Internet-Draft teep usecase for CC in network July 2023
Yang, et al. Expires 5 January 2024 [Page]
Workgroup:
TEEP Working Group
Internet-Draft:
draft-ietf-teep-usecase-for-cc-in-network-04
Published:
Intended Status:
Informational
Expires:
Authors:
P. Yang
China Mobile
M. Chen
China Mobile
L. Su
China Mobile
T. Pang
Huawei Technology Co.,Ltd.

TEEP Usecase for Confidential Computing in Network

Abstract

Confidential computing is the protection of data in use by performing computation in a hardware-based Trusted Execution Environment. Confidential computing could provide integrity and confidentiality for users who want to run applications and process data in that environment. When confidential computing is used in scenarios which need network to provision user data and applications in the TEE environment, TEEP architecture[I-D.ietf-teep-architecture] and protocol [I-D.ietf-teep-protocol] could be used. This document focuses on using TEEP to provision Network User data and applications in confidential computing. This document is a use case and extension of TEEP and could provide guidance for cloud computing, [MEC] and other scenarios to use confidential computing in network.

Status of This Memo

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

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This Internet-Draft will expire on 5 January 2024.

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Table of Contents

1. Introduction

The Confidential Computing Consortium defined the concept of confidential computing as the protection of data in use by performing computation in a hardware-based Trusted Execution Environment [CCC-White-Paper]. In detail, computing unit with confidential computing feature could generate an isolated hardware-protected area, in which data and applications will be protected from illegal access or tampering. When using network to provision confidential computing environment, users need to attest and deploy their data and applications in the TEE environment inside confidential computing device by network. This network could be a cloud, MEC or other network that provide confidential computing resource to users. For example in MEC, the autonomous vehicles could deploy private applications and data on confidential computing device to calculate on-vehicle and destination road information without knowing by MEC platform.

The TEEP WG defined the standardization of an architecture and protocol for managing the lifecycle of trusted applications running inside a TEE. In confidential computing, the TEE can also be provisioned and managed by TEEP architecture and protocol.

This document illustrates how a network user uses the TEEP protocol to provision its private data and applications in confidential computing device. The intended audiences for this use case are network users and operators who are interested in using confidential computing in network.

2. Terminology

2.1. Terms

The following terms are used in this document.

  • Network Management/Orchestration Center(Network M/OC): M/OC exists in the management and orchestration layer of network. Network User uses the M/OC to request for computing resource. The TAM is inside the M/OC to provide management function to TEEP Agent via TEEP broker.
  • Network User: Network User possesses personalization data and applications that need to be deployed on confidential computing device.
  • Confidential Computing Device: Confidential Computing Device is connected by the network and can provide confidential computing service to Network User.
  • Package: Package is a unit that is owned by Network User and could be deployed on TEE/REE or treated as application data. TA (Trusted Application) in confidential computing could be an application, or packaged with other components like library, TEE shim or even Guest OS. The specific package of confidential computing could refers to the white paper of [CCC_Common_Terminology] by CCC.
  • Personalization Data(PD): Data that holds by Network User and needs to be protected by TEE during processing. Other terms like TAM, TEE, REE, TA will reuse the term definition defined in [I-D.ietf-teep-architecture].

2.2. Requirements Language

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 RFC 2119 [RFC2119].

3. Notional Architecture of using confidential computing in network

Figure 1 is the architecture of confidential computing in network. Two new components Network User and Network M/OC are introduced in this document. The connection between Network User and M/OC depends on the implementation of specific network. The connection between network user and UA (Untrusted Application) or TA depends on the implementation of application. The connection between TAM, TEEP Broker and TEEP Agent refers to the TEEP protocol. Interactions of all components in this scenario are described in the Usecase section.

+--------------------------------------+
| Confidential Computing Device        |
|                       +--------+     |   +------------+
|  +-------------+      |        |     |   |Network M/OC|
|  | TEE         |      | TEEP   |     |   | +-------+  |
|  | +--------+  |  +---> Broker <----------->       |  |
|  | | TEEP   |  |  |   |        |     |   | |  TAM  |  |
|  | | Agent  |<----+   |        |     |   | |       |  |
|  | +--------+  |      |        <--+  |   | +---^---+  |
|  |             |      +--------+  |  |   +-----|------+
|  | +--------+  |                  |  |         |
|  | |   TA   |  |      +-------+   |  |         |
|  | |        |<-------->       |<--+  |         |
|  | +--------+  |      |  UA   |      |   +-----V------+
|  +-------------+      |       |<--------->Network User|
|                       +-------+      |   | (Package)  |
+--------------------------------------+   +------------+
Figure 1: notional architecture of confidential computing in network

4. Use Cases

The basic process of how a Network User utilizes confidential computing is shown below. At present, the main instances types exist in industry of confidential computing are confidential process, confidential container and confidential VM. The following use cases are possible packaging models.

