encryption in CGI routine
 

I need to encrypt a small file received from an HTML form through a CGI routine. This file needs to be converted back to plain text later (HASH not suitable).

The main problem I face is to have the pass phrase or password automatically provided when requested through stdin. The CGI routines are written in assembly, I only have a basic knowledge of C and PHP and no knowledge of Perl.

Can anyone suggest how to proceed? Point to suitable links? Give a hint?

Thank you.

I've found it's possible with PHP. I'll update this post with the results after trying the PHP solution.

You would do well to study the features of a full-featured encryption package such as openssl, which should be readily available now on your system and for which interfaces exist in both php and perl.

Key-management, authentication, spoofing-prevention, forgery-prevention and so on are all important issues, and all of them have been ably handled. You won't do any better "on your own."

Thanks to sundialsvcs.
I am probably expecting it to be easier than possible. Seen from your perspective, I should first determine what I need to learn for my needs: OpenSSL or Gnupg or whatever. I'm doing this as a volunteer for a Not-For-Profit and will only learn what is absolutely necessary to get it going, then the pros can take over when finance permits.
Perhaps you can advise what package to learn and use when you consider that the encryption/decryption mentioned above is all I need.