Java 加密 encrypt 有哪些常用方法？-杰瑞科技汇

Java 加密 (Encrypt) 指南

Java 提供了多种加密方式,以下是一些常见的加密实现方法：

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对称加密 (AES)

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;
public class AESEncryption {
    private static final String ALGORITHM = "AES";
    // 生成AES密钥
    public static String generateKey() throws Exception {
        KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM);
        keyGenerator.init(256); // 256位密钥
        SecretKey secretKey = keyGenerator.generateKey();
        return Base64.getEncoder().encodeToString(secretKey.getEncoded());
    }
    // 加密
    public static String encrypt(String data, String key) throws Exception {
        SecretKeySpec secretKeySpec = new SecretKeySpec(Base64.getDecoder().decode(key), ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
        byte[] encrypted = cipher.doFinal(data.getBytes());
        return Base64.getEncoder().encodeToString(encrypted);
    }
    // 解密
    public static String decrypt(String encryptedData, String key) throws Exception {
        SecretKeySpec secretKeySpec = new SecretKeySpec(Base64.getDecoder().decode(key), ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
        byte[] decoded = Base64.getDecoder().decode(encryptedData);
        byte[] decrypted = cipher.doFinal(decoded);
        return new String(decrypted);
    }
    public static void main(String[] args) throws Exception {
        String originalData = "这是一个秘密消息";
        String key = generateKey();
        String encrypted = encrypt(originalData, key);
        System.out.println("加密后: " + encrypted);
        String decrypted = decrypt(encrypted, key);
        System.out.println("解密后: " + decrypted);
    }
}

非对称加密 (RSA)

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
public class RSAEncryption {
    public static KeyPair generateKeyPair() throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(2048);
        return keyPairGenerator.generateKeyPair();
    }
    public static String encrypt(String data, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] encrypted = cipher.doFinal(data.getBytes());
        return Base64.getEncoder().encodeToString(encrypted);
    }
    public static String decrypt(String encryptedData, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] decoded = Base64.getDecoder().decode(encryptedData);
        byte[] decrypted = cipher.doFinal(decoded);
        return new String(decrypted);
    }
    public static String publicKeyToString(PublicKey publicKey) {
        return Base64.getEncoder().encodeToString(publicKey.getEncoded());
    }
    public static String privateKeyToString(PrivateKey privateKey) {
        return Base64.getEncoder().encodeToString(privateKey.getEncoded());
    }
    public static PublicKey stringToPublicKey(String publicKeyStr) throws Exception {
        byte[] decoded = Base64.getDecoder().decode(publicKeyStr);
        X509EncodedKeySpec spec = new X509EncodedKeySpec(decoded);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePublic(spec);
    }
    public static PrivateKey stringToPrivateKey(String privateKeyStr) throws Exception {
        byte[] decoded = Base64.getDecoder().decode(privateKeyStr);
        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(decoded);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePrivate(spec);
    }
    public static void main(String[] args) throws Exception {
        String originalData = "这是一个秘密消息";
        KeyPair keyPair = generateKeyPair();
        String publicKeyStr = publicKeyToString(keyPair.getPublic());
        String privateKeyStr = privateKeyToString(keyPair.getPrivate());
        System.out.println("公钥: " + publicKeyStr);
        System.out.println("私钥: " + privateKeyStr);
        String encrypted = encrypt(originalData, stringToPublicKey(publicKeyStr));
        System.out.println("加密后: " + encrypted);
        String decrypted = decrypt(encrypted, stringToPrivateKey(privateKeyStr));
        System.out.println("解密后: " + decrypted);
    }
}

哈希加密 (SHA-256)

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class SHA256Hash {
    public static String hash(String input) {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-256");
            byte[] hashBytes = md.digest(input.getBytes());
            StringBuilder hexString = new StringBuilder();
            for (byte b : hashBytes) {
                String hex = Integer.toHexString(0xff & b);
                if (hex.length() == 1) {
                    hexString.append('0');
                }
                hexString.append(hex);
            }
            return hexString.toString();
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }
    public static void main(String[] args) {
        String originalString = "这是一个需要哈希的字符串";
        String hashedString = hash(originalString);
        System.out.println("原始字符串: " + originalString);
        System.out.println("SHA-256哈希: " + hashedString);
    }
}

PBKDF2 密码哈希

import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.util.Base64;
public class PBKDF2Hash {
    private static final int ITERATIONS = 10000;
    private static final int KEY_LENGTH = 256;
    private static final String ALGORITHM = "PBKDF2WithHmacSHA256";
    public static String hashPassword(String password, String salt) throws NoSuchAlgorithmException, InvalidKeySpecException {
        PBEKeySpec spec = new PBEKeySpec(password.toCharArray(), salt.getBytes(), ITERATIONS, KEY_LENGTH);
        SecretKeyFactory skf = SecretKeyFactory.getInstance(ALGORITHM);
        byte[] hash = skf.generateSecret(spec).getEncoded();
        return Base64.getEncoder().encodeToString(hash);
    }
    public static String generateSalt() {
        SecureRandom random = new SecureRandom();
        byte[] salt = new byte[16];
        random.nextBytes(salt);
        return Base64.getEncoder().encodeToString(salt);
    }
    public static boolean verifyPassword(String originalPassword, String storedHash, String salt) 
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        String newHash = hashPassword(originalPassword, salt);
        return newHash.equals(storedHash);
    }
    public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeySpecException {
        String password = "mySecurePassword123";
        String salt = generateSalt();
        String hashedPassword = hashPassword(password, salt);
        System.out.println("密码哈希: " + hashedPassword);
        System.out.println("盐值: " + salt);
        boolean isValid = verifyPassword(password, hashedPassword, salt);
        System.out.println("密码验证结果: " + isValid);
    }
}