Java与.NET兼容的RSA密钥持久化方法

默认情况下，.NET生成的RSA密钥对可以用XML或字节流来保存，而JAVA中生成的RSA密钥对只能用字节流来保存。而它们的字节流格式不同，就导致Java中生成的RSA密钥对不能在.NET中使用，而.NET中生成的密钥对又不能在Java中使用。而.NET的XML保存方法我觉得比较有通用性，于是就以.NET中RSA密钥保存的XML格式作为兼容格式，这样它们就可以通用了。下面是Java代码：

PS:在Chrome上用博客园的编辑器设置不了代码折叠，保存后折叠的代码就打不开了。。。

=============================================

文件：StringHelper.java

字符串操作辅助类

文件：Base64Helper.java

Base64字符串和字节流互转的辅助类

文件：RsaHelper.java

代码中主要方法说明：

KeyPair generateRSAKeyPair();//生成密钥对

String encodePublicKeyToXml(PublicKey key);//将公钥转换为XML字符串

PublicKey decodePublicKeyFromXml(String xml);//从XML字符串得到公钥

String encodePrivateKeyToXml(PrivateKey key);//将私钥转换为XML字符串

PrivateKey decodePrivateKeyFromXml(String xml);//从XML字符串得到私钥

========================================================

StringHelper.java

/*

 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package com.scbeta.helpers;

/**
 *
 * @author aaa
 */
public class StringHelper {

    //数组中是否包括某字符串
    public static boolean arrayContainsString(String[] array, String key) {
        for (String tmpString : array) {
            if (tmpString.equals(key)) {
                return true;
            }
        }
        return false;
    }

    public static String GetLeftString(String source, String strTail) {
        return GetLeftString(source, strTail, false);
    }

    public static String GetLeftString(String source, String strTail, boolean KeepHeadAndTail) {
        return GetMiddleString(source, "", strTail, KeepHeadAndTail);
    }

    public static String GetRightString(String source, String strHead) {
        return GetRightString(source, strHead, false);
    }

    public static String GetRightString(String source, String strHead, boolean KeepHeadAndTail) {
        return GetMiddleString(source, strHead, "", KeepHeadAndTail);
    }

    public static String GetMiddleString(String source, String strHead, String strTail) {
        return GetMiddleString(source, strHead, strTail, false);
    }

    public static String GetMiddleString(String source, String strHead, String strTail, boolean KeepHeadAndTail) {
        try {
            int indexHead, indexTail;

            if (strHead == null || strHead.isEmpty()) {
                indexHead = 0;
            } else {
                indexHead = source.indexOf(strHead);
            }

            if (strTail == null || strTail.isEmpty()) {
                indexTail = source.length();
            } else {
                indexTail = source.indexOf(strTail, indexHead + strHead.length());
            }
            if (indexTail < 0) {
                indexTail = source.length();
            }

            String rtnStr = "";
            if ((indexHead >= 0) && (indexTail >= 0)) {
                if (KeepHeadAndTail) {
                    rtnStr = source.substring(indexHead, indexTail + strTail.length());
                } else {
                    rtnStr = source.substring(indexHead + strHead.length(), indexTail);
                }
            }
            return rtnStr;
        } catch (Exception ex) {
            return "";
        }
    }
}

Base64Helper.java:

package com.scbeta.helpers;

import java.io.IOException;

public class Base64Helper {

    public static String encode(byte[] byteArray) {
        sun.misc.BASE64Encoder base64Encoder = new sun.misc.BASE64Encoder();
        return base64Encoder.encode(byteArray);
    }

    public static byte[] decode(String base64EncodedString) {
        sun.misc.BASE64Decoder base64Decoder = new sun.misc.BASE64Decoder();
        try {
            return base64Decoder.decodeBuffer(base64EncodedString);
        } catch (IOException e) {
            return null;
        }
    }
} 

RsaHelper.java:

//===================
//作者：aaaSoft
//日期：2011年11月30日
//博客：http://www.cnblogs.com/aaaSoft/
//Email：scbeta@qq.com
//说明：原创文章，转载请注明出处并保留作者信息
//===================

package com.scbeta.helpers.security;

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateCrtKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateCrtKeySpec;
import java.security.spec.RSAPublicKeySpec;

import javax.crypto.Cipher;

import com.scbeta.helpers.Base64Helper;
import com.scbeta.helpers.StringHelper;

public class RsaHelper {
    /**
     * 生成RSA密钥对(默认密钥长度为1024)
     * 
     * @return
     */
    public static KeyPair generateRSAKeyPair() {
        return generateRSAKeyPair(1024);
    }

