Session Keys |
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- Diffie-Hellman exponential key exchange allows a secret key to be generated by public exchange of information between two people
- A and B exchange two integers n, m with 1 < n < m, m large
- Each decides on a secret number a and b
- A transmits the number n^a (mod m)
- B transmits the number n^b (mod m)
- Each can then calculate (n^a)^b = (n^b)^a = n^(a*b) (mod m)
- This is the private key, for use in, say, DES
- It is hard to calculate this from the public information
- This does not authenticate the other user

Slide 57 | ©Copyright 1997 | Jan Newmarch |