Internet DRAFT - draft-ietf-teep-otrp-over-http
draft-ietf-teep-otrp-over-http
TEEP WG D. Thaler
Internet-Draft Microsoft
Intended status: Standards Track 27 March 2023
Expires: 28 September 2023
HTTP Transport for Trusted Execution Environment Provisioning: Agent
Initiated Communication
draft-ietf-teep-otrp-over-http-15
Abstract
The Trusted Execution Environment Provisioning (TEEP) Protocol is
used to manage code and configuration data in a Trusted Execution
Environment (TEE). This document specifies the HTTP transport for
TEEP communication where a Trusted Application Manager (TAM) service
is used to manage code and data in TEEs on devices that can initiate
communication to the TAM.
Status of This Memo
This Internet-Draft is submitted 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 https://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 28 September 2023.
Copyright Notice
Copyright (c) 2023 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 (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. TEEP Broker . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Use of Abstract APIs . . . . . . . . . . . . . . . . . . 5
4. Use of HTTP as a Transport . . . . . . . . . . . . . . . . . 5
5. TEEP/HTTP Client Behavior . . . . . . . . . . . . . . . . . . 6
5.1. Receiving a request to install a new Trusted
Application . . . . . . . . . . . . . . . . . . . . . . . 6
5.1.1. Session Creation . . . . . . . . . . . . . . . . . . 7
5.2. Receiving a notification that a Trusted Application is no
longer needed . . . . . . . . . . . . . . . . . . . . . . 7
5.3. Getting a TAM URI and message back from a TEEP Agent . . 8
5.4. Receiving an HTTP response . . . . . . . . . . . . . . . 8
5.5. Handling checks for policy changes . . . . . . . . . . . 9
5.6. Error handling . . . . . . . . . . . . . . . . . . . . . 10
6. TEEP/HTTP Server Behavior . . . . . . . . . . . . . . . . . . 10
6.1. Receiving an HTTP POST request . . . . . . . . . . . . . 10
6.2. Getting an empty message back from the TAM . . . . . . . 11
6.3. Getting a message from the TAM . . . . . . . . . . . . . 11
6.4. Error handling . . . . . . . . . . . . . . . . . . . . . 11
7. Sample message flow . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
A Trusted Execution Environment (TEE) is an environment that enforces
that any code within that environment cannot be tampered with, and
that any data used by such code cannot be read or tampered with by
any code outside that environment. The Trusted Execution Environment
Provisioning (TEEP) protocol is designed to provision authorized code
and configuration into TEEs.
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To be secure against malware, a TEEP implementation (referred to as a
TEEP "Agent" on the client side is expected to run inside a TEE, and
a "Trusted Application Manager (TAM)" on the server side) might or
might not run inside a TEE. However, the transport for TEEP, along
with the underlying TCP/IP stack, does not necessarily run inside a
TEE. This split allows the set of highly trusted code to be kept as
small as possible, including allowing code (e.g., TCP/IP or QUIC
[RFC9000]) that only sees encrypted messages, to be kept out of the
TEE. See section 6.2 of [I-D.ietf-teep-architecture] for a depiction
of various implementation models.
The TEEP specification [I-D.ietf-teep-protocol] describes the
behavior of TEEP Agents and TAMs, but does not specify the details of
the transport. The purpose of this document is to provide such
details. That is, a TEEP-over-HTTP (TEEP/HTTP) implementation
delivers messages up to a TEEP implementation, and accepts messages
from the TEEP implementation to be sent over a network. The TEEP-
over-HTTP implementation can be implemented either outside a TEE
(i.e., in a TEEP "Broker") or inside a TEE.
There are two topological scenarios (among others) in which TEEP
could be deployed:
1. TAMs are reachable on the Internet, and Agents are on networks
that might be behind a firewall or stateful NAT, so that
communication must be initiated by an Agent. Thus, the Agent has
an HTTP Client and the TAM has an HTTP Server.
2. Agents are reachable on the Internet, and TAMs are on networks
that might be behind a firewall or stateful NAT, so that
communication must be initiated by a TAM. Thus, the Agent has an
HTTP Server and the TAM has an HTTP Client.
The remainder of this document focuses primarily on the first
scenario as depicted in Figure 1, but some sections (Section 4 and
Section 8) may apply to the second scenario as well. A more complete
discussion of the second scenario may be handled by a separate
document.
