X-Git-Url: http://git.chise.org/gitweb/?a=blobdiff_plain;f=README;h=b438bd3330e83010f5e01ce59e33527d0b1ba665;hb=359180decf50389e8a5313a3fb04c88a6a93f69e;hp=1072f4d39fa7bc4539309c0255e5753524687ee5;hpb=3196c5138136a3c3a24e04a4ee6e45268ffe42a4;p=elisp%2Fepg.git

diff --git a/README b/README
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 * 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.
+EasyPG is yet another GnuPG interface for Emacs.  It consists of two parts:
 
-* Requirements
+- "The EasyPG Assistant" which provides basic GUI of GnuPG
+- "The EasyPG Library" which enables use of various features of GnuPG
 
-** GNU Emacs 21.4 or later
+NOTE: EasyPG is neither a fork nor a re-implementation of Gnus/PGG.
 
-** XEmacs 21.4 or later
+* Requirements
 
-** GnuPG 1.4.3 or later
+** GNU Emacs 21.4 or XEmacs 21.4
 
-** Gnus 5.10.8 or later (optional)
+** GnuPG 1.4.3
 
 * Quick start
 
-** Transparent file encryption
-
-EasyPG provides transparent file encryption similar to crypt++,
-alpaca.el, hedgehog.  To enable this feature, put (require 'epg-file)
-in your ~/.emacs.el, C-x C-f ~/test.txt.gpg.
+** Installation
 
-** Using with Gnus/PGG
+  $ ./configure
+  $ sudo make install
 
-EasyPG provides an implementation of the backend interface of
-Gnus/PGG.  To use EasyPG instead of pgg-gpg, install pgg-epg.el and
-add the following line to your ~/.gnus
+Add the following line to your ~/.emacs
 
-(setq pgg-scheme 'epg)
+  (require 'epa-setup)
 
-* Advantages over other competitors
+Then you can browse your keyring by M-x epa-list-keys.  In addition,
+you can do some cryptographic operations on dired.
 
-There are many competitors of EasyPG such as Mailcrypt, PGG, gpg.el,
-etc.  EasyPG has some advantages over them.
+  M-x dired
+  (mark some files)
+  : e (or M-x epg-dired-do-encrypt)
+  (select recipients and click [OK])
 
-** EasyPG avoides potential security flaws of Emacs.
+* Security consideration
 
-*** `call-process-region' writes data in region to temporary files.
+** `call-process-region' writes data in region to a temporary file
 
-`call-process-region' writes data in region to temporary files.  PGG
-and gpg.el use `call-process-region' to communicate with a gpg
-subprocess.  Your passphrases 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.
 
-*** There is no way to clear strings safely.
+** `(fillarray string 0)' is not enough to clear passphrases
 
-If Emacs crashed and dumps core, passphrase strings in memory are also
+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.  It is recommended that as
-soon as you are done with passphrase you should clear it manually.
-However, PGG and gpg.el can keep passphrase strings in cache for a
-while and this behavior is their default!
-
-** GnuPG features are directly accessible from Emacs
-
-Other competitors provide only specific features of GnuPG since they
-still support PGP 2.*, 5.*, 6.*.  As the name indicates, EasyPG is
-inspired by GPGME (GnuPG Made Easy), and the library interface is
-close to GPGME.  With EasyPG you can benefit from a lot of features of
-GnuPG.
+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.
+
+Fortunately, there is more secure way to cache passphrases - use
+gpg-agent.
+
+Elisp programs can set `epg-context-passphrase-callback' to cache
+user's passphrases, it is not recommended though.