* What's this?
-EasyPG is yet another GnuPG interface for Emacs. It consists of two parts:
-
-- "The EasyPG Assistant" which provides basic GUI of GnuPG
-- "The EasyPG Library" which enables use of various features of GnuPG
-
-NOTE: EasyPG is neither a fork nor a re-implementation of Gnus/PGG.
+EasyPG is a GnuPG interface for Emacs. It has two aspects: convenient
+tools which allow to use GnuPG from Emacs (EasyPG Assistant), and a
+fully functional interface library to GnuPG (EasyPG Library.)
* Requirements
(require 'epa-setup)
-Then you can browse your keyring by M-x epa-list-keys. In addition,
+Then you can browse your keyring by `M-x epa-list-keys'. In addition,
you can do some cryptographic operations on dired.
M-x dired
(mark some files)
- : e (or M-x epg-dired-do-encrypt)
- (select recipients and click [OK])
+ : e (or M-x epa-dired-do-encrypt)
+ (select recipients by 'm' and click [OK])
+
+* MUA Integration
+
+The EasyPG Library can be used in combination with various MUA (Mail
+User Agents.)
+
+** CVS version of Gnus
+
+CVS version of Gnus supports EasyPG natively, simply put the following
+line into your ~/.emacs.
+
+ (setq mml2015-use 'epg)
+
+Other options which affect on the binding are
+
+ mml2015-signers
+ mml2015-encrypt-to-self
+ mml2015-cache-passphrase
+ mml2015-passphrase-cache-expiry
+ mml2015-verbose
+
+NOTE: You need not to install pgg-epg.el in this case.
+
+** PGG based MUA
+
+PGG is somewhat outdated PGP library used by old Gnus, MH-E, etc.
+
+There is a PGG backend using EasyPG called pgg-epg.el. However,
+EasyPG API is a superset of PGG, so pgg-epg.el just emulates the old
+behavior of pgg.el. Major features which PGG lacks are
+
+- Key selection user interface
+- Diagnosis interface to the verify operation
+- Web of trust
+- S/MIME using gpgsm
+
+** SEMI based MUA
+
+SEMI is the MIME library used by Wanderlust, cmail, T-gnus, etc.
+
+There is an EasyPG capable SEMI library called EMIKO-EasyPG. It can
+be downloaded from the same site of the EasyPG distribution point.
+
+* Security
+
+There are security pitfalls around Emacs.
-* Security consideration
+** Passphrase may leak to a temporary file.
-** `call-process-region' writes data in region to a temporary file
+The function call-process-region writes data in region to a temporary
+file. If your PGP library used this function, your passphrases would
+leak to the filesystem.
-`call-process-region' writes data in region to a temporary file.
-EasyPG does *not* use `call-process-region' to communicate with a gpg
-subprocess.
+The EasyPG Library does not use call-process-region to communicate
+with a gpg subprocess.
-** `(fillarray string 0)' is not enough to clear passphrases
+** Passphrase may be stolen from a core file.
-If Emacs crashes and dumps core, passphrase strings in memory are also
-dumped within the core file. `read-passwd' function clears passphrase
-strings by `(fillarray string 0)'. However, Emacs performs compaction
-in gc_sweep phase. If GC happens before `fillarray', passphrase
-strings may be moved elsewhere in memory.
+If Emacs crashes and dumps core, Lisp strings in memory are also
+dumped within the core file. read-passwd function clears passphrase
+strings by (fillarray string 0) to avoid this risk. However, Emacs
+performs compaction in gc_sweep phase. If GC happens before fillarray,
+passphrase strings may be moved elsewhere in memory. Therefore,
+passphrase caching in elisp is generally a bad idea.
-Fortunately, there is gpg-agent to cache passphrases in more secure
-way, so the EasyPG Library dares to disable passphrase caching. Elisp
-programs can set `epg-context-passphrase-callback' to cache user's
-passphrases.
+The EasyPG Library dares to disable passphrase caching. Fortunately,
+there is more secure way to cache passphrases - use gpg-agent.
projects / elisp / epg.git / blobdiff