Patent ID: 8595501
Filing Date: 2013-11-26
Classification: H04L

Abstract:
1. A method operational on a networked helper to assist a verifier in authenticating a token device, comprising: receiving a plurality of encoded puzzles associated with a token identifier and a secret key from a token provisioner, each of the encoded puzzles, when solved, produces an associated puzzle secret and an associated puzzle identifier; storing the plurality of encoded puzzles; receiving a request from the verifier for puzzles associated with the token identifier during an initial authentication stage between the verifier and the token device in which a symmetric key is established between the verifier and the token device; selecting a subset of the stored plurality of encoded puzzles associated with the token identifier; and sending the selected subset of encoded puzzles to the verifier that allows the verifier to solve at least one of the encoded puzzles in the subset, to generate the symmetric key from the associated puzzle secret, and to provide the associated puzzle identifier to the token device, and that allows the token device to reproduce the at least one of the encoded puzzles and the associated puzzle secret corresponding to the token identifier from the associated puzzle identifier and the stored secret key, and to generate the symmetric key based on the associated puzzle secret.