Java密码术创建签名

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.PrivateKey;

import java.security.Signature;

import java.util.Scanner;



public class CreatingDigitalSignature {

   public static void main(String args[]) throws Exception {

      //Accepting text from user

      Scanner sc = new Scanner(System.in);

      System.out.println("Enter some text");

      String msg = sc.nextLine();



      //Creating KeyPair generator object

      KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("DSA");



      //Initializing the key pair generator

      keyPairGen.initialize(2048);



      //Generate the pair of keys

      KeyPair pair = keyPairGen.generateKeyPair();



      //Getting the private key from the key pair

      PrivateKey privKey = pair.getPrivate();



      //Creating a Signature object

      Signature sign = Signature.getInstance("SHA256withDSA");



      //Initialize the signature

      sign.initSign(privKey);

      byte[] bytes = "msg".getBytes();



      //Adding data to the signature

      sign.update(bytes);



      //Calculating the signature

      byte[] signature = sign.sign();



      //Printing the signature

      System.out.println("Digital signature for given text: "+new String(signature, "UTF8"));

   }

}