draft-ietf-teep-protocol-03.txt   draft-ietf-teep-protocol-04.txt 
TEEP H. Tschofenig TEEP H. Tschofenig
Internet-Draft Arm Ltd. Internet-Draft Arm Ltd.
Intended status: Standards Track M. Pei Intended status: Standards Track M. Pei
Expires: January 14, 2021 Broadcom Expires: May 6, 2021 Broadcom
D. Wheeler D. Wheeler
Intel Intel
D. Thaler D. Thaler
Microsoft Microsoft
A. Tsukamoto A. Tsukamoto
AIST AIST
July 13, 2020 November 2, 2020
Trusted Execution Environment Provisioning (TEEP) Protocol Trusted Execution Environment Provisioning (TEEP) Protocol
draft-ietf-teep-protocol-03 draft-ietf-teep-protocol-04
Abstract Abstract
This document specifies a protocol that installs, updates, and This document specifies a protocol that installs, updates, and
deletes Trusted Applications (TAs) in a device with a Trusted deletes Trusted Applications (TAs) in a device with a Trusted
Execution Environment (TEE). This specification defines an Execution Environment (TEE). This specification defines an
interoperable protocol for managing the lifecycle of TAs. interoperable protocol for managing the lifecycle of TAs.
The protocol name is pronounced teepee. This conjures an image of a The protocol name is pronounced teepee. This conjures an image of a
wedge-shaped protective covering for one's belongings, which sort of wedge-shaped protective covering for one's belongings, which sort of
skipping to change at page 1, line 44 skipping to change at page 1, line 44
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 14, 2021. This Internet-Draft will expire on May 6, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Message Overview . . . . . . . . . . . . . . . . . . . . . . 3 3. Message Overview . . . . . . . . . . . . . . . . . . . . . . 4
4. Detailed Messages Specification . . . . . . . . . . . . . . . 5 4. Detailed Messages Specification . . . . . . . . . . . . . . . 6
4.1. Creating and Validating TEEP Messages . . . . . . . . . . 5 4.1. Creating and Validating TEEP Messages . . . . . . . . . . 6
4.1.1. Creating a TEEP message . . . . . . . . . . . . . . . 5 4.1.1. Creating a TEEP message . . . . . . . . . . . . . . . 6
4.1.2. Validating a TEEP Message . . . . . . . . . . . . . . 6 4.1.2. Validating a TEEP Message . . . . . . . . . . . . . . 6
4.2. QueryRequest . . . . . . . . . . . . . . . . . . . . . . 6 4.2. QueryRequest Message . . . . . . . . . . . . . . . . . . 7
4.3. QueryResponse . . . . . . . . . . . . . . . . . . . . . . 8 4.3. QueryResponse Message . . . . . . . . . . . . . . . . . . 9
4.4. TrustedAppInstall . . . . . . . . . . . . . . . . . . . . 10 4.4. Install Message . . . . . . . . . . . . . . . . . . . . . 12
4.5. TrustedAppDelete . . . . . . . . . . . . . . . . . . . . 11 4.5. Delete Message . . . . . . . . . . . . . . . . . . . . . 13
4.6. Success . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.6. Success Message . . . . . . . . . . . . . . . . . . . . . 14
4.7. Error . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.7. Error Message . . . . . . . . . . . . . . . . . . . . . . 14
5. Mapