Patent ID: 8885818

Claim:
A method for encoding a data stream comprising a plurality of data frames, the method comprising: generating a cryptographic value of a number N of successive data frames and configuration information using a cryptographic hash function; wherein N is greater than one; wherein the configuration information comprises information for rendering the data stream; inserting the cryptographic value into a frame of the data stream subsequent to the N successive data frames; and iteratively generating an intermediate cryptographic value of each of the N successive frames using a starting state for the cryptographic hash function; wherein the starting state for the cryptographic hash function for generating the intermediate cryptographic value of a frame of the N successive frames is the intermediate cryptographic value of a previous frame of the N successive frames; wherein the starting state for the cryptographic hash function for generating the intermediate cryptographic value of the first frame of the N successive frames is an intermediate cryptographic value of the configuration information; wherein the cryptographic value which is inserted into a frame of the data stream subsequent to the N successive data frames is the intermediate cryptographic value of the N th frame; and wherein the intermediate cryptographic values of the first to (N−1) th frame are not inserted into the data stream.