Patent ID: 7769168

Claim:
A method comprising: dividing a stream of data into a sequence of data blocks, wherein a minimum of a block size for each data block is determined at least upon a maximum length of bits and sequences of bits forbidden by a syntax specification; partitioning the sequence of data blocks into a plurality of logical blocks, wherein each logical block comprises a data block to be encrypted, encrypted data of one or more previous data blocks immediately preceding the data block to be encrypted and unencrypted data of one or more next blocks immediately following the data block to be encrypted, and wherein the plurality of logical blocks overlap with each other; and iteratively encrypting the data block to be encrypted in each logical block in turn until, for each logical block, a first spanning sequence including stream data consisting of encrypted data of the block to be encrypted and the encrypted data of the one or more previous blocks immediately preceding the block to be encrypted, and a second spanning sequence including the encrypted data of the block to be encrypted and the unencrypted data of one or more next blocks immediately following the block to be encrypted are compliant with the syntax specification.