Patent ID: 8646104

Claim:
A computer-implemented method comprising: broadcasting a request to a server group from a client of a client group using a stateless challenge-response protocol, wherein the stateless challenge-response protocol accumulates state information relating to interaction between the client and the server group; receiving a tamper-evident challenge from any one server of the server group at any one client of the client group, wherein the tamper-evident challenge comprises the request and an encrypted nonce that can be solved by an entity holding a secret key, and wherein the entire tamper-evident challenge is embedded in a tamper-resistant structure using a second secret key known to any one of the server group to allow the any one of the server group to detect any attempt by the client to circumvent the tamper-evident challenge; verifying the tamper-evident challenge to ensure that the request received in the tamper-evident challenge correctly describes the request to the server group; decrypting the encrypted nonce of the tamper-evident challenge to obtain a solution; broadcasting a response with a solution to the tamper-evident challenge to any one server of the server group, the response including the request; and receiving a result to the request upon any one server of the server group verifying the response being valid and the request being unmodified.