digitalsignature2example.java

本程序是用java程序包实现RSA安全认证算法的实现程序

import java.security.Signature;
import java.security.KeyPairGenerator;
import java.security.KeyPair;
import java.security.SignatureException;

public class DigitalSignature2Example
{  public static void main(String[] args)throws Exception
{ if(args.length!=1)
  {System.err.println("Usage:java DigitalSignature2Example");
   System.exit(1);
   }
   byte[] plainText=args[0].getBytes("UTF8");
   System.out.println("initial value is:"+new String(plainText,"UTF8"));
   System.out.println("Start generating RSA key");
   KeyPairGenerator keyGen=KeyPairGenerator.getInstance("RSA");
   keyGen.initialize(1024);
   KeyPair key=keyGen.generateKeyPair();
   System.out.println("Finish generating RSA key");
   System.out.println(key.getPublic());	
    System.out.println(key.getPrivate());	
   Signature sig=Signature.getInstance("SHA1withRSA");
   sig.initSign(key.getPrivate());
   sig.update(plainText);//The data plainText is passed to the object signature by calling the update method
   byte[] signature=sig.sign();//signature contains the text after the encrytion;
   System.out.println(sig.getProvider().getInfo());
   //System.out.println("b."+new String(signature,"UTF8"));
   System.out.println("Start signature verification");
   sig.initVerify(key.getPublic());
   sig.update(plainText);//The data plainText is passed to the object by calling the update method
   try{ if(sig.verify(signature))//use the public key to decrypt the text
       {System.out.println("Signature verified");
	}
       else System.out.println("Signature failed");}
   catch(SignatureException e)
  {System.out.println("Signature failed");}}
}