Re: Using other compression algos with GnuPG
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. 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. 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 :). [1] http://tukaani.org/lzma/benchmarks On 1/21/06, Ryan Malayter <[EMAIL PROTECTED]> wrote: > On 1/20/06, David Shaw <[EMAIL PROTECTED]> wrote: > > It's always possible for someone to add a nonstandard algorithm, but > > if you really want a particular algorithm, it's healthier to get the > > OpenPGP working group to add it officially. > > 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). > > See http://en.wikipedia.org/wiki/RAR > > 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. > > > -- >RPM > = > All problems can be solved by diplomacy, but violence and treachery > are equally effective, and more fun. > -Anonymous > > ___ > Gnupg-users mailing list > Gnupg-users@gnupg.org > http://lists.gnupg.org/mailman/listinfo/gnupg-users > ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: Using other compression algos with GnuPG
Roscoe wrote: > On 1/21/06, Ryan Malayter <[EMAIL PROTECTED]> 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). >> >>See http://en.wikipedia.org/wiki/RAR >> >>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. -- Alphax | /"\ Encrypted Email Preferred | \ / ASCII Ribbon Campaign OpenPGP key ID: 0xF874C613 |X Against HTML email & vCards http://tinyurl.com/cc9up| / \ signature.asc Description: OpenPGP digital signature ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: Using other compression algos with GnuPG
On Fri, Jan 20, 2006 at 04:49:11PM -0600, Ryan Malayter wrote: > On 1/20/06, David Shaw <[EMAIL PROTECTED]> wrote: > > It's always possible for someone to add a nonstandard algorithm, but > > if you really want a particular algorithm, it's healthier to get the > > OpenPGP working group to add it officially. > > 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). > > See http://en.wikipedia.org/wiki/RAR > > 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. In fact, BZIP2 was added pretty much for archival purposes: http://www.imc.org/ietf-openpgp/mail-archive/msg04624.html I wouldn't be against LZMA if it was significantly better than BZIP2. David ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: Using other compression algos with GnuPG
On Sat, Jan 21, 2006 at 11:30:15PM +1030, Alphax wrote: > > 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" :) I don't recall that LZMA was considered. BZIP2 was added pretty much for the reason you'd expect: better compression. It does not preclude LZMA. It doesn't preclude any new compression algorithm. Compression algorithms are different than ciphers and hashes, where it is prudent to carefully scrutinize each new algorithm. Compression algorithms don't really impact security, so the barrier for inclusion is significantly lower than for ciphers and hashes. David ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: Using other compression algos with GnuPG
David Shaw wrote: > In fact, BZIP2 was added pretty much for archival purposes: > http://www.imc.org/ietf-openpgp/mail-archive/msg04624.html > > I wouldn't be against LZMA if it was significantly better than BZIP2. My understanding of the reason behind compression in OpenPGP is that it was less to give you a smaller output file than it was to reduce obvious redundancy in the message so as to improve resistance to cryptanalysis. Is it cryptographically useful to have LZMA over zlib or bzip2? Wouldn't a better approach be to add detection of compressed data to GnuPG? This way it can turn off compression if it sees precompressed data. If you are looking for better compression, you can then pipe your data through your compressor-du-jour first, and then run it through GnuPG. signature.asc Description: OpenPGP digital signature ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: Using other compression algos with GnuPG
On Sat, Jan 21, 2006 at 09:22:36AM -0700, Kurt Fitzner wrote: > David Shaw wrote: > > > In fact, BZIP2 was added pretty much for archival purposes: > > http://www.imc.org/ietf-openpgp/mail-archive/msg04624.html > > > > I wouldn't be against LZMA if it was significantly better than BZIP2. > > My understanding of the reason behind compression in OpenPGP is that it > was less to give you a smaller output file than it was to reduce obvious > redundancy in the message so as to improve resistance to cryptanalysis. No. The removing obvious redundancy is a nice side benefit, but compression is not intended to be secure in any way. If the cipher isn't enough to make you safe without compression, you're not going to be really safe no matter what you do with compression. > Is it cryptographically useful to have LZMA over zlib or bzip2? No. But similarly, it is not really cryptographically useful to have bzip2 over zlib. Or zlib over zip. > Wouldn't a better approach be to add detection of compressed data to > GnuPG? This way it can turn off compression if it sees precompressed > data. If you are looking for better compression, you can then pipe your > data through your compressor-du-jour first, and then run it through GnuPG. GnuPG in fact does this. David ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