    /**
     * 生成RSA密钥对
     * 
     * @param keyLength
     *            密钥长度，范围：512～2048
     * @return
     */
    public static KeyPair generateRSAKeyPair(int keyLength) {
        try {
            KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
            kpg.initialize(keyLength);
            return kpg.genKeyPair();
        } catch (NoSuchAlgorithmException e) {
            return null;
        }
    }

    public static String encodePublicKeyToXml(PublicKey key) {
        if (!RSAPublicKey.class.isInstance(key)) {
            return null;
        }
        RSAPublicKey pubKey = (RSAPublicKey) key;
        StringBuilder sb = new StringBuilder();

        sb.append("<RSAKeyValue>");
        sb.append("<Modulus>")
                .append(Base64Helper.encode(pubKey.getModulus().toByteArray()))
                .append("</Modulus>");
        sb.append("<Exponent>")
                .append(Base64Helper.encode(pubKey.getPublicExponent()
                        .toByteArray())).append("</Exponent>");
        sb.append("</RSAKeyValue>");
        return sb.toString();
    }

    public static PublicKey decodePublicKeyFromXml(String xml) {
        xml = xml.replaceAll("\r", "").replaceAll("\n", "");
        BigInteger modulus = new BigInteger(1, Base64Helper.decode(StringHelper
                .GetMiddleString(xml, "<Modulus>", "</Modulus>")));
        BigInteger publicExponent = new BigInteger(1,
                Base64Helper.decode(StringHelper.GetMiddleString(xml,
                        "<Exponent>", "</Exponent>")));

        RSAPublicKeySpec rsaPubKey = new RSAPublicKeySpec(modulus,
                publicExponent);

        KeyFactory keyf;
        try {
            keyf = KeyFactory.getInstance("RSA");
            return keyf.generatePublic(rsaPubKey);
        } catch (Exception e) {
            return null;
        }
    }

    public static PrivateKey decodePrivateKeyFromXml(String xml) {
        xml = xml.replaceAll("\r", "").replaceAll("\n", "");
        BigInteger modulus = new BigInteger(1, Base64Helper.decode(StringHelper
                .GetMiddleString(xml, "<Modulus>", "</Modulus>")));
        BigInteger publicExponent = new BigInteger(1,
                Base64Helper.decode(StringHelper.GetMiddleString(xml,
                        "<Exponent>", "</Exponent>")));
        BigInteger privateExponent = new BigInteger(1,
                Base64Helper.decode(StringHelper.GetMiddleString(xml, "<D>",
                        "</D>")));
        BigInteger primeP = new BigInteger(1, Base64Helper.decode(StringHelper
                .GetMiddleString(xml, "<P>", "</P>")));
        BigInteger primeQ = new BigInteger(1, Base64Helper.decode(StringHelper
                .GetMiddleString(xml, "<Q>", "</Q>")));
        BigInteger primeExponentP = new BigInteger(1,
                Base64Helper.decode(StringHelper.GetMiddleString(xml, "<DP>",
                        "</DP>")));
        BigInteger primeExponentQ = new BigInteger(1,
                Base64Helper.decode(StringHelper.GetMiddleString(xml, "<DQ>",
                        "</DQ>")));
        BigInteger crtCoefficient = new BigInteger(1,
                Base64Helper.decode(StringHelper.GetMiddleString(xml,
                        "<InverseQ>", "</InverseQ>")));

        RSAPrivateCrtKeySpec rsaPriKey = new RSAPrivateCrtKeySpec(modulus,
                publicExponent, privateExponent, primeP, primeQ,
                primeExponentP, primeExponentQ, crtCoefficient);

        KeyFactory keyf;
        try {
            keyf = KeyFactory.getInstance("RSA");
            return keyf.generatePrivate(rsaPriKey);
        } catch (Exception e) {
            return null;
        }
    }

    public static String encodePrivateKeyToXml(PrivateKey key) {
        if (!RSAPrivateCrtKey.class.isInstance(key)) {
            return null;
        }
        RSAPrivateCrtKey priKey = (RSAPrivateCrtKey) key;
        StringBuilder sb = new StringBuilder();

