\input texinfo @c -*-texinfo-*-
@setfilename pgg
+@settitle PGG @value{VERSION}
@set VERSION 0.1
-@direntry
-* PGG: (pgg). Emacs interface to various PGP implementations.
-@end direntry
-
-@settitle PGG @value{VERSION}
+@copying
+This file describes PGG @value{VERSION}, an Emacs interface to various
+PGP implementations.
-@ifinfo
-This file describes the PGG.
-
-Copyright (C) 2003, 2004 Free Software Foundation, Inc.
-Copyright (C) 2001 Daiki Ueno.
+Copyright @copyright{} 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
+2010 Free Software Foundation, Inc.
+@quotation
Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
+under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
-Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
-Texts. A copy of the license is included in the section entitled "GNU
-Free Documentation License".
-@end ifinfo
+Invariant Sections, with the Front-Cover texts being ``A GNU Manual,''
+and with the Back-Cover Texts as in (a) below. A copy of the license
+is included in the section entitled ``GNU Free Documentation License.''
+
+(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
+modify this GNU manual. Buying copies from the FSF supports it in
+developing GNU and promoting software freedom.''
+@end quotation
+@end copying
-@tex
+@dircategory Emacs
+@direntry
+* PGG: (pgg). Emacs interface to various PGP implementations.
+@end direntry
@titlepage
@title PGG
@page
@vskip 0pt plus 1filll
-Copyright @copyright{} 2001 Daiki Ueno.
-
-Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with no
-Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
-Texts. A copy of the license is included in the section entitled "GNU
-Free Documentation License".
+@insertcopying
@end titlepage
-@page
-@end tex
+@contents
@node Top
@top PGG
-This manual describes PGG. PGG is an interface library between Emacs
+
+PGG is an interface library between Emacs
and various tools for secure communication. PGG also provides a simple
user interface to encrypt, decrypt, sign, and verify MIME messages.
+@ifnottex
+@insertcopying
+@end ifnottex
+
@menu
* Overview:: What PGG is.
* Prerequisites:: Complicated stuff you may have to do.
* How to use:: Getting started quickly.
* Architecture::
* Parsing OpenPGP packets::
+* GNU Free Documentation License:: The license for this documentation.
* Function Index::
* Variable Index::
@end menu
This document assumes that you have already obtained and installed them
and that you are familiar with its basic functions.
-By default, PGG uses GnuPG, but Pretty Good Privacy version 2 or version
-5 are also supported. If you are new to such a system, I recommend that
-you should look over the GNU Privacy Handbook (GPH) which is available
-at @uref{http://www.gnupg.org/gph/}.
+By default, PGG uses GnuPG. If you are new to such a system, I
+recommend that you should look over the GNU Privacy Handbook (GPH)
+which is available at @uref{http://www.gnupg.org/documentation/}.
+
+When using GnuPG, we recommend the use of the @code{gpg-agent}
+program, which is distributed with versions 2.0 and later of GnuPG.
+This is a daemon to manage private keys independently from any
+protocol, and provides the most secure way to input and cache your
+passphrases (@pxref{Caching passphrase}). By default, PGG will
+attempt to use @code{gpg-agent} if it is running. @xref{Invoking
+GPG-AGENT,,,gnupg,Using the GNU Privacy Guard}.
+
+PGG also supports Pretty Good Privacy version 2 or version 5.
@node How to use
@chapter How to use
@lisp
(autoload 'pgg-encrypt-region "pgg"
"Encrypt the current region." t)
+(autoload 'pgg-encrypt-symmetric-region "pgg"
+ "Encrypt the current region with symmetric algorithm." t)
(autoload 'pgg-decrypt-region "pgg"
"Decrypt the current region." t)
(autoload 'pgg-sign-region "pgg"
* User Commands::
* Selecting an implementation::
* Caching passphrase::
-* Default user identity::
+* Default user identity::
@end menu
@node User Commands
fails immediately, but if the function had been called interactively, it
would ask you to retrieve the signer's public key from the server.
-@deffn Command pgg-encrypt-region start end recipients &optional sign
+@deffn Command pgg-encrypt-region start end recipients &optional sign passphrase
Encrypt the current region between @var{start} and @var{end} for
@var{recipients}. When the function were called interactively, you
would be asked about the recipients.
the accessible portion) with the resulting data.
If optional argument @var{sign} is non-@code{nil}, the function is
-request to do a combined sign and encrypt. This currently only work
-with GnuPG.
+request to do a combined sign and encrypt. This currently is
+confirmed to work with GnuPG, but might not work with PGP or PGP5.
+
+If optional @var{passphrase} is @code{nil}, the passphrase will be
+obtained from the passphrase cache or user.
+@end deffn
+
+@deffn Command pgg-encrypt-symmetric-region &optional start end passphrase
+Encrypt the current region between @var{start} and @var{end} using a
+symmetric cipher. After invocation you are asked for a passphrase.
