* What's this?
EasyPG is yet another GnuPG interface for Emacs. It consists of two
-parts: transparent file encryption utility and easy-to-use elisp
-library to interact with GnuPG.
+parts:
-* Requirements
+- "The EasyPG Assistant"
+ A GUI frontend of GnuPG
+- "The EasyPG Library"
+ A library to interact with GnuPG
-** GNU Emacs 21.4 or later
+* Requirements
-** XEmacs 21.4 or later
+** GNU Emacs 21.4 or XEmacs 21.4
-** GnuPG 1.4.3 or later
+** GnuPG 1.4.3
* Quick start
-(0) Put (require 'epg-file) in your ~/.emacs.el
+** Installation
+
+ $ ./configure
+ $ sudo make install
+
+Add the following line to your ~/.emacs
+
+ (require 'epa-setup)
+
+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 epa-dired-do-encrypt)
+ (select recipients and click [OK])
+
+* Security
+
+There are security pitfalls around Emacs.
+
+** Passphrase may leak 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.
+
+The EasyPG Library does not use call-process-region to communicate
+with a gpg subprocess.
-(1) Restart emacs
+** Passphrase may be stolen from a core file.
-(2) C-x C-f ~/test.gpg
+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.
-* Advantages over other competitors
+The EasyPG Library dares to disable passphrase caching. Fortunately,
+there is more secure way to cache passphrases - use gpg-agent.
-There are many competitors of EasyPG such as Mailcrypt, PGG, gpg.el,
-etc. EasyPG has some advantages over them.
+* MUA Integration
-** EasyPG avoides potential security flaws of Emacs.
+The EasyPG Library can be used in combination with MUA (Mail User
+Agents).
-*** `call-process-region' writes data in region to a temporary file.
+** SEMI based MUA
-PGG and gpg.el use `call-process-region' to communicate with a gpg
-subprocess. Your passphrases may leak to the filesystem.
+SEMI is the MIME library used by Wanderlust, cmail, T-gnus, etc.
-*** There is no way to clear strings safely.
+There is an EasyPG capable SEMI library called EMIKO-EasyPG. It can
+be downloaded from the same site of the EasyPG distribution point.
-If Emacs crashed and dumps core, passphrase strings in memory are also
-dumped with the core file. `read-passwd' function clears passphrase
-strings by `(fillarray string 0)'. However, it is not perfect. Emacs
-does compaction of small strings in gc_sweep phase. If GC happens
-before `fillarray', passphrase strings may be copied elsewhere in
-memory. So, it is recommended that if you are done with passphrase
-you should clear it manually. However, PGG and gpg.el enables
-passphrase caching by default.
+** PGG based MUA
-** Most GnuPG features are accessible from Emacs
+PGG is somewhat outdated PGP library used by Gnus, MH-E, etc.
-As the name indicates, EasyPG is inspired by GPGME (GnuPG Made Easy),
-and the library interface is close to GPGME.
+There is a PGG backend using EasyPG called pgg-epg.el. However,
+pgg-epg.el provides no more additional features than pgg-gpg.el,
+because PGG's API is restricted so that it supports old PGP 2.x/5.x.