4.1. Case 1: UA, TA and PD are bundled as a package

In this case, UA, TA and PD are bundled as a package. If Network User provides this package, the process of TEEP is as follow.

  1. Network User requests for confidential computing resource to Network M/OC.
  2. M/OC orchestrates confidential computing device to undertake the request.
  3. TAM requests remote attestation to TEEP Agent, TEEP Agent then sends the evidence to TAM. TAM works as Verifier in [RFC9334].
  4. After verification, Network User works as Relying Party to receive the attestation result. If positive, Network User establishes secure channel [NIST-Special-Publication-800-133-V2] with TEEP Agent, and transfers this package to TEEP Agent.
  5. TEEP Agent deploys TA and personalization data in TEE, then deploy UA in REE.

As for informing Network Users to develop their applications and data, the mapping of UA, TA and implementations are shown in figure 2. This document gathers the main hardware architectures that support confidential computing, which include [TrustZone], [SGX], [SEV-SNP], [CCA] and [TDX]. The brace means the operation steps to deploy packages. The arrow means deploy package to a destination. The "att" means attestation challenge for the target.

+-------------+--------------------------------------------------+
|Package Mode |                Case 1 (UA, TA, PD)               |
+-------------+----------------+----------------+----------------+
|             |  Confidential  |  Confidential  |                |
|  Instance   |   Process in   |  Container in  |  Confidential  |
|    Type     |   Physical or  |  Physical or   |       VM       |
|             | Virtual Machine| Virtual Machine|                |
+-------------+----------------+----------------+----------------+
|  Hardware   |   TrustZone,   |  TrustZone,SGX,|                |
| Architecture|      SGX       |  SEV-SNP, CCA, | SEV-SNP,CCA,TDX|
|             |                |      TDX       |                |
+-------------+----------------+----------------+----------------+
|             |{att TEEP Agent,|{att TEEP Agent,|{att TEEP Agent,|
|    Load     |  (UA,TA,PD)->  |  (UA,TA,PD)->  |  (UA,TA,PD)->  |
|  Sequence   |  Confidential  |  Confidential  |  Confidential  |
|             |    Process,    |   Container,   |       VM,      |
|             |    UA->REE}    |    UA->REE}    |    UA->REE}    |
+-------------+----------------+----------------+----------------+
Figure 2: TEEP Implementation of Case 1

4.2. Case 2: PD is a separate package, TA and UA are integrated

In this use case, PD is a separate package, the UA and TA are integrated as a package. If Network User provides packages like this, the process of TEEP is as follow.

  1. Network User requests for confidential computing resource to Network M/OC.
  2. M/OC orchestrates confidential computing device to undertake the request.
  3. Network User transfers UA and TA to confidential computing device via TAM. TAM then deploys these two applications in REE and TEE respectively. (In SGX, UA must be deployed first, then let UA to load TA in SGX.)
  4. TAM requests remote attestation to TEEP Agent, TEEP Agent then sends the evidence to TAM. TAM works as Verifier in RATs architecture.
  5. After verification, Network User works as Relying Party to receive the attestation result. If positive, Network User establishes secure channel with TA, and deploys personalization data to TA.

The mapping of UA, TA and implementations are shown in figure 3.

+-------------+--------------------------------------------------+
|Package Mode |               Case 2 (UA, TA) (PD)               |
+-------------+----------------+----------------+----------------+
|             |  Confidential  |  Confidential  |                |
|  Instance   |   Process in   |  Container in  |  Confidential  |
|    Type     |   Physical or  |  Physical or   |       VM       |
|             | Virtual Machine| Virtual Machine|                |
+-------------+----------------+----------------+----------------+
|  Hardware   |    TrustZone,  | TrustZone, SGX,|                |
| Architecture|      SGX       |  SEV-SNP, CCA, |   SEV,CCA,TDX  |
|             |                |      TDX       |                |
+-------------+----------------+----------------+----------------+
|             |   {UA->REE,    |    {UA->REE,   |   {UA->REE,    |
|             |TA->Confidential|TA->Confidential|TA->Confidential|
|    Load     |    Process,    |   Container,   |       VM,      |
|  Sequence   | att TEEP Agent,| att TEEP Agent,| att TEEP Agent,|
|             |    PD->TA}     |    PD->TA}     |     PD->TA}    |
+-------------+----------------+----------------+----------------+
Figure 3: TEEP Implementation of Case 2

4.3. Case 3: TA and PD are bundled as a package, with or without UA

In this case, the process of TEEP is as follow.

