当前位置：首页 > Java

Java如何加密string

2026-03-25 13:11:49Java

使用Java内置的MessageDigest进行哈希加密

哈希加密（如MD5、SHA-256）适用于不可逆的场景，如密码存储。以下示例使用SHA-256：

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class HashExample {
    public static String encryptSHA256(String input) throws NoSuchAlgorithmException {
        MessageDigest digest = MessageDigest.getInstance("SHA-256");
        byte[] hashBytes = digest.digest(input.getBytes());
        StringBuilder hexString = new StringBuilder();
        for (byte b : hashBytes) {
            hexString.append(String.format("%02x", b));
        }
        return hexString.toString();
    }
}

调用方法：encryptSHA256("yourString")返回16进制哈希值。

使用对称加密（AES）

AES加密需密钥，适用于可逆加密场景。需依赖javax.crypto包：

Java如何加密string

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.util.Base64;

public class AESExample {
    public static SecretKey generateKey() throws Exception {
        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
        keyGenerator.init(256); // 密钥长度
        return keyGenerator.generateKey();
    }

    public static String encryptAES(String input, SecretKey key) throws Exception {
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] encryptedBytes = cipher.doFinal(input.getBytes());
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }
}

生成密钥后调用encryptAES("text", key)，返回Base64编码的密文。

使用非对称加密（RSA）

RSA通过公钥加密、私钥解密，适用于安全传输场景：

Java如何加密string

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

public class RSAExample {
    public static KeyPair generateKeyPair() throws Exception {
        KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
        generator.initialize(2048);
        return generator.generateKeyPair();
    }

    public static String encryptRSA(String input, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] encryptedBytes = cipher.doFinal(input.getBytes());
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }
}

调用encryptRSA("data", keyPair.getPublic())加密数据。

使用第三方库（如Bouncy Castle）

如需更多算法（如ChaCha20），可添加Bouncy Castle依赖：

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk15on</artifactId>
    <version>1.70</version>
</dependency>

示例代码：

import org.bouncycastle.crypto.engines.ChaChaEngine;
import org.bouncycastle.crypto.params.KeyParameter;

public class BouncyCastleExample {
    public static byte[] encryptChaCha(byte[] input, byte[] key) {
        ChaChaEngine cipher = new ChaChaEngine();
        cipher.init(true, new KeyParameter(key));
        byte[] output = new byte[input.length];
        cipher.processBytes(input, 0, input.length, output, 0);
        return output;
    }
}