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- Jyothirmai

November 9, 2005, 2:11 pm

I have read in schneier's "Applied Cryptography" about OWA and an

applicatiion of it is given by taking the example of Cabal Inc. where

each member calculates the hash of the all other persons and gives it to

other person whom he/she is meeting along with his/her own name. The

other person calculates the hash of both and confirms the name given.

The following function is given:

A(Xi, y) = (X(i-1))^y mod n

n = product of primes

X0 must be agreed upon in advance.

The accumulation of y1, y2, y3 ... would be

((X0^y1 mod n)^y2 mod n)^y3 mod n

Here are some of my questions. Kindly provide the answers if you know:

1. Is the security coming from the fact that it is not easy to find a

product of two numbers (a & b) such that (ab mod n) gives the hash?

2. If Alice meets Bob and each of them exchange their hashes then the

secret which provides the authentication is revealed to the other party

which can be used by him/her to impersonate. How is this addressed?

3. Are there any industrial strength OWA algorithms? If so can you point

me the links?

4. Is it appropriate to quote the portions of the text in the news

groups? The above example has the origin from a paper submitted in

EUROCRYPT'93.

Thanks

J

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