+
+If optional @var{passphrase} is @code{nil}, the passphrase will be
+obtained from the passphrase cache or user.
+
+symmetric-cipher encryption is currently only implemented for GnuPG.
@end deffn
-@deffn Command pgg-decrypt-region start end
+@deffn Command pgg-decrypt-region start end &optional passphrase
Decrypt the current region between @var{start} and @var{end}. If
decryption is successful, it replaces the current region contents (in
the accessible portion) with the resulting data.
+
+If optional @var{passphrase} is @code{nil}, the passphrase will be
+obtained from the passphrase cache or user.
@end deffn
-@deffn Command pgg-sign-region start end &optional cleartext
+@deffn Command pgg-sign-region start end &optional cleartext passphrase
Make the signature from text between @var{start} and @var{end}. If the
optional third argument @var{cleartext} is non-@code{nil}, or the
function is called interactively, it does not create a detached
signature. In such a case, it replaces the current region contents (in
the accessible portion) with the resulting data.
+
+If optional @var{passphrase} is @code{nil}, the passphrase will be
+obtained from the passphrase cache or user.
@end deffn
@deffn Command pgg-verify-region start end &optional signature fetch
Verify the current region between @var{start} and @var{end}. If the
-optional third argument @var{signature} is non-@code{nil}, or the function
-is called interactively, it is treated as the detached signature of the
-current region.
+optional third argument @var{signature} is non-@code{nil}, it is treated
+as the detached signature file of the current region.
If the optional 4th argument @var{fetch} is non-@code{nil}, or the
function is called interactively, we attempt to fetch the signer's
select cipher algorithm from 3DES, CAST5, BLOWFISH, and so on, but on
the other hand the version 2 of PGP only supports IDEA.
-By default, if the variable @code{pgg-scheme} is not set, PGG searches the
-registered scheme for an implementation of the requested service
-associated with the named algorithm. If there are no match, PGG uses
-@code{pgg-default-scheme}. In other words, there are two options to
-control which command is used to process the incoming PGP armors. One
-is for encrypting and signing, the other is for decrypting and
-verifying.
+Which implementation is used is controlled by the @code{pgg-scheme}
+variable. If it is @code{nil} (the default), the value of the
+@code{pgg-default-scheme} variable will be used instead.
@defvar pgg-scheme
-Force specify the scheme of PGP implementation for decrypting and verifying.
-The value can be @code{gpg}, @code{pgp}, and @code{pgp5}.
+Force specify the scheme of PGP implementation. The value can be set to
+@code{gpg}, @code{pgp}, and @code{pgp5}. The default is @code{nil}.
@end defvar
@defvar pgg-default-scheme
-Force specify the scheme of PGP implementation for encrypting and signing.
-The value can be @code{gpg}, @code{pgp}, and @code{pgp5}.
+The default scheme of PGP implementation. The value should be one of
+@code{gpg}, @code{pgp}, and @code{pgp5}. The default is @code{gpg}.
@end defvar
@node Caching passphrase
@section Caching passphrase
-PGG uses a simple passphrase caching mechanism, which is enabled by
-default.
+When using GnuPG (gpg) as the PGP scheme, we recommend using a program
+called @code{gpg-agent} for entering and caching
+passphrases@footnote{Actually, @code{gpg-agent} does not cache
+passphrases but private keys. On the other hand, from a user's point
+of view, this technical difference isn't visible.}.
+
+@defvar pgg-gpg-use-agent
+If non-@code{nil}, attempt to use @code{gpg-agent} whenever possible.
+The default is @code{t}. If @code{gpg-agent} is not running, or GnuPG
+is not the current PGP scheme, PGG's own passphrase-caching mechanism
+is used (see below).
+@end defvar
+
+To use @code{gpg-agent} with PGG, you must first ensure that
+@code{gpg-agent} is running. For example, if you are running in the X
+Window System, you can do this by putting the following line in your
+@file{.xsession} file:
+
+@smallexample
+eval "$(gpg-agent --daemon)"
+@end smallexample
+
+For more details on invoking @code{gpg-agent}, @xref{Invoking
+GPG-AGENT,,,gnupg,Using the GNU Privacy Guard}.
+
+Whenever you perform a PGG operation that requires a GnuPG passphrase,
+GnuPG will contact @code{gpg-agent}, which prompts you for the
+passphrase. Furthermore, @code{gpg-agent} ``caches'' the result, so
+that subsequent uses will not require you to enter the passphrase
+again. (This cache usually expires after a certain time has passed;
+you can change this using the @code{--default-cache-ttl} option when
+invoking @code{gpg-agent}.)
+
+If you are running in a X Window System environment, @code{gpg-agent}
+prompts for a passphrase by opening a graphical window. However, if
+you are running Emacs on a text terminal, @code{gpg-agent} has trouble
+receiving input from the terminal, since it is being sent to Emacs.
+One workaround for this problem is to run @code{gpg-agent} on a
+different terminal from Emacs, with the @code{--keep-tty} option; this
+tells @code{gpg-agent} use its own terminal to prompt for passphrases.
