Open SigComp: Standards Implemented

RFC 3320: SigComp, Version 1

Price, R., Bormann, C., Christoffersson, J., Hannu, H., Liu, Z., and J. Rosenberg, "Signaling Compression (SigComp)", RFC 3320, January 2003.

RFC 3320 defines the base version (version 1) of the SigComp specification.

RFC 4077: SigComp, Version 2

Roach, A. B., "A Negative Acknowledgement Mechanism for Signaling Compression", RFC 4077, May 2005.

RFC 4077 amends SigComp to allow for recovery from common error cases. When applied to RFC 3320, it forms version 2 of the SigComp specification. The IETF considers RFC 4077 an update to SigComp to fix a major shortcoming in the protocol's original design. Implementation of RFC 4077 is required to deploy SigComp reliably in real-world networks.

RFC 3485: SIP SigComp Library

Garcia-Martin, M., et al, "The Session Initiation Protocol (SIP) and Session Description Protocol (SDP) Static Dictionary for Signaling Compression (SigComp)", RFC 3485, February 2003.

RFC 3485 defines a standard, well-known dictionary of SIP and SDP phrases that can be used to assist with compression of messages when SigComp is used in conjunction with the SIP protocol.

FIPS PUB 180-1: SHA-1

Federal Information Processing Standards, "Secure Hash Standard," FIPS PUB 180-1, April 1995

FIPS 180-1 defines the SHA-1 algorithm used by SigComp. For the purposes of portability, The Open SigComp library contains its own implementation of SHA-1 -- in fact, it contains two. One implementation is highly optimized for speed, while the other trades off a bit of performance for a smaller footprint. Both implementations have been tested against the standard reference vectors to ensure compliance.

Additionally, for systems on which the Open SSL library (libcrypto) is available, the Open SigComp library can take advantage of its hand-optimized assembly implementation of SHA-1 on x86 and AMD64 platforms.