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Versions: 00 01 02 draft-schmitt-ace-twowayauth-for-iot

Network Working Group                                         C. Schmitt
Internet-Draft                                                B. Stiller
Intended status: Standards Track                    University of Zurich
Expires: August 15, 2014                               February 11, 2014


        DTLS-based Security with two-way Authentication for IoT
           <draft-schmitt-two-way-authentication-for-iot-02>

Abstract

   In this draft the first key idea for a full two-way authentication
   security scheme for the Internet of Things (IoT) based on existing
   Internet standards, specifically the Datagram Transport Layer
   Security (DTLS) protocol, is introduced.  By relying on an
   established standard, existing implementations, engineering
   techniques, and security infrastructure can be reused, which enables
   an easy security uptake.  The proposed security scheme is, therefore,
   based on RSA, the most widely used public key cryptography algorithm.
   It is designed to work over standard communication stacks that offer
   UDP/IPv6 networking for Low power Wireless Personal Area Networks
   (6LoWPANs).  RSA is a bulky solution at the moment but shows that it
   is possible using it on constraint devices for security purposes.  An
   optimization would be to use elliptic curve cryptography.  For sure
   the proposed handshake will stay the same.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 15, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Document Structure . . . . . . . . . . . . . . . . . . . .  3

   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4

   3.  High Level Design Requirements . . . . . . . . . . . . . . . .  4
     3.1.  Implementation of A Standards Based Design . . . . . . . .  4
     3.2.  Focus on Application Layer and End-to-End Security . . . .  4
     3.3.  Support for Unreliable Transport Protocols . . . . . . . .  5

   4.  Two-way authentication handshake . . . . . . . . . . . . . . .  5
     4.1.  DTLS Standard - RFC 6347 . . . . . . . . . . . . . . . . .  6
     4.2.  A Standard Based End-to-End Security Architecture  . . . .  6
       4.2.1.  Handshake description  . . . . . . . . . . . . . . . .  8
       4.2.2.  Certificate creation . . . . . . . . . . . . . . . . .  8

   5.  Architecture Description . . . . . . . . . . . . . . . . . . .  9
     5.1.  Use-cases  . . . . . . . . . . . . . . . . . . . . . . . . 10
     5.2.  Requirements . . . . . . . . . . . . . . . . . . . . . . . 11
     5.3.  Data Access Procedure  . . . . . . . . . . . . . . . . . . 12

   6.  Hardware Requirements  . . . . . . . . . . . . . . . . . . . . 14

   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14

   8.  Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . . 15

   9.  Formal Syntax  . . . . . . . . . . . . . . . . . . . . . . . . 15

   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     10.1. Norminative References . . . . . . . . . . . . . . . . . . 16
     10.2. Informative References . . . . . . . . . . . . . . . . . . 17

   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18




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1.  Introduction

   Today, there is a multitude of envisioned and implemented use cases
   for the Internet of Things (IoT) and wireless sensor networks
   (WSNs).In many of these scenarios it is intended to make the
   collected data globally accessible to authorized users and data
   processing units through the Internet.  Most of these data collected
   in such scenarios is of sensitive nature due to the relation to
   location and personal information or IDs.  Even seemingly
   inconspicuous data, such as the energy consumption measured by a
   smart meter, can lead to potential infringements in the users'
   privacy, e.g., by allowing an eavesdropper to conclude whether or not
   a user is currently at home.  From an industry perspective, there is
   also a pressing need for security solutions based on standards as
   pointed out by the market research firm Gartner Inc. [1].  Regarding
   the infrastructure, security risks are aggravated by the trend toward
   a separation of sensor network infrastructure and applications.
   Therefore, a true end-to-end security solution is required to achieve
   an adequate level of security for IoT.  Protecting the data once it
   leaves the scope of the local network is not sufficient.

   A similar scenario in the traditional computing world would be a user
   browsing the Internet over an unsecured WLAN.  Assuming attackers in
   physical proximity of the user it can happen that the attacker can
   capture the traffic between the user and a Web server.
   Countermeasures against such attacks include the establishment of a
   secured connection to the Web server via HTTPS, the use of a VPN
   tunnel to securely connect to a trusted VPN endpoint, and using
   wireless network security such as WPA.

