Using other compression algos with GnuPG

Alphax alphasigmax at
Sat Jan 21 14:00:15 CET 2006

Roscoe wrote:
> On 1/21/06, Ryan Malayter <ryan at> wrote:
>>The RAR compression algorithm proprietary and closed source, so it is
>>not likely to make it into any standards. RARlabs has refused for
>>years to allow anyone else to make RAR encoders (although they exist
>>in violation of the RARlabs license).
>>A much better choice would be the LZMA algorithm from 7zip, which is
>>open-source and unpatented. It compresses with similar efficiency and
>>speed to RAR.
>>In any case, though, such slow-but-compact algorithms are really only
>>useful for archival purposes. While I have used PGP for some
>>archiving, this is not the most common usage of PGP, and probably not
>>an OpenPGP design goal.
>>There are much faster file encryption tools than PGP out there. We
>>actually use 7zip to compress and encrypt backups for offsite storage,
>>as its AES implementation is so much more efficient than GnuPG's.
> LZMA seems to be notably[1] faster/better than BZIP2, which has made
> it into the standard so I wouldn't immediately rule out its
> suitability for OpenPGP.

How well was LZMA known when BZIP2 made it in? Why was BZIP2 included
when ZIP and ZLIB were already available? Does this preclude LZMA? I
don't mind adding functionality so long as it is widely supported and
will "just work" :)

> That said I don't much think it should be included. It could *replace*
> BZIP2 but replacing BZIP2 with LZMA would break backwards
> compatibility a bit, and adding it resulting in  having both BZIP2 and
> LZMA seems a bit redundant when we've been getting along fine with
> just BZIP2.

Don't forget that ZIP and ZLIB are also there... I regularly use a
machine which has GPG 1.4.1 without BZIP2. Interestingingly enough bzip2
exists on the system...

> Back to on-topic-ness...
> I'd just use whatever compression scheme you want and pipe it into
> |gpg --compress-algo none.
> One tool one job :).

Yes, this has the added "advantage" that your recipient has to be able
to deal with whatever non-standard compression you choose. YMMV.

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