JAVA 非對稱加密算法RSA

jopen 11年前發布 | 33K 次閱讀加密安全相關

非對稱加密算法 RSA過程：以甲乙雙方為例

1、初始化密鑰構建密鑰對,生成公鑰、私鑰保存到keymap中
KeyPairGenerator ---> KeyPair --> RSAPublicKey、RSAPrivateKey
2、甲方使用私鑰加密, 加密后在用私鑰對加密數據進行數據簽名，然后發送給乙方
RSACoder.encryptByPrivateKey(data, privateKey);
RSACoder.sign(encodedData, privateKey);
3、乙方則通過公鑰驗證簽名的加密數據，如果驗證正確則在通過公鑰對加密數據進行解密
RSACoder.verify(encodedData, publicKey, sign);
RSACoder.decryptByPublicKey(encodedData, publicKey);
4、乙方在通過公鑰加密發送給甲方
RSACoder.encryptByPublicKey(decodedData, publicKey);
5、甲方通過私鑰解密該數據
RSACoder.decryptPrivateKey(encodedData, privateKey);
流程圖如下：

JAVA 非對稱加密算法RSA

java代碼實現如下：

package com.bank.utils;

import java.security.MessageDigest;

import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public abstract class Coder {
    public static final String KEY_SHA = "SHA";
    public static final String KEY_MD5 = "MD5";

    /** 
     * MAC算法可選以下多種算法 
     *  
     * <pre> 
     * HmacMD5  
     * HmacSHA1  
     * HmacSHA256  
     * HmacSHA384  
     * HmacSHA512 
     * </pre> 
     */  
    public static final String KEY_MAC = "HmacMD5";

    /**
     * BASE64解密
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptBASE64( String key ) throws Exception{
        return (new BASE64Decoder()).decodeBuffer(key);
    }

    /**
     * BASE64加密
     * @param key
     * @return
     * @throws Exception
     */
    public static String encryptBASE64( byte[] key) throws Exception{
        return (new BASE64Encoder()).encodeBuffer(key);
    }

    /**
     * MD5 加密
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptMD5( byte[] data) throws Exception {
        MessageDigest md5 = MessageDigest.getInstance(KEY_MD5);
        md5.update(data);

        return md5.digest();
    }

    /**
     * SHA 加密
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptSHA( byte[] data) throws Exception {
        MessageDigest sha = MessageDigest.getInstance(KEY_SHA);
        sha.update(data);

        return sha.digest();
    }

    /** 
     * 初始化HMAC密鑰 
     *  
     * @return 
     * @throws Exception 
     */  
    public static String initMacKey() throws Exception{
        KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_MAC);

        SecretKey secretKey = keyGenerator.generateKey();
        return encryptBASE64(secretKey.getEncoded());
    }

    /**
     * HMAC  加密
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptHMAC( byte[] data, String key) throws Exception{
        SecretKey secretKey = new SecretKeySpec(decryptBASE64(key), KEY_MAC);
        Mac mac = Mac.getInstance(secretKey.getAlgorithm());
        mac.init(secretKey);
        return mac.doFinal(data);
    }
}

package com.bank.utils;

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.Signature;
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;


public abstract class RSACoder extends Coder{
    public static final String KEY_ALGORITHM = "RSA";
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    private static final String PUBLIC_KEY = "RSAPublicKey";
    private static final String PRIVATE_KEY = "RSAPrivatekey";

    /**
     * 用私鑰對信息生成數字簽名
     * @param data 加密數據
     * @param privateKey 私鑰
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        //解密由base64編碼的私鑰
        byte[] keyBytes = decryptBASE64(privateKey);

        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(keyBytes);

        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

        //取私鑰對象
        PrivateKey pKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);

        //用私鑰生成數字簽名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(pKey);
        signature.update(data);

        return encryptBASE64(signature.sign());
    }

    /**
     * 校驗數字簽名
     * @param data 加密數據
     * @param publicKey 公鑰
     * @param sign 數字簽名
     * @return
     * @throws Exception
     */
    public static boolean verify(byte[] data, String publicKey, String sign) throws Exception{

        //解密有base64編碼的公鑰
        byte[] keyBytes = decryptBASE64(publicKey);

        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);

        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

        //取公鑰對象
        PublicKey pKey = keyFactory.generatePublic(keySpec);

        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pKey);
        signature.update(data);
        //驗證簽名是否正常
        return signature.verify(decryptBASE64(sign));
    }

    /**
     * 解密 
     *  用私鑰解密
     * @param data 加密數據
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptPrivateKey(byte[] data, String key) throws Exception{
        byte[] keyBytes = decryptBASE64(key);

        //取得私鑰
        PKCS8EncodedKeySpec encodedKeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory factory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key pKey = factory.generatePrivate(encodedKeySpec);

        //對數據解密
        Cipher cipher = Cipher.getInstance(factory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, pKey);

        return cipher.doFinal(data);
    }

    /**
     * 用公鑰解密
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey( byte[] data, String key) throws Exception{

        //解密
        byte[] keyBytes = decryptBASE64(key);

        //取得公鑰
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key pKey = keyFactory.generatePublic(keySpec);