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+------------------+ TEEP +------------------+
| TEEP Agent | <----------------------> | TAM |
+------------------+ +------------------+
| |
+------------------+ TEEP-over-HTTP +------------------+
| TEEP/HTTP Client | <----------------------> | TEEP/HTTP Server |
+------------------+ +------------------+
| |
+------------------+ HTTP +------------------+
| HTTP Client | <----------------------> | HTTP Server |
+------------------+ +------------------+
Figure 1: Agent Initiated Communication
This document specifies the middle layer (TEEP-over-HTTP), whereas
the top layer (TEEP) is specified in [I-D.ietf-teep-protocol] and the
bottom layer (HTTP) is specified in [RFC9110].
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document also uses various terms defined in
[I-D.ietf-teep-architecture], including Trusted Execution Environment
(TEE), Trusted Application (TA), Trusted Application Manager (TAM),
TEEP Agent, TEEP Broker, and Rich Execution Environment (REE).
3. TEEP Broker
Section 6 of the TEEP architecture [I-D.ietf-teep-architecture]
defines a TEEP "Broker" as being a component on the device, but
outside the TEE, that facilitates communication with a TAM. That
document further explains that the protocol layer at which the TEEP
broker operates may vary by implementation, and it depicts several
exemplary models. An implementation is free to choose any of these
models, although model A is the one we will use in our examples.
Passing information from an REE component to a TEE component is
typically spoken of as being passed "in" to the TEE, and information
passed in the opposite direction is spoken of as being passed "out".
In the protocol layering sense, information is typically spoken of as
being passed "up" or "down" the stack. Since the layer at which
information is passed in/out may vary by implementation, we will
generally use "up" and "down" in this document.
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3.1. Use of Abstract APIs
This document refers to various APIs between a TEEP implementation
and a TEEP/HTTP implementation in the abstract, meaning the literal
syntax and programming language are not specified, so that various
concrete APIs can be designed (outside of the IETF) that are
compliant.
Some TEE architectures (e.g., SGX) may support API calls both into
and out of a TEE. In other TEE architectures, there may be no calls
out from a TEE, but merely data returned from calls into a TEE. This
document attempts to be agnostic as to the concrete API architecture
for Broker/Agent communication. Since in model A, the Broker/Agent
communication is done at the layer between the TEEP and TEEP/HTTP
implementations, and there may be some architectures that do not
support calls out of the TEE (which would be downcalls from TEEP in
model A), we will refer to passing information up to the TEEP
implementation as API calls, but will simply refer to "passing data"
back down from a TEEP implementation. A concrete API might pass data
back via an API downcall or via data returned from an API upcall.
This document will also refer to passing "no" data back out of a TEEP
implementation. In a concrete API, this might be implemented by not
making any downcall, or by returning 0 bytes from an upcall, for
example.
4. Use of HTTP as a Transport
This document uses HTTP [RFC9110] as a transport. For the motivation
behind the HTTP recommendations in this document, see the discussion
of HTTP as a transport in [RFC9205].
Redirects MUST NOT be automatically followed. Cookies are not used.
Content is not intended to be treated as active by browsers and so
HTTP responses with content MUST have the following header fields as
explained in Section 4.13 of [RFC9205] (using the TEEP media type
defined in [I-D.ietf-teep-protocol]):
Content-Type: application/teep+cbor
X-Content-Type-Options: nosniff
Content-Security-Policy: default-src 'none'
Referrer-Policy: no-referrer
Only the POST method is specified for TAM resources exposed over
HTTP. Since POST responses without explicit freshness information
are uncacheable (see Section 9.3.3 of [RFC9110]), the Cache-Control
header MUST NOT be used.
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A URI of such a resource is referred to as a "TAM URI". A TAM URI
can be any HTTP(S) URI. The URI to use is configured in a TEEP Agent
via an out-of-band mechanism, as discussed in the next section.
It is RECOMMENDED that implementations use HTTPS. Although TEEP is
protected end-to-end inside of HTTP, there is still value in using
HTTPS for transport, since HTTPS can provide additional protections
as discussed in Section 6 of [RFC9205].
However, there may be constrained nodes where code space is an issue.
[RFC7925] provides TLS profiles that can be used in many constrained
nodes, but in rare cases the most constrained nodes might need to use
HTTP without a TLS stack, relying on the end-to-end security provided
by the TEEP protocol. See Sections 4.4.2 and 6 of [RFC9205] for more
discussion of additional security considerations that apply in this
case.
When HTTPS is used, clients MUST use the procedures detailed in
Section 4.3.4 of [RFC9110] to verify the authenticity of the server.
See [BCP195] for additional TLS recommendations and [RFC7925] for TLS
recommendations related to IoT devices.