   These solutions are comparable to security approaches in the IoT
   area.  Using WPA is similar to the traditional use of link layer
   encryption.  The VPN solution is equivalent to creating a secure
   connection between a sensor node and a security end-point, which may
   or may not be the final destination of the sensor data.  Establishing
   a HTTPS connection with the server is comparable to the approach
   described in this draft: The use of the DTLS protocol in an end-to-
   end security architecture for IoT is investigated, where a two-way
   authentication handshake is processed in order to establish a secured
   communication channel requiring authentication of both communication
   parties.

1.1.  Document Structure

   Section 2 mentions conventions used in this draft.  Afterwards the
   assumed high level design requirements are briefly mentioned in
   Section 3.  Section 4 describes a two-way authentication handshake
   for constraint devices in order to establish an end-to-end security



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   in constraint networks (e.g., wireless sensor networks).  In this
   section a brief description of the standard DTLS protocol based on
   RFC 6347 is given, as well as the description of the proposed
   solution for a standard based end-to-end security architecture
   including handshake and message details.  The assumed use-case with
   its requirements and architecture is described in Section 5.
   Section 6 defines the hardware requirements, followed by security
   considerations.


2.  Terminology

   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].

   A publisher represents any kind of device that makes its data public
   available in a network using WLAN or LAN connection.

   A subscriber represents any kind of device that wants to access data.

   An Access Control server (AC) is an entity in the network that
   regulates the access of data and issues an access ticket for
   subscribers based on legal and regulative implications.


3.  High Level Design Requirements

   Due to the usage of DTLS for establishing an end-to-end security
   architecture for IoT three high-level design decisions have to be
   made.

3.1.  Implementation of A Standards Based Design

   Standardization has helped the widespread uptake of technologies.
   Radio chips can rely on IEEE 802.15.4 for the physical and the MAC
   layer.  Routing functionality is provided by the so-called 'IPv6
   Routing Protocol for Low power and Lossy Networks' (RPL) [RFC6550] or
   6LoWPAN [RFC4944].  COAP [2] defines the application layer.  So far,
   no such efforts have addressed security in a wider context of IoT.

3.2.  Focus on Application Layer and End-to-End Security

   An end-to-end protocol provides security even if the underlying
   network infrastructure is only partially under the user's control.
   As the infrastructure for Machine-to-Machine (M2M) communication is
   getting increasingly commoditized, this scenario becomes more likely:
   The European Telecommunications Standard Institute (ETSI) plans to



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   standardize the transport of local device data to a remote data
   center.  For stationary installations security functionality could be
   provided by the gateway to the higher-level network.  However, such
   gateways may present a high-value target for an attacker.  If the
   devices are mobile, as it is possible within a logistic application,
   there may be no gateway to a provider's network that is under the
   user's control, similar to how users of smart phones connect directly
   to their carrier's network.  Another example that favors end-to-end
   security is a multi-tenancy office building being equipped with a
   common infrastructure for metering and climate-control purposes.
   Tenants share the infrastructure but are still able to keep their
   devices' data private from other members of the network.

   DTLS is located between the transport and the application layer.
   Thus, it is not necessary that providers of the infrastructure
   support security mechanisms.  It is purely in the hands of the two
   communicating applications to establish security.  If the security is
   provided by a network layer protocol (e.g., IPsec) the same is true
   to a lower degree, because network stacks of both devices have to
   support the same security protocols.

3.3.  Support for Unreliable Transport Protocols

   Reliable transport protocols like TCP incur an overhead over simpler,
   unreliable protocols such as UDP.  Especially for energy starved,
   battery powered devices this overhead is often too costly and TCP has
   been shown to perform poorly in low-bandwidth scenarios [3].  This is
   reflected in the design of the emerging standard COAP, which uses UDP
   transport and defines a binding to DTLS for security [2].  By using
   DTLS in conjunction with UDP this draft does not force the
   application developer to use reliable transport - as it would be the
   application developer to use reliable transport - as it would be the
   case if TLS would be used.  It is still possible to use DTLS over
   transport protocols like TCP, since DTLS only assumes unreliable
   transport.

