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Re: splited file encrypted with blowfish secure?
From: Ansgar Wiechers <bugtraq () planetcobalt net>
Date: Tue, 4 Nov 2008 19:40:42 +0100

On 2008-11-04 Andre Pawlowski wrote:
I have a question about the security of my encryption. I have written
a program in php which splits a file in small parts, encrypts each of
them with blowfish and put it together. It uses the same key for every
encryption of the parts. The reason I do it like this is that php is
only allowed to use 16MB of memory space and so it cannot encrypt or
decrypt large files.

Here is my question. Is it less secure when I encrypt a file not as
one big file? I mean, is it easier for someone to get the key or plain
data of a file if he has 100 parts encrypted with the same key in
comparison with only having one big file?

Yes.

http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Electronic_codebook_.28ECB.29

Regards
Ansgar Wiechers
-- 
"All vulnerabilities deserve a public fear period prior to patches
becoming available."
--Jason Coombs on Bugtraq


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