RATS                                                             M. Chen
Internet-Draft                                                    Li. Su
Intended status: Informational                              China Mobile
Expires: July 31, 2021                                  January 27, 2021


                           Use Cases for RATS
                       draft-chen-rats-usecase-03

Abstract

   This document presents three scenarios from the Internet Service
   Providers' perspective as an supplement use case of the RATS work
   group.  And make some discussions of access authentication,
   application authentication and trusted link.  The requirements of
   trusted link is put forward to establish a protecttive network
   connection, thus ensure the native network security.

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   the Trust Legal Provisions and are provided without warranty as
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Access authentication based on different method . . . . .   4
     3.2.  Application authentication based on different system  . .   5
     3.3.  virtualization-based systems  . . . . . . . . . . . . . .   5
     3.4.  Use case based on trusted routing . . . . . . . . . . . .   6
   4.  Requirements of trusted link  . . . . . . . . . . . . . . . .   7
     4.1.  New equipment into the network  . . . . . . . . . . . . .   7
     4.2.  Device status updating  . . . . . . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   At present, it is necessary to complete the authentication before
   accessing the operator's network to obtain the service.  RATS aimed
   at the solutions to provide interoperable way for domain-specific
   attestation mechanisms, within RATS relying party may not to maintain
   the authentication background, as an ISP what may be involved at the
   level of access authentication is preshared secret keys based
   authentication, the authentication based on PSK(Preshared secret
   keys) is different from identity-based authentication, such as
   IBC(Identity-Based Cryptograph).

   After access to the network, operators can also provide application
   layer authentication services for a variety of applications.  At
   present, there are many application layer authentication methods, it
   can be divided into certificate-based and non-certificate-based
   certification systems, so there are the following situations.  One
   application authenticated by certificate-based PKI system may request
   resource access to a server or service, but the server or service's
   authentication function is based on identity which is belong to non-
   certificate-based certification systems.  These are all possible
   future demand scenarios, also in the context of the RATS.  Due to
   limitation of resource, many companies are unable to operate their
   own certification and willing to rely on the result from operator to
   reduce their cost, and operator can provide authentication services.
   Multiple certification centers would be made due to different kinds
   of request from service and perspective of deployment, before



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   obtaining a certification center's service, certification center need
   proof for identification, including software and hardware health
   information.  These certification centers are based on regions then
   there have manage barriers, how can clients from a certification
   center asstest themselves' identities to another certification
   center.  Especially now there are more virtual resources, cloud
   resources, one need to prove whether it has access to the resources
   and can protect the data.  From an internal business perspective, how
   to integrate resources, achieve cross-domain trust and break down
   management barriers in order to streamline and improve flexibility
   will also be something rats[I-D.ietf-rats-architecture] can do.

   AS Communication Technology and Internet Technology are converging,
   especially mobile communication network have stepped into 5G era,
   besides 5G network slice safety needs attention, basic routing is
   also need to pay much more attention since damage points of routing
   nodes will affect the security of the whole link.  In some scenarios
   we need to form a trusted routing link. in the internet draft draft-
   voit-rats-trustworthy-path-routing-00 also have mentioned this
   problem.

   A trusted link means that every device on the link is proven to be
   trusted dymaticly.  In the real world, a new device or a small
   network is need to add into the core network, newly added associated
   equipments are required Security and Trustworthy.  After the
   formation of deterministic networks, three problems need to be
   solved: how to dynamically check the security of equipment, how to
   dynamically select the best route based on business requirements, how
   to ensure computing and security capabilities.

2.  Terminology

   The readers should be familiar with the terms defined in.

   In addition, this document makes use of the following terms:

   PSK:  Preshared secret keys means keys are shared in advance between
      the authentication parties.

   IBC:  Identity-Based Cryptograph, it is an asymmetric public key
      cryptosystem.

   PKI:  Public Key Infrastructure, an infrastructure built with a
      public-key mechanism.







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3.  Use Cases

   This section describes use cases which happens inside an ISP.

