Resource entity using resource request entity for verification

1. A first entity comprising 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 being configured to:

receive a request from a second entity to perform an operation on the resource data, the second entity having 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.

2. A first entity according to claim 1 , wherein the second variant key is stored in the second entity.

3. A first entity according to claim 1 , wherein the second base key is stored in a third entity.

4. A first entity according to claim 1 , wherein the one way function is a hash function.

5. A first entity according to claim 4 , wherein the one way function is SHA1.

6. A third entity configured for use with the first entity of claim 1 .