   This is a weaker property than the reliability provided by TCP.
   However, adaptations of DTLS for unreliable transport introduce
   additional overhead when compared to TLS.  There MAY be a benefit in
   using TCP during the handshake phase but the DTLS reliability
   mechanism SHOULD be adapted to the special requirements of constraint
   networks.


4.  Two-way authentication handshake






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4.1.  DTLS Standard - RFC 6347

   The Datagram Transport Layer Security (DTLS) protocol in version 1.2
   was standardized under the RFC 6347 [RFC6347].  All messages sent via
   DTLS are prepended with a 13 Byte long DTLS record header.  This
   header specifies the content of the message (e.g. application data or
   handshake data), the version of the protocol employed, as well as the
   64 bit sequence number and the record length.  The top two bytes of
   the sequence number are used to specify the epoch of the message,
   which changes once new encryption parameters have been negotiated
   between client and server.

   The key material and cipher suite, consisting of a block cipher and a
   hash algorithm, are negotiated between the client and the server
   during the handshake phase, which commences before any application
   data can be transferred.  Three types of handshake exist:
   unauthenticated, server authenticated, and fully authenticated
   handshakes.  The latter handshake type is assumed for the proposed
   two-way authentication solution in this draft in order to establish
   end-to-end security.

4.2.  A Standard Based End-to-End Security Architecture

   The proposed system architecture in this draft is following the IoT
   model.  It is assumed that IPv6 connects the Internet and parts of it
   run 6LoWPAN.  The transport layer in 6LoWPAN is UDP, which can be
   considered unreliable; the routing layer is RPL or Hydro [3].  Both
   routing protocols are similar enough and, therefore, a change has
   negligible impact on the results.  IEEE 802.15.4 is used for the
   physical and MAC layer.  Based on this protocol stack DTLS was
   selected as the security protocol and placed in the application layer
   on top of the UDP transportation layer.  Figure 1 shows the network
   stack used in this draft [6], while BLIP is a special 6LoWPAN
   implementation including several IP protocols [7].

















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               +--------------------------------------+
               |  Application Layer: COAP, XML, ....  |
               |                                      |
               |   +-------------------------+        |
               |   | Security Layer: DTLS    |        |
               |   +-------------------------+        |
               +--------------------------------------+
               |  Transport Layer: UDP--              |
               |                       |-->BLIP,RPL   |
               |  Network Layer: IPv6---              |
               +--------------------------------------+
               |  Medium Access Layer: IEEE 802.15.4  |
               +--------------------------------------+
               |  Physical Layer: IEEE 802.15.4       |
               +--------------------------------------+


                      Figure 1: Assumed Network Stack

   In order to support end-to-end communication security the need for
   proper authentication of data publishing devices and access control
   throughout the network is required.  Thus, an Access Control (AC)
   server is integrated in the assumed system architecture.  The AC is a
   trusted entity and a resource-rich server, on which access rights for
   the publisher (= sensor nodes) of the secured network are stored.
   The identity of a default subscriber is usually preconfigured on a
   publisher before it is deployed.

   If any additional subscribers want to initialize a connection with
   the publisher, they first have to obtain an access ticket from the
   AC.  The AC verifies that the subscriber has the right to access the
   information available from the publisher.  In the next step the
   publisher only has to evaluate the identity of the subscriber and has
   to verify the ticket it has received from the AC.  This requires a
   unique identity for a publisher in the network.

   In the Internet, identities are usually established via public key
   cryptography (PKC) and identifiers are provided through X.509
   certificates.  An X.509 certificate contains, among other
   information, the public key of an entity and its common name.  A
   trusted third party, called the Certificate Authority (CA), signs the
   certificate.

   The CA serves two purposes: Firstly, the signature allows the
   receiver to detect modifications to the certificate.  Secondly, it
   also states that the CA has verified the identity of the entity that
   requested the certificate.  In the following sections the proposed
   two-way authentication handshake is specified and message structure



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   is presented in detail.

