import java.io.*;
import java.util.*;

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

import javax.activation.*;
import javax.mail.*;
import javax.mail.internet.*;

import com.dstc.security.smime.*;
import com.dstc.security.provider.DSTC;

public class SMIMEReceiver {

   private static final char[] ksPasswd = {'a', 'b', 'c', 'd', 'e', 'f'};
   private static final char[] keyPasswd = {'f', 'e', 'd', 'c', 'b', 'a'};

   public static void main(String[] args) {
      Security.addProvider(new DSTC());

      try {
         // Hämta ett mime-meddelande
         MimeMessage msg1 = getMessage(args[0], args[1], args[2]);
         System.out.println("DONE GETTING MESSAGE");

         // Läs in privata nyckeln - måste vara initierad med RSA
         KeyStore ks = KeyStore.getInstance("JKS");
         BufferedInputStream bis = new BufferedInputStream(new FileInputStream("keystore"));
         ks.load(bis, ksPasswd);
         PrivateKey privKey = (PrivateKey) ks.getKey("pierre", keyPasswd);
         System.out.println("DONE LOADING KEY FROM KEYSTORE");

         // Extrahera certifikatet och lägg in det som pålitligt (här kan det givetvis vara flera :), root-certifikatet finns på nätet
         X509Certificate myCert = (X509Certificate)ks.getCertificate("pierre");
         Vector trustedCerts = new Vector();
         trustedCerts.add(myCert);
         System.out.println("DONE ADDING TRUSTED CERTIFICATES");

         // Dekryptera!
         SMIMECipher cipher = new SMIMECipher();
         cipher.initDecrypt(privKey, myCert);
         cipher.setMessage(msg1);
         DecryptionResult decRes = cipher.decrypt();
         MimeMessage msg2 = decRes.getMessage();
         System.out.println("DONE DECRYPTING");

         // Verifiera
         SMIMESignature sig = new SMIMESignature();
         sig.initVerify(trustedCerts, null);
         sig.setMessage(msg2);
         VerificationResult res = sig.verify();
         MimeMessage msg3 = res.getMessage();
         System.out.println("DONE VERIFYING");

         // Skriv ut
         System.out.println(msg3.getContent() + "\n");
      } catch (Exception e) {
         e.printStackTrace();
      }
   }

   private static MimeMessage getMessage(String host, String username, String password) {
      try {
         // Skapa en session
         Properties props = new Properties();
         Session session = Session.getDefaultInstance(props, null);

         // Hämta affär :)
         Store store = session.getStore("pop3");
         store.connect(host, username, password);

         // Hämta katalog
         Folder folder = store.getFolder("INBOX");
         folder.open(Folder.READ_ONLY);

         // Hämta meddelande
         Message messages[] = folder.getMessages();

         // Stäng rubbet
         //folder.close(false);
         //store.close();

         return (MimeMessage)messages[0];
      } catch(Exception e) {
         e.printStackTrace();
         return null;
      }
   }
}