Patent ID: 8307209

Claim:
A method for two-way authentication using a challenge and response system where a requester apparatus initiates a request for authentication to an authenticator apparatus, the method comprising the steps of: the authenticator apparatus passing its unique identifier and a randomly generated character string to the requester apparatus; the requester apparatus using the identifier to retrieve an encryption key for the authenticator apparatus and encrypting the passed in randomly generated character string; passing the encrypted character string, a unique identifier of the requester apparatus, and a new randomly generated character string back to the authenticator apparatus; the authenticator apparatus retrieving an encryption key corresponding to the received identifier and decrypting the passed back encrypted character string; determining that authentication fails and terminating communication when the decrypted character string does not match the random character string sent in the initial request; encrypting the random character string from the requester apparatus; passing the encrypted character string back to the requester apparatus with the unique identifier of the authenticator apparatus; the requester apparatus using the identifier to retrieve the encryption key for the authenticator apparatus and decrypting the encrypted character string; determining that both parties are authenticated when the decrypted character string matches the random character string sent in the initial request; and replacing encryption keys by: the authenticator apparatus creating a second one-time encryption key, encrypting the second one-time encryption key using a third one-time encryption key, and transmitting the encrypted second one-time encryption key to the requester apparatus; the requester apparatus decrypting the encrypted second one-time encryption key with the third one-time encryption key; and the requester apparatus and authenticator apparatus each replacing the first one-time encryption key with the second one-time encryption key.