Re: Unique number generation

From: Unruh (unruh-spam_at_physics.ubc.ca)
Date: 04/29/05 

Date: 29 Apr 2005 14:10:27 GMT

paul@atom.sbrk.co.uk writes:

>I'd like to be able to generate some secure unique numbers. A simple
>implementation might be val = encrypt(secret, seq_no), however that
>doesn't ensure that the numbers will be unique. Ok, I could remove

Yes, it does. If secret is the same for all numbers then val is unique if
seq_no is. Encryption is a one-one and onto map.

>duplicates afterwards, but it would be nice if there were an algorithm
>that ensures that f(secret, n) != f(secret, m) for any n!=m. Ok, some
>form of x|(encrypt(secret,x) ensures that but I don't want to reveal
>the sequence number either. Any ideas?

encrypt(secret,x) ensures that. Otherwise how could you decrypt?

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