[Metalab] Cryptography Challenge

[Hans-Joerg Schurr]

> why don't you post the algorithm? (I hope your crypto system
> consists of an algorithm with independent keys.) Then the strength
> of the crypto system can be assessed. There is a consensus, that
> any crypto system can be broken, only the effort to do so can
> be "high" or "low" (except one-time-pads with perfect random).
This more sounds like a riddle then a serious effort to develop a
cryptosystem. Therefore posting an algorithm may already spoil the fun.

Nevertheless I am not very fond of riddles. 
> 
> For example this encrypted message:
> 
> -----BEGIN PGP MESSAGE-----
> 
> jA0EAwMCmnvGm93055yzyTwS0W6kUqAlm5qZs8Ls9hTEKj9a3oWsNzQO2gn96xAS
> OoFrz0XQRb9TqkoBvDeHpaDF22M9M3S5NS4xnPI=
> =4tKK
> -----END PGP MESSAGE-----
> 
> is CAST5 encrypted with a passphrase (in this case "Passphrase")
> and I can have confidence that the message can only be decrypted
> with an effort that can be assessed quite good: The effort is
> based on the length and entropy of my chosen passphrase and
> the effort to attack CAST5 (which is well examined and discussed).
> 
> Self written "crypto systems" often can be reversed with a
> middle-school level of mathematics.
> Here is an example from Thawte:
> https://www.cryptochallenge.com/home/archive/Alpha
> 
> About your crypto system:
> Can you provide more samples?
> 
> A few things hits the unaided eye immediately:
> - "*" at begin and end
> - "a" is the only lower case letter, rest uppercase
> - "/" is only used once
> 
> Regards,
> 
> MiKa
> 
> On 13/08/13/ 06:40, Benjamin Schwarz wrote:
> > Hello Metalab,
> > 
> > 
> > my father just posted the following on Facebook:
> > 
> >     This is a question. The code was invented by me and a friend
> > back in the 80s:
> > 
> >     *aCBLFDZHDFLMIY/PKJJTIFBPCZASGNYIGIWWTNJKXZAOKMTTUGQSGXENU*
> > 
> >     If someone should be able to read this, send me the correct
> > answer. I can't imagine this code is breakable...
> > 
> > 
> > The result should be a German text, although he said he doesn't
> > think this information would be helpful.
> > Who wants to try and break it?
> > 
> > 
> > Have fun!
> > Ben
> > 
> > 
> > _______________________________________________
> > Metalab mailing list
> > Metalab at lists.metalab.at
> > https://lists.metalab.at/mailman/listinfo/metalab
> > 
> 
> 
> _______________________________________________
> Metalab mailing list
> Metalab at lists.metalab.at
> https://lists.metalab.at/mailman/listinfo/metalab