md5withrsa.java

采用RSA公秘钥体制和MD5签名算法的安全通信

import java.io.DataInputStream;
import java.io.IOException;
import java.security.GeneralSecurityException;
import java.security.InvalidKeyException;

import java.security.NoSuchAlgorithmException;
import java.security.*;
import java.security.Signature;
import java.security.SignatureException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;


public class MD5withRSA {
	private static PrivateKey privateKey;
	private static  PublicKey publicKey;
	private static Signature signature ;
	public static void setPublicKey( PublicKey key){
		publicKey = key;
	}
	public static void setPrivateKey( PrivateKey key){
		privateKey = key;
	}
    
 public static byte[] sign(byte[] in){//对in里的内容进行签名
    	byte[] signedmsg = null;
    	  
    	try {
			signature = Signature.getInstance("MD5withRSA");
			signature.initSign(privateKey);
			signature.update(in);
 
			signedmsg = signature.sign();
			 
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}   
		return signedmsg;
    }
    public static boolean verify(byte[] in,byte[] signedmsg){
    	 boolean flag = false;
    	try {
			signature = Signature.getInstance("MD5withRSA");
			signature.initVerify(publicKey);
			signature.update(in);
			if(signature.verify(signedmsg))
				flag = true;
			else {flag =false;
			System.out.println("false");}
			 
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}  
		return flag;
    }

}