| 2119 | Key words for use in RFCs to Indicate Requirement LevelsS. Bradner | Best Current Practice | March 1997 |
| 2560 | X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSPM. Myers, R. Ankney, A. Malpani, S. Galperin, C. Adams · obsoleted by RFC 6960 | Proposed Standard | June 1999 |
| 3161 | Internet X.509 Public Key Infrastructure Time-Stamp Protocol (TSP)C. Adams, P. Cain, D. Pinkas, R. Zuccherato | Proposed Standard | August 2001 |
| 3275 | (Extensible Markup Language) XML-Signature Syntax and ProcessingD. Eastlake 3rd, J. Reagle, D. Solo | Draft Standard | March 2002 |
| 3470 | Guidelines for the Use of Extensible Markup Language (XML) within IETF ProtocolsS. Hollenbeck, M. Rose, L. Masinter | Best Current Practice | January 2003 |
| 3629 | UTF-8, a transformation format of ISO 10646F. Yergeau | Internet Standard | November 2003 |
| 3688 | The IETF XML RegistryM. Mealling | Best Current Practice | January 2004 |
| 3986 | Uniform Resource Identifier (URI): Generic SyntaxT. Berners-Lee, R. Fielding, L. Masinter | Internet Standard | January 2005 |
| 4051 | Additional XML Security Uniform Resource Identifiers (URIs)D. Eastlake 3rd · obsoleted by RFC 6931 | Proposed Standard | April 2005 |
| 4648 | The Base16, Base32, and Base64 Data EncodingsS. Josefsson | Proposed Standard | October 2006 |
| 4810 | Long-Term Archive Service RequirementsC. Wallace, U. Pordesch, R. Brandner | Informational | March 2007 |
| 4998 | Evidence Record Syntax (ERS)T. Gondrom, R. Brandner, U. Pordesch | Proposed Standard | August 2007 |
| 5055 | Server-Based Certificate Validation Protocol (SCVP)T. Freeman, R. Housley, A. Malpani, D. Cooper, W. Polk | Proposed Standard | December 2007 |
| 5126 | CMS Advanced Electronic Signatures (CAdES)D. Pinkas, N. Pope, J. Ross | Informational | March 2008 |
| 5226 | Guidelines for Writing an IANA Considerations Section in RFCsT. Narten, H. Alvestrand · obsoleted by RFC 8126 | Best Current Practice | May 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 |
| 5652 | Cryptographic Message Syntax (CMS)R. Housley | Internet Standard | September 2009 |
| 5698 | Data Structure for the Security Suitability of Cryptographic Algorithms (DSSC)T. Kunz, S. Okunick, U. Pordesch | Proposed Standard | November 2009 |
| 5741 | RFC Streams, Headers, and BoilerplatesL. Daigle, Ed., O. Kolkman, Ed., IAB · obsoleted by RFC 7841 | Informational | December 2009 |