java中RSA加密解密的使用

作为常用的非对称加密算法，本篇文章大致记录一下，在java代码中如何生成RSA的密钥对以及加密解密的使用。

1、生成密钥对

public class RSAUtils {

    // 填充方式
    public static final String RSA_ALGORITHM_NOPADDING = "RSA";
    public static final String RSA_ALGORITHM = "RSA/ECB/PKCS1Padding";

    /**
     * 生成密钥对
     * @return
     */
    public static Map<String, String> createKeyPairs() {
        try {
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(RSA_ALGORITHM_NOPADDING);
            keyPairGenerator.initialize(2048);
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
            return new HashMap<String, String>(){{
                put("publicKey", Base64.encodeBase64String(publicKey.getEncoded()));
                put("privateKey", Base64.encodeBase64String(privateKey.getEncoded()));
            }};
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }

}

 

2、加密

    /**
     * 通过公钥对数据进行加密
     * @param publicKeyStr
     * @param data
     * @return
     */
    public static String encryptRSADefault(String publicKeyStr, String data) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM_NOPADDING);  // 指定算法，返回keyFactory对象
            byte[] publicKeyByte = Base64.decodeBase64(publicKeyStr);  // 或：Base64.decodeBase64(publicKeyStr.getBytes())
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(publicKeyByte);  // 创建X509编码公钥规范
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);  // 根据X5090编码密钥规范产生公钥对象
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM_NOPADDING);  // 根据算法名称，生成密码对象
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);  // 使用公钥初始化cipher对象（encrypt加密模式）
            byte[] encryptByte = cipher.doFinal(data.getBytes());  // 对数据进行加密
            return Base64.encodeBase64String(encryptByte);  // 将字节数组，经过base64编码后，以US-ASCII编码输出为字符串
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

 

3、解密

    public static String decryptRSADefault(String privateKeyStr, String data) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM_NOPADDING);
            byte[] privateKeyByte = Base64.decodeBase64(privateKeyStr);
            PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(privateKeyByte);  //  密钥为pkcs8格式
            PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);  // 生成私钥对象
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM_NOPADDING);
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] decryptByte = cipher.doFinal(Base64.decodeBase64(data.getBytes()));
            return new String(decryptByte, "UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

 

4、测试

    public static void main(String[] args) {
        Map<String, String> keyPairs = createKeyPairs();
        System.out.println("公钥：\n" + keyPairs.get("publicKey"));
        System.out.println("私钥：\n" + keyPairs.get("privateKey"));

        if (null != keyPairs) {
            String encryptMsg = RSAUtils.encryptRSADefault(keyPairs.get("publicKey"), "hello world");
            System.out.println("加密后的内容：" + encryptMsg);
            String decryptMsg = RSAUtils.decryptRSADefault(keyPairs.get("privateKey"), encryptMsg);
            System.out.println("解密后的内容：" + decryptMsg);
        }

 

输出结果：