AES-GCM Authenticated Encryption in the Secure Real-time Transport Protocol (SRTP)
RFC 7714
Internet Engineering Task Force (IETF) D. McGrew
Request for Comments: 7714 Cisco Systems, Inc.
Category: Standards Track K. Igoe
ISSN: 2070-1721 National Security Agency
December 2015
AES-GCM Authenticated Encryption
in the Secure Real-time Transport Protocol (SRTP)
Abstract
This document defines how the AES-GCM Authenticated Encryption with
Associated Data family of algorithms can be used to provide
confidentiality and data authentication in the Secure Real-time
Transport Protocol (SRTP).
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7714.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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McGrew & Igoe Standards Track [Page 1]
RFC 7714 AES-GCM for SRTP December 2015
Table of Contents
1. Introduction ....................................................3
2. Conventions Used in This Document ...............................4
3. Overview of the SRTP/SRTCP AEAD Security Architecture ...........4
4. Terminology .....................................................5
5. Generic AEAD Processing .........................................6
5.1. Types of Input Data ........................................6
5.2. AEAD Invocation Inputs and Outputs .........................6
5.2.1. Encrypt Mode ........................................6
5.2.2. Decrypt Mode ........................................7
5.3. Handling of AEAD Authentication ............................7
6. Counter Mode Encryption .........................................7
7. Unneeded SRTP/SRTCP Fields ......................................8
7.1. SRTP/SRTCP Authentication Tag Field ........................8
7.2. RTP Padding ................................................9
8. AES-GCM Processing for SRTP .....................................9
8.1. SRTP IV Formation for AES-GCM ..............................9
8.2. Data Types in SRTP Packets ................................10
8.3. Handling Header Extensions ................................11
8.4. Prevention of SRTP IV Reuse ...............................12
9. AES-GCM Processing of SRTCP Compound Packets ...................13
9.1. SRTCP IV Formation for AES-GCM ............................13
9.2. Data Types in Encrypted SRTCP Compound Packets ............14
9.3. Data Types in Unencrypted SRTCP Compound Packets ..........16
9.4. Prevention of SRTCP IV Reuse ..............................17
10. Constraints on AEAD for SRTP and SRTCP ........................17
11. Key Derivation Functions ......................................18
12. Summary of AES-GCM in SRTP/SRTCP ..............................19
13. Security Considerations .......................................20
13.1. Handling of Security-Critical Parameters .................20
13.2. Size of the Authentication Tag ...........................21
14. IANA Considerations ...........................................21
14.1. SDES .....................................................21
14.2. DTLS-SRTP ................................................22
14.3. MIKEY ....................................................23
15. Parameters for Use with MIKEY .................................23
16. Some RTP Test Vectors .........................................24
16.1. SRTP AEAD_AES_128_GCM ....................................25
16.1.1. SRTP AEAD_AES_128_GCM Encryption ..................25
16.1.2. SRTP AEAD_AES_128_GCM Decryption ..................27
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