rsa.java

采用RSA公秘钥体制和MD5签名算法的安全通信

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;

import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;


public class RSA {
	private Cipher cipher;
	private PublicKey publicKey;
	private PrivateKey privateKey;
	RSA(){
		try{
			KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
			keyPairGen.initialize(1040);//指定密匙长度（取值范围：512～2048）
			KeyPair keyPair = keyPairGen.generateKeyPair();//生成‘密匙对’，其中包含着一个公匙和一个私匙的信息
			privateKey = keyPair.getPrivate();//获得私匙
		  	publicKey = keyPair.getPublic();//获得公匙	
		  	}
		  	catch(NoSuchAlgorithmException e){e.printStackTrace();}
	}
	
	public PublicKey getPublicKey(){
		return publicKey;
	}
	public PrivateKey getprivateKey(){
		return privateKey;
	}
	public void setPublicKey(PublicKey key)
	{
		publicKey = key;
	}
	public void setPrivateKey(PrivateKey key)
	{
		privateKey = key;
	}
 	public byte [] wrapkey(Key key){//用publickey来包装DES,包装的结果是一个byte[]
    	byte [] wrapedkey = null;
    	try {
			 cipher = Cipher.getInstance("RSA");
			 cipher.init(Cipher.WRAP_MODE, publicKey);
			 wrapedkey = cipher.wrap(key);
			 
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
		return wrapedkey;
	}
	
    public Key unwrapkey(byte []wrapedkey){
    	//将DES的私钥用RSA解密
	    Key key=null;
	try {
		 cipher = Cipher.getInstance("RSA");
		 cipher.init(Cipher.UNWRAP_MODE, privateKey);
		 key = cipher.unwrap(wrapedkey, "DES", Cipher.SECRET_KEY);
		 
	} catch (Exception e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	} 
	return key;
}
}