🚀 go-pugleaf

In article <1993Jan12.095445.1@vax.sonoma.edu> gallaghe@vax.sonoma.edu (mycal) writes:
>OK now that we have seen the crypted and uncrypted text, naybe someone should
>post the encryption routine and how it was decrypted.  it might shed some
>light for us lesser skilled.

The thing's actually so easy that the only reason to talk about the
decryption is for the opportunity to repeat Frank L.  Lewis' dictum on
approaching an unknown cipher. <Look> at the thing, with your eyes rather
than programs, and see what's strange about it.  Ask yourself what could
cause that strangeness.

So uudecode the stuff and do an 'od' on it and see what you get:

0000000  f5ac 9c8a 8c9e d3df 9b9a 899a df8d 969c
0000020  9796 9a9b 9a8d 9adf 9693 df9c 9a8d 8b96
...
0000700  df9d 8a8d 909c 8d9e 8596 9ede dfbe 8d8d
0000720  9689 9a9b 9a8d 9c96 d1df f5f5 f5f5

The first thing that jumps out at you is that the high bit is on
everywhere.  Clearly this is going to be a very silly cipher.  For our
first trick, let's assume he's added some number to everything: a Caesar
cipher.  Try a quicky C program that subtracts all possible offsets from
the ciphertext.  No luck.  Try again using XOR instead of subtraction.
Aha -- at offset FF (hex) the whole thing falls out.  For the version I
posted, I stripped the high bit first, and didn't bother to get some of
the special characters, figuring that it was busted to the point of
clearly not being interesting.  The "real" decrypt is:

    Scusa, deve richiedere il certificato inscrizione al'univerita

    Perche` cose le serve il certificato

    Per rinviare di un anno, il servizio militare

    Deve presentare il domano scritta su un foglio di carta bollata

    He askes "When can I pick it up?"

    Alla fine del mese

    Ma scusa, perche` cose tardi? Non capisco proprio.

    In questo periodo, abbiamo molto lavoro da svolgere e` molte pratiche di
    finire

    Capisco. Non c`e niente da fare. E` la solita burocrazia! Arrivederci.

So the short answer is: flip all the bits in the plaintext and you get
the ciphertext.  And anybody who even looks at it sideways will get it
instantly.

-- 
	Jim Gillogly
	Sterday, 21 Afteryule S.R. 1993, 18:39