Challenge-response procedure
Procedure for authentication. The destination system outputs a randomly generated challenge. The user wishing to authenticate him/herself to the destination system answers with an appropriate response. This response is computed on the basis of the challenge by the software or what is called a token card. The procedure is far superior to using conventional passwords, since firstly each response is valid for only one access operation, and listening in will not help an attacker; and secondly, when a token card is employed the user needs both the card itself and a password for activating it.
