import java.io.*;
import java.security.*;
import java.security.cert.*;

public class VerifyHandler {

   public static void main(String[] args) {
      // Läs in publika nyckeln
      PublicKey publicKey = null;
      try {
         FileInputStream fis = new FileInputStream(args[1]);
         CertificateFactory cf = CertificateFactory.getInstance("X.509");
         java.security.cert.Certificate cert = cf.generateCertificate(fis);
         publicKey = cert.getPublicKey();
         System.out.println("DONE LOADING PUBLIC KEY FROM CERTIFICATE");
      } catch(CertificateException ce) {
         System.out.println("CertificateException generated");
      } catch(IOException ioe) {
         System.out.println("NoSuchProviderException generated");
      }
  
      // Gör signingEngineAndVerifyEngine
      Signature signAndVerifyEngine = null;
      try {
         signAndVerifyEngine = Signature.getInstance("SHA1withDSA", "SUN");
         System.out.println("DONE MAKING SIGNING/VERIFYING ENGINE");
      } catch(NoSuchAlgorithmException nsae) {
         System.out.println("NoSuchAlgorithmException generated");
      } catch(NoSuchProviderException nspe) {
         System.out.println("NoSuchProviderException generated");
      }

      // Initialisera maskinen
      try {
         signAndVerifyEngine.initVerify(publicKey);
      } catch(InvalidKeyException ike) {
         System.out.println("InvalidKeyException generated");
      }

      // Läs in den givna signaturen
      byte[] sigToVerify = null;
      try {
         FileInputStream fis = new FileInputStream(args[2]);
         sigToVerify = new byte[fis.available()];
         fis.read(sigToVerify);
         fis.close();
      } catch(IOException ioe) {
         System.out.println("IOException generated");
      }

      // Tillför signaturen text-meddelandet
      try {
         BufferedInputStream bis = new BufferedInputStream(new FileInputStream(args[0]));
         byte[] buffer = new byte[1024];
         int length;
         while(bis.available() != 0) {
            length = bis.read(buffer);
            signAndVerifyEngine.update(buffer, 0, length);
         }
         bis.close();
         System.out.println("DONE DELIVERING DATA TO SIGNATURE/VERIFYING ENGINE");
      } catch(SignatureException ike) {
         System.out.println("SignatureException generated");
      } catch(IOException ioe) {
         System.out.println("IOException generated");
      }

      // Verifiera
      try {
         if(signAndVerifyEngine.verify(sigToVerify)) {
            System.out.println("*** SIGNATURE VERIFIES ***");
         } else {
            System.out.println("*** SIGNATURE VERIFIES NOT ***");
         }
      } catch(SignatureException se) {
         System.out.println("SignatureException");
      }     
   }
}