        sb.append("<RSAKeyValue>");
        sb.append("<Modulus>")
                .append(Base64Helper.encode(priKey.getModulus().toByteArray()))
                .append("</Modulus>");
        sb.append("<Exponent>")
                .append(Base64Helper.encode(priKey.getPublicExponent()
                        .toByteArray())).append("</Exponent>");
        sb.append("<P>")
                .append(Base64Helper.encode(priKey.getPrimeP().toByteArray()))
                .append("</P>");
        sb.append("<Q>")
                .append(Base64Helper.encode(priKey.getPrimeQ().toByteArray()))
                .append("</Q>");
        sb.append("<DP>")
                .append(Base64Helper.encode(priKey.getPrimeExponentP()
                        .toByteArray())).append("</DP>");
        sb.append("<DQ>")
                .append(Base64Helper.encode(priKey.getPrimeExponentQ()
                        .toByteArray())).append("</DQ>");
        sb.append("<InverseQ>")
                .append(Base64Helper.encode(priKey.getCrtCoefficient()
                        .toByteArray())).append("</InverseQ>");
        sb.append("<D>")
                .append(Base64Helper.encode(priKey.getPrivateExponent()
                        .toByteArray())).append("</D>");
        sb.append("</RSAKeyValue>");
        return sb.toString();
    }

    // 用公钥加密
    public static byte[] encryptData(byte[] data, PublicKey pubKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, pubKey);
            return cipher.doFinal(data);
        } catch (Exception e) {
            return null;
        }
    }

    // 用私钥解密
    public static byte[] decryptData(byte[] encryptedData, PrivateKey priKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, priKey);
            return cipher.doFinal(encryptedData);
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * 根据指定私钥对数据进行签名(默认签名算法为"SHA1withRSA")
     * 
     * @param data
     *            要签名的数据
     * @param priKey
     *            私钥
     * @return
     */
    public static byte[] signData(byte[] data, PrivateKey priKey) {
        return signData(data, priKey, "SHA1withRSA");
    }

    /**
     * 根据指定私钥和算法对数据进行签名
     * 
     * @param data
     *            要签名的数据
     * @param priKey
     *            私钥
     * @param algorithm
     *            签名算法
     * @return
     */
    public static byte[] signData(byte[] data, PrivateKey priKey,
            String algorithm) {
        try {
            Signature signature = Signature.getInstance(algorithm);
            signature.initSign(priKey);
            signature.update(data);
            return signature.sign();
        } catch (Exception ex) {
            return null;
        }
    }

    /**
     * 用指定的公钥进行签名验证(默认签名算法为"SHA1withRSA")
     * 
     * @param data
     *            数据
     * @param sign
     *            签名结果
     * @param pubKey
     *            公钥
     * @return
     */
    public static boolean verifySign(byte[] data, byte[] sign, PublicKey pubKey) {
        return verifySign(data, sign, pubKey, "SHA1withRSA");
    }

    /**
     * 
     * @param data 数据
     * @param sign 签名结果
     * @param pubKey 公钥
     * @param algorithm 签名算法
     * @return
     */
    public static boolean verifySign(byte[] data, byte[] sign,
            PublicKey pubKey, String algorithm) {
        try {
            Signature signature = Signature.getInstance(algorithm);
            signature.initVerify(pubKey);
            signature.update(data);
            return signature.verify(sign);
        } catch (Exception ex) {
            return false;
        }
    }
}

==============================

下面是测试代码：

    public static void main(String[] args) {

        KeyPair kp = RsaHelper.generateRSAKeyPair();
        PublicKey pubKey = kp.getPublic();
        PrivateKey priKey = kp.getPrivate();

        String pubKeyXml = RsaHelper.encodePublicKeyToXml(pubKey);
        String priKeyXml = RsaHelper.encodePrivateKeyToXml(priKey);
        System.out.println("====公钥====");
        System.out.println(pubKeyXml);
        System.out.println("====私钥====");
        System.out.println(priKeyXml);

        PublicKey pubKey2 = RsaHelper.decodePublicKeyFromXml(pubKeyXml);
        PrivateKey priKey2 = RsaHelper.decodePrivateKeyFromXml(priKeyXml);

        System.out.println("====公钥对比====");
        System.out.println(pubKey.toString());
        System.out.println("------");
        System.out.println(pubKey2.toString());

