Encrypting files with Blowfish

[Shane Kirk]

For the past couple of days, I've been experimenting with Blowfish 
encrypting/decrypting with Crypto++ 5.2.1. I'm having a bit of a problem 
that maybe some of you have come across before. I'm hoping that maybe 
someone can shed some light as to what I'm doing wrong and/or maybe 
suggest a better approach to what I'm trying to accomplish.

I'm trying to encrypt some fairly large, binary files. As you can see 
from the short test program below, it's based off the sample code that 
comes with Crypto++. I encrypt a large file (~20MB) and then decrypt it. 
I then manually compare the original and decrypted files. It always 
seems that the last few bytes (it varies depending on the size) of the 
decrypted file aren't correct. I'm sure this has something to do with 
the final block not being a valid size. But I'm not sure how to deal 
with it.

Any thoughts or suggestions?

-Shane

----CODE STARTS HERE----

#include <fstream>

#include "crypto521/cryptlib.h"
#include "crypto521/modes.h"
#include "crypto521/blowfish.h"
#include "crypto521/files.h"

#include "crypto521/hex.h"

using namespace CryptoPP;

static char mykey[] = "testkey";

void Encode() {

   std::ifstream infile("orig.bin", std::ios::binary);
   std::ofstream outfile("enc.bin", std::ios::binary);

   byte inbuffer[1024];
   byte outbuffer[1024];
   int read = 0;

   ECB_Mode<Blowfish>::Encryption enc((byte *)mykey, strlen(mykey));

   int oldpos = 0;
   while (infile.good() && !(infile.eof())) {
       memset(inbuffer, 0, 1024);
       memset(outbuffer, 0, 1024);
       infile.read((char *)inbuffer, 1024);
       int read = infile.gcount();
       enc.ProcessData(outbuffer, inbuffer, read);
       outfile.write((char *)outbuffer, read);
   }

   outfile.close();
   infile.close();

}

void Decode() {

   std::ifstream infile("enc.bin", std::ios::binary);
   std::ofstream outfile("dec.bin", std::ios::binary);

   byte inbuffer[1024];
   byte outbuffer[1024];
   int read = 0;

   ECB_Mode<Blowfish>::Decryption dec((byte *)mykey, strlen(mykey));

   while (infile.good() && !(infile.eof())) {
       memset(inbuffer, 0, 1024);
       memset(outbuffer, 0, 1024);
       infile.read((char *)inbuffer, 1024);
       int read = infile.gcount();
       dec.ProcessData(outbuffer, inbuffer, read);
       outfile.write((char *)outbuffer, read);
   }
   outfile.close();
   infile.close();
}

int main(int argc, char **argv) {
   Encode();
   Decode();
}