| 2046 | Multipurpose Internet Mail Extensions (MIME) Part Two: Media TypesN. Freed, N. Borenstein | Draft Standard | November 1996 |
| 2119 | Key words for use in RFCs to Indicate Requirement LevelsS. Bradner | Best Current Practice | March 1997 |
| 2585 | Internet X.509 Public Key Infrastructure Operational Protocols: FTP and HTTPR. Housley, P. Hoffman | Proposed Standard | May 1999 |
| 2898 | PKCS #5: Password-Based Cryptography Specification Version 2.0B. Kaliski · obsoleted by RFC 8018 | Informational | September 2000 |
| 3204 | MIME media types for ISUP and QSIG ObjectsE. Zimmerer, J. Peterson, A. Vemuri, L. Ong, F. Audet, M. Watson, M. Zonoun | Proposed Standard | December 2001 |
| 3261 | SIP: Session Initiation ProtocolJ. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, E. Schooler | Proposed Standard | July 2002 |
| 3265 | Session Initiation Protocol (SIP)-Specific Event NotificationA. B. Roach · obsoleted by RFC 6665 | Proposed Standard | July 2002 |
| 3370 | Cryptographic Message Syntax (CMS) AlgorithmsR. Housley | Proposed Standard | September 2002 |
| 3760 | Securely Available Credentials (SACRED) - Credential Server FrameworkD. Gustafson, M. Just, M. Nystrom | Informational | April 2004 |
| 3853 | S/MIME Advanced Encryption Standard (AES) Requirement for the Session Initiation Protocol (SIP)J. Peterson | Proposed Standard | July 2004 |
| 3903 | Session Initiation Protocol (SIP) Extension for Event State PublicationA. Niemi, Ed. | Proposed Standard | November 2004 |
| 4086 | Randomness Requirements for SecurityD. Eastlake 3rd, J. Schiller, S. Crocker | Best Current Practice | June 2005 |
| 4366 | Transport Layer Security (TLS) ExtensionsS. Blake-Wilson, M. Nystrom, D. Hopwood, J. Mikkelsen, T. Wright · obsoleted by RFC 5246, RFC 6066 | Proposed Standard | April 2006 |
| 4474 | Enhancements for Authenticated Identity Management in the Session Initiation Protocol (SIP)J. Peterson, C. Jennings · obsoleted by RFC 8224 | Proposed Standard | August 2006 |
| 4662 | A Session Initiation Protocol (SIP) Event Notification Extension for Resource ListsA. B. Roach, B. Campbell, J. Rosenberg | Proposed Standard | August 2006 |
| 5246 | The Transport Layer Security (TLS) Protocol Version 1.2T. Dierks, E. Rescorla · obsoleted by RFC 8446, RFC 9846 | Proposed Standard | August 2008 |
| 5280 | Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) ProfileD. Cooper, S. Santesson, S. Farrell, S. Boeyen, R. Housley, W. Polk | Proposed Standard | May 2008 |
| 5649 | Advanced Encryption Standard (AES) Key Wrap with Padding AlgorithmR. Housley, M. Dworkin | Informational | September 2009 |
| 5741 | RFC Streams, Headers, and BoilerplatesL. Daigle, Ed., O. Kolkman, Ed., IAB · obsoleted by RFC 7841 | Informational | December 2009 |
| 5751 | Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message SpecificationB. Ramsdell, S. Turner · obsoleted by RFC 8551 | Proposed Standard | January 2010 |
| 5754 | Using SHA2 Algorithms with Cryptographic Message SyntaxS. Turner | Proposed Standard | January 2010 |
| 5958 | Asymmetric Key PackagesS. Turner | Proposed Standard | August 2010 |
| 5959 | Algorithms for Asymmetric Key Package Content TypeS. Turner | Proposed Standard | August 2010 |