PGP::Sign version 0.13 (Create detached PGP signatures for data) Copyright 1997, 1998 by Russ Allbery . All rights reserved. This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself. INTRODUCTION One important thing to clear up right away: THIS IS NOT A GENERAL PGP MODULE For wonderful general PGP modules that will encrypt, decrypt, manage key rings, slice, dice, fold, spindle, and mutilate your data, see the PGP by-module directory at your local CPAN mirror. This module sprung out of a need to do one thing and one thing only, do it securely, and do it well. This module creates and checks detached signatures for data. That's it. If you want to do anything else that PGP lets you do, look elsewhere. The original purpose of this module was to factor out common code in a News::Article class written by Andrew Gierth that did PGPMoose signatures and signed control messages. It should now be possible to reimplement PGPMoose, signcontrol, and pgpverify using this module, and the second and parts of the first have already been done. So much for the "one thing only" part. For the "do it securely" part, this module uses a pipe and PGPPASSFD to pass the secret key password to PGP, rather than a command line flag or an environment variable as seen in other modules. Both of those are subject to snooping by other users; this approach isn't. For the "do it well" part, the interface to this module takes every form of data known to man. Scalars and arrays are no problem, of course, but if you give it a reference to an array, it'll walk the array to avoid making a copy of a potentially large data structure. You can also give it an open file (in the form of a glob, a reference to a glob, a FileHandle object, an IO::Handle object, or anything derived from either) and it'll walk that too. Or you can give it a reference to a scalar if you really want to and it's cool with that. Or, if you want to get really exciting, you can give it a reference to a sub and it'll call the sub repeatedly to get more data until the sub returns undef. Perfect for walking some complex data structure you don't want to make an internal copy of. And if there's any other interesting data structure you want to throw at it, tell me about it, and the next version will probably support that too. See the documentation for all the gory details, which really aren't that gory. At least yet. REQUIREMENTS This module requires a version of PGP that supports PGPPASSFD. 2.6.2 and 2.6.3i do. I can't personally vouch for any other version. This module also requires an operating system that's capable of coping with pipes, forking, and passing file descriptors through an exec(). If your operating system can't, that's considered by this module author to be a bug in your operating system and not in this module. INSTALLATION Follow the standard installation procedure for Perl modules, which is to type the following commands: perl Makefile.PL make make test make install You'll probably need to do the last as root. When you run make, you will be prompted for the path to PGP; make sure this is correct, since this will be coded into the module when it's installed. There is a small test suite that uses the files in data to make sure that signing and checking of signatures work. More test cases are welcome, particularly if you find a bug. THANKS To Andrew Gierth for the inspiration and motivation to write this and the reminder that PGPPASSFD existed, and also for being one of the two people who caught the mistake I made with $? and open3(). To Jon Ribbens for pointing out that $? isn't guaranteed to contain the exit status of something called from open3() unless you do a waitpid() for it first. To Andrew Ford for adding PGPPATH support and adding a test suite and code in Makefile.PL to search for an installed version of PGP. To David Lawrence and Greg Rose for signcontrol and PGPMoose respectively, the motivating applications. To Phil Zimmermann, because Phil should be listed in the thank you list for anything related to PGP, given that he wrote it and went through legal hell to make sure we still had it available. Send any comments, bug reports, feature requests, flames, thank yous, offers of vast quantities of money, lutefisk, and large green Martian dogs named Ralf to rra@stanford.edu. Enjoy!