Internet DRAFT - draft-mglt-ipsecme-diet-esp-requirements

draft-mglt-ipsecme-diet-esp-requirements







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-IPsec: Requirements for new IPsec/ESP protocols according to IoT
                               use cases
            draft-mglt-ipsecme-diet-esp-requirements-00.txt

Abstract

   IPsec/ESP is used to secure end-to-end communications.  This document
   lists the requirements Diet-ESP should meet to design IPsec/ESP for
   IoT.

Status of This Memo

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   This Internet-Draft will expire on January 3, 2015.

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Table of Contents

   1.  Requirements notation . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Byte-Alignment  . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Crypto-Suites . . . . . . . . . . . . . . . . . . . . . . . .   3
   6.  Compression . . . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  Flexibility . . . . . . . . . . . . . . . . . . . . . . . . .   4
   8.  Code Complexity . . . . . . . . . . . . . . . . . . . . . . .   5
   9.  Usability . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   10. Compatibility with IP compression Protocols . . . . . . . . .   5
   11. Compatibility with Standard ESP . . . . . . . . . . . . . . .   6
   12. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   13. Security Considerations . . . . . . . . . . . . . . . . . . .   6
   14. Acknowledgment  . . . . . . . . . . . . . . . . . . . . . . .   6
   15. Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Appendix A.  Power Consumption Example  . . . . . . . . . . . . .   7
   Appendix B.  Document Change Log  . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

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

   IoT devices can carry all kind of small applications and some of them
   require a secure communication.  They can be life critical devices
   (like a fire alarm), security critical devices (like home theft
   alarms) and home automation devices.  Smart grid is one application
   where supplied electricity is based on information provided by each
   home.  Similarly, home temperature might be determined by servo-
   controls based on information provided by temperature sensors.

   Using IPsec [RFC4301] in the IoT world provides some advantages, such
   as:

   -  IPsec secures application communications transparently as security
      is handled at the IP layer.  As such, applications do not need to
      be modified to be secured.

   -  IPsec does not depend on the transport layer.  As a result, the
      security framework remains the same for all transport protocols,
      like UDP or TCP.




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   -  IPsec is well designed for sleeping nodes as there are no
      sessions.

   -  IPsec defines security rules for the whole device, which outsource
      the device security to a designated area.  Therefore IPsec can be
      seen like a tiny firewall securing all communication for an IoT
      device.

   A common disadvantage of IPsec is that it is mostly implemented in
   the kernel, whereas application are in the user space.  As there are
   no real distinctions between these two spaces in IoT and that IoT
   devices are mostly designed to a specific and unique task, this may
   not be an issue anymore.

   IoT constraints have not been considered in the early design of
   IPsec.  In fact IPsec has mainly been designed to secure
   infrastructure.  This document describes the requirements of Diet-
   ESP, the declination of IPsec/ESP for IoT, enabling optimized IPsec/
   ESP for the IoT.

3.  Terminology

   -  IoT: Internet of Things

4.  Byte-Alignment

   IP extension headers MUST have 32 bit Byte-Alignment in IPv4 (section
   3.1 of [RFC0791] - Padding description) and a 64 bit Byte-Alignment
   in IPv6 (section 4 of [RFC2460]).  As ESP [RFC4303] is such an
   extension header, padding is mandatory to meet the alignment
   constraint.  This alignment is mostly caused by compiler and OS
   requirements dealing with a 32 or 64 Bit processor.  In the world of
   IoT, processors and compilers are highly specialized and alignment is
   often not necessary 32 Bit, but 16 or 8 bit.

   R1:  Diet-ESP SHOULD support Byte-Alignment that are different from
        32 bits or 64 bits to prevent unnecessary padding.

   R2:  Each peer SHOULD be able to advertise and negotiate the Byte-
        Alignment, used for Diet-ESP.  This could be done for example
        during the IKEv2 exchange.

5.  Crypto-Suites

   IEEE 802.15.4 defines AES-CCM*, that is AES-CTR and CBC-MAC, for link
   layer security with upper layer key-management.  Therefore it is
   usually supported by hardware acceleration.




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   R3:  Diet-ESP MUST support AES-CCM and MUST be able to take advantage
        of AES-CCM hardware acceleration.  Diet-ESP MAY support other
        modes.

6.  Compression

   Sending data is very expensive regarding to power consumption, as
   illustrated in Appendix A.  Compression can be performed at different
   layers.  An encrypted ESP packet is an ESP Clear Text Data encrypted
   and eventually concatenated with the Initialization Vector IV to form
   an Encrypted Data Payload.  This encrypted Data Payload is then
   placed between an ESP Header and an ESP Trailer.  Eventually, this
   packet is authenticated with an ICV appended to ESP Trailer.
   Compression can be performed at the ESP layer that is to say for the
   fields of the ESP Header, ESP Trailer and the ICV.  In addition, ESP
   Clear Text Data may also be compressed with non ESP mechanisms like
   ROHC [RFC3095], [RFC5225] for example, resulting in a smaller payload
   to be encrypted.  If ESP is using encryption, these mechanisms MUST
   be performed over the ESP Clear Text Data before the ESP/Diet-ESP
   processing as missing of encrypted fields make decryption harder.

   R4:  Diet-ESP SHOULD be able to compress/remove all static ESP fields
        (SPI, Next Header) as well as the other fields SN, PADDING, Pad
        Length or ICV.

   R5:  Diet-ESP SHOULD also allow compression mechanisms before the
        IPsec/ESP processing.

   R6:  Diet-ESP SHOULD NOT allow compressed fields, not aligned to 1
        byte in order to prevent alignment complexity.  In other words,
        Diet-ESP do not consider finer granularity than the byte.

7.  Flexibility

   Diet-ESP can compress some of the ESP fields as Diet-ESP is optimized
   for IoT.  Which field may be compressed or not, depends on the
   scenario and current and future scenarios cannot been foreseen.  In
   fact Diet-ESP and ESP differs in the following point: ESP has been
   designed so that any ESP secured communication on any device is able
   to communicate with another.  This means that ESP has been designed
   to work for large Security Gateway under thousands of connections, as
   well as devices with a single ESP communication.  Because, ESP has
   been designed not to introduce any protocol limitations, counters and
   identifiers may become over-sized in an IoT context.

   R7:  The developer SHOULD be able to specify the maximum level of
        compression.




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   R8:  Diet-ESP SHOULD be able to compress any field independent from
        another.

   R9:  Diet-ESP SHOULD be able to define different compression method,
        when appropriated.

   R10: Each peer SHOULD be able to announce and negotiate the different
        compressed fields as well as the used method.

8.  Code Complexity

   IoT devices have limited space for memory and storage.

   R11: Diet-ESP SHOULD be able to be implemented with minimal
        complexity.  More especially, Diet-ESP SHOULD consider small
        implementation that implement only a subset of all Diet-ESP
        capabilities without requiring involving standard ESP, specific
        compressors and de-compressors.

9.  Usability

   Application Developer usually do not want to take care about the
   underlying protocols and security.  Standard ESP addresses the goal
   by providing a framework that secures communication in any
   circumstances.  Although application developers for IoT are expected
   to pay more attention to the device security and system requirements,
   we do not expect them to be security aware developers.  As a result,
   some default parameters that provides a standard secure framework for
   most cases should be provided.  This is of course performed at the
   expense of some optimization, but it makes possible for application
   developers to have "standard" security and standard Diet-ESP
   compression by setting a single bit "DIET-ESP secure".  More advanced
   developers will be able to tune the security parameters for their
   needs.

   R12: Diet-ESP SHOULD provide default configurations, which can be
        easily set up by a developer.

10.  Compatibility with IP compression Protocols

   There are different protocols providing IP layer compression for
   constraint devices like IoT (6LoWPAN [RFC6282] ) or Mobile Devices
   (ROHC).

   R13: Diet-ESP SHOULD be able to interact with IP compression
        protocols.  More especially, this means that a Diet-ESP packet
        SHOULD be able to be sent in a ROHC or a 6LowPAN packet.  Diet-
        ESP document should explicitly detail how this can be achieved.



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   R14: Diet-ESP SHOULD also detail how compression of layers above IP
        with ROHC or 6LowPAN is compatible with Diet-ESP.

11.  Compatibility with Standard ESP

   IPsec/ESP is widely deployed by different vendors on different
   machines.  IoT devices MAY have to communicate with Standard ESP
   implementations.

   R15: Diet-ESP SHOULD be able to interact with Standard ESP
        implementations on a single platform.

   R16: Diet-ESP SHOULD be able to communicate with Standard ESP.

12.  IANA Considerations

   There are no IANA consideration for this document.

13.  Security Considerations

14.  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.

15.  Normative References

   [GUGG14]   Guggemos, TG., "Diet-ESP: Applying IP-Layer Security in
              Constrained Environments (Masterthesis)", September 2014.

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791, September
              1981.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, December 1998.









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   [RFC3095]  Bormann, C., Burmeister, C., Degermark, M., Fukushima, H.,
              Hannu, H., Jonsson, L-E., Hakenberg, R., Koren, T., Le,
              K., Liu, Z., Martensson, A., Miyazaki, A., Svanbro, K.,
              Wiebke, T., Yoshimura, T., and H. Zheng, "RObust Header
              Compression (ROHC): Framework and four profiles: RTP, UDP,
              ESP, and uncompressed", RFC 3095, July 2001.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)", RFC
              4303, December 2005.

   [RFC5225]  Pelletier, G. and K. Sandlund, "RObust Header Compression
              Version 2 (ROHCv2): Profiles for RTP, UDP, IP, ESP and
              UDP-Lite", RFC 5225, April 2008.

   [RFC6282]  Hui, J. and P. Thubert, "Compression Format for IPv6
              Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
              September 2011.

Appendix A.  Power Consumption Example

   IoT devices are often installed once and left untouched for a couple
   of years.  Furthermore they often do not have a power supply
   wherefore they have to be fueled by a battery.  This battery may have
   a limited capacity and maybe not replaceable.  Therefore, power can
   be a limited resource in the world of IoT.  Table 1 and Table 2 shows
   the costs for transmitting data and computation

   Note these data are mentioned here with an illustrative purpose, for
   our motivations.  These data may vary from one device to another, and
   may change over time.

             +-------------------------+---------------------+
             |                         | power consumption   |
             +-------------------------+---------------------+
             | low-power radios < 10mW | (100nJ - 1uJ) / bit |
             +-------------------------+---------------------+

             Table 1: Power consumption for data transmission.










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        +----------------------------------+---------------------+
        |                                  | power consumption   |
        +----------------------------------+---------------------+
        | energy-efficient microprocessors | 0.5nJ / instruction |
        | high-performance microprocessors | 200nJ / instruction |
        +----------------------------------+---------------------+

                Table 2: Power consumption for computation.

   From these tables, sending 1 bit costs as much as 10-100 instructions
   in the CPU.  Therefore there is a high interest to reduce the number
   of bits sent on the wire, even if it generates costs for computation.

Appendix B.  Document Change Log

   [draft-mglt-ipsecme-diet-ipsec-requirements-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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