Network Working Group S. Kent Request for Comments: 2406 BBN Corp Obsoletes: 1827 R. Atkinson Category: Standards Track @Home Network November 1998 IP Encapsulating Security Payload (ESP) Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1998). All Rights Reserved. Table of Contents 1. Introduction..................................................2 2. Encapsulating Security Payload Packet Format..................3 2.1 Security Parameters Index................................4 2.2 Sequence Number .........................................4 2.3 Payload Data.............................................5 2.4 Padding (for Encryption).................................5 2.5 Pad Length...............................................7 2.6 Next Header..............................................7 2.7 Authentication Data......................................7 3. Encapsulating Security Protocol Processing....................7 3.1 ESP Header Location......................................7 3.2 Algorithms..............................................10 3.2.1 Encryption Algorithms..............................10 3.2.2 Authentication Algorithms..........................10 3.3 Outbound Packet Processing..............................10 3.3.1 Security Association Lookup........................11 3.3.2 Packet Encryption..................................11 3.3.3 Sequence Number Generation.........................12 3.3.4 Integrity Check Value Calculation..................12 3.3.5 Fragmentation......................................13 3.4 Inbound Packet Processing...............................13 3.4.1 Reassembly.........................................13 3.4.2 Security Association Lookup........................13 3.4.3 Sequence Number Verification.......................14 3.4.4 Integrity Check Value Verification.................15 Kent & Atkinson Standards Track