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PKWare Zips to Growth
Rob Kennedy writes "The Milwaukee Journal Sentinel has a story about PKWare's new business plan. It talks about the investment group that bought the company after founder Phil Katz's death in 2000, and the plan for PKWare to produce what president and COO Timothy H. Kennedy (no relation) calls 'the next generation of zip' by adding various security features."
PGP compresses files during the encryption process.
cs94_002.tar.bz2 (Source) 10.7Meg,
cs94_002.tar.gz (Source) 12.6Meg,
cs94_002.zip (Source) 16.7Meg
As a side note, winrar will extract bzip2 but not create it.
Religion is a gateway psychosis. -- Dave Foley
By the guy who did ARJ, JAR implimeneted GOST as it's encryption.
It's Christmas everyday with BitTorrent.
With MS Office, try setting a password on your document. It gets compressed before being encrypted, so this is the easiest way to save disk space provided you can remember the password. At least, this was the case with the last versions of Word I used.
-- Ed Avis ed@membled.com
Hah. He took the established ARC format, which had copyrighted free-as-in-beer public domain routines in C, and rewrote them in x86 asm for speed... and then sold PKARC (Phil Katz ARC) as a commercial product. The original inventors of ARC sued him and won - he even kept the same misspellings in the strings, for fuck's sake. He settled for a lump sum in court, then ended up making a couple of changes to the ARC format and renamed it PKZip.
That, and if you actually look at the ZIP format, you'll notice that it's all routines invented by other people. "Shrink" is dynamic LZW, "Reduce" is RLE with a second-pass probabalistic encoder, and "Implode" is a sliding dictionary with post-compression using Huffman/SF-tree encoding.
Katz was an excellent promotor and had good networking skills. I admire him for that much, and for establishing a defacto format that scaled nicely to 64-bit sizes and arbitrary-length Unicode filenames. HOWEVER, he was hardly a pioneer in compression algorithm design. Give him credit where credit is due.
You must mean Hildegard Katz, Phil's mom, who was the VP of PKWare.
There used to be a photo on the wall of PKWare's boardroom that said volumes... It showed a beautifully done show-booth at some convention, with Phil buried in a laptop on a small podium completely ignoring all the convention-goers milling around him.
If anyone promoted and networked for PKWare, it probably wasn't Phil.
Well the other reason for doing encryption after compression, is to mitigate dictionary attacks. So the cost of breaking in by brute force includes both decryption as well as decompressing.
the future of winzip is basically death since zip compression in browsing s built into xp
/var/db/pkg/pkzip-2.5
pkzip is still a command line utility elsewhere
drwxr-xr-x 2 root wheel 512 Oct 11 09:06
There are places where the networks are not touching,and there are places where they are-Boeing's Lori Gunter
That's what Windows XP does, and indeed what several Windows shell extensions have done before.
The first new feature they introduce will create an incompatability with InfoZIP & other clones. I'm sure the users of such products will complain loudly.
The 7z format used by 7-Zip is an open architecture. There are several available compression methods and bzip2 is one of them.
Programs that encrypt computer files tend to make the files much larger, gobbling up valuable room on a hard drive or ...
This is bullshit. I do not know of even a single cipher which makes the files larger. Indeed all ciphers commonly used today for file-archiving are block-ciphers which transform a fixed-size (typically 64 bit) cleartext-block into an identically sized ciphertext-block. Examples of such ciphers include DES, IDEA, Blowfish, 3-DES, AES, Twofish and many others.
Combining encryption with data compression is a natural, said Stephen Crawford, vice president of marketing.
The vice-president of marketing is not typically a good person to ask about technical issues. In this case he is correct though, it is a good idea to compress files prior to encryption, this both saves place, aswell as making certain attacks a little bit harder due to more entrophy in the compressed plaintext than in the plaintext itself.
Unfortunately for him this idea is so obvious that it's been implemented in typical encryption-programs for ages. Both PGP and GPG for example by default compress the plaintext priorto encrypting it. This is hardly novel.
Therefore the Unix model of tar and then a separate compression program makes more sense - even though tar is such a crusty and wasteful format.
:)
Joerg Schilling, the author of the famous cdrecord, probably disagrees with you. tar has everything you need, and a lot more. The problem is that all the different tar implementations suck. GNU tar, for example, is _not_ POSIX-compliant. 'file' recognizes this and will tell you what kind of archive it is. gnutar also doesn't support very large files.
Joerg Schilling has written an excellent tar program by the name of star. To overcome the limitations of the "other" tar formats, he has produced his own, without any limitations. Features of star that completely blow away anything else:
- fully ANSI/Posix 1003.1 compatible
- ACL support
- automatically detects several common archive formats and adopts to them. Supported archive types are: Old tar, gnu tar, ansi tar, star, POSIX.1-2001 PAX, Sun's Solaris tar (GNU tar supports only one foramt--its own)
- stores/restores all 3 times of a file (even creation time)
- pattern matcher
As you can see, the "tar" format no longer sucks.
Schilling has written a very good comparison between star and gnutar, entitled STARvsGNUTAR. I highly recommend reading it. Another cool document is a listing of bugs in every other implementation of tar.
You can grab LSB-compliant RPMs of this at my RPM page.
7 Zip is good but you might also check out JZip. JZip looks more like Winzip which is what most users are used to.
Or try FreeExtractor which creates self extracting exe's. I have a whole collection of Open Source Software for Windows.
Georgia summer camps
'tar xvf' is fine; 'tar zxvf' is not because it has to read the whole archive sequentially and decompress it. (At least I think it does; in principle it could do a little better because gzip compression works in 32Kbyte blocks AFAIK.)
-- Ed Avis ed@membled.com
The bloat already happened.
In August of 2000, I bought PKZip Explorer from PKWare. Figured for the $10 special promotion, what the hell, and it would be nice to have PKZIP that could handle Windows long file names. Also assumed it would have the same feature set as PKZIP for DOS, and their promo literature certainly *sounded* like it would.
Well, it was one of the poorest $10 purchases I ever made. The installer (a two-step, partially online-only process due to paranoia about piracy) is about 6mb, and the installed program is apparently scattered thruout Windows. So I was already annoyed by the time it was finally installed and running.
On to making my first ZIP with it. Turns out the ONLY thing it can do is grab the specified files and create a new ZIP, or unzip a specified ZIP. That's ALL it can do. It's absolutely devoid of ALL the switches and options that made PKZIP for DOS so useful. The only good thing I can say about it, is that it's fast.
Now, maybe it's improved some since then, but if it didn't even have its own ancestral feature set in 2000, yet was already 3x the size of competing products like WinZIP and WinRAR, I have scant hope for later incarnations.
And thanks to this experience, chances are I'll never buy another product from PKWare.
~REZ~ #43301. Who'd fake being me anyway?
- Encryption doesn't make files bigger at all. (Maybe a couple of extra bytes of header depending on the wrapping format, but not the data).
- (working) encryption kills compression stone dead (compression loooks for patterns in the data - encryption hides all patterns), thats all.
- Compress-before-encrypt is obvious and well known. PGP did it way back. GPG does it. TLS/SSL now does it. ssh has it built in. IPSec has it as an option now.
If RSA is involved, maybe they're just using the PK name to legitamise a new version of RSA Mailsafe - a lame PGP clone from DOS days (that wasn't compatible with PGP). RSA never did make much from PGP, but it's still popular and used, unlike s/mime and the public PKI, which is going nowhere.