RSA加密工具类（非对称加密算法）

Posted 2021-02-03 yuyuanno1

 
import com.jfinal.log.Log;

import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

/**
 * RSA安全编码组件
 */
public abstract class ToolRSA {

    private static final Log log = Log.getLog(ToolRSA.class);

    /**
     * 非对称加密密钥算法
     */
    public static final String KEY_ALGORITHM = "RSA";

    /**
     * 公钥
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";

    /**
     * 私钥
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    /**
     * RSA密钥长度 默认1024位， 密钥长度必须是64的倍数， 范围在512至65536位之间。
     */
    private static final int KEY_SIZE = 512;

    /**
     * 私钥解密
     *
     * @param data 待解密数据
     * @param key  私钥
     * @return byte[] 解密数据
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] data, byte[] key) throws Exception {
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);

        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

        // 生成私钥
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);

        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());

        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        return cipher.doFinal(data);
    }

    /**
     * 公钥解密
     *
     * @param data 待解密数据
     * @param key  公钥
     * @return byte[] 解密数据
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data, byte[] key) throws Exception {

        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);

        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

        // 生成公钥
        PublicKey publicKey = keyFactory.generatePublic(x509KeySpec);

        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());

        cipher.init(Cipher.DECRYPT_MODE, publicKey);

        return cipher.doFinal(data);
    }

    /**
     * 公钥加密
     *
     * @param data 待加密数据
     * @param key  公钥
     * @return byte[] 加密数据
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, byte[] key) throws Exception {
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);

        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

        PublicKey publicKey = keyFactory.generatePublic(x509KeySpec);

        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());

        cipher.init(Cipher.ENCRYPT_MODE, publicKey);

        return cipher.doFinal(data);
    }

    /**
     * 私钥加密
     *
     * @param data 待加密数据
     * @param key  私钥
     * @return byte[] 加密数据
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, byte[] key) throws Exception {
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);

        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

        // 生成私钥
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);

        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());

        cipher.init(Cipher.ENCRYPT_MODE, privateKey);

        return cipher.doFinal(data);
    }

    /**
     * 取得私钥
     *
     * @param keyMap 密钥Map
     * @return byte[] 私钥
     * @throws Exception
     */
    public static byte[] getPrivateKey(Map<String, Object> keyMap) throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return key.getEncoded();
    }

    /**
     * 取得公钥
     *
     * @param keyMap 密钥Map
     * @return byte[] 公钥
     * @throws Exception
     */
    public static byte[] getPublicKey(Map<String, Object> keyMap) throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return key.getEncoded();
    }

    /**
     * 初始化密钥
     *
     * @return Map 密钥Map
     * @throws Exception
     */
    public static Map<String, Object> initKey() throws Exception {
        // 实例化密钥对生成器
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);

        // 初始化密钥对生成器
        keyPairGen.initialize(KEY_SIZE);

        // 生成密钥对
        KeyPair keyPair = keyPairGen.generateKeyPair();

        // 公钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

        // 私钥
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

        // 封装密钥
        Map<String, Object> keyMap = new HashMap<String, Object>(2);

        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);

        return keyMap;
    }


    public static void main(String[] args) {
        try {
            String dataStr = "今天天气很好";
            Map<String, Object> keyMap = initKey();//初始化公钥和私钥
            byte[] publicKey = getPublicKey(keyMap);
            byte[] privateKey = getPrivateKey(keyMap);
            byte[] beforData = encryptByPublicKey(dataStr.getBytes(), publicKey);
            log.info(new String(beforData));
            byte[] afterData = decryptByPrivateKey(beforData, privateKey);
            log.info(new String(afterData));

        } catch (Exception e) {
            e.printStackTrace();
        }


    }

}