There is a package called PGP4Pine which allows you use PGP version 2.6 with pine. (If you are using PGP version 5, you may have some difficulties; you may prefer to switch to GPG, or switch to mutt, or both.)
After installing the PGP4Pine package according to its instructions, you need to edit your ~/.pinerc file and change two lines:
display-filters=_BEGINNING("-----BEGIN PGP")_ /usr/lib/pinepgp/check _TMPFILE_ _RESULTFILE_
sending-filters=/usr/lib/pinepgp/pgp _TMPFILE_ _RECIPIENTS_
The path /usr/lib/pinepgp is what Debian uses for this package, which it
calls pinepgp. On your computer,
you may have PGP4Pine installed elsewhere; change the path names
appropriately. This will allow you to receive and send messages which
have been signed and/or encrypted with PGP.
To sign or encrypt a message in pine, compose the message as you normally would, and then when you get to this menu:
Send message (unfiltered)? _
Y [Yes] ^P Prev Filter
^C Cancel N No ^N Next Filter
Press Ctrl-N, and the menu will change:
Send message (filtered thru "pgp")? _
Y [Yes] ^P Prev Filter
^C Cancel N No ^N Next Filter
Pressing y brings up a separate PGP menu:
PINE/PGP send message --------------------- s - sign r - encrypt e - sign & encrypt n - do nothing f - finger address c - cancel [default = sign] Operation? _From here, you can sign the message, or encrypt it, or do both.