浅析java消息摘要与数字签名

importjava.io.unsupportedencodingexception;

import java.security.messagedigest;

import java.security.nosuchalgorithmexception;

import org.apache.commons.codec.binary.base64;

public class msgdigestdemo{

  public static void main(string args[]) throws nosuchalgorithmexception, unsupportedencodingexception {

   string msg = "hello world!" ;

   messagedigest md5digest = messagedigest.getinstance( "md5" );

   // 更新要计算的内容

   md5digest.update(msg.getbytes());

   // 完成哈希计算，得到摘要

   byte [] md5encoded = md5digest.digest();

   messagedigest shadigest = messagedigest.getinstance( "sha" );

   // 更新要计算的内容

   shadigest.update(msg.getbytes());

   // 完成哈希计算，得到摘要

   byte [] shaencoded = shadigest.digest();

   system.out.println( "原文: " + msg);

   system.out.println( "md5摘要: " + base64.encodebase64urlsafestring(md5encoded));

   system.out.println( "sha摘要: " + base64.encodebase64urlsafestring(shaencoded));

  }

}

importjavax.crypto.mac;

import javax.crypto.spec.secretkeyspec;

import org.apache.commons.codec.binary.base64;

public class hmaccoder{

  /**

   * jdk支持hmacmd5, hmacsha1,hmacsha256, hmacsha384, hmacsha512

   */

  public enum hmactypeen {

   hmacmd5, hmacsha1, hmacsha256, hmacsha384, hmacsha512;

  }

  public static byte [] encode( byte [] plaintext, byte [] secretkey, hmactypeen type) throwsexception {

   secretkeyspec keyspec = new secretkeyspec(secretkey, type.name());

   mac mac = mac.getinstance(keyspec.getalgorithm());

   mac.init(keyspec);

   return mac.dofinal(plaintext);

  }

  public static void main(string[] args) throws exception {

   string msg = "hello world!" ;

   byte [] secretkey = "secret_key" .getbytes( "utf8" );

   byte [] digest = hmaccoder.encode(msg.getbytes(), secretkey, hmactypeen.hmacsha256);

   system.out.println( "原文: " + msg);

   system.out.println( "摘要: " + base64.encodebase64urlsafestring(digest));

  }

}

importjava.security.keyfactory;

import java.security.keypair;

import java.security.keypairgenerator;

import java.security.privatekey;

import java.security.publickey;

import java.security.signature;

import java.security.spec.pkcs8encodedkeyspec;

import java.security.spec.x509encodedkeyspec;

import org.apache.commons.codec.binary.base64;

public class dsacoder{

  public static final string key_algorithm = "dsa" ;

  public enum dsatypeen {

   md5withdsa, sha1withdsa

  }

  /**

   * dsa密钥长度默认1024位。 密钥长度必须是64的整数倍，范围在512~1024之间

   */

  private static final int key_size = 1024 ;

  private keypair keypair;

  public dsacoder() throws exception {

   keypair = initkey();

  }

  public byte [] signature( byte [] data, byte [] privatekey) throws exception {

   pkcs8encodedkeyspec keyspec = new pkcs8encodedkeyspec(privatekey);

   keyfactory keyfactory = keyfactory.getinstance(key_algorithm);

   privatekey key =keyfactory.generateprivate(keyspec);

   signature signature = signature.getinstance(dsatypeen.sha1withdsa.name());

   signature.initsign(key);

   signature.update(data);

   return signature.sign();

  }

  public boolean verify( byte [] data, byte [] publickey, byte [] sign) throws exception {

   x509encodedkeyspec keyspec = new x509encodedkeyspec(publickey);

   keyfactory keyfactory = keyfactory.getinstance(key_algorithm);

   publickey key =keyfactory.generatepublic(keyspec);

   signature signature = signature.getinstance(dsatypeen.sha1withdsa.name());

   signature.initverify(key);

   signature.update(data);

   return signature.verify(sign);

  }

  private keypair initkey() throws exception {

   // 初始化密钥对生成器

   keypairgenerator keypairgen = keypairgenerator.getinstance(key_algorithm);

   // 实例化密钥对生成器

   keypairgen.initialize(key_size);

   // 实例化密钥对

   return keypairgen.genkeypair();

  }

  public byte [] getpublickey() {

   return keypair.getpublic().getencoded();

  }

  public byte [] getprivatekey() {

   return keypair.getprivate().getencoded();

  }

  public static void main(string[] args) throws exception {

   string msg = "hello world" ;

   dsacoder dsa = new dsacoder();

   byte [] sign = dsa.signature(msg.getbytes(), dsa.getprivatekey());

   boolean flag = dsa.verify(msg.getbytes(), dsa.getpublickey(), sign);

   string result = flag ? "数字签名匹配" : "数字签名不匹配" ;

   system.out.println( "数字签名：" + base64.encodebase64urlsafestring(sign));

   system.out.println( "验证结果：" + result);

  }

}