* epa.el (epa-decrypt-region): New command.

[elisp/epg.git] / README

diff --git a/README b/README
index c144956..e0c2104 100644 (file)
--- a/README
+++ b/README
@@ -2,16 +2,18 @@
 
 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 directly interacts with GnuPG
+- "The EasyPG Assistant"
+  A GUI frontend of GnuPG
+- "The EasyPG Library"
+  A library to interact with GnuPG
 
-NOTE: EasyPG is not a fork or a re-implementation of Gnus/PGG.
+NOTE: EasyPG is neither a fork nor a re-implementation of PGG.
 
 * Requirements
 
-** GNU Emacs 21.4 or later, 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
 
@@ -24,30 +26,34 @@ Add the following line to your ~/.emacs
 
   (require 'epa-setup)
 
-Then you can do some cryptographic operations on dired.
+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)
+  : e (or M-x epa-dired-do-encrypt)
   (select recipients and click [OK])
 
-* Security consideration
+* Security
 
-** `call-process-region' writes data in region to a temporary file
+There are security pitfalls around Emacs.
+
+** Passphrase may leak to a temporary file.
 
 `call-process-region' writes data in region to a temporary file.
-EasyPG does *not* use `call-process-region' to communicate with a gpg
+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 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.
+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 *not* to cache passphrase by itself.
-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.  Elisp
+programs can set `epg-context-passphrase-callback' to cache user's
+passphrases, it is not recommended though.