Patent ID: 8793780

Claim:
A method implemented at an authenticating device, the method comprising: storing, prior to receiving any authorization requests, a plurality of group shared secrets in memory accessible to the authenticating device, the plurality of group shared secrets comprising at least a first group shared secret and a second group shared secret, the first group shared secret being also stored in memory of each of a first plurality of requesting devices prior to transmission of any authorization request by any of the first plurality of requesting devices to the authenticating device; the second group shared secret being also stored in memory of each of a second plurality of requesting devices prior to transmission of any authorization request by any of the second plurality of requesting devices to the authenticating device, the first plurality of requesting devices and the second plurality of requesting devices each comprising different subsets of a set of requesting devices while also including at least one common requesting device from the set of requesting devices; receiving a pre-authentication request comprising at least a reference for the first group shared secret of the plurality of group shared secrets, the pre-authentication request being transmitted from a first requesting device of the first plurality of requesting devices; verifying, at the authenticating device, the received pre-authentication request using said first group shared secret; receiving an authentication request comprising proof of knowledge of a secret shared exclusively between the authenticating device and the first requesting device; and when the authentication request is determined to have been transmitted from said first requesting device, authenticating the first requesting device in response to the authentication request.