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在Jini,RMI和Applet中如何实现代码签名


  第一段代码:生成公开/私有密钥对并在命令行中指定文件,把密钥对写入该文件.
  import java.security.*;
  import java.io.*;
  public class KeyPairGen
  {
  public static void main(String[] args)
  {
  if(args.length!=1)
  {
  System.out.println("Usage: java KeyPairGen KeyFile");
  System.exit(1);
  }
  KeyPairGen obj=new KeyPairGen();
  try{
  obj.gen(args[0]);
  }catch(NoSuchAlgorithmException ex)
  {
  System.out.println("NoSuchAlgorithmException");
  }
  catch(FileNotFoundException ex)
  {
  System.out.println("FileNotFoundException");
  }
  catch(IOException ex)
  {
  System.out.println("IOException");
  }
  }
  public void gen(String source) throws NoSuchAlgorithmException,
  FileNotFoundException,IOException
  {
  KeyPairGenerator kpGen=KeyPairGenerator.getInstance("DSA");
  kpGen.initialize(512);
  KeyPair kPair=kpGen.genKeyPair();
  FileOutputStream fos=new FileOutputStream(source);
  ObjectOutputStream oos=new ObjectOutputStream(fos);
  oos.writeObject(kPair);
  fos.close();
  oos.close();
  }
  }
  第二段代码,命令行中指定存放密钥的文件,用于签名的字符串(这里使用字符串只是为了简单,其实在真正实际使用中应该换成用MD5或SHA1算法计算某一文件流的消息摘要值)和签名所存放的文件.功能是计算出签名并把该签名存放在文件中.
  import java.security.*;
  import java.io.*;
  public class SignGen
  {
  public static void main(String[] args)
  {
  if(args.length!=3)
  {
  System.out.println("Usage: java SignGen KeyFile String SigFile");
  System.exit(1);
  }
  SignGen obj=new SignGen();
  try{
  obj.genSignature(args[0],args[1],args[2]);
  }catch(NoSuchAlgorithmException ex)
  {
  System.out.println("NoSuchAlgorithmException");
  }
  catch(InvalidKeyException ex)
  {
  System.out.println("InvalidKeyException");
  }
  catch(SignatureException ex)
  {
  System.out.println("SignatureException");
  }
  catch(ClassNotFoundException ex)
  {
  System.out.println("ClassNotFoundException");
  }
  catch(FileNotFoundException ex)
  {
  System.out.println("FileNotFoundException");
  }
  catch(IOException ex)
  {
  System.out.println("IOException");
  }
  }
  public void genSignature(String keyFile,String str,String sigFile)
  throws NoSuchAlgorithmException,InvalidKeyException,SignatureException,
  ClassNotFoundException,FileNotFoundException,IOException
  {
  FileInputStream fis=new FileInputStream(keyFile);
  ObjectInputStream ois=new ObjectInputStream(fis);
  KeyPair kp=(KeyPair)ois.readObject();
  PublicKey pubKey=kp.getPublic();
  PrivateKey priKey=kp.getPrivate();
  fis.close();
  ois.close();
  Signature sig=Signature.getInstance("SHA1WithDSA");
  sig.initSign(priKey);
  sig.update(str.getBytes());
  byte[] b=sig.sign();
  FileOutputStream fos=new FileOutputStream(sigFile);
  ObjectOutputStream oos=new ObjectOutputStream(fos);
  oos.writeObject(b);
  fos.close();
  oos.close();
  }
  }
  第三段代码当然是用于验证签名了.命令行中指定三个参数.密钥文件,更新验证的字符串和签名文件.
  import java.security.*;
  import java.io.*;
  public class SignVerify
  {
  public static void main(String[] args)
  {
  if(args.length!=3)
  {
  System.out.println("Usage: java SignVerify KeyFile String SigFile");
  System.exit(1);
  }
  SignVerify obj=new SignVerify();
  try{
  obj.verify(args[0],args[1],args[2]);
  }catch(NoSuchAlgorithmException ex)
  {
  System.out.println("NoSuchAlgorithmException");
  }
  catch(InvalidKeyException ex)
  {
  System.out.println("InvalidKeyException");
  }
  catch(SignatureException ex)
  {
  System.out.println("SignatureException");
  }
  catch(ClassNotFoundException ex)
  {
  System.out.println("ClassNotFoundException");
  }
  catch(FileNotFoundException ex)
  {
  System.out.println("FileNotFoundException");
  }
  catch(IOException ex)
  {
  System.out.println("IOException");
  }
  }
  public void verify(String keyFile,String str,String sigFile) throws
  NoSuchAlgorithmException,InvalidKeyException,SignatureException,
  ClassNotFoundException,FileNotFoundException,IOException
  {
  FileInputStream fis=new FileInputStream(keyFile);
  ObjectInputStream ois=new ObjectInputStream(fis);
  KeyPair kp=(KeyPair)ois.readObject();
  PublicKey pubKey=kp.getPublic();
  PrivateKey priKey=kp.getPrivate();
  fis.close();
  ois.close();
  FileInputStream fis1=new FileInputStream(sigFile);
  ObjectInputStream ois1=new ObjectInputStream(fis1);
  byte[] b=(byte[])ois1.readObject();
  fis1.close();
  ois1.close();
  Signature sig=Signature.getInstance("SHA1WithDSA");
  sig.initVerify(pubKey);
  sig.update(str.getBytes());
  if(sig.verify(b))
  {
  System.out.println("Verify OK!");
  }
  else
  {
  System.out.println("Verify Error!");
  }
  }
  }
  在验证过程中,密钥对,字符串和签名一个都不能错,否则无法通过验证.
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