  1. Network User requests for confidential computing resource to Network M/OC.
  2. TAM in M/OC orchestrates confidential computing device to undertake the request.
  3. If there has UA, Network User deploys UA in REE.
  4. TAM requests remote attestation to TEEP Agent, TEEP Agent then sends the evidence to TAM. The TAM works as Verifier in RATs architecture.
  5. After verification, Network User works as Relying Party to receive the attestation result. If positive, Network User establishes secure channel with TEEP Agent and transfers TA and PD package to TEEP Agent. 
+-------------+--------------------------------------------------+
|Package Mode |      Case 3 (TA, PD) (UA) or (TA, PD)            |
+-------------+----------------+----------------+----------------+
|             |  Confidential  |  Confidential  |                |
|  Instance   |   Process in   |  Container in  |  Confidential  |
|    Type     |   Physical or  |  Physical or   |       VM       |
|             | Virtual Machine| Virtual Machine|                |
+-------------+----------------+----------------+----------------+
|  Hardware   |    TrustZone,  | TrustZone, SGX,|                |
| Architecture|      SGX       |  SEV-SNP, CCA, |   SEV,CCA,TDX  |
|             |                |      TDX       |                |
+-------------+----------------+----------------+----------------+
|             |   {UA->REE,    |    {UA->REE,   |    {UA->REE,   |
|    Load     | att TEEP Agent,| att TEEP Agent,| att TEEP Agent,|
|  Sequence   |   (TA,PD)->    |   (TA,PD)->    |    (TA,PD)->   |
|             |  Confidential  |  Confidential  |  Confidential  |
|             |   Process}     |   Container}   |       VM}      |
+-------------+----------------+----------------+----------------+
Figure 4: TEEP Implementation of Case 3

4.4. Case 4: TA and PD are separate packages, with or without UA

In this case, Network User provides TA and PD as separate packages with or without UA. The process of TEEP in this case is as follow.

  1. Network User requests for confidential computing resource to Network M/OC.
  2. TAM in M/OC orchestrates confidential computing device to undertake the request.
  3. Network User transfers UA to TAM, then TAM deploys UA in REE.
  4. Network User transfers TA to TAM, then TAM transfers TA to TEEP Agent.
  5. TAM requests remote attestation to TEEP Agent, TEEP Agent then sends the evidence to TAM. TAM works as Verifier in RATs architecture.
  6. After verification, Network User works as Relying Party to receive the attestation result. If positive, Network User establishes secure channel with TA and transfers PD to it. 
+-------------+--------------------------------------------------+
|Package Mode |        Case 4 (TA),(PD) or (TA),(PD),(UA)        |
+-------------+----------------+----------------+----------------+
|             |  Confidential  |  Confidential  |                |
|  Instance   |   Process in   |  Container in  |  Confidential  |
|    Type     |   Physical or  |  Physical or   |       VM       |
|             | Virtual Machine| Virtual Machine|                |
+-------------+----------------+----------------+----------------+
|  Hardware   |    TrustZone,  | TrustZone, SGX,|   SEV,CCA,TDX  |
| Architecture|      SGX       |  SEV, CCA, TDX |                |
+-------------+----------------+----------------+----------------+
|    Load     |    {UA->REE,   |    {UA->REE,   |   {UA->REE,    |
|  Sequence   |TA->Confidential|TA->Confidential|TA->Confidential|
|             |    Process,    |    Container   |       VM,      |
|             | att TEEP Agent,| att TEEP Agent,| att TEEP Agent,|
|             |    PD->TA}     |    PD->TA}     |    PD->TA}     |
+-------------+----------------+----------------+----------------+
Figure 5: TEEP Implementation of Case 6

5. IANA Considerations

This document does not require actions by IANA.

