Slashdot Mirror
PKWare and Winzip Reach A Secure Zip Compromise
richard_za writes "Until now the rival compression software vendors PKWare and Winzip have had different (incompatible) ways of password protecting the ZIP format. In a bid to prevent fragmentation of the standard they have agreed to have their software support opening of the other's files. They have however not agreed to support a single standard. PKZip's encryption is RSA-based while Winzip use an AES approach which is fully documented here.
The Register is running this story. PKWare has this press release."
Zip file management has virtually been absorbed into both Windows and Linux, and even if these two vendors agreed on a standard it would not mean much. PKzip became irrelevant when Infozip's portable zip tool became widely available, around 15 years ago. Further, all archiving tools today already deal with such a variety of formats that I can't see the crying need for a standard.
Ceci n'est pas une signature
There is still a problem with interoperability at the level of creating encrypted ZIP files. There is no longer a problem with interoperability at the level of reading encrypted ZIP files. The best way for this problem to go away would be for PKWARE to expand the SecureZIP standard to include RSA and AES encryption.
What about those people who use a version that isn't the latest and greatest?
2 standards only cause confusion. Remember the Word 95/97/2000 confusion?
"Call him back and tell him we need it saved as Word 95!"
Old zip-encryption used three internal 32-bit keys - which by today's standard is quite easy to break. You need 11 bytes (or was it 14?) of known cleartext though when searching.
The breaking of zip-encryption was considered to be quite a feat when it happened in the middle of the 90's, if memory serves me correctly.
it's in my head
I doubt that PKZip is based only on RSA. RSA is an asymmetric encryption. For some purposes this is nice, but it is inefficient. For that reason you almost always use asymmetric encryption together with a symmetric encryption. You generate a one time symmetric encryption key. The data is encrypted with the symmetric key, typically in CBC or CFB mode. Then only the symmetric encryption key is encrypted asymmetrically, which means much better speed.
Actually I think this is one of the cases, where there is no need for asymmetric encryption at all. So AES sounds like a better idea. Can anybody explain why PKZip use RSA? And which symmetric cipher is it combined with?
Do you care about the security of your wireless mouse?
Here's a brief history of Phil Katz
7zip is pretty cool - much better compression than ordinary zip. So I wonder if 7zip will support PKZip/WinZip encryption... From the looks of their fileformat page, they support AES encryption... :)
Oh yeah and 7zip is under the LGPL license
Any technology distinguishable from magic, is insufficiently advanced.
I have PGP to encrypt the zip files.. This software has recieved a lot attention and we know that it's probably okay!
The new standard these guys may agree will have recieved little public analysis when it is fielded.. Not something to trust at all!
Simon.
I couldn't care less about WinZip. WinRAR came in version 3.30 today, for the same price as WinZip and a lot more features. IMHO, it would be better than WinZip even if it didn't support RAR, simply from its arhiver support and features. :-)
:-)
:-P
That it happens to use the superior RAR format makes the decision easy for me. We're installing it at our company too, since it isn't even a hard to use archiver for geeks in any way. I know about for example bzip2 and 7-zip, but 7-zip still seems like a rather immature archiver, although it's interesting. The problem is the lack of a good feature set besides the core archiving part. And the official bzip2 package compiled for Windows doesn't come with a GUI so that makes it a bit less useful to me at least, especially when RAR has a comparable compression ratio. Sure, I can use a command line archiver, but I wouldn't like to.
The only downside I can see is that RAR is a closed source format, with only the decompressor being open.
Sometimes, I think it's better to not have two different companies trying to get control over a single format.
Beware: In C++, your friends can see your privates!
My passwords are usually >16 characters long, some are more than 30 (depends on the strength of the algorithm they're used in). While I agree that a lot of people use easy to guess passwords, the old zip encryption was most easily broken through the internal key - NOT by brute forcing the password. Do the math if you don't believe me ;)
A-Z,a-z,0-9 and a few special chars makes a 24 char password contain 128 bits of entropy. That's secure enough for everyone using symmetric ciphers.
it's in my head
As plugins to existing applications are so popular these days, I see this issue as an irrelevance.
/path -Bxvf -
Both sides are competing using incompatible creeping featurism. Last I looked, Zip applications where supposed to combine and squash files (and that was enough).
What should be done is to separate the operations:
- file browsing (WinRAR's interface trumps both)
- archiving (combining files)
- compression
- encryption
and implement the latter three as functions of the first using plugins (and let the user choose).
Incidentally, Zip's file format (directory last) sucks. It is practically impossible to do the following using zip:
tar Bcf - . | gzip -1c | rsh -n over_there gzip -dc | tar -C
To this end, plugins suggested above should be written as filters where possible.
I have no problem with browser-like interfaces combining other functions, but the Golden Rule still stands: One Tool, One Job.