TEEP Usecase for Confidential Computing in Network

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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. 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

## Terms¶

• Network Management/Orchestration Center(Network M/OC): MO/C 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. 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.¶
• 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].¶

3. Architecture

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)  |
+--------------------------------------+   +------------+

4. Use Cases

The basic process of how a Network User utilizes confidential computing is shown below. In confidential computing, the bundle of an UA, TA, and PD refers to case 1,2,3,4 of TEEP architecture section 4.4. Case 5 and 6 are new cases that possible in implementation. At present, the main instances types exist in industry of confidential computing are confidential process, confidential container and confidential VM.¶

+-------------+--------------------------------------------------+
|Package Mode |                Case 1 (UA, TA, PD)               |
+-------------+----------------+----------------+----------------+
|  Instance   |   Process in   |  Container in  |                |
|    Type     |   Physical or  |  Physical or   |       VM       |
|             | Virtual Machine| Virtual Machine|                |
+-------------+----------------+----------------+----------------+
|  Hardware   |                |    TrustZone,  |                |
| Architecture|    TrustZone   |  SEV-SNP, CCA, | SEV-SNP,CCA,TDX|
|             |                |      TDX       |                |
+-------------+----------------+----------------+----------------+
|             |{att TEEP Agent,|{att TEEP Agent,|{att TEEP Agent,|
|    Load     |    TA->TEE,    |  TA->Trsuted   | TA->Trsuted VM |
|  Sequence   |    PD->TA,     |   Container,   |     PD->TA,    |
|             |    UA->REE}    |    PD->TA,     | UA->Untrusted  |
|             |                |    UA->REE}    |       VM}      |
+-------------+----------------+----------------+----------------+

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

+-------------+--------------------------------------------------+
|Package Mode |               Case 4 (TA, PD) (UA)               |
+-------------+----------------+----------------+----------------+
|  Instance   |   Process in   |  Container in  |                |
|    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->untrusted |
|    Load     | att TEEP Agent,| att TEEP Agent,|      VM,       |
|  Sequence   |   TA&PD->TEE}  | TA&PD->trusted | att TEEP Agent,|
|             |                |   Container}   | TA->trusted VM}|
+-------------+----------------+----------------+----------------+

+-------------+--------------------------------------------------+
|Package Mode |                 Case 5 (TA, PD)                  |
+-------------+----------------+----------------+----------------+
|  Instance   |   Process in   |  Container in  |                |
|    Type     |   Physical or  |  Physical or   |       VM       |
|             | Virtual Machine| Virtual Machine|                |
+-------------+----------------+----------------+----------------+
|  Hardware   |    TrustZone,  | TrustZone, SGX,|   SEV,CCA,TDX  |
| Architecture|      SGX       |  SEV, CCA, TDX |                |
+-------------+----------------+----------------+----------------+
|    Load     |{att TEEP Agent,|{att TEEP Agent,|{att TEEP Agent,|
|  Sequence   |   TA&PD->TEE}  | TA&PD->trusted | TA->trusted VM}|
|             |                |   Container}   |                |
+-------------+----------------+----------------+----------------+

+-------------+--------------------------------------------------+
|Package Mode |                 Case 6 (TA), (PD)                |
+-------------+----------------+----------------+----------------+
|  Instance   |   Process in   |  Container in  |                |
|    Type     |   Physical or  |  Physical or   |       VM       |
|             | Virtual Machine| Virtual Machine|                |
+-------------+----------------+----------------+----------------+
|  Hardware   |    TrustZone,  | TrustZone, SGX,|   SEV,CCA,TDX  |
| Architecture|      SGX       |  SEV, CCA, TDX |                |
+-------------+----------------+----------------+----------------+
|    Load     |    {TA->TEE,   | {TA->trusted   |{TA->trusted VM,|
|  Sequence   | att TEEP Agent,|   Container,   | att TEEP Agent,|
|             |     PD->TA}    | att TEEP Agent,|     PD->TA}    |
|             |                |    PD->TA}     |                |
+-------------+----------------+----------------+----------------+

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.¶

Appendix A. Appendix 1 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