[Metalab] Cryptography Challenge

[Michael Kafka]

Hi Ben,

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).

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
>