Patent ID: 8677134

Claim:
A method for signing data transferred over a network, comprising: receiving a request for a first resource; generating a first header field of a set of header fields, the first header field associated with a content identifier for the first resource; generating a second header field of the set of header fields, the second header field associated with a content expiration time for the first resource; determining a plurality of header fields corresponding with a message digest, the plurality of header fields includes at least one of the first header field or the second header field; generating the message digest, the generating the message digest includes hashing the plurality of header fields and at least a portion of the first resource; generating a supplemental header, the supplemental header specifies the plurality of header fields used to generate the message digest; generating a digital signature based on the message digest; embedding the set of header fields, the supplemental header, and the digital signature into a response header; and transmitting a response message, the response message includes the response header and the at least a portion of the first resource, wherein the plurality of header fields is a subset of the set of header fields; the response header is an HTTP response header; the first resource comprises a file; the supplemental header comprises a non-standard HTTP header; and the response header includes a cache expiration field, the cache expiration field specifies a time at which cached copies of the at least a portion of the first resource must be refreshed, the content expiration time is at a time prior to the cache expiration time.