Patent US 8,300,809

Disclosed herein are methods for obfuscating data via a modulus operation. A client device receives input data, stores an operation value, performs a modulus obfuscation on the operation value, performs a modulus operation on the operation value and the input data, performs a modulus transformation on the operation value and the input data to obtain client output data, and checks if the client output data matches corresponding server output data. A corresponding server device receives input data, performs a modulus transformation on the input data to obtain a result, performs a plain operation on the result and an operation value to obtain server output data, and checks if the server output data matches corresponding client output data from the client device. The client and/or server can optionally authenticate the client input data and the server input data if the server output data matches the client output data.