Network Security Enforcement System

1 . A network enforcement security system comprising:

a central location adapted to send a challenge;

at least one client station, each of said at least one client station being provided with an agent and being in communication with said central location;

a set of S independent one-time passwords, each of said one-time passwords being associated with an index value;

whereby, in response to a challenge sent by the central location to at least one of said at least one client station, said agent returns a one-time password to said central location corresponding to the correct response otherwise said central location considers said client station insecure.

2 . A system according to claim 1 , wherein said client station is an RFID tag, and said set of S independent one-time passwords includes a subset S′ of independent one-time passwords, each of the one-time passwords of the subset S′ being associated with an index i, said subset S′ being securely stored in said RFID tag, said challenge that is sent by the central location is a random index i and said one-time password that is returned to said central location is the one-time password corresponding to said index i.

3 . A system according to claim 1 , wherein said client station is adapted to calculate a one-time password based on an initial secret and on iterations of a cryptographic function f of the initial secret.

4 . A system according to claim 2 , wherein communication between said central controller and said client station is encrypted.

5 . A system according to claim 3 , wherein communication between said central controller and said client station is encrypted.

6 . A system according to claim 1 , wherein said agents are adapted to perform a predetermined list of commands, said list of commands being stored in said central location, whereby when said agent executes a command that is not on the list of commands, said central locations determines that the client station on which is stored the agent is compromised.

7 . A system according to claim 1 , wherein communication between said central location and said client station is compressed prior to being sent.

8 . A system according to claim 1 , wherein said central location is provided with a signature list of all of the active client stations, and wherein said central location polls said client stations to build an inventory.

9 . A system according to claim 1 , wherein said client station is an RFID tag, a casino chip, a computer, a hand-held device, a portable digital assistant, or a combination thereof.

10 . A method for securely communicating between a central location and at least one client station, comprising the steps of:

(a) generating an initial secret and storing the same in the central location;

(b) generating a set of one-time passwords, each of the one-time passwords being associated with an index;

(c) storing a subset of the set of one time passwords in the client station;

(d) sending a challenge to the client station from the central location, wherein said challenge is an index of said subset of the set of one-time passwords;

(e) sending from the client station to the central location the one-time password associated with the index.

11 . A method for securely communicating between a central location and at least one client station, comprising the steps of:

(a) generating an initial secret and storing the same in the central location and the at least one client station;

(b) sending a challenge from said central location to said at least one client station, said challenge being an index;

(c) generating a one-time password at said client station, said one-time password being an iteration of a cryptographic function on the initial secret, said iteration being related to said index;

(d) sending the one-time password to the central location.

12 . A method according to claim 11 , wherein said at least one client station is an RFID tag, said RFID tag further provided with a unique serial number, wherein said unique serial number is used to generate the initial secret.