1 | Each individual A and B picks a random number rA and rB which are only known to themselves and a fresh for session to be authenticated. There is shared key KAB which is not to be transmitted but A needs to know that B knows KAB and B needs to know that A knows KAB. The random numbers are known as challenges. |
2 | rA |
3 | Decrypt xA and see it gives rA |
4 | Encrypt rA to give xA |
5 | xA |
6 | rB |
7 | Encrypt rB to give xB |
8 | xB |
9 | Decrypt xB and see it gives rB |