byte[] decryptedBytes = cipher.doFinal(encryptedBytes);
            return new String(decryptedBytes);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static void main(String[] args) {
        String data = "Hello, world!";
        KeyPair keyPair = generateKeyPair();
        String encryptedData = encrypt(data, keyPair.getPublic());
        System.out.println("Encrypted data: " + encryptedData);
        String decryptedData = decrypt(encryptedData, keyPair.getPrivate());
        System.out.println("Decrypted data: " + decryptedData);
    }
}

以上是Java中实现数据安全传输和存储的两种加密函数示例，使用这些加密函数可以对数据进行加密和解密操作，保障数据的安全性。