Re: decryption of string

From: anonymous (anon747@hotmail.com)
Date: 02/01/03 

From: anon747@hotmail.com (anonymous)
Date: 1 Feb 2003 07:19:52 -0800

"Mike" <sorry@sorry.com> wrote in message news:<b1elqd$7km$1@geraldo.cc.utexas.edu>...
> Forgive my lack of knowledge, I've only studied encryption/decryption
> algorithms for a few weeks in a networking class a few years back.
>
> I have an upcoming project in which a session cookie is set on a client by
> another server, and I am supposed to get information from that cookie on my
> server.
>
> The info appears to be encrypted (indeed it is as the team I spoke with
> mentioned that). And I'm supposed to decrypt it and get some useful info
> from it.
>
> They mentioned MD5, but I'm confused because MD5 does not seem to be
> involved in the decryption process. I will also have a public key.
>
> Just so I can prepare for our next meeting, does anyone have any possible
> suggestions for how I might go about decrypting the info in that cookie?
>
> Does an MD5 decryption algorithm even exist (i.e. even if you are not
> supposed to, can you)?
>
> Thanks alot!

I don't know a lot about encryption either but, according to AC2,
MD5 is a hash function.

It is a one way function.

My knowledge of cryptography is very bad, but probably you use the MD5
hash to error-check or authenticate the cookie.

The book Applied Cryptography(ISBN 0-471-11709-9) has something about
using these functions as encryption. But as you said that MD5 is
probably not used to decrypt. I need more info though.

see http://www.ciphersbyritter.com/GLOSSARY.HTM#Hash for more info
about hash functions.

I would probably say the public key you were given probably
permits something like PGP to decrypt the cookie. (Although it may
only be used
for encryption.)

Hope this helps.

Some of my info may be incorrect.

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