RSA加密算法的使用正確姿勢

　　RSA加密算法是一種非對稱加密算法。在公開密鑰加密和電子商業中RSA被廣泛使用。

 

 通過公鑰加密信息，通過私鑰解密信息；場景如下：A服務器通過一套秘鑰中的公鑰加密信息，將加密后的信息傳給服務器B，服務B拿到加密后的信息，用該秘鑰中的私鑰進行解密獲取到正確信息；達到服務器安全通信目的；

 

1.該工具類所需要的jar包

import org.apache.tomcat.util.codec.binary.Base64;
import java.io.FileOutputStream;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

2.生成公鑰私鑰

public static void generateKey() {
        try {
            // 基於RSA算法生成對象
            KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
            //初始化密鑰對生成器，密鑰大小為1024位
            keyPairGen.initialize(512);  // 最小值是512，一般設置值為1024，該值越大加密信息越安全，對計算機消耗也越大
            //生成一個密鑰對，保存在keyPair中
            KeyPair keyPair = keyPairGen.generateKeyPair();
            //得到私鑰 RSAPrivateKey
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
            //得到公鑰 RSAPublicKey
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
            System.out.println("私鑰：" + Base64.encodeBase64String(privateKey.getEncoded()));
            System.out.println("公鑰：" + Base64.encodeBase64String(publicKey.getEncoded()));
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

 3.將公鑰的字符串轉成PublicKey公鑰對象

　　/**
     * @Description 根據字符串生產公鑰
     * @return java.security.PublicKey
     * @throws @Author zhanglei
     * @Date 14:25 2019/4/29
     * @Param [key]
     **/
    public static PublicKey getPublicKey(String publicKeys) throws Exception {
        byte[] keyBytes;
        keyBytes = Base64.decodeBase64(publicKeys);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
        return publicKey;
    }

4.將私鑰字符串轉成PrivateKey對象

/**
     * String轉私鑰PrivateKey
     * @param
     * @return
     * @throws Exception
     */
    public static PrivateKey getPrivateKey(String privateKeys) throws Exception {
        byte[] keyBytes;
        keyBytes = Base64.decodeBase64(privateKeys);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }

5.加密

public byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) throws NoSuchAlgorithmException,
            NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {

        if (publicKey != null) {
            // Cipher負責完成加密或解密工作，基於RSA
            Cipher cipher = Cipher.getInstance("RSA");
            // 根據公鑰，對Cipher對象進行初始
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            byte[] resultBytes = cipher.doFinal(srcBytes);
            return resultBytes;
        }
        return null;
    }

6.解密

public byte[] decrypt(RSAPrivateKey privateKey, byte[] srcBytes) throws NoSuchAlgorithmException,
            NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        if (privateKey != null) {
            // Cipher負責完成加密或解密工作，基於RSA
            Cipher cipher = Cipher.getInstance("RSA");
            // 根據公鑰，對Cipher對象進行初始化
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] resultBytes = cipher.doFinal(srcBytes);
            return resultBytes;
        }
        return null;
    }

7. 將byte數組與字符串之間轉換

　　（由於加密機密后都是返回byte數組，直接用new String（byte[]）會導致其中數組中負數信息轉譯，導致數據無法還原，即此處通過Base64工具來轉換）

    /**
     * Sring轉byte數組
     */
    public static byte[] stringToByte(String msg) {
        byte[] msgByte = Base64.decodeBase64(msg);
        return msgByte;
    }

    /**
     * byte數組轉字符串
     */
    public static String byteToString(byte[] bytes) {
        String msg = Base64.encodeBase64String(bytes);
        return msg;
    }

　　具體該文件可訪問如下地址：https://github.com/zlAdmin/didactic-enigma/blob/master/MapDemo/src/main/java/com/zl/unit/printunit/EncrypRSA.java