Greg

Once you start using DotNetZip you'll never want to go back to SharpZip. We 
changed our code base over about a year ago and the API is so much cleaner and 
nicer its unreal. Often we were replacing 20 - 30 lines of code with 3-5. The 
learning curve is very low as it is just so intuitive to use (and we are doing 
more than just vanilla zipping). It's clear to me that the API was designed 
from the caller's perspective and then the code was written to implement the 
API. For SharpZip it felt the other way around. I can't recommend DotNetZip 
highly enough.

Ben

________________________________
From: [email protected] [mailto:[email protected]] On 
Behalf Of Greg Keogh
Sent: Thursday, 30 June 2011 2:35 PM
To: 'ozDotNet'
Subject: PKZIPC encryption, keys and reliability

Folks, for several weeks now I have been stuffing backups into cloud storage. 
Simply because it's convenient in batch files, I have been using PKZIPC V6 with 
switch like these -cryptalg=AES,256 -pass=MyL0ngSafePassw0rd to prepare the 
files for backup. I mentioned this to my cat and he asked me some interesting 
overlapping questions:


1.       Can you restore your backups in managed code?

2.       Can you create backups in managed code that are PKZIPC V6 compatible.

3.       How is the AES 256-bit key generated from the PKZIPC V6 password 
string?

4.       Is the PKZIPC V6 encryption compatible with other convenient utilities?

Worryingly, the answer to most of these is "dunno", but I'm looking for 
answers. In any case, I must be sure that my cloud backups are secure and 
usable in the long term. Imagine having backups you can't read or decrypt 
sometime in the future.

I'm going to run a few tests to see if I can create or read PKZIPC V6 
compatible files in managed code.  I've been using SharpZip for many years, but 
it only supports the original weak encryption. I'll probably have to use 
DotNetZip<http://dotnetzip.codeplex.com/> in my tests, but it's a new library 
for me and I'll have to get the hang of it.

Then question 3 comes into play. Yoiiks!

Greg

P.S. There are no real questions in this post, just some mental notes and 
warnings to others doing this sort of thing.


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