| 822 | STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGESD. Crocker · obsoleted by RFC 2822 | Internet Standard | August 1982 |
| 2119 | Key words for use in RFCs to Indicate Requirement LevelsS. Bradner | Best Current Practice | March 1997 |
| 2401 | Security Architecture for the Internet ProtocolS. Kent, R. Atkinson · obsoleted by RFC 4301 | Proposed Standard | November 1998 |
| 2406 | IP Encapsulating Security Payload (ESP)S. Kent, R. Atkinson · obsoleted by RFC 4303, RFC 4305 | Proposed Standard | November 1998 |
| 2437 | PKCS #1: RSA Cryptography Specifications Version 2.0B. Kaliski, J. Staddon · obsoleted by RFC 3447 | Informational | October 1998 |
| 2451 | The ESP CBC-Mode Cipher AlgorithmsR. Pereira, R. Adams | Proposed Standard | November 1998 |
| 2822 | Internet Message FormatP. Resnick, Ed. · obsoleted by RFC 5322 | Proposed Standard | April 2001 |
| 2865 | Remote Authentication Dial In User Service (RADIUS)C. Rigney, S. Willens, A. Rubens, W. Simpson | Draft Standard | June 2000 |
| 3162 | RADIUS and IPv6B. Aboba, G. Zorn, D. Mitton | Proposed Standard | August 2001 |
| 3447 | Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1J. Jonsson, B. Kaliski · obsoleted by RFC 8017 | Informational | February 2003 |
| 3579 | RADIUS (Remote Authentication Dial In User Service) Support For Extensible Authentication Protocol (EAP)B. Aboba, P. Calhoun | Informational | September 2003 |
| 3664 | The AES-XCBC-PRF-128 Algorithm for the Internet Key Exchange Protocol (IKE)P. Hoffman · obsoleted by RFC 4434 | Proposed Standard | January 2004 |
| 3748 | Extensible Authentication Protocol (EAP)B. Aboba, L. Blunk, J. Vollbrecht, J. Carlson, H. Levkowetz, Ed. | Proposed Standard | June 2004 |
| 3775 | Mobility Support in IPv6D. Johnson, C. Perkins, J. Arkko · obsoleted by RFC 6275 | Proposed Standard | June 2004 |
| 3810 | Multicast Listener Discovery Version 2 (MLDv2) for IPv6R. Vida, Ed., L. Costa, Ed. · obsoleted by RFC 9777 | Proposed Standard | June 2004 |
| 3948 | UDP Encapsulation of IPsec ESP PacketsA. Huttunen, B. Swander, V. Volpe, L. DiBurro, M. Stenberg | Proposed Standard | January 2005 |
| 4282 | The Network Access IdentifierB. Aboba, M. Beadles, J. Arkko, P. Eronen · obsoleted by RFC 7542 | Proposed Standard | December 2005 |
| 4291 | IP Version 6 Addressing ArchitectureR. Hinden, S. Deering | Draft Standard | February 2006 |
| 4301 | Security Architecture for the Internet ProtocolS. Kent, K. Seo | Proposed Standard | December 2005 |
| 4306 | Internet Key Exchange (IKEv2) ProtocolC. Kaufman, Ed. · obsoleted by RFC 5996 | Proposed Standard | December 2005 |
| 4307 | Cryptographic Algorithms for Use in the Internet Key Exchange Version 2 (IKEv2)J. Schiller · obsoleted by RFC 8247 | Proposed Standard | December 2005 |
| 4434 | The AES-XCBC-PRF-128 Algorithm for the Internet Key Exchange Protocol (IKE)P. Hoffman | Proposed Standard | February 2006 |
| 4478 | Repeated Authentication in Internet Key Exchange (IKEv2) ProtocolY. Nir | Experimental | April 2006 |