RSA公钥私钥加密算法

**

1、RsaUtils

**

/**
 * @project:     adomv
 * @title:          RSAUtils.java
 * @copyright: ©2018 www.bmsoft.com.cn. All rights reserved.
 */
package com.webapp.mobile.util;

import java.io.ByteArrayOutputStream;
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;

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.springframework.util.Base64Utils;


public class RsaUtils {

    /**
     * 加密算法RSA
     */
    public static final String  KEY_ALGORITHM       = "RSA";
    /**
     * Ciper transformation
     */
    public static final String  CIPHER_ALGORITHM        = "RSA/ECB/PKCS1Padding";
    /**
     * 签名算法
     */
    public static final String  SIGNATURE_ALGORITHM = "MD5withRSA";

    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY          = "RSAPublicKey";
    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY         = "RSAPrivateKey";
    /**
     * 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;

    /**
     * 生成密钥对(公钥和私钥)
     * 
     * @return Map<String, Object> 密钥对(公钥和私钥)
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    }

    /**
     * 获取公钥
     * 
     * @param keyMap密钥对
     * @return 公钥 BASE64字符串
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap){
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return Base64Utils.encodeToString(key.getEncoded());
    }

    /**
     * 获取私钥
     * 
     * @param keyMap 密钥对
     * @return 私钥 BASE64字符串
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap){
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64Utils.encodeToString(key.getEncoded());
    }

    /**
     * 用私钥对信息生成数字签名
     * 
     * @param data
     *            已加密数据
     * @param privateKey
     *            私钥(BASE64编码)
     * @return String 
     *            数字签名
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = Base64Utils.decodeFromString(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return Base64Utils.encodeToString(signature.sign());
    }

    /**
     * 校验数字签名
     * 
     * @param data
     *            已加密数据
     * @param publicKey
     *            公钥(BASE64编码)
     * @param sign
     *            数字签名
     * @return boolean 
     *            数字签名校验结果
     * @throws Exception
     * 
     */
    public static boolean verify(byte[] data, String publicKey, String sign) throws Exception {
        byte[] keyBytes = Base64Utils.decodeFromString(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return signature.verify(Base64Utils.decodeFromString(sign));
    }

    /**
     * 公钥加密
     * 
     * @param data
     *            源数据
     * @param publicKey
     *            公钥(BASE64编码)
     * @return byte[]
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, String publicKey) throws Exception {
        byte[] keyBytes = Base64Utils.decodeFromString(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
//        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
        Cipher cipher= Cipher.getInstance(CIPHER_ALGORITHM, new BouncyCastleProvider());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * 公钥解密
     * 
     * @param encryptedData
     *            已加密数据
     * @param publicKey
     *            公钥(BASE64编码)
     * @return byte[]
     *            解密数据
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey) throws Exception {
        byte[] keyBytes = Base64Utils.decodeFromString(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
//        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
        Cipher cipher= Cipher.getInstance(CIPHER_ALGORITHM, new BouncyCastleProvider());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher
                        .doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher
                        .doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /**
     * 私钥加密
     * 
     * @param data
     *            源数据
     * @param privateKey
     *            私钥(BASE64编码)
     * @return byte[]
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = Base64Utils.decodeFromString(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
//        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
        Cipher cipher= Cipher.getInstance(CIPHER_ALGORITHM, new BouncyCastleProvider());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * 私钥解密
     * 
     * @param encryptedData
     *            已加密数据
     * @param privateKey
     *            私钥(BASE64编码)
     * @return byte[]
     *            解密数据
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedData,String privateKey) throws Exception {
        byte[] keyBytes = Base64Utils.decodeFromString(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher= Cipher.getInstance(CIPHER_ALGORITHM, new BouncyCastleProvider());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher
                        .doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /**
     * 公钥加密
     * 
     * @param data
     *      要加密的字符串
     * @param publicKey
     *      公钥(BASE64编码)
     * @throws Exception 
     */
    public static String encryptedDataOnJava(String data, String publicKey) throws Exception {
        return Base64Utils.encodeToString(encryptByPublicKey(data.getBytes(),publicKey));
    }

    /**
     * 私钥解密
     * 
     * @param data
     *      要解密的字符串
     * @param publicKey
     *      私钥(BASE64编码)
     * @throws Exception 
     */
    public static String decryptDataOnJava(String data, String privateKey) throws Exception {
        String decryptStr = new String(decryptByPrivateKey(Base64Utils.decodeFromString(data), privateKey),"UTF-8"); // 以utf-8的方式生成字符串;
        return decryptStr;
    }




}