C# Java间进行RSA加密解密交互（二）

接着前面一篇文章C# Java间进行RSA加密解密交互，继续探讨这个问题。

在前面，虽然已经实现了C# Java间进行RSA加密解密交互，但是还是与项目中要求的有所出入。在项目中，客户端（Java）的加密是通过这么一个方法实现的：

/**
* RSA加密
* @param text--待加密的明文
* @param key--公钥，由服务器端提供的经base64编码的字符串
* @return
*/
public static String RSAEncryptoWithPublicKey(String text, String key) {
String result = null;
try {
byte[] publicKeyByte = base64Decrypto(key);

X509EncodedKeySpec x509 = new X509EncodedKeySpec(publicKeyByte);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(x509);

Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, publicKey);

result = base64Encrypto(cipher.doFinal(text.getBytes()));
} catch (Exception e) {
e.printStackTrace();
return null;
}
return result;
}

在上一篇中的实现，需要客户端先做一次解析工作，而已经开发好的客户端是没有这一层的，所以得想个办法，在服务器端（C#）完成这项工作。但是经过多次尝试，依然未果。于是换一种方式，密钥对不由C#提供，而转而有Java提供，生成客户端需要的公钥形式，并解析公钥私钥，组装C# 的XML格式的密钥对字符串。

下面贴一下RSA密钥对生成代码（参考RSA的密钥把JAVA格式转换成C#的格式）

import java.io.UnsupportedEncodingException;
import java.lang.reflect.Method;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateCrtKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;

/**
* @author Administrator
*
*/
public class RSAJavaToCSharp {
public static void main(String[] args) throws Exception {
HashMap<String, Object> map = getKeys();
RSAPublicKey publicKey = (RSAPublicKey) map.get("PUBLIC");
RSAPrivateKey privateKey = (RSAPrivateKey) map.get("PRIVATE");

String publicKeyString = getRSAPublicKeyAsNetFormat(publicKey.getEncoded());
String privateKeyString = getRSAPrivateKeyAsNetFormat(privateKey.getEncoded());

System.out.println(encodeBase64(publicKey.getEncoded()));//此处为客户端加密时需要的公钥字符串
System.out.println(encodePublicKeyToXml(publicKey));
System.out.println(publicKeyString);
System.out.println(privateKeyString);
}

/**获取密钥对
* @return
* @throws NoSuchAlgorithmException
*/
public static HashMap<String, Object> getKeys()
throws NoSuchAlgorithmException {
HashMap<String, Object> map = new HashMap<String, Object>();
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(1024);
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
map.put("PUBLIC", publicKey);
map.put("PRIVATE", privateKey);
return map;
}

/**
* 私钥转换成C#格式
* @param encodedPrivkey
* @return
*/
private static String getRSAPrivateKeyAsNetFormat(byte[] encodedPrivateKey) {
try {
StringBuffer buff = new StringBuffer(1024);

PKCS8EncodedKeySpec pvkKeySpec = new PKCS8EncodedKeySpec(
encodedPrivateKey);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPrivateCrtKey pvkKey = (RSAPrivateCrtKey) keyFactory
.generatePrivate(pvkKeySpec);

buff.append("<RSAKeyValue>");
buff.append("<Modulus>"
+ encodeBase64(removeMSZero(pvkKey.getModulus()
.toByteArray())) + "</Modulus>");

buff.append("<Exponent>"
+ encodeBase64(removeMSZero(pvkKey.getPublicExponent()
.toByteArray())) + "</Exponent>");

buff.append("<P>"
+ encodeBase64(removeMSZero(pvkKey.getPrimeP()
.toByteArray())) + "</P>");

buff.append("<Q>"
+ encodeBase64(removeMSZero(pvkKey.getPrimeQ()
.toByteArray())) + "</Q>");

buff.append("<DP>"
+ encodeBase64(removeMSZero(pvkKey.getPrimeExponentP()
.toByteArray())) + "</DP>");

buff.append("<DQ>"
+ encodeBase64(removeMSZero(pvkKey.getPrimeExponentQ()
.toByteArray())) + "</DQ>");

buff.append("<InverseQ>"
+ encodeBase64(removeMSZero(pvkKey.getCrtCoefficient()
.toByteArray())) + "</InverseQ>");

buff.append("<D>"
+ encodeBase64(removeMSZero(pvkKey.getPrivateExponent()
.toByteArray())) + "</D>");
buff.append("</RSAKeyValue>");

return buff.toString();
} catch (Exception e) {
System.err.println(e);
return null;
}
}

