Let N be a positive integer. Let M be a n integer relatively prime to
N, and let d be an integer relatively prime to \phi(N), where \phi(N)
denotes Euler's \phi function.
Prove that if M*=M^d(mod N) then M=M*^d*(mod N), where d* is the
inverse of d (mod \phi(N)):
dd*=1(mod \phi(N)).

given that i am generating an 8 character hex block which will give
collisions every 2^46 times, and that i am using a chain of blocks to create
the internal state key, 1 block for each character in the passkey, so an 8
character passkey will produce 8 hex blocks of 8 characters long, a 64
character internal state key. does it stack? by that i mean if it's 2^46 for
one hex block, is it 2^92 for 2 blocks, 2^138 for three blocks etc.

I've been messing around with the code for an older PC game called
"Aliens versus Predator". I've managed to add a few things to the Linux
port and I'm working on a few others.

One irritating thing is that the files are stored encrypted on the
install CD, and the Windows install executable (that does the
decryption) doesn't easily work under Linux. You need to use VMWare or
a real Windows box to install the files. After that you can copy the
game data to Linux, but installation is a bit of a pain.

I've been looking into how hard it would be to break the encryption on
these files. (Note: I am *not* trying to violate copyright. I'm just
trying to make it possible to install these files from a valid CD under
Linux.) Since I have decrypted versions of these files from a Windows
install, it becomes basically a known-plaintext attack.

I've done some (very) simple checks - e.g. some simple XORs of the
encrypted and plaintext versions, by byte or short or integer. No
trivial solutions, but it's clear that it's not a complex algorithm -
comparing a plot of the plain file vs. the encrypted one, you can see
that different 'regions' of the files look different.

There's a new show starting tonight on Channel4 (UK) about
cryptography.

The show looks like it's going to be a history orientanted show with a
Cryptogram as the thread running through the show.

The initial Codex can be found at:

http://www.channel4.com/history/microsites/C/codex/pdf/codex_week1.pdf

or (if you can't be bothered with the symbols)

ab cdeefe abg fheihg'i eaj; fha'k fbakhla hk hdd, ieen hokopahd chdd.

Not very difficult to solve but may make for an interesting show. The
answer to the Codex this week is below.

There's a new show starting tonight on Channel4 (UK) about
cryptography.

The show looks like it's going to be a history orientanted show with a
Cryptogram as the thread running through the show.

The initial Codex can be found at:

http://www.channel4.com/history/microsites/C/codex/pdf/codex_week1.pdf

or (if you can't be bothered with the symbols)

ab cdeefe abg fheihg'i eaj; fha'k fbakhla hk hdd, ieen hokopahd chdd.

Not very difficult to solve but may make for an interesting show. The
answer to the Codex this week is below.

SPOILER BELOW

NO FLEECE NOR CAESAR'S END; CAN'T CONTAIN AT ALL, SEEK AUTUMNAL FALL.