* epa.texi (Caching Passphrases): New section.

doc/misc/ChangeLog

+2010-10-06  Daiki Ueno  <ueno@unixuser.org>
+
+	* epa.texi (Caching Passphrases): New section.
+
 2010-10-06  Glenn Morris  <rgm@gnu.org>
 
 	* Makefile.in (SHELL): Set it.

doc/misc/epa.texi

@@ -66,6 +66,7 @@ called EasyPG Library.
 * Overview::                    
 * Quick start::                 
 * Commands::                    
+* Caching Passphrases::         
 * Bug Reports::                 
 @end menu
 
@@ -399,6 +400,43 @@ If non-@code{nil}, disable auto-saving when opening an encrypted file.
 The default value is @code{t}.
 @end defvar
 
+@node Caching Passphrases
+@chapter Caching Passphrases
+
+Typing passphrases is an irritating task if you frequently open and
+close the same file.  GnuPG and EasyPG Assistant provide mechanisms to
+remember your passphrases.  However, the configuration is a bit
+confusing since it depends on your GnuPG installation (GnuPG version 1 or
+GnuPG version 2), encryption method (symmetric or public key), and whether or
+not you want to use gpg-agent.  Here are some questions:
+
+@enumerate
+@item Do you use GnuPG version 2 instead of GnuPG version 1?
+@item Do you use symmetric encryption rather than public key encryption?
+@item Do you want to use gpg-agent?
+@end enumerate
+
+Here are configurations depending on your answers:
+
+@multitable {111} {222} {333} {configuration configuration configuration}
+@item @b{1} @tab @b{2} @tab @b{3} @tab Configuration
+@item Yes @tab Yes @tab Yes @tab Nothing to do.
+@item Yes @tab Yes @tab No @tab You can't, without gpg-agent.
+@item Yes @tab No @tab Yes @tab Nothing to do.
+@item Yes @tab No @tab No @tab You can't, without gpg-agent.
+@item No @tab Yes @tab Yes @tab Set up elisp passphrase cache.
+@item No @tab Yes @tab No @tab Set up elisp passphrase cache.
+@item No @tab No @tab Yes @tab Nothing to do.
+@item No @tab No @tab No @tab You can't, without gpg-agent.
+@end multitable
+
+To setup gpg-agent, follow the instruction in GnuPG manual.
+@pxref{Invoking GPG-AGENT, , Invoking GPG-AGENT, gnupg}.
+
+To set up elisp passphrase cache, set
+@code{epa-file-cache-passphrase-for-symmetric-encryption}.
+@xref{Encrypting/decrypting *.gpg files}.
+
 @node Bug Reports
 @chapter Bug Reports