GnuPG with Java on Windows?

[Jean-Christian Imbeault]

I'm trying to write a small Java program that will decrypt content 
encrypted with GnuPG. I've scoured the archives and have found links and 
even some code examples.

The problem I am running in to is that I can't get the code examples to 
run under Windows. GnuPg keeps giving an error.

For example the following will work fine on the command line in windows:

gpg --no-secmem-warning --passphrase-fd 0 --batch --decrypt 
C:\DOCUME~1\Jc1\LOCALS~1\Temp\AAA9691.tmp

But if run from Java as:

String cmd, path;
path = " C:\DOCUME~1\Jc1\LOCALS~1\Temp\AAA9691.tmp";
cmd  = "gpg --no-secmem-warning --passphrase-fd 0 --batch --decrypt";
Runtime.getRuntime().exec(cmd + path);

I get the following error:

gpg error >> code: 2 >> gpg: can't open 
`C:\DOCUME~1\Jc1\LOCALS~1\Temp\AAA9691.tmp'

gpg: decrypt_message failed: file open error


Why can't gpg open the file when run from Java but can open when run 
from the command line? What did I miss?

Can anyone giver me some pointers on why I get this error and how I can 
fix my code to make it work? (code included at bottom)

Or if anyone can point me to a simple implementation of decryption using 
gpg in Java (under windows?) that might prove useful also.

Thanks,

Jc

PS The code I am using was shamelessly lifted from 
http://www.eurielec.etsit.upm.es/~jamc/work/jfreevote-1.0/ :)

package TAL.Encryption;

import java.io.*;

public class GnuPG {
     private static String gpg_comm = "gpg --no-secmem-warning ";
     private static String decrypt_param = "--passphrase-fd 0 --batch 
--decrypt ";

     public GnuPG() {}

     public String decrypt(String str, String passphrase) throws Exception {
       Process p = null;
       File f = null;

       try {
         f = File.createTempFile("AAA", null);
         FileWriter fw = new FileWriter(f);
         fw.write(str);
         fw.flush();
       } catch (Exception e) {
         throw new Exception("A- gpg error >> " + e.toString());
       }

       try {
         p = Runtime.getRuntime().exec(gpg_comm + decrypt_param + 
f.getAbsoluteFile());
         System.out.println("New process with:\n" + gpg_comm + 
decrypt_param + f.getAbsoluteFile());
       } catch (Exception e) {
         throw new Exception("gpg error >> " + e.toString());
       }

       ProcessStreamReader psr_stdout = new 
ProcessStreamReader(p.getInputStream());
       ProcessStreamReader psr_stderr = new 
ProcessStreamReader(p.getErrorStream());

       psr_stdout.start();
       psr_stderr.start();

       BufferedWriter out = new BufferedWriter(new 
OutputStreamWriter(p.getOutputStream()));

       try {
         out.write(passphrase);
         out.close();
       } catch (Exception e) {
         throw new Exception("1- gpg error >> " + e.toString());
       }

       try {
         p.waitFor();
         psr_stdout.join();
         psr_stderr.join();
       } catch (Exception e) {
         throw new Exception("2- gpg error >> " + e.toString());
       }

       if (p.exitValue() != 0) {
         throw new Exception("3- gpg error >> code: " + p.exitValue() + 
" >> " + psr_stderr.getString());
       }

       try {
         f.delete();
       } catch (Exception e) {
         throw new Exception("4- gpg error >> " + e.toString());
       }
       return psr_stdout.getString();
     }

     public static void main(String[] args) {
       GnuPG gpg = new GnuPG();

       String encrypted = "";

       encrypted =
  "-----BEGIN PGP MESSAGE-----\n"+
  "Version: GnuPG v1.0.7 (GNU/Linux)\n"+
  "\n"+ 
"hQIOA1O09Ob0n2sjEAgAod5W1wtN3LoRl3wJ1QEkGSu2UT3YzgQXrV8KRxGtaG5R\n"+
"c5JYRfAR1Z3t5SpEFIEMCU8oJxqnZQBSlRJ1UeFvE77Gqg6qFMWvSqJ6FiIOHuw3\n"+
"ZL3lBoom8GFl7z7InKBbAN3ZksJhDTd20IEakwpYB7Y669vTUbI4g91i7K2NT9ee\n"+
"l3OJtgahw9IEvGUN+mwhm6jtvUVq4UAhArf4ujiU9BJa8yH42jzjgYxpErrJdQ5S\n"+
"LGFgI9zipwKXeO4sP3VLnRfWgXMtw4E7gw9fDjq4DLsgOBWyi6GlaQpLZT3q88YA\n"+
"uGcJ4FF6faAGYZgVh1KiDQuZZ5HH0W3tRpvNKTKtTQgAm9uzYVX3iTv8YaN3CB8q\n"+
"Gxwy1tYF7FFiMxkdLDUBlETwZBkfitUgBMeZM/aCjhBv4jiomndJGmYP0TCjxDzv\n"+
"Df2B1y5LYNn1Hj8/IfUEkx1G9fEmDPxWhIK0iJetPOdicIEMXxw+YLMpmtgFwYcp\n"+
"KQx+RkXJbbyXtHVC0UoXk/QlWH/LV887H3lSPLcWXxC7hxBdRWiIql6LKTnMh6HK\n"+
"d3c73hsz4VUvb2gjCOQLEpWlNc6lTPcvJ/PhoTmd9o6+bfbotKL3sfu6ZHai2t3S\n"+
"yxrexotKfrOnFBR6zIBkSpCrEWZHOTjuZY0/lPMs6oyaVGCrDdwVAt4YMyx0ylad\n"+
"p9JSAYlUjojW5T+pxejtMSJVFj0Qgkqm2B+nucffOaLBNGfJ/85pLTt2Zps6K74L\n"+
"eMF0OgTjQ0s7NNxkVkhLZetAF51Rt+OWM/NXr+nWP70azQYJaw==\n"+
"=sAZg\n"+
"-----END PGP MESSAGE-----\n";

       String decrypted = "";
       try {
         decrypted = gpg.decrypt(encrypted, "The passphrase 4 TAL gpg");
       } catch (Exception e) {System.out.println("Error:\n" + e);}
       System.out.println("Decrypted is:\n" + decrypted);
     }
}

class ProcessStreamReader extends Thread {
   StringBuffer stream;
   InputStreamReader in;

   final static int BUFFER_SIZE = 256;

   public ProcessStreamReader(InputStream in) {
     super();
     this.in = new InputStreamReader(in);
     this.stream = new StringBuffer();
   }

   public void run() {
     try {
       int read;
       char[] c = new char[BUFFER_SIZE];

       while ((read = in.read(c, 0, BUFFER_SIZE - 1)) > 0) {
         stream.append(c, 0, read);
         if (read < BUFFER_SIZE - 1) {
           break;
         }
       }
     } catch (IOException io) {
       ;
     }
   }

   public String getString() {
     return stream.toString();
   }
}