System and method for framing and protecting variable-lenght packet streams

Abstract

A method and a system for framing variable-length packets in a data communications system are disclosed. The successive variable-length packets carrying users' data, are formed in a stream of chained packets comprising a header. Two CRC's are computed. One over the data and another one over the header however, including also the data CRC of the immediate previous packet, thus chaining successive packets in a steam of such packets. The invention also assumes that encryption is performed independently over header and corresponding CRC's and, on the other hand, over the data of current packet. The invention allows to better adapt the transportation of multi-media users' data in packets of variable-lengths while securing transport by chaining successive packets, thus preventing that accidental or malicious deletion and insertion of packets occur and remain undetected. Also, the invention permits that intermediate transport nodes, owning keys to decrypt headers, may perform packet add/drop multiplexing without requiring that users' data need to be decrypted on their way to their final destination.

Dependencies are inferred from the claim text.