verifysign.java

java编写的一个对文件的数字签名,是对内容进行签名适合于小文件..特别是一些密码文件

import java.io.*;
import java.security.*;
import java.security.spec.*;
public class VerifySign{
	public static void main(String [] args)
	{
		if(args.length!=3){
		System.out.println("Usage:VerifySign <PublicKey> <dataFile> <SignatureFile>");
		System.out.println("Option:");
		System.out.println("<Public Key >The filename of the public key.");
		System.out.println("<DataFile>The filename that want to signature");
		System.out.println("<SignatureFile>:The file name containing signature data.");
		System.exit(0);
		}
		try{
		FileInputStream fileIn=new FileInputStream(args[0]);
		byte[] encodedpubKey =new byte[fileIn.available()];
		fileIn.read(encodedpubKey);
		fileIn.close();
		X509EncodedKeySpec pubKeySpec=
		new X509EncodedKeySpec(encodedpubKey);
		KeyFactory keyFactory=KeyFactory.getInstance("DSA");
		PublicKey pubKey=keyFactory.generatePublic(pubKeySpec);
		FileInputStream sigStream=new FileInputStream(args[2]);
		byte[] signature=new byte[sigStream.available()];
		sigStream.read(signature);
		sigStream.close();
		Signature sigObj=Signature.getInstance("SHAwithDSA");
		sigObj.initVerify(pubKey);
		fileIn=new FileInputStream(args[1]);
		byte b;
		while(fileIn.available()!=0)
		{
		b=(byte)fileIn.read();
		sigObj.update(b);
		};
		fileIn.close();
		boolean verifies=sigObj.verify(signature);
		System.out.println("Signature verifies:"+verifies);
		System.out.println(sigObj.toString());

		}catch(Exception e){/////////////
		}
	}
}