CDR: "ChronoCryption" algorithm - $50 reward for spotting a flaw

[Ray Dillinger]

On Sun, 3 Sep 2000, Marcello 'R.D.O.' Magnifico wrote:

>3. I expected a lot of tech issues and found instead a bunch of:
>	-discussions on racism, religion, gov't behavior worldwide
>	-"we hate pigs"
>	-US local laws discussions (see 1)
>	-simple fluff and/or flaming.

I'm with him, actually, about list content.  I had hoped to find 
tech discussions going on.  

In the interest of making  some news if you don't like the news 
you're getting, I present -- the Country Mile Cipher.  Algorithm 
details available (for now) on 

	http://www.sonic.net/~bear/crypto/countrymile.html

This is a stream cipher based on the Blum-Blum-Shub pseuodo-
random number generator -- and on work done more recently by 
Ronald Rivest, who "digitally sealed" a message that he expects 
to take 30 years of continuous computing to unscramble. 

The Country Mile Cipher has one interesting property; You can 
choose when you encrypt a message how much computing power it 
will require to decrypt it.

This interesting property has two useful applications:  First, 
you can make it that much more difficult to "brute-force" a 
key, so even if you are restricted in key length, you can still 
achieve reasonable security. 

Second, you can use it to "digitally seal" messages to people 
that will not unseal without a specified amount of computing 
time.  I can foresee protocols where someone not having information 
for a specified length of time after it's delivered would be useful 
- It could be treated as a "bit commitment scheme" where the person 
making the commitment does not need to do anything else. 

Anyway - there's very little here that's my own invention.  The 
Blum-Blum-Shub Random Number Generator is well-tested, and the 
mathematics for predicting its state into the future are explained 
in Schnier's book.  I haven't really done anything except put some 
well-known and well-tested pieces together, so I'm pretty confident
of the security of the Country Mile Cipher. 

So confident, in fact, that if anyone can come up with a viable 
attack on it, I will cheerfully pay the *first* person to do so 
fifty US dollars.  :-)

			Ray Dillinger