        //對數據解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, pKey);

        return cipher.doFinal(data);
    }

    /**
     * 用公鑰加密
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey( byte[] data, String key) throws Exception{

        byte[] keyBytes = decryptBASE64(key);

        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key pKey = keyFactory.generatePublic(keySpec);


        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, pKey);

        return cipher.doFinal(data);
    }

    /**
     * 用私鑰加密
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String key) throws Exception{

        byte[] keyBytes = decryptBASE64(key);

        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(keySpec);

        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);

        return cipher.doFinal(data);
    }

    /**
     * 取得私鑰
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPrivateKey( Map<String, Object> keyMap) throws Exception{

        Key key = (Key) keyMap.get(PRIVATE_KEY);

        return encryptBASE64(key.getEncoded());
    }

    /**
     * 取得公鑰
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPublicKey( Map<String, Object> keyMap) throws Exception{

        Key key = (Key) keyMap.get(PUBLIC_KEY);

        return encryptBASE64(key.getEncoded());
    }
    /**
     * 初始化密鑰
     * @return
     * @throws Exception
     */
    public static Map<String, Object> initKey() throws Exception{

        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGenerator.initialize(1024);

        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        //公鑰
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

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

        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PRIVATE_KEY, privateKey);
        keyMap.put(PUBLIC_KEY, publicKey);
        return keyMap;
    }
}

package com.bank.test;

import java.util.Map;

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

import com.bank.utils.RSACoder;

public class RSACoderTest {
    private String publicKey;
    private String privateKey;
    /*
     * 非對稱加密算法   RSA過程 ： 以甲乙雙方為例
     *      1、初始化密鑰 構建密鑰對,生成公鑰、私鑰保存到keymap中
     *              KeyPairGenerator --->    KeyPair     -->      RSAPublicKey、RSAPrivateKey
     *      2、甲方使用私鑰加密, 加密后在用私鑰對加密數據進行數據簽名，然后發送給乙方
     *              RSACoder.encryptByPrivateKey(data, privateKey);
     *              RSACoder.sign(encodedData, privateKey);
     *      3、乙方則通過公鑰驗證簽名的加密數據，如果驗證正確則在通過公鑰對加密數據進行解密
     *              RSACoder.verify(encodedData, publicKey, sign);
     *              RSACoder.decryptByPublicKey(encodedData, publicKey);                
     * 
     *      4、乙方在通過公鑰加密發送給甲方
     *              RSACoder.encryptByPublicKey(decodedData, publicKey);
     *      5、甲方通過私鑰解密該數據       
     *              RSACoder.decryptPrivateKey(encodedData, privateKey);                
     */
    @Before
    public void setUp() throws Exception {

        Map<String , Object> keyMap = RSACoder.initKey();

        publicKey = RSACoder.getPublicKey(keyMap);
        privateKey = RSACoder.getPrivateKey(keyMap);

        System.out.println("公鑰：\n" + publicKey);
        System.out.println("私鑰：\n" + privateKey);
    }
    @Test
    public void test() throws Exception{
        String inputStr = "abc";
        byte[] data = inputStr.getBytes();//每次的得到的字節數組是不一樣的。
        //第二步 私鑰加密
        byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);
        //私鑰進行數據簽名
        String sign = RSACoder.sign(encodedData, privateKey);

        //第三步 公鑰驗證數字簽名
        boolean flag = RSACoder.verify(encodedData, publicKey, sign);
        System.out.println("flag:" + flag);
        //用公鑰對數據解密
        byte[] decodedData = RSACoder.decryptByPublicKey(encodedData, publicKey);

        System.out.println("data:" + data + "加密數據：" + encodedData + "    解密數據：" + decodedData);
        System.out.println("加密前數據-：" + new String(data) + "     解密后數據： " + new String(decodedData));

        //第四步使用公鑰加密數據
        encodedData = RSACoder.encryptByPublicKey(decodedData, publicKey);

        //第五步 使用私鑰解密數據
        decodedData = RSACoder.decryptPrivateKey(encodedData, privateKey);


        System.out.println("data:" + data + "加密數據：" + encodedData + "    解密數據：" + decodedData);
        System.out.println("加密前數據：" + inputStr + "     解密后數據： " + new String(decodedData));
    }


    @Test
    public void test1() throws Exception{
        System.out.println("私鑰加密-----公鑰解密");
        String inputStr = "abc";
        byte[] data = inputStr.getBytes();
        System.out.println("data:" + data);

        byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);
        byte[] decodedData = RSACoder.decryptByPublicKey(encodedData, publicKey);

        String outputStr = new String( decodedData );

        System.out.println("加密前：" + inputStr +"\n 解密后：" + outputStr);

        Assert.assertEquals(inputStr, outputStr);


        System.out.println("私鑰簽名---公鑰驗證簽名");
        //產生簽名
        String sign = RSACoder.sign(encodedData, privateKey);
        System.out.println("簽名：\r" + sign);

        //驗證簽名
        boolean flag = RSACoder.verify(encodedData, publicKey, sign);

        System.out.println("狀態：\r" + flag);

        Assert.assertTrue(flag);
    }
}

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