[Cialug] corrupt zip files

[Josh More]

Ken's points are good.  I'd just to like to add (in case you are making
your own), that zip files are composed of blocks.  If I recall
correctly, they're eight-bit blocks, and the last block is null
padded...

Why would this matter?  Well, as I found out, several open-source
encryption algorithms are also block-based with the final block being
null-padded.  If you code to strip off the null padding, the outer
option (unzip or decrypt) will succeed, but the inner will fail 7 out of
8 times due to an incomplete ending block.

If you're coding your own operation, there are numerous techniques that
I'd be happy to discuss off list.  If you're not, feel free to ignore my
techno-ramblings.

-Josh More

---- Original Message ----
Subj: Re: [Cialug] corrupt zip files
On 4/6/07, Dan Hockey <icepuck2k at mchsi.com> wrote:
> Has anyone been able to fix a corrupt zip file under (mandriva) linux?
> -dh