If you're using these patches without understanding the license, you should browse to MediaCrypt's FAQ on licensing issues. MediaCrypt is the Swiss company that holds the patent on the IDEA symmetric cipher.
These patches are based on this source code. Click here for more on GPG and IDEA.
These patches are provided under the GPL and there is no warranty provided or indemnification against any problems that could arise from their use.
Why should you download these patches and use IDEA? Well you probably shouldn't because you probably don't need it. However, if you're dealing with PGP 2.x users that refuse to upgrade you might want to expend the effort.
I keep these patches up-to-date where up-to-date is defined as "will apply to current source code". This means that it might not have the same version as what you download, but the patch hunks will be fuzzily applied. You can prod me to make a new patch if a new version has been released and you're really worried about it or a hunk gets rejected. If a hunk gets rejected I will most likely fix it. If you're just worried about the fact that a new version has been released, I might fix it. I don't maintain patches for versions of GPG that have been ported to some version of *BSD or Linux. I also don't maintain patches for development versions of GPG. I maintain patches for releases only.
After untarring the source and changing directory into the untarred source distribution directory and before compiling, you apply the patch using this command:
bzip2 -dc gnupg-<VERSION>_idea_static_patch.bz2 | patch -p1
If you didn't understand these last two paragraphs you shouldn't be trying this.
| patch | sha1 checksum |
| gnupg-1.4.1_idea_static_patch.bz2 | cf6baa701200a6b67d7b1244518e3fda40cb870c |
| Use the 1.2.5 patch for GPG 1.2.6 | not applicable |
| gnupg-1.2.5_idea_static_patch.bz2 | f5d211f101d4538cba5e6f7e8793ab3111746fc4 |
| gnupg-1.2.4_idea_static_patch.bz2 | 228aeadd5709d19d72b71a8f16c8ec6aff5f9bac |
| gnupg-1.2.3_idea_static_patch.bz2 | e2ef8424ef1b299c932c4c721a419fc07a63818b |
| gnupg-1.2.1_idea_static_patch.bz2 | 2d796a6aeb8b21887e57db7851e8d0216155ac9b |
The GnuPG maintainers have simplified inclusion of IDEA in GnuPG. You can apply the 1.4.1 patch, or de-compress and un-archive the following after extracting the GnuPG source from the top-level source directory. idea.c and idea.h will be placed into the cipher sub-directory. When you run configure, it should find everything it needs to build IDEA into GnuPG. I will no longer be maintaining patches for GnuPG, unless they change the software so they are necessary again.
| archive | sha1 checksum |
| idea_algorithm.tar.bz2 | 07f277e1c087f637d9c2cb92332e1463b6015bf9 |
last updated 23 May, 2005.