5. TEEP/HTTP Client Behavior
5.1. Receiving a request to install a new Trusted Application
In some environments, an application installer can determine (e.g.,
from an application manifest) that the application being installed or
updated has a dependency on a given Trusted Application (TA) being
available in a given type of TEE. In such a case, it will notify a
TEEP Broker, where the notification will contain the following:
* A unique identifier of the TA
* Optionally, any metadata to provide to the TEEP Agent. This might
include a TAM URI provided in the application manifest, for
example.
* Optionally, any requirements that may affect the choice of TEE, if
multiple are available to the TEEP Broker.
When a TEEP Broker receives such a notification, it first identifies
in an implementation-dependent way which TEE (if any) is most
appropriate based on the constraints expressed. If there is only one
TEE, the choice is obvious. Otherwise, the choice might be based on
factors such as capabilities of available TEE(s) compared with TEE
requirements in the notification. Once the TEEP Broker picks a TEE,
it passes the notification to the TEEP/HTTP Client for that TEE.
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The TEEP/HTTP Client then informs the TEEP Agent in that TEE by
invoking an appropriate "RequestTA" API that identifies the TA needed
and any other associated metadata. The TEEP/HTTP Client need not
know whether the TEE already has such a TA installed or whether it is
up to date.
The TEEP Agent will either (a) pass no data back, (b) pass back a TAM
URI to connect to, or (c) pass back a message and TAM URI to send it
to. The TAM URI passed back may or may not be the same as the TAM
URI, if any, provided by the TEEP/HTTP Client, depending on the TEEP
Agent's configuration. If they differ, the TEEP/HTTP Client MUST use
the TAM URI passed back.
5.1.1. Session Creation
If no data is passed back, the TEEP/HTTP Client simply informs its
caller (e.g., the application installer) of success.
If the TEEP Agent passes back a TAM URI with no message, the TEEP/
HTTP Client attempts to create session state, then sends an HTTP(S)
POST to the TAM URI with an Accept header field with the TEEP media
type specified in [I-D.ietf-teep-protocol], and an empty body. The
HTTP request is then associated with the TEEP/HTTP Client's session
state.
If the TEEP Agent instead passes back a TAM URI with a message, the
TEEP/HTTP Client attempts to create session state and handles the
message as specified in Section 5.3.
Session state consists of:
* Any context (e.g., a handle) that the TEEP Agent wishes to be
provided back to it in any later conceptual API calls into it
related to this session.
* Any context that identifies an HTTP request, if one is
outstanding. Initially, none exists.
5.2. Receiving a notification that a Trusted Application is no longer
needed
In some environments, an application installer can determine (e.g.,
from an application manifest) that a given Trusted Application is no
longer needed, such as if the application that previously depended on
the TA is uninstalled or updated in a way that removes the
dependency. In such a case, it will notify a TEEP Broker, where the
notification will contain the following:
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* A unique identifier of the TA
* Optionally, any metadata to provide to the TEEP Agent. This might
include a TAM URI provided in the original application manifest,
for example.
* Optionally, any requirements that may affect the choice of TEE, if
multiple are available to the TEEP Broker.
When a TEEP Broker receives such a notification, it first identifies
in an implementation-dependent way which TEE (if any) is believed to
contain the TA that is no longer needed, similar to the process in
Section 5.1. Once the TEEP Broker picks a TEE, it passes the
notification to the TEEP/HTTP Client for that TEE.
The TEEP/HTTP Client then informs the TEEP Agent in that TEE by
invoking an appropriate "UnrequestTA" API that identifies the
unneeded TA. The TEEP/HTTP Client need not know whether the TEE
actually has the TA installed.
Finally, the TEEP Agent responds to the TEEP/HTTP Client as in
Section 5.1. Specifically, the TEEP Agent will either (a) pass no
data back, (b) pass back a TAM URI to connect to, or (c) pass back a
message and TAM URI to send it to. The TAM URI passed back may or
may not be the same as the TAM URI, if any, provided by the TEEP/HTTP
Client, depending on the TEEP Agent's configuration. If they differ,
the TEEP/HTTP Client MUST use the TAM URI passed back.
Processing then continues as in Section 5.1.1.
5.3. Getting a TAM URI and message back from a TEEP Agent
When a TEEP Agent passes a TAM URI and optionally a message to a
TEEP/HTTP Client, the TEEP/HTTP Client MUST do the following, using
the TEEP/HTTP Client's session state associated with its API call to
the TEEP Agent.
The TEEP/HTTP Client sends an HTTP POST request to the TAM URI with
Accept and Content-Type header fields with the TEEP media type, and a
body containing the TEEP message (if any) provided by the TEEP Agent.
The HTTP request is then associated with the TEEP/HTTP Client's
session state.
5.4. Receiving an HTTP response
When an HTTP response is received in response to a request associated
with a given session state, the TEEP/HTTP Client MUST do the
following.
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If the HTTP response body is empty, the TEEP/HTTP Client's task is
complete, and it can delete its session state, and its task is done.
If instead the HTTP response body is not empty, the TEEP/HTTP Client
passes (e.g., using the "ProcessTeepMessage" API as mentioned in
Section 6.2.1 of [I-D.ietf-teep-architecture]) the response body up
to the TEEP Agent associated with the session. The TEEP Agent will
then either pass no data back, or pass back a message.
If no data is passed back, the TEEP/HTTP Client's task is complete,
and it can delete its session state, and inform its caller (e.g., the
application installer) of success.
If instead the TEEP Agent passes back a message, the TEEP/HTTP Client
handles the message as specified in Section 5.3.
5.5. Handling checks for policy changes
An implementation MUST provide a way to periodically check for TAM
policy changes, such as a Trusted Application needing to be deleted
from a TEE because it is no longer permitted, or needing to be
updated to a later version. This can be done in any implementation-
specific manner, such as any of the following or a combination
thereof:
A) The TEEP/HTTP Client might call up to the TEEP Agent at an
interval previously specified by the TEEP Agent. This approach
requires that the TEEP/HTTP Client be capable of running a periodic
timer.
B) The TEEP/HTTP Client might be informed when an existing TA is
invoked, and call up to the TEEP Agent if more time has passed than
was previously specified by the TEEP Agent. This approach allows the
device to go to sleep for a potentially long period of time.
C) The TEEP/HTTP Client might be informed when any attestation
attempt determines that the device is out of compliance, and call up
to the TEEP Agent to remediate.
The TEEP/HTTP Client informs the TEEP Agent by invoking an
appropriate "RequestPolicyCheck" API. The TEEP Agent will either (a)
pass no data back, (b) pass back a TAM URI to connect to, or (c) pass
back a message and TAM URI to send it to. Processing then continues
as specified in Section 5.1.1.
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The TEEP Agent might need to talk to multiple TAMs, however, as shown
in Figure 1 of [I-D.ietf-teep-architecture]. To accomplish this, the
TEEP/HTTP Client keeps invoking the "RequestPolicyCheck" API until
the TEEP Agent passes no data back, so that the TEEP Agent can return
each TAM URI in response to a separate API call.
5.6. Error handling
If any local error occurs where the TEEP/HTTP Client cannot get a
message (empty or not) back from the TEEP Agent, the TEEP/HTTP Client
deletes its session state, and informs its caller (if any, e.g., the
application installer) of a failure. Note that no timeout check is
used at the TEEP/HTTP Client layer; any timeout would be done inside
the TEEP Agent.
If any HTTP request results in an HTTP error response or a lower
layer error (e.g., network unreachable), the TEEP/HTTP Client calls
the TEEP Agent's "ProcessError" API, and then deletes its session
state and informs its caller of a failure.
6. TEEP/HTTP Server Behavior
6.1. Receiving an HTTP POST request
If the TAM does not receive the appropriate Content-Type header field
value, the TAM SHOULD fail the request, returning a 415 Unsupported
Media Type response. Similarly, if an appropriate Accept header
field is not present, the TAM SHOULD fail the request with an
appropriate error response. (This is for consistency with common
implementation practice to allow the HTTP server to choose a default
error response, since in some implementations the choice is done at
the HTTP layer rather than the layer at which TEEP-over-HTTP would be
implemented.) Otherwise, processing continues as follows.
When an HTTP POST request is received with an empty body, this
indicates a request for a new TEEP session, and the TEEP/HTTP Server
invokes the TAM's "ProcessConnect" API. The TAM will then pass back
a message.
When an HTTP POST request is received with a non-empty body, this
indicates a message on an existing TEEP session, and the TEEP/HTTP
Server passes the request body to the TAM (e.g., using the
"ProcessTeepMessage" API mentioned in [I-D.ietf-teep-architecture]).
The TAM will then pass back a (possibly empty) message.
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6.2. Getting an empty message back from the TAM
If the TAM passes back an empty message, the TEEP/HTTP Server sends a
successful (2xx) response with no body. It SHOULD be status 204 (No
Content).
6.3. Getting a message from the TAM
If the TAM passes back a non-empty message, the TEEP/HTTP Server
generates a successful (2xx) response with a Content-Type header
field with the TEEP media type, and with the message as the body.
6.4. Error handling
If any error occurs where the TEEP/HTTP Server cannot get a message
(empty or not) back from the TAM, the TEEP/HTTP Server generates an
appropriate HTTP 5xx error response. Note that no timeout check is
used at the TEEP/HTTP Client layer; any timeout would be handled
inside the TEEP Agent.
7. Sample message flow
The following shows a sample TEEP message flow that uses application/
teep+cbor as the Content-Type.
1. An application installer determines (e.g., from an application
manifest) that the application has a dependency on TA "X", and
passes this notification to the TEEP Broker. The TEEP Broker
picks a TEE (e.g., the only one available) based on this
notification, and passes the information to the TEEP/HTTP Client
for that TEE.
2. The TEEP/HTTP Client calls the TEEP Agent's "RequestTA" API,
passing TA Needed = X.
3. The TEEP Agent finds that no such TA is already installed, but
that it can be obtained from a given TAM. The TEEP Agent passes
back the TAM URI (e.g., "https://example.com/tam") to the TEEP/
HTTP Client.
4. The TEEP/HTTP Client sends an HTTP POST request to the TAM URI:
POST /tam HTTP/1.1
Host: example.com
Accept: application/teep+cbor
Content-Length: 0
User-Agent: Foo/1.0
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where the TEEP/HTTP Client fills in an implementation-specific
value in the User-Agent header field.
5. On the TAM side, the TEEP/HTTP Server receives the HTTP POST
request, and calls the TAM's "ProcessConnect" API.
6. The TAM generates a TEEP message (where typically QueryRequest
is the first message) and passes it to the TEEP/HTTP Server.
7. The TEEP/HTTP Server sends an HTTP successful response with the
TEEP message in the body:
HTTP/1.1 200 OK
Content-Type: application/teep+cbor
Content-Length: [length of TEEP message here]
Server: Bar/2.2
X-Content-Type-Options: nosniff
Content-Security-Policy: default-src 'none'
Referrer-Policy: no-referrer
[TEEP message here]
where the TEEP/HTTP Server fills in an implementation-specific
value in the Server header field.
8. Back on the TEEP Agent side, the TEEP/HTTP Client gets the HTTP
response, extracts the TEEP message and passes it up to the TEEP
Agent.
9. The TEEP Agent processes the TEEP message, and generates a TEEP
response (e.g., QueryResponse) which it passes back to the TEEP/
HTTP Client.
10. The TEEP/HTTP Client gets the TEEP message and sends an HTTP
POST request to the TAM URI, with the TEEP message in the body:
POST /tam HTTP/1.1
Host: example.com
Accept: application/teep+cbor
Content-Type: application/teep+cbor
Content-Length: [length of TEEP message here]
User-Agent: Foo/1.0
[TEEP message here]
11. The TEEP/HTTP Server receives the HTTP POST request, and passes
the payload up to the TAM.
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12. Steps 6-11 are then repeated until the TAM passes no data back
to the TEEP/HTTP Server in step 6.
13. The TEEP/HTTP Server sends an HTTP successful response with no
body:
HTTP/1.1 204 No Content
Server: Bar/2.2
14. The TEEP/HTTP Client deletes its session state.
8. Security Considerations
Section 4 discussed security recommendations for HTTPS transport of
TEEP messages. See Section 6 of [RFC9205] for additional discussion
of HTTP(S) security considerations. See section 9 of
[I-D.ietf-teep-architecture] for security considerations specific to
the use of TEEP. See Section 7 of [RFC3986] for security
considerations on dereferencing URIs.
9. IANA Considerations
This document has no actions for IANA.
10. References
10.1. Normative References
[BCP195] Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/rfc/rfc9325>.
[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-12, 13 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-teep-
protocol-12>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
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[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>.
[RFC7925] Tschofenig, H., Ed. and T. Fossati, "Transport Layer
Security (TLS) / Datagram Transport Layer Security (DTLS)
Profiles for the Internet of Things", RFC 7925,
DOI 10.17487/RFC7925, July 2016,
<https://www.rfc-editor.org/rfc/rfc7925>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/rfc/rfc9110>.
10.2. Informative References
[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, 24 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-teep-
architecture-19>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/rfc/rfc9000>.
[RFC9205] Nottingham, M., "Building Protocols with HTTP", BCP 56,
RFC 9205, DOI 10.17487/RFC9205, June 2022,
<https://www.rfc-editor.org/rfc/rfc9205>.
Author's Address
Dave Thaler
Microsoft
Email: dthaler@microsoft.com
Thaler Expires 28 September 2023 [Page 14]