3.1.  Access authentication based on different method

   This section considers the level of access authentication.  For
   operators, the access of users is usually based on preshared secret
   keys, preset with symmetric secret keys before the release.  The
   first access only needs to be activated, and subsequent
   authentication uses PSK to complete data protection which is based on
   Symmetric secret key system.  In addition, there are other identity-
   based authentication methods, the access authentication based on
   identity is asymmetric and the identity is the public key, this
   approach makes it easier for the peer to obtain the public key of the
   other peer.

   In short, these are two different authentication methods.  When a
   psk-based authentication device needs to request an identity-based
   service, it needs to prove its' trustworthiness to the other party
   and the whole process need to ensure the confidentiality of evidences
   and attestation results.


               (relying party1)               (relying party2)
               +---------------+              +---------------+
               |PSK Auth_Center|              |IBC Auth_Center|
               +---------------+              +---------------+
                      |\          +------------//      |
                      |Evidence  /Attestation          |
         Attestation  |         /    Result            |
             Result  \|        /                       |
            +-------------------+       +-------------------+
           |App/SIMCard/IoTCard|         |App/SIMCard/IoTCard|
          +-------------------+           +-------------------+
                (attester)

           Figure 1: different access authentication methods within RATS


   The format and content of the evidence: TBD

   The format of the Attestation Result: TBD

   The transmission protocol for evidence or attestation result: TBD






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3.2.  Application authentication based on different system

   At the application level, due to limitation of resource, many
   applications need operators to provide business authentication
   services.  At present, there are two business authentication methods:
   one is certification-based PKI system authentication, because the
   management of certificates is always a very big problem, so the other
   is non-certificated, such as identity-based authentication whose
   identity is readable.

   When cross-business authentication is required, how to prove one's
   identity to the other will be a common problem.


           (relying party1)                            (relying party2)
  +-----------------------------------+     +-----------------------------------+
  |Application authentication platform|     |Application authentication platform|
  |     based on certificate          |-----|      based on non-certificate     |
  +-----------------------------------+     +-----------------------------------+
                    |        {Attestation}  /|                  |
                    |        {    Result } /                    |
                    |           ----------                      |
                    |         /                                 |
            +---------------+                           +---------------+
            |  application  |                           |  application  |
            +---------------+                           +---------------+
                 (attester1)                                (attester2)

  Figure 2: different application authentication methods in RATS architecture

   The format and content of the evidence: TBD

   The format of the Attestation Result: TBD

   The transmission protocol for evidence or attestation result: TBD

   Certification-based authentication process: TBD

   Identity-based authentication process: TBD

3.3.  virtualization-based systems

   Cloud computing and other virtualized environment also need remote
   attestation, one service offered through cloud computing is
   Infrastructure as a Service (IaaS), which provides virtualized
   computing resources to enterprises, typically over the Internet.  The
   virtualization platform or virtualization system needs to provide
   evidence to the user or third party, the process may involve vTPM,



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   which support for establishing trust in a virtualized environment,
   especially remote verification of software integrity.

3.4.  Use case based on trusted routing

   5G provides security slices based on routing security, routing
   devices can be hijacked because of vulnerabilities, damaged equipment
   could be monitored, so ISP need to be able to dynamically retrieve
   the status of routing devices, according to the state of the devices
   dynamicly form a safety link, RATS needs to be used in this case.
   There are two scenarios for this case: a trusted link is formed
   within a single operator and a trusted link is formed across
   operators.  The default prerequisite is routing devices support TPM
   or other relevant standard.

