From: skyhawk@cpac.washington.edu Date: Tue, 27 Jul 93 0:52:36 PDT X-Mailer: ELM [version 2.3 PL0]
From: jpp@markv.com <jpp/daemon> Subject: Alpha testers wanted: GNU Emacs, RMAIL, and PGP
[...] Pgpmail also helps fix a known security hole -- it doesn't send you passphrase on the command line, but uses the environment instead.
The security-conscious way to send something to a subprocess is to use a pipe. Looking at environment variables requires just a single extra flag to ps(1). If PGP can't be set up to use a pipe to get the passphrase, it would be best to modify PGP to clear its arguments when it's done getting a copy of them. It already does clear the passphrase argument when using -z, but it's trivial to use a file descriptor to send the passphrase to pgp, either using the PGPPASSFD environment variable to give it the descriptor, or if PGPPASSFD is 0, then pgp will look on the first line of piped input for the passphrase. (check out pgp.c) -Sam