IPSECME D. Migault, Ed.
Internet-Draft Orange
Intended status: Standards Track T. Guggemos, Ed.
Expires: January 3, 2015 Orange / LMU Munich
July 2, 2014
Diet-ESP: Generating compressed IV and SN
draft-mglt-ipsecme-diet-esp-iv-generation-00.txt
Abstract
Diet-ESP describes how to compress the various ESP fields, thanks to
the Diet-ESP Context. This document describes how the IV fields that
belong to the encrypted payload can be compressed.
The document describes the extensions of the the Diet-ESP Context as
well as the compression protocol.
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Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Diet-ESP context extension . . . . . . . . . . . . . . . . . 4
5. Pseudo Random Function . . . . . . . . . . . . . . . . . . . 4
6. Protocol Description . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informational References . . . . . . . . . . . . . . . . 6
10.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Appendix A. Document Change Log . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in[RFC2119].
2. Introduction
Diet-ESP [I-D.mglt-ipsecme-diet-esp] describes how to compress ESP
fields. Fields are compressed according to a Diet-ESP Context.
Diet-ESP has been described as a specific ROHC [RFC5795] framework
that has no IR, IR-DYN nor any feed back ROHC message. It works in
the Unidirectional mode of operation (U mode), and all necessary
parameters are transmitted via the Diet-ESP Context that is
negotiated between the two peers. As a result Diet-ESP defines a
very specific and simplified ROHC framework which makes possible to
implement Diet-ESP without implementing the whole ROHC.
In fact, Diet-ESP avoids ROHC complexity as a lot of parameters have
already been negotiated with IKEv2 [RFC5996].
The Initialization Vector (IV) is defined as a input for AES
encryption and decryption. In order to provide the appropriated IV
value AES-CBC [RFC3602] and AES-CTR [RFC3686] sends the IV in each IP
packet as shown in figure Figure 1. In fact the output of AES-CTR
and AES-CBC outputs a payload where the encrypted data is appended to
the IV.
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The IV MUST have to properties 1) they MUST be unpredictable by
someone observing the network, then 2) the IV MUST be unique. The
size of the IV differs depending on the encryption algorithm. AES-
CTR has an 8 byte IV and AES-CBC a 16 byte IV.
This document defines a way to avoid sending the IV in each packet.
Instead peers agree on a suite of pseudo random bytes. This makes
the IV predictable by both peers only, and random to the rest of the
world. As the IV can be derived by both peers, it may be removed
completely from each IP packet. Another way is to only provide the
LSB of the generated IV so receiver can better identify the
appropriated IV used for decryption.
Note that the ICV of standard ESP [RFC4303] and Diet-ESP ICV includes
the whole IV. As a result, the IV MUST be restored prior to the ICV
check.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
| Security Parameters Index (SPI) | ^
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Sequence Number | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | |Int.
~ Initialization Vector (variable) ~ |Cov-
| | |ered
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | |
~ Encrypted Payload (variable) ~ |
| | v
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ------
| |
~ Authentication Data (variable) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The IV in the ESP payload.
Section 4 describes the new parameters for the Diet-ESP Context.
Section 5 describes how the Pseudo Random Function is derived, and
Section 6 describes the protocol.
3. Terminology
- IoT: Internet of Things
- IV: Initialization Vector
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- ICV: Integrity Check Value
- PRF: Pseudo Random Function
4. Diet-ESP context extension
To enable the compression of the IV, the Diet-ESP context defined in
[I-D.mglt-ipsecme-diet-esp] is extended with to values:
IV_COMPRESSION:
Defines if the IV is generated and compresses.
IV_PRFT (optional):
Defines the Pseudo Random Function Transform used for the Pseudo
Random Function. Available IDs are defined in [1]
Section Transform Type 2 - Pseudo random Function Transform IDs.
Section 2.13 [RFC5996] defines how the PRF is derived. By default
PRF_AES_128_CBC is the Pseudo Random Function Transform
considered.
IV_LSB:
Defines the number of Least Significant Bytes of the IV carried by
the payload.
5. Pseudo Random Function
The Pseudo Random Function (PRF) is defined from the Pseudo Random
Function Transform in Section 2.13 [RFC5996]. Unless specified
otherwise PRF_AES128_XCBC [RFC4434] is the default Pseudo Random
Function Transform.
The PRF "prf+" described in Section 2.13 [RFC5996] takes two
arguments designated as K and S. In this document K is the
encryption key and S is the authentication key appended to the string
"IV random generation". The string results in non null S value even
if no integrity algorithms are negotiated.
6. Protocol Description
IV generation and compression is performed only and only if
IV_COMPRESSION is set. Otherwise, the IV is embedded into the packet
and sent on the wire as described in [RFC4303].
When IV_COMPRESSION is set, the PRD is defined as described in
Section 5. On the sending part, the ICV or Diet-ESP ICV is computed,
the IV is compressed to its LSB, before it is sent on the wire. On
te receiver part, the IV is decompress prior to the ICV check, then
decryption is performed with the decompressed IV.
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7. IANA Considerations
There are no IANA consideration for this document.
8. Security Considerations
9. Acknowledgment
The current draft represents the work of Tobias Guggemos while his
internship at Orange [GUGG14] .
Diet-ESP is a joint work between Orange and Ludwig-Maximilians-
Universitaet Munich. We thank Daniel Palomares and Carsten Bormann
for their useful remarks, comments and guidance.
10. References
10.1. Normative References
[I-D.mglt-ipsecme-diet-esp]
Migault, D., Guggemos, T., and D. Palomares, "Diet-ESP: a
flexible and compressed format for IPsec/ESP", draft-mglt-
ipsecme-diet-esp-00 (work in progress), March 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3602] Frankel, S., Glenn, R., and S. Kelly, "The AES-CBC Cipher
Algorithm and Its Use with IPsec", RFC 3602, September
2003.
[RFC3686] Housley, R., "Using Advanced Encryption Standard (AES)
Counter Mode With IPsec Encapsulating Security Payload
(ESP)", RFC 3686, January 2004.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC
4303, December 2005.
[RFC4434] Hoffman, P., "The AES-XCBC-PRF-128 Algorithm for the
Internet Key Exchange Protocol (IKE)", RFC 4434, February
2006.
[RFC5795] Sandlund, K., Pelletier, G., and L-E. Jonsson, "The RObust
Header Compression (ROHC) Framework", RFC 5795, March
2010.
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[RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
"Internet Key Exchange Protocol Version 2 (IKEv2)", RFC
5996, September 2010.
10.2. Informational References
[GUGG14] Guggemos, TG., "Diet-ESP: Applying IP-Layer Security in
Constrained Environments (Masterthesis)", September 2014.
10.3. URIs
[1] http://www.iana.org/assignments/ikev2-parameters/
ikev2-parameters.xhtml#ikev2-parameters-6
Appendix A. Document Change Log
[draft-mglt-ipsecme-diet-esp-IV-generation-00.txt]: First version
published.
Authors' Addresses
Daniel Migault (editor)
Orange
38 rue du General Leclerc
92794 Issy-les-Moulineaux Cedex 9
France
Phone: +33 1 45 29 60 52
Email: daniel.migault@orange.com
Tobias Guggemos (editor)
Orange / LMU Munich
Am Osteroesch 9
87637 Seeg, Bavaria
Germany
Email: tobias.guggemos@gmail.com
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