        System.out.println("====私钥对比====");
        System.out.println(priKey.toString());
        System.out.println("------");
        System.out.println(priKey2.toString());

        try {
            String pubKeyXml3 = "<RSAKeyValue><Modulus>rHESyuI3ny4MLsqDBalW9ySaodCL0e6Bsrl01Q5G1qm2wjUoGULazZSNqZY+JQNjU92tW3Snk5RPIkv+wDj+uOT9LTUjQImltHnzqMvbt06GipVXDOyBLTa7G/zRIe/CrjyJ+XEYX2xIhpe5ayowl3HHUpZ71jRNioyxaVVZ8S0=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
            String priKeyXml3 = "<RSAKeyValue><Modulus>rHESyuI3ny4MLsqDBalW9ySaodCL0e6Bsrl01Q5G1qm2wjUoGULazZSNqZY+JQNjU92tW3Snk5RPIkv+wDj+uOT9LTUjQImltHnzqMvbt06GipVXDOyBLTa7G/zRIe/CrjyJ+XEYX2xIhpe5ayowl3HHUpZ71jRNioyxaVVZ8S0=</Modulus><Exponent>AQAB</Exponent><P>5a7uM+IeY8QMVQl0q88ZTqWbB555l7+366cUIClTN8z2ZXzTnWFCNoQzUrG14FouJFYumFZD12Ni5MkJK6gqSw==</P><Q>wDMhwwO4kz82uSG+FlCBr06fYk2COTg0TofmSp/5OrVqgkBIe7FgpTpVGzGLk0mvOLcy6UZftq//W0Saow6nZw==</Q><DP>FbjDgliiMyE5YVlxlUYSyKNU1BWivj09caXte1UtL5vMubBiewHVtz4tdGamIr+kmX8lDPcrl1Uo5yY0HdLbnQ==</DP><DQ>kIjjJsgxkWnEOUyKqjU4kSDK8x3ehDEkBLpmEFBlGCU9R14YJAyr5RUM0zpbABQ1VK1P9+UYLUYE/hmFQIHQmQ==</DQ><InverseQ>pxQDThwSnUZ4EaNaCPl1ovYypdQUZaZ/Sld1+0n8FEjkmRcGP1R9VMuj1ViPZg3rvm2GeP8Xv1SJqJUVueWiGA==</InverseQ><D>DxBNoPWEAF7IZ6n/KhZx52MGMw6BuFQKdm9m+lml7Iik03BLUXGapYzNlzvtr9QM8D2UMEIPhX/WLdvPpEEWVzGnD7XpLXjGwfu1ZkJRcXPEZEZ2subh5ZBqOWCFWKv5WwgGYWuYDLHfrBlBgSFWR8cZuyqkmMsWl4CiadXqGA0=</D></RSAKeyValue>";

            System.out.println((new Date()).toLocaleString() + ": 加载公钥中。。。");
            PublicKey pubKey3 = RsaHelper.decodePublicKeyFromXml(pubKeyXml3);
            System.out.println((new Date()).toLocaleString() + ": 加载私钥中。。。");
            PrivateKey priKey3 = RsaHelper.decodePrivateKeyFromXml(priKeyXml3);

            String dataStr = "Java与.NET和平共处万岁！";
            byte[] dataByteArray = dataStr.getBytes("utf-8");
            System.out.println("data的Base64表示："
                    + Base64Helper.encode(dataByteArray));

            System.out.println((new Date()).toLocaleString() + ": 加密中。。。"); // 加密
            byte[] encryptedDataByteArray = RsaHelper.encryptData(
                    dataByteArray, pubKey3);

            System.out.println("encryptedData的Base64表示："
                    + Base64Helper.encode(encryptedDataByteArray));
            System.out.println((new Date()).toLocaleString() + ": 解密中。。。"); // 解密
                                                                            // byte[]
            byte[] decryptedDataByteArray = RsaHelper.decryptData(
                    encryptedDataByteArray, priKey3);
            System.out.println(new String(decryptedDataByteArray, "utf-8"));// 签名
            System.out.println((new Date()).toLocaleString() + ": 签名中。。。");
            byte[] signDataByteArray = RsaHelper.signData(dataByteArray,
                    priKey3);
            System.out.println("signData的Base64表示："
                    + Base64Helper.encode(signDataByteArray)); // 验签
            System.out.println((new Date()).toLocaleString() + ": 验签中。。。");
            boolean isMatch = RsaHelper.verifySign(dataByteArray,
                    signDataByteArray, pubKey3);
            System.out.println("验签结果：" + isMatch);

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

最后，补充一段C#产生密钥对的代码片段如下：

using System.Security.Cryptography;
//密钥位数
int keySize = 1024;
//产生密钥对
RSACryptoServiceProvider rSACryptoServiceProvider = new RSACryptoServiceProvider(keySize);
//得到公钥
String publicKey = rSACryptoServiceProvider.ToXmlString(false);
//得到私钥
String privateKey = rSACryptoServiceProvider.ToXmlString(true);

附上我用C#编写的“RSA密钥对生成器”，点此下载。