6. Security Considerations

Besides the security considerations in TEEP architecture, there is no more security and privacy issues in this document.

7. Acknowledgements

TBD

8. References

8.1. Normative Reference

[I-D.ietf-teep-architecture]
Pei, M., Tschofenig, H., Thaler, D., and D. M. Wheeler, "Trusted Execution Environment Provisioning (TEEP) Architecture", Work in Progress, Internet-Draft, draft-ietf-teep-architecture-19, , <https://datatracker.ietf.org/doc/html/draft-ietf-teep-architecture-19>.
[I-D.ietf-teep-protocol]
Tschofenig, H., Pei, M., Wheeler, D. M., Thaler, D., and A. Tsukamoto, "Trusted Execution Environment Provisioning (TEEP) Protocol", Work in Progress, Internet-Draft, draft-ietf-teep-protocol-15, , <https://datatracker.ietf.org/doc/html/draft-ietf-teep-protocol-15>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC9334]
Birkholz, H., Thaler, D., Richardson, M., Smith, N., and W. Pan, "Remote ATtestation procedureS (RATS) Architecture", RFC 9334, DOI 10.17487/RFC9334, , <https://www.rfc-editor.org/info/rfc9334>.

8.2. Informative Reference

[CCA]
ARM, "Arm Confidential Computing Architecture", , <https://www.arm.com/architecture/security-features/arm-confidential-compute-architecture>.
[CCC-White-Paper]
Confidential Computing Consortium, "Confidential Computing: Hardware-Based Trusted Execution for Applications and Data", , <https://confidentialcomputing.io/white-papers-reports/>.
[CCC_Common_Terminology]
Confidential Computing Consortium, "Common Terminology for Confidential Computing", , <https://github.com/confidentialcomputing/governance/blob/main/terminology/commonterminology.md>.
[MEC]
ETSI, "Multi-access Edge Computing (MEC);Framework and Reference Architecture", , <https://www.etsi.org/deliver/etsi_gs/MEC/001_099/003/03.01.01_60/gs_MEC003v030101p.pdf>.
[NIST-Special-Publication-800-133-V2]
NIST, "Recommendation for Cryptographic Key Generation", , <https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-133r2.pdf>.
[SEV-SNP]
Advanced Micro Devices, "AMD SEV-SNP: Strengthening VM-isolation-with-integrity-protection-and-more", , <https://www.amd.com/system/files/TechDocs/SEV-SNP-strengthening-vm-isolation-with-integrity-protection-and-more.pdf>.
[SGX]
Intel, "Overview of Intel Software Guard Extension", , <https://www.intel.com/content/www/us/en/developer/tools/software-guard-extensions/overview.html>.
[TDX]
Intel, "Intel Trust Domain Extensions", , <https://www.intel.com/content/www/us/en/developer/articles/technical/intel-trust-domain-extensions.html>.
[TrustZone]
HUAWEI Technologies, "Kunpeng BoostKit for Confidential Computing TrustZone Kit", , <https://www.hikunpeng.com/document/detail/en/kunpengcctrustzone/overview/kunpengcctrustzone.html>.

Appendix A. Submodules in TEEP Agent

The original design of TEEP only includes TEEP Agent and TA inside TEE. While in confidential computing implementation, other submodules may also be involved in the TEE. In TEEP, these submodules could be covered by TEEP Agent.

In SGX based confidential computing, submodule could provide convenient environment or API in which TA does not have to modify its source code to fit into SGX instructions. Submodules like Gramine and Occlum .etc are examples that could be included in TEEP Agent. If there is no submodule in TEEP Agent, the TA and UA need to be customized applications which fit into the SGX architecture.

In SEV and other architectures that support whole guest VM as a TEE, TEEP Agent doesn't have to use extra submodule to work as a middleware or API. However with some submodules like Enarx which works as a runtime JIT compiler, TA could be deployed in a hardware independent way. In this scenario, TA could be deployed in different hardware architecture without re-compiling.

Authors' Addresses

Penglin Yang
China Mobile
32 Xuanwumen West Street, Xicheng District
Beijing
100053
China
Meiling Chen
China Mobile
32 Xuanwumen West Street, Xicheng District
Beijing
100053
China
Li Su
China Mobile
32 Xuanwumen West Street, Xicheng District
Beijing
100053
China
Ting Pang
Huawei Technology Co.,Ltd.
127 Jinye Road, Yanta District
Xi'an
710077
China