java实现RSA加密

java实现RSA加密

流程分析： 
    1、甲方构建密钥对儿，将公钥公布给乙方，将私钥保留。 
    2、甲方使用私钥加密数据，然后用私钥对加密后的数据签名，发送给乙方签名以及加密后的数据；乙方使用公钥、签名来验证待解密数据是否有效，如果有效使用公钥对数据解密。 
    3、乙方使用公钥加密数据，向甲方发送经过加密后的数据；甲方获得加密数据，通过私钥解密。 

    通过java代码实现如下： 
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;   

/** *//** 
* RSA安全编码组件 
*   
* @version 1.0 
* @since 1.0 
*/ 
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));   
    }   

    /** *//** 
     * 解密
 
* 用私钥解密 http://www.5a520.cn http://www.feng123.com
     *   
     * @param data 
     * @param key 
     * @return 
     * @throws Exception 
     */ 
    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
 
     * 用私钥解密 
     *   
     * @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
 
     * 用公钥加密 
     *   
     * @param data 
     * @param key 
     * @return 
     * @throws Exception 
     */ 
    public static byte[] encryptByPublicKey(byte[] 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);   
    }   

    /** *//** 
     * 加密
 
     * 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 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 keyMap)   
            throws Exception {   
        Key key = (Key) keyMap.get(PUBLIC_KEY);   

        return encryptBASE64(key.getEncoded());   
    }   

    /** *//** 
     * 初始化密钥 
     *   
     * @return 
     * @throws Exception 
     */ 
    public static Map initKey() throws Exception {   
        KeyPairGenerator keyPairGen = KeyPairGenerator   
                .getInstance(KEY_ALGORITHM);   
        keyPairGen.initialize(1024);   

        KeyPair keyPair = keyPairGen.generateKeyPair();   

        // 公钥   
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();   

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

        Map keyMap = new HashMap(2);   

        keyMap.put(PUBLIC_KEY, publicKey);   
        keyMap.put(PRIVATE_KEY, privateKey);   
        return keyMap;   
    }   
} 

再给出一个测试类： 

import static org.junit.Assert.*;   

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

import java.util.Map;   

/** *//** 
*   
* @version 1.0 
* @since 1.0 
*/ 
public class RSACoderTest {   
    private String publicKey;   
    private String privateKey;   

    @Before 
    public void setUp() throws Exception {   
        Map 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[] data = inputStr.getBytes();   

        byte[] encodedData = RSACoder.encryptByPublicKey(data, 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:\r" + sign);   

        // 验证签名   
        boolean status = RSACoder.verify(encodedData, publicKey, sign);   
        System.err.println("状态:\r" + status);   
        assertTrue(status);   

    }   

} 

---------2013-07-08   更新：新增Coder代码------------------------------

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

/**
 * @author wangxinyou.jason
 */
public class Coder {

    /**
     * Base64解码
     * @param key
     * @return
     */
    public static byte[] decryptBASE64(String key){
        return Base64.decodeBase64(key);
    }
    
    /**
     * Base64编码
     * @param sign
     * @return
     */
    public static String encryptBASE64(byte[] sign){
        return Base64.encodeBase64String(sign);
    }
}