/**
* 公钥转成C#格式
* @param encodedPrivkey
* @return
*/
private static String getRSAPublicKeyAsNetFormat(byte[] encodedPublicKey) {
try {
StringBuffer buff = new StringBuffer(1024);

//Only RSAPublicKeySpec and X509EncodedKeySpec supported for RSA public keys
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKey pukKey = (RSAPublicKey) keyFactory
.generatePublic(new X509EncodedKeySpec(encodedPublicKey));

buff.append("<RSAKeyValue>");
buff.append("<Modulus>"
+ encodeBase64(removeMSZero(pukKey.getModulus()
.toByteArray())) + "</Modulus>");
buff.append("<Exponent>"
+ encodeBase64(removeMSZero(pukKey.getPublicExponent()
.toByteArray())) + "</Exponent>");
buff.append("</RSAKeyValue>");
return buff.toString();
} catch (Exception e) {
System.err.println(e);
return null;
}
}

/**
* 公钥转换成C#格式
* @param key
* @return
* @throws Exception
*/
public static String encodePublicKeyToXml(PublicKey key) throws Exception {
if (!RSAPublicKey.class.isInstance(key)) {
return null;
}
RSAPublicKey pubKey = (RSAPublicKey) key;
StringBuilder sb = new StringBuilder();

sb.append("<RSAKeyValue>");
sb.append("<Modulus>")
.append(encodeBase64(removeMSZero(pubKey.getModulus()
.toByteArray()))).append("</Modulus>");
sb.append("<Exponent>")
.append(encodeBase64(removeMSZero(pubKey.getPublicExponent()
.toByteArray()))).append("</Exponent>");
sb.append("</RSAKeyValue>");
return sb.toString();
}

/**
* @param data
* @return
*/
private static byte[] removeMSZero(byte[] data) {
byte[] data1;
int len = data.length;
if (data[0] == 0) {
data1 = new byte[data.length - 1];
System.arraycopy(data, 1, data1, 0, len - 1);
} else
data1 = data;

return data1;
}

/**
* base64编码
* @param input
* @return
* @throws Exception
*/
public static String encodeBase64(byte[] input) throws Exception {
Class clazz = Class
.forName("com.sun.org.apache.xerces.internal.impl.dv.util.Base64");
Method mainMethod = clazz.getMethod("encode", byte[].class);
mainMethod.setAccessible(true);
Object retObj = mainMethod.invoke(null, new Object[] { input });
return (String) retObj;
}

/**
* base64解码
* @param input
* @return
* @throws Exception
*/
public static byte[] decodeBase64(String input) throws Exception {
Class clazz = Class
.forName("com.sun.org.apache.xerces.internal.impl.dv.util.Base64");
Method mainMethod = clazz.getMethod("decode", String.class);
mainMethod.setAccessible(true);
Object retObj = mainMethod.invoke(null, input);
return (byte[]) retObj;
}

public static String byteToString(byte[] b)
throws UnsupportedEncodingException {
return new String(b, "utf-8");
}
}

为了方便在服务器端使用，初始想法是想将java文件封装为.dll文件，共C#调用，测试后，发现这样做行不通，bug提示类找不到，这是因为java代码中还导入了其他jar包的缘故。

于是，退而求其次，将上述java文件Export为可执行的jar文件，并将生成的密钥对写入相应文件中。再由C#读取，提供给客户端。

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C# Java间进行RSA加密解密交互

C# Java间进行RSA加密解密交互（三）