Patent ID: 8086865

Claim:
A system for authenticating messages, comprising: a source computing device having a shared key, security logic and a set of publicly known constants required to implement the security logic on messages transmitted by the source computing device; and a target computing device also having the shared key and the security logic, the target computing device further configured to receive the set of publicly known constants from the source computing device, wherein the source computing device transmits a message, a first message authentication code, and the set of publicly known constants, to the target computing device and the target computing device authenticates the transmitted message based on the first message authentication code and the set of publicly known constants received with the transmitted message and first message authentication code, wherein the set of publicly known constants comprises a plurality of publicly known constants used by the security logic to implement a security function on the transmitted message, and wherein the target computing device does not store the set of publicly known constants either before receipt of the transmitted message or after processing the transmitted message in response to receiving the transmitted message.