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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）

转自：http://blog.csdn.net/dslinmy/article/details/37881067