RSA前段加密，後段解密

import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
/**
 * Description: RSA 工具
 *
 * @author cy
 * @date 2019年08月05日 11:22
 * Version 1.0
 */
public class RsaUtil {
    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;

    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;
    /**
     * 編碼
     */
    private static String charset = "utf-8";

    /**
     * 獲取密鑰對
     *
     * @return 密鑰對
     */
    public static KeyPair getKeyPair() throws Exception {
        KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
        generator.initialize(1024);
        return generator.generateKeyPair();
    }

    /**
     * 獲取私鑰
     *
     * @param privateKey 私鑰字符串
     * @return
     */
    public static PrivateKey getPrivateKey(String privateKey) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes(charset));
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
        return keyFactory.generatePrivate(keySpec);
    }

    /**
     * 獲取公鑰
     *
     * @param publicKey 公鑰字符串
     * @return
     */
    public static PublicKey getPublicKey(String publicKey) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes(charset));
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
        return keyFactory.generatePublic(keySpec);
    }

    /**
     * RSA加密
     *
     * @param data 待加密數據
     * @param publicKey 公鑰
     * @return
     */
    public static String encrypt(String data, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        int inputLen = data.getBytes(charset).length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offset = 0;
        byte[] cache;
        int i = 0;
        // 對數據分段加密
        while (inputLen - offset > 0) {
            if (inputLen - offset > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data.getBytes(charset), offset, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data.getBytes(charset), offset, inputLen - offset);
            }
            out.write(cache, 0, cache.length);
            i++;
            offset = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        // 獲取加密內容使用base64進行編碼,並以UTF-8爲標準轉化成字符串
        // 加密後的字符串
        return Base64.encodeBase64String(encryptedData);
    }

    /**
     * RSA解密
     *
     * @param data 待解密數據
     * @param privateKey 私鑰
     * @return
     */
    public static String decrypt(String data, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] dataBytes = Base64.decodeBase64(data);
        int inputLen = dataBytes.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offset = 0;
        byte[] cache;
        int i = 0;
        // 對數據分段解密
        while (inputLen - offset > 0) {
            if (inputLen - offset > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(dataBytes, offset, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
            }
            out.write(cache, 0, cache.length);
            i++;
            offset = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        // 解密後的內容
        return new String(decryptedData, "UTF-8");
    }

    /**
     * 簽名
     *
     * @param data 待簽名數據
     * @param privateKey 私鑰
     * @return 簽名
     */
    public static String sign(String data, PrivateKey privateKey) throws Exception {
        byte[] keyBytes = privateKey.getEncoded();
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey key = keyFactory.generatePrivate(keySpec);
        Signature signature = Signature.getInstance("MD5withRSA");
        signature.initSign(key);
        signature.update(data.getBytes(charset));
        return new String(Base64.encodeBase64(signature.sign()),charset);
    }

    /**
     * 驗籤
     *
     * @param srcData 原始字符串
     * @param publicKey 公鑰
     * @param sign 簽名
     * @return 是否驗籤通過
     */
    public static boolean verify(String srcData, PublicKey publicKey, String sign) throws Exception {
        byte[] keyBytes = publicKey.getEncoded();
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey key = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance("MD5withRSA");
        signature.initVerify(key);
        signature.update(srcData.getBytes(charset));
        return signature.verify(Base64.decodeBase64(sign.getBytes(charset)));
    }

    public static void main(String[] args) {
        try {
            // 生成密鑰對
            //KeyPair keyPair = getKeyPair();
            //String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));
            //String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));
            //System.out.println("私鑰:" + privateKey);
            //System.out.println("公鑰:" + publicKey);
            // RSA加密
            String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCIDV8I1zpoazcFmv3VNtG/E9/QC14gDhBoW9Yq6o9UNLaOZC41yoGa7hjHqjuPOcmPJ61Wmv7i5UbB5BceGRl2i0pSyOzeAeYpoY5cNRStfQlXFlwV1Ig1P081rxBcCgkWZvhodsWp9yRdKOTTHUCj0FpgD94/2QhvqkxOaW9vAwIDAQAB";
            String privateKey = "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";
            String data = "12312aawevrdgr312332312312312";
            String encryptData = encrypt(data, getPublicKey(publicKey));
            System.out.println("加密後內容:" + encryptData);
            // RSA解密
            String decryptData = decrypt(encryptData, getPrivateKey(privateKey));
            System.out.println("解密後內容:" + decryptData);

            // RSA簽名
            String sign = sign(data, getPrivateKey(privateKey));
            // RSA驗籤
            boolean result = verify(data, getPublicKey(publicKey), sign);
            System.out.print("驗簽結果:" + result);
        } catch (Exception e) {
            e.printStackTrace();
            System.out.print("加解密異常");
        }
    }

}

 

轉載於:https://www.cnblogs.com/chengyangyang/p/11302354.html

備註：RsaUtil工具爲轉載，下面案列爲個人項目中使用

案例1：

登錄頁面的後臺：

Session session = UserUtils.getSession();
try {
    KeyPair keyPair = RsaUtil.getKeyPair();
    String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));
    String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));
//公鑰生成
    session.setAttribute("publicKey",RsaUtil.getPublicKey(publicKey));
//私密未加工
    session.setAttribute("privateKey",privateKey);
//公鑰帶入前臺
    model.addAttribute("publicKey",publicKey);

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

 

前段：

//需要引入jsencrypt.min.js

<script src="${ctxStatic}/jsencrypt/jsencrypt.min.js" type="text/javascript"></script>

var publicKey = '${publicKey}';
var password = $("#password").val();
var encrypt=new JSEncrypt();
encrypt.setPublicKey(publicKey)
//加密後的密碼賦值給password
$("#password").val(encrypt.encrypt(password));
//表單提交
$("#loginForm").submit();

後臺：

----------省略-------------
String privateKey=(String) session.getAttribute("privateKey");//獲取未加工的私鑰
String plainText ="";
try {
   String pw=String.valueOf(token.getPassword()) ;//獲取前臺傳過來加密的密碼，這個不是重點
   plainText= RsaUtil.decrypt(pw, RsaUtil.getPrivateKey(privateKey));//解密
   token.setPassword(plainText.toCharArray());
} catch (Exception e) {
   e.printStackTrace();
}

----------省略-------------