[RC5] My contribution to RC5

Ganesh Sittampalam ganesh.sittampalam at magd.ox.ac.uk
Sat Apr 4 11:35:17 EST 1998

>     It is not unreasonable to assume that a concerted "real" crack 
>     against a ciphertext has the following information about the 
>     plaintext:
>     1) What cipher was used to encrypt
>     2) What the keylength is
>     3) What headers were used to encode (wrapped) the plaintext
>     4) Who sent it
>     5) Who was to receive it
>     6) What (classification, not detail) the message contains
>     For most real communication, the important one of those is 3.  Since 
>     most headers have a well-defined format, non-compliant trial 
>     ciphertexts generated in brute-force decryption efforts indicate a 
>     failed attempt.  4 and 5 can also help you narrow down the legal 
>     character set for the plaintext.  6 gives keywords to search for in 
>     the trial plaintext.

If I wanted to send something secret, then as the final stage before encrypting
it, I would compress it into some format with no header information whatsoever.
How would you handle cracking that efficiently?

ganesh.sittampalam at magd.ox.ac.uk
Life is a terminal illness
PGP Key 0xFDE02725 Fingerprint 4CD6 D38E 0CB3 A9F8 2308 7637 7A3C 0565
To unsubscribe, send 'unsubscribe rc5' to majordomo at lists.distributed.net
rc5-digest subscribers replace rc5 with rc5-digest

More information about the rc5 mailing list