gnus-article-encrypt-protocol

gnus-article-encrypt-protocol is a variable defined in `gnus-art.el'.
Its value is

"PGP"

Documentation:
The protocol used for encrypt articles.
It is a string, such as "PGP". If nil, ask user.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 22.1 of Emacs.