* What's this?
-EasyPG is yet another GnuPG interface for Emacs. It consists of a
-transparent file encryption application and easy-to-use elisp library
-to interact with GnuPG.
+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.
+
+* Requirements
+
+** GNU Emacs 21.4 or XEmacs 21.4
+
+** 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 epg-dired-do-encrypt)
+ (select recipients and click [OK])
-(1) Restart emacs
+* Security consideration
-(2) C-x C-f ~/test.gpg
+** `call-process-region' writes data in region to a temporary file
-* Advantages over other competitors
+`call-process-region' writes data in region to a temporary file.
+EasyPG does *not* use `call-process-region' to communicate with a gpg
+subprocess.
-** EasyPG avoides potential security flaws of Emacs.
+** `(fillarray string 0)' is not enough to clear passphrases
-*** `call-process-region' writes data in region to a temporary file.
-PGG and gpg.el use `call-process-region' to communicate with a
-subprocess "gpg". So, your passphrases may leak to the filesystem.
+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)'. 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. The EasyPG Library dares to
+disable passphrase caching.
-*** There is no way to clear strings safely.
-To prevent passphrases from been stealing from cores, `read-passwd'
-function clears passphrase strings by `(fillarray string 0)'.
-However, it is not enough. In GC sweep phase, Emacs does compaction
-on small strings. If GC happens before `fillarray', passphrase
-strings may be copied elsewhere in the memory.
+Fortunately, there is more secure way to cache passphrases - use
+gpg-agent.
-PGG and gpg.el enables passphrase caching by default.
+Elisp programs can set `epg-context-passphrase-callback' to cache
+user's passphrases, it is not recommended though.