(THIS INFORMATION COMES FROM http://www.spywarewarrior.com)
The "official" Win32 builds of GnuPG do not include support for the IDEA algorithm, which is patented.* This can prove to be a problem when exchanging messages and files with PGP users (esp. PGP 2.6.x users) or importing old PGP keys. This web page explains how to install the IDEA module for GnuPG so that GnuPG can use the IDEA algorithm.
The IDEA module has been distributed as both a source code file (IDEA.C) and a compiled .DLL (IDEA.DLL). Unless you plan to compile the source code yourself, you want the IDEA.DLL, which is placed somewhere in the GnuPG installation directory and loaded with the load-extension option.
Please note that the IDEA module, its location within the GnuPG installation directory, and the method for loading that module with the load-extension option have changed over successive versions of GnuPG:
Please consult the appropriate directions for your version of GnuPG. All of the versions of the IDEA module discussed on this page are available for download from this site -- see the
Downloadssection below.
* The IDEA is patented in many countries, including the U.S., and may be used for non-commercial
purposes. For commercial uses you'll need to buy a license from MediaCrypt. For the "official"
explanation of why the IDEA algorithm is not supported in GnuPG by default see HERE.
GnuPG 1.2.0 and later
There were big changes in
GnuPG 1.2.0 with respect to the IDEA module. There's a new
IDEA.DLL as well as a change from previous versions in the way the
IDEA.DLL is loaded.
From the
GnuPG 1.2.0 Announcement:
* All modules are now linked statically; the --load-extension
option is in general not useful anymore. The only exception is
to specify the deprecated IDEA cipher plugin.
* The IDEA plugin has changed. Previous versions of the IDEA
plugin will no longer work with GnuPG. However, the current
version of the plugin will work with earlier GnuPG versions.
Files
For "official" versions of GnuPG (from
gnupg.org), a new set of IDEA files is available from
ftp.gnupg.dk (
idea.c.gz &
ideadll.zip):
File | Size (kb) | Notes |
idea.c | 13815/13727 | new source (gnupg.org) |
idea.dll | 8192 | new Win32 DLL (gnupg.org) |
File | Size (kb) | Notes |
idea.dll | 45056 | Disastry's IDEA module |
See the
Downloads section below for links to these files.
To Install
1. Place the IDEA.DLL in \LIB sub-dir of the GnuPG installation dir.
2. Add the following line to the GPG.CONF file (in previous GnuPG
versions it was in the OPTIONS file):
- load-extension Lib\idea
You can also specify a full path to the IDEA.DLL file:
- load-extension C:\GnuPG\Lib\idea.dll
This
GPG.CONF file option line works for both the
"official" and
Nullify GnuPG builds.