+
+When @code{gpg-agent} is not being used, PGG prompts for a passphrase
+through Emacs. It also has its own passphrase caching mechanism,
+which is controlled by the variable @code{pgg-cache-passphrase} (see
+below).
+
+There is a security risk in handling passphrases through PGG rather
+than @code{gpg-agent}. When you enter your passphrase into an Emacs
+prompt, it is temporarily stored as a cleartext string in the memory
+of the Emacs executable. If the executable memory is swapped to disk,
+the root user can, in theory, extract the passphrase from the
+swapfile. Furthermore, the swapfile containing the cleartext
+passphrase might remain on the disk after the system is discarded or
+stolen. @code{gpg-agent} avoids this problem by using certain tricks,
+such as memory locking, which have not been implemented in Emacs.
@defvar pgg-cache-passphrase
If non-@code{nil}, store passphrases. The default value of this
-variable is @code{t}. If you were worry about security issue, however,
-you could stop caching with setting it @code{nil}.
+variable is @code{t}. If you are worried about security issues,
+however, you could stop the caching of passphrases by setting this
+variable to @code{nil}.
@end defvar
@defvar pgg-passphrase-cache-expiry
Elapsed time for expiration in seconds.
@end defvar
+If your passphrase contains non-ASCII characters, you might need to
+specify the coding system to be used to encode your passphrases, since
+GnuPG treats them as a byte sequence, not as a character sequence.
+
+@defvar pgg-passphrase-coding-system
+Coding system used to encode passphrase.
+@end defvar
+
@node Default user identity
@section Default user identity
Since PGG was designed for accessing and developing PGP functionality,
the architecture had to be designed not just for interoperability but
also for extensiblity. In this chapter we explore the architecture
-while finding out how to write the PGG backend.
+while finding out how to write the PGG back end.
@menu
* Initializing::
-* Backend methods::
+* Back end methods::
* Getting output::
@end menu
(defun pgg-make-scheme-gpg ()
(or pgg-scheme-gpg-instance
(setq pgg-scheme-gpg-instance
- (luna-make-entity 'pgg-scheme-gpg))))
+ (luna-make-entity 'pgg-scheme-gpg))))
@end lisp
The name of the function must follow the
-regulation---@code{pgg-make-scheme-} follows the backend name.
+regulation---@code{pgg-make-scheme-} follows the back end name.
-@node Backend methods
-@section Backend methods
+@node Back end methods
+@section Back end methods
-In each backend, these methods must be present. The output of these
+In each back end, these methods must be present. The output of these
methods is stored in special buffers (@ref{Getting output}), so that
these methods must tell the status of the execution.
keyrings.
@end deffn
-@deffn Method pgg-scheme-encrypt-region scheme start end recipients &optional sign
+@deffn Method pgg-scheme-encrypt-region scheme start end recipients &optional sign passphrase
Encrypt the current region between @var{start} and @var{end} for
@var{recipients}. If @var{sign} is non-@code{nil}, do a combined sign
and encrypt. If encryption is successful, it returns @code{t},
otherwise @code{nil}.
@end deffn
-@deffn Method pgg-scheme-decrypt-region scheme start end
+@deffn Method pgg-scheme-encrypt-symmetric-region scheme start end &optional passphrase
+Encrypt the current region between @var{start} and @var{end} using a
+symmetric cipher and a passphrases. If encryption is successful, it
+returns @code{t}, otherwise @code{nil}. This function is currently only
+implemented for GnuPG.
+@end deffn
+
+@deffn Method pgg-scheme-decrypt-region scheme start end &optional passphrase
Decrypt the current region between @var{start} and @var{end}. If
decryption is successful, it returns @code{t}, otherwise @code{nil}.
@end deffn
-@deffn Method pgg-scheme-sign-region scheme start end &optional cleartext
+@deffn Method pgg-scheme-sign-region scheme start end &optional cleartext passphrase
Make the signature from text between @var{start} and @var{end}. If the
optional third argument @var{cleartext} is non-@code{nil}, it does not
create a detached signature. If signing is successful, it returns
@node Getting output
@section Getting output
-The output of the backend methods (@ref{Backend methods}) is stored in
+The output of the back end methods (@ref{Back end methods}) is stored in
special buffers, so that these methods must tell the status of the
execution.
If non-@code{nil}, don't check the checksum of the packets.
@end defvar
+@node GNU Free Documentation License
+@appendix GNU Free Documentation License
+@include doclicense.texi
+
@node Function Index
-@chapter Function Index
+@unnumbered Function Index
@printindex fn
@node Variable Index
-@chapter Variable Index
+@unnumbered Variable Index
@printindex vr
-@summarycontents
-@contents
@bye
@c End:
+
+@ignore
+ arch-tag: 0c205838-34b9-41a5-b9d7-49ae57ccac85
+@end ignore
projects / gnus / blobdiff