RSA algorithm JS encryption JAVA decryption

There is such a requirement that the username and password of the front-end login must be encrypted. However, MD5 cannot be used. Since the background needs to detect the complexity of the password, then pass the password to the background under the premise of ensuring security. The answer is to use the RSA asymmetric encryption algorithm.

java code

Need to rely on the commons-codec package
RSACoder.java

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by lake on 17-4-12.
 */
public class RSACoder {
    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";

    public static byte[] decryptBASE64(String key) {
        return Base64.decodeBase64(key);
    }

    public static String encryptBASE64(byte[] bytes) {
        return Base64.encodeBase64String(bytes);
    }

    /**
     * 用私钥对信息生成数字签名
     *
     * @param data       加密数据
     * @param privateKey 私钥
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64编码的私钥
        byte[] keyBytes = decryptBASE64(privateKey);
        // 构造PKCS8EncodedKeySpec对象
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取私钥匙对象
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 用私钥对信息生成数字签名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(priKey);
        signature.update(data);
        return encryptBASE64(signature.sign());
    }

    /**
     * 校验数字签名
     *
     * @param data      加密数据
     * @param publicKey 公钥
     * @param sign      数字签名
     * @return 校验成功返回true 失败返回false
     * @throws Exception
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        // 解密由base64编码的公钥
        byte[] keyBytes = decryptBASE64(publicKey);
        // 构造X509EncodedKeySpec对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取公钥匙对象
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pubKey);
        signature.update(data);
        // 验证签名是否正常
        return signature.verify(decryptBASE64(sign));
    }

    public static byte[] decryptByPrivateKey(byte[] data, String key) throws Exception{
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key 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);
    }

    /**
     * 解密<br>
     * 用私钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(String data, String key)
            throws Exception {
        return decryptByPrivateKey(decryptBASE64(data),key);
    }

    /**
     * 解密<br>
     * 用公钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key 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);
    }

    /**
     * 加密<br>
     * 用公钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(String data, String key)
            throws Exception {
        // 对公钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key 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.getBytes());
    }

    /**
     * 加密<br>
     * 用私钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key 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
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Key> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return encryptBASE64(key.getEncoded());
    }

    /**
     * 取得公钥
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Key> keyMap)
            throws Exception {
        Key key = keyMap.get(PUBLIC_KEY);
        return encryptBASE64(key.getEncoded());
    }

    /**
     * 初始化密钥
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Key> initKey() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator
                .getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        Map<String, Key> keyMap = new HashMap(2);
        keyMap.put(PUBLIC_KEY, keyPair.getPublic());// 公钥
        keyMap.put(PRIVATE_KEY, keyPair.getPrivate());// 私钥
        return keyMap;
    }
}

Test class
RSACoderTest.java

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

import java.security.Key;
import java.util.Map;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

/**
 * Created by lake on 17-4-12.
 */
public class RSACoderTest {
    private String publicKey;
    private String privateKey;

    @Before
    public void setUp() throws Exception {
        Map<String, Key> keyMap = RSACoder.initKey();
        publicKey = RSACoder.getPublicKey(keyMap);
        privateKey = RSACoder.getPrivateKey(keyMap);
        System.err.println("公钥: \n\r" + publicKey);
        System.err.println("私钥： \n\r" + privateKey);
    }

    @Test
    public void test() throws Exception {
        System.err.println("公钥加密——私钥解密");
        String inputStr = "abc";
        byte[] encodedData = RSACoder.encryptByPublicKey(inputStr, publicKey);
        byte[] decodedData = RSACoder.decryptByPrivateKey(encodedData,
                privateKey);
        String outputStr = new String(decodedData);
        System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
        assertEquals(inputStr, outputStr);
    }

    @Test
    public void testSign() throws Exception {
        System.err.println("私钥加密——公钥解密");
        String inputStr = "sign";
        byte[] data = inputStr.getBytes();
        byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);
        byte[] decodedData = RSACoder.decryptByPublicKey(encodedData, publicKey);
        String outputStr = new String(decodedData);
        System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
        assertEquals(inputStr, outputStr);
        System.err.println("私钥签名——公钥验证签名");
        // 产生签名
        String sign = RSACoder.sign(encodedData, privateKey);
        System.err.println("签名:" + sign);
        // 验证签名
        boolean status = RSACoder.verify(encodedData, publicKey, sign);
        System.err.println("状态:" + status);
        assertTrue(status);
    }
}

front-end code

Depends on the jsencrypt project

<script src="bin/jsencrypt.min.js"></script>
<script type="text/javascript">
    var encrypt = new JSEncrypt();
    encrypt.setPublicKey('java生成的公钥');
    var encrypted = encrypt.encrypt('加密的字符串');
</script>

illustrate

The front-end generates an encrypted string encryptedand sends it to the back-end, and java can decrypt it using the private key.