                 +---------------------------------+
                 |                                 |
                 |  Trusted Identification System  |
                 |                                 |
                 +-------- -------^--+-------------+
                                  |  |
                                  |  |
                                  |  |
              Device Conditions   |  | Latest trusted status
               (evidence)or       |  |
               (Appraisal results)|  |
                                  |  |
   +-----------------+            |  |          +------------------+
   |                 |            |  |          |                  |
   | Routing Device  +------------+  +---------->   Orchestrator   |
   |                 |                          |                  |
   +-----------------+                          +--------+---------+
                                                         |
                                                         v
                                               Form a routing path
     Figure 3: a trusted link is formed within an ISP in RATS

            ISP A                                         ISP B
   +-------------------+                          +--------------------+
   |                   |      Appraisal results   |                    |
   |  Trusted Path     +-------------------------^+    Trusted Path    |
   |                   <--------------------------+                    |
   +-------------------+ cross-domain trusted link+--------------------+

     Figure 4: a trusted link is formed between ISPs in RATS






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4.  Requirements of trusted link

   From the operator's point of view, a more secure link capability will
   be more competitive for external service.  Therefore, Operators
   attach great importance to the innate security of links, the links
   innate security highly relied on each networking device that is the
   routing equipment.

4.1.  New equipment into the network

   How to add a new device to the network without the consideration of
   trustworthiness? new routing devices go through four steps before
   they are actually added to the network, step 1: manually configure
   the IP address; step 2: discovery device by broadcast protocol; step
   3: Verify the identity of the device; step 4: Device Manager issues
   routing configuration policies.  After completing these four steps,
   the route neighbor is formed.

              +------------+
      +-------+Orchestrator+---------+
      |       +----+--+----+         |
      |            |  ^              |
      |       step2|  |step3         |
      |       step4|  |              |
      |            v  |              |
   +--+-+         ++--++          +--+-+
   | RT |         | RT |step1     | RT |
   +----+         +----+          +----+
                   NEW
   Figure 5-1: a new router added to network

   How to add a new device to the network with the consideration of
   devices' trustworthiness?  A trusted link has been formed by default,
   when a new equipment apply to join the network, new router should
   provide evidences to the verifier, the orchestrator play the role of
   verifier, and feed back the attestation result back to the new
   router, it depends on the implementation.  Provision of evidence and
   trustworthiness assessment actually happens in the Step3 which
   described in the figure above.  After complete the trustworthiness
   assessment, the orchestrator forms routing policies based on the
   trustworthiness and issues them, the trusted link establishment is
   complete.









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          +------------------------------------+
          |                                    |
          | +------------+                     |
    Step3 | |            |       Result +----+ |
          | |Ochestrator +<-------------> RT | |
          | +-----+------+  evidence    +----+ |
          |       |                       NEW  |
          +------------------------------------+
                  |
   +--------------+--------------------------+
   |  +----+         +----+          +----+  |
   |  | RT +---------+ RT +----------+ RT |  |
   |  +----+   1     +----+     2    +----+  |
   +-----------------------------------------+
               Trusted link

   Figure 5-2: a new router added to network

4.2.  Device status updating

   How to maintain the freshness of trusted links for the network is
   always under threat of attack when need to form a trusted link to
   provide to the user for transmission.  The Ochestrator can collect
   routing information in real time or periodically, including device
   information, log information, fault information, and trusty measure
   vendors.  Then Ochestrator forms a path link based on users'
   trustworthiness requirements while the whole network has fault
   convergence.

               +-----------+
               |Ochestrator|
               +-+--+---+--+
                 ^  ^   ^
                 |  |   |
      +----------+  |   +-----------+
      |          evidence           |
      |             |               |
   +--+-+         +-+--+          +-+--+
   | RT +---------+ RT +----------+ RT |
   +----+   1     +----+     2    +----+

                Trusted link

   Figure 6: a new router added to network







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5.  Security Considerations

   TBD

6.  IANA Considerations

   This document does not require any action from IANA.

7.  Acknowledgement

   TBD

8.  Informative References

   [I-D.ietf-rats-architecture]
              Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
              W. Pan, "Remote Attestation Procedures Architecture",
              draft-ietf-rats-architecture-08 (work in progress),
              December 2020.

Authors' Addresses

   Meiling Chen
   China Mobile
   32, Xuanwumen West
   BeiJing, BeiJing  100053
   China

   Email:
            chenmeiling@chinamobile.com


   Li Su
   China Mobile

               32, Xuanwumen West


               BeiJing

               100053


               China


   Email:
             suli@chinamobile.com



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