A first entity is provided having a first bit-pattern, resource data, a first base key, and a first variant key which is the result of applying a one way function to a second base key and the first bit-pattern. The first entity is configured to receive a request from a second entity to perform an operation on the resource data, where the second entity has a second bit-pattern and a second variant key which is the result of applying a one way function to the first base key and the second bit-pattern, perform the operation in the request to generate a response, digitally sign the response using the first base key to generate a digital signature, and send the response and the digital signature to the second entity so the second entity can verify the response using the second variant key.