4.2.1.  Handshake description

   Based on the hardware equipment (cf. Section 6) the proposed two-way
   authentication handshake has to support a solution for TPM equipped
   devices and without.

   Figure 2 summarizes the message flow during the two-way
   authentication handshake.  Here client and server represent the two
   communication parties that want to exchange data.  Client
   (Subscriber) is each entity that requests data from another entity
   and a server (Publisher) can be each entity that has the data.



                  Client                                Server
                    |                                     |
                    |---ClientHello---------------------->|
                    |                                     |
                    |<----------------ClientHelloVerify---|
                    |                                     |
                    |---ClientHello---------------------->|
                    |                                     |
                    |<----------------------ServerHello---|
                    |<----------------------Certificate---|
                    |<-------------[CertificateRequest]---|
                    |<------------------ServerHelloDone---|
                    |                                     |
                    |---[Certificate]-------------------->|
                    |---ClentKeyExchange----------------->|
                    |---[CertificateVerify]-------------->|
                    |---ChangeCipherSpec----------------->|
                    |---Finished------------------------->|
                    |                                     |
                    |<-----------------ChangeCipherSpec---|
                    |<-------------------------Finished---|
                    |                                     |
                    |                                     |


        Figure 2: Message flow of two-way authentication handshake

4.2.2.  Certificate creation

   When the network consists of devices with TPM it is processed like
   shown in Figure 2.  Before deploying the devices certificates and
   individual 2048 bit RSA keys should be created and stored.



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   Therefore, it is recommended to use an OpenSSL implementation on the
   server site [13].

   The certificate should include the following details:
   1.  Serial number
   2.  Validity:
       *  Not Before: Date and time
       *  Not After: Date and time
   3.  Subject
       *  commonName = localhost
   4.  X509v3 extensions:
       *  X509v3 Basic Constraints: CA:FALSE
       *  Netscape Comment: OpenSSL Generated Certificate
       *  X509v3 Subject Key Identifier
       *  X509v3 Authority Key Identifier

   Depending on the implementation additional information should be
   requested that will be incorporated into the certificate request.
   This informatiion may include the following:
   1.  Country Name (2 letter code) [CH]
   2.  State or Providence Name (full name) [Zurich]
   3.  Locality Name (e.g., city) [Zurich-Oerlikon]
   4.  Organization Name (e.g., company) [UZH]
   5.  Organisation Unit Name (e.g., section) [IFI]
   6.  Common Name (e.g., YOUR name) [opal-device10]
   7.  Email Address []
   8.  optional
       *  A challenge password []
       *  An optional company name []


5.  Architecture Description

   As briefly mentioned in Section 1 data is connected to sensitive
   information and can lead to potential infringements in the users'
   privacy.  This fact becomes a security risk if the data is
   transmitted over long distances, perhaps several hops, to a specified
   global sink [10].  Depending on the setting it might happen that the
   data is also transmitted via the Internet and might be cached in
   between.  The latter case is inspired by the project FLAMINGO, which
   deals with access regulations based on legal and regulative
   implications in IP networks [9].  By definition of the Internet of
   Things it can be assumed that IP communication is supported by all
   devices in wireless sensor networks, which allows the adaptation of
   standards in IP networks to constraint networks.






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5.1.  Use-cases

   The idea of the Internet of Thing includes any device connection that
   supports IPv6 communication.  Thus, the diversity of use-cases is
   manifold and not limited to the following list of use-cases:

   Home Automation

      Different devices (e.g., temperature, light, movement sensors) are
      deployed in a house.  Those devices transmit collected data to a
      central entitiy that is responsible for further processing
      including data publishing if other devices (e.g., HVAC unit,
      mobile devices) subscribe to data in order to create an action
      (e.g., turn on heating or light).

   Health Monitoring

      Devices are carried by patients that monitor health status (e.g.,
      heart beat, oxigen concentration).  Data is transmitted to central
      unit that again publishs the data and makes it available to a
      doctor or health care center.

   Emergency Alerts

      Devices measure environment, transmit data to central unit to
      publish it.  Authenticated entities subscribe to data for
      emergency warnings (e.g. earth quake warning system, fire
      department).

   Logistics

      Logistic devices are equipped with sensors (e.g., graviation,
      humidity, GPS).  Data is monitored and made available to owners to
      locate the equipment during transportation.


   Several use-cases are specified in reference [12].  All use-cases
   have in common that data is collected to monitore something, is
   transmitted to central unit that published data.  This data can than
   be accessed by authorized entities (e.g., device, persons).  Usually,
   the data includes sensitive information and, therefore, secure
   transmission is required as proposed by the aforementioned sections.
   The projects FLAMINGO [9] and SmartenIT [8] deal with some of those
   use-cases and investigate the security issues with focus on two-way
   authentication issues for secure data transmission.






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5.2.  Requirements

   In order to show the applicability of the proposed solution
   throughout the above sections a common network structure consisting
   of a global sink and several sensor nodes is assumed.  Additionally,
   an Access Control server (AC) is integrated into the network.  The AC
   is a trusted entity and a more resource-rich server, on which the
   access rights for the publishers (= sensor nodes) of the secured
   network are stored.  Therefore, every publisher in the network MUST
   have an unique identity.  Figure 3 illustrates the assumed
   architecture, where it is assumed that also the subscriber,
   publisher, and sensors have individual certificates received from the
   Certificate Authority.



          +-----------------------+
          | Certificate Authority |
          +-----------------------+
              |               |
              |               |
    +------------+       +----------------------+       +---------+
    | Subscriber |-------| Access Control Server|-------| Gateway |
    +------------+       +----------------------+       +---------+
                                                             |
                                                             |
                                                       +-----------+
                                                       | Publisher |
                                                       +-----------+
                                                             |
                               +------------+----------------+
                               |            |                |
                        +----------+  +----------+     +----------+
                        | Sensor 1 |  | Sensor 2 | ... | Sensor n |
                        +----------+  +----------+     +----------+


                          Figure 3: Architecture

   As mentioned the concept of Internet of Things forms the basis for
   this draft, which include also the basic understanding of the
   Internet.  Thus, it is assumed that identities are usually
   established via public key cryptography and the identifiers provided
   through X.509 certificates [RFC5280].  In general, X.509 certificate
   contains the public key of an entity and its common name.  A trusted
   third party - Certificate Authority (CA) - signs that certificate.
   This signing allows the receiver to detect modifications to the
   certificate and that the identity of the entity, who requested the



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   certificate, has been verified by the CA.  The CA can be run by the
   administrator of the network or an established Internet certificate
   authority can be used.

   Furthermore, it is assumed that the identity of a default subscriber
   is usually preconfigured on a publisher before it is deployed.

5.3.  Data Access Procedure

   Based on the FLAMINGO project the following use-case is assumed [9]:
   A sensor node has published its data, which is transmitted in
   direction to the global sink (cf. Figure 3 where global sink is
   located in the gateway component).  Therefore, it is assumed that a
   two-way authentication handshake between those two communication
   parties was successful performed before.  In between the data can be
   cashed in order to make it accessible more quicker to subscribers.
   In this case the cached entity functions as a publisher.

   Assuming the new subscriber wants to access the data, it must
   initialize a connection with the publisher.  Therefore, the
   subscriber MUST obtain an access ticket from the AC before.  The
   functionality of the AC is to verify that the subscriber has the
   right to access the data available from the publisher.  Those rights
   are influenced by legal and regulative implications (e.g., rights
   connected to an ISP region, where the subscriber belongs to).  If the
   subscriber received a valid access ticket, it is presented to the
   publisher.  The publisher must evaluate the identity of the
   subscriber and verify the ticket it has received from the AC.

   If the validation was successful the subscriber can access the data.
   Before every kind of data exchange, where sensitive information is
   involved, takes place the proposed two-way authentication handshake
   is performed in order to establish a highly secured communication
   channel between the entities.  Figure 4 summarizes the aforementioned
   work flow and will be defined in detail in the upcoming subsections.
















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                           Access
                           Control
   Subscriber              Server    Gateway            Publisher
       |                     |         |                    |
       |                     |         |                    |
       |                     |         |      Two-way       |
       |                     |         |<--authentication-->|
       |                     |         |      Handshake     |
       |                     |         |                    |
       |                     |         |                    |
       |                     |         |<--Measured Data----|
       |                     |         |                    |
       |      Two-way        |         |                    |
       |<--authentication -->|         |                    |
       |     Handshake       |         |                    |
       |                     |         |                    |
       |                     |         |                    |
       |      Connection     |         |                    |
       |------- request ---->|         |                    |
       |     for Publisher   |         |                    |
       |                     |         |                    |
       |                     |         |                    |
       |                 Check of      |                    |
       |                  Request      |                    |
       |                     |         |                    |
       |                     |         |                    |
       |       Copy of       |         |                    |
       |<------ Access ------+-Subscriber`s Access ticket-->|
       |        Ticket       |         |                    |
       |                     |         |                    |
       |                     |         |            Validation of
       |                     |         |            Access Ticket
       |                     |         |                    |
       |                     |         |                    |
       |      Two-way authentication handshake between      |
       |<-------------------------------------------------->|
       |            Subscriber and Publisher                |
       |                     |         |                    |
       |                     |         |                    |
       |<-----Data exchange using DTLS secured channel----->|
       |                     |         |                    |
       |                     |         |                    |


             Figure 4: Flow Diagram for Data Access Procedure






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6.  Hardware Requirements

   Hu et al. showed that RSA, the most commonly used public key
   algorithm in the Internet, can be used in sensor networks with the
   assistance of a Trusted Platform Module (TPM), which costs less than
   5% of a common sensor node [4].  A TPM is an embedded chip that
   provides tamper proof generation and storage of RSA keys as well as
   hardware support for the RSA algorithm.  The certificate of a TPM
   equipped publisher and the certificate of a trusted CA MUST be stored
   on the publisher prior to deployment.

   For publishers that are not equipped with TPM chips the
   authentication can be proposed via the DTLS pre-shared key cipher-
   suite, which requires a small number of random bytes, from which the
   actual key is derived, to be preloaded to the publisher before
   deployment.  This secret MUST also be made available to the AC
   server, which will disclose the key to devices with sufficient
   authorization.


7.  Security Considerations

   The following security goals are addressed by the key idea presented
   in this draft:

   Authenticity

      Recipients of a message can identify their communication partners
      and can detect if the sender information has been forged.

   Integrity

      Communication partners can detect changes to a message during
      transmission.

   Confidentiality

      Attackers cannot gain knowledge about the content of a secured
      message.


   By choosing DTLS as the security protocol those goals can be
   achieved.  DTLS is a modification of TLS for the unreliable UDP and
   inherits its security properties [5].  Furthermore, if hardware
   including TPM is available, it is recommended to use it especially on
   vulnerable points (e.g., cluster heads, aggregation points,
   publisher, subscriber) within the network.




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8.  Acknowledgement

   The draft authors thank Thomas Kothmayr from Technische Universitaet
   Muenchen (Germany) for developing the idea of this draft and
   implementing a first solution.  Additional thanks to Wen Hu from
   CSIRO ICT Centre (Australia) who supported the complete approach and
   funding the required sensor node`s hardware with TPM technology.

   The ongoing work is supported partially by the SmartenIT [8] and the
   FLAMINGO [9] projects, funded by the EU FP7 Program under Contract
   No.  FP7-2012-ICT-317846 and No.  FP7-2012-ICT-318488, respectively.


9.  Formal Syntax

   6LoWPAN - IPv6 over Low power Wireless Personal Area Network (RFC
   4944)

   AC - Access Control Server

   BLIP - Berkeley Low-power IP stack

   CA - Certificate Authority

   CBC - Cipher-Block Chaining

   COAP - Constrained Application Protocol

   DTLS - Datagram Transport Layer Security protocol (RFC 6347)

   ECC - Elliptic Curve Cryptography

   ETSI - European Telecommunications Standard Institute

   H - Header

   HVAC - Heating, Ventilation, and Air Conditioning

   HMAC - Hash-based Message Authentication Code

   IoT - Internet of Things

   IV - Initialization Vector

   PKC - Public Key Cryptography

   RPL - Routing Protocol for Low power and Lossy Networks (RFC 6550)




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   T-A - Token A

   T-B - Token B

   TCP - Transmission Control Protocol (RFC 793)

   TLS - The Transport Layer Security (TLS) Protocol Version 1.2 (RFC
   5246)

   TPM - Trusted Platform Module

   UDP - User Datagram Protocol (RFC 768)

   WSN - Wireless Sensor Network


10.  References

10.1.  Norminative References

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

   [RFC6550]  Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R.,
              Levis, P., Pister, K., Struik, R., Vasseur, JP., and R.
              Alexander, "RPL: IPv6 Routing Protocol for Low-Power and
              Lossy Networks", RFC 6550, March 2012.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, January 2012.

   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
              "Transmission of IPv6 Packets over IEEE 802.15.4
              Networks", RFC 4944, September 2007.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [2]        Shelby et al., Z., "Constrained Application Protocol
              (CoAP),
              http://tools.ietf.org/html/draft-ietf-core-coap-14",
              March 2013.

   [3]        Dawson-Haggerty et al., S., "Hydro: A Hybrid Routing
              Protocol for Low-power and Lossy Networks", In Proceedings
              of the 1st IEEE International Conference on Smart Grid



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              Communications, SmartGridComm, Gaithersburg, Maryland,
              U.S.A. , 2010.

   [5]        Modadugu et al., N., "The Design and Implementation of
              Datagram TLS", In Proceedings of the Network and
              Distributed System Security Symposium (NDSS), San Diego,
              California, U.S.A. , 2004.

   [12]       Seitz et al., L., "Use cases for CoRE security, http://
              tools.ietf.org/html/draft-seitz-core-sec-usecases-00",
              IETF Draft draft-seitz-core-sec-usecases-00, Version 0,  ,
              2012.

10.2.  Informative References

   [1]        LeHong, H., "Hype Cycle for the Internet of Things", Tech.
              rep., Gartner Inc. , 2012.

   [4]        Hu, W., "Toward Trusted Wireless Sensor Networks", ACM
              Transactions on Sensor Networks, Vol. 7, No.5. , 2010.

   [6]        Kothmayr et al., T., "DTLS Based Security and Two-Way
              Authentication for the Internet of Things", Elsevier,
              Journal Ad Hoc Networks , 2013.

   [7]        Dawson-Haggerty, S. and D. Culler, "Berkeley IP
              Information, Berkeley WEBS Wireless Embedded Systems,
              http://smote.cs.berkeley.edu:8000/tracenv/wiki/blip",
              2010.

   [8]        SmartenIT Consortium, "Socially-aware Management of New
              Overlay Application Traffic combined with Energy
              Efficiency in the Internet (SmartenIT),
              http://www.smartenit.eu/", 20103.

   [9]        Flamingo Consortium, "FLAMINGO - Management of the Future
              Internet, http://www.fp7-flamingo.eu/", 2013.

   [10]       Schmitt, C., "Secure Data Transmission in Wireless Sensor
              Networks, Dissertation", Network Architectures and
              Services (NET), ISBN: 3-937201-36-X, ISSN: 1868-2634
              (print), DOI: 10.2313/NET-2013-07-2 , 2013.

   [11]       Boyd, C. and A. Mathuria, "Protocols for Authentication
              and Key Establishment (Information Security and
              Cryptography)", Springer, ISBN 3540431071 , 2003.

   [13]       "OpenSSL - Cryptography and SSL/TLS Toolkit,



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              https://www.openssl.org/", 2014.


Authors' Addresses

   Corinna Schmitt
   Univerity of Zurich
   Department for Informatics
   Communication Systems Group
   Binzmuehlestrasse 14
   Zurich  8050
   Switzerland

   Email: schmitt@ifi.uzh.ch


   Burkhard Stiller
   Univerity of Zurich
   Department for Informatics
   Communication Systems Group
   Binzmuehlestrasse 14
   Zurich  8050
   Switzerland

   Email: stiller@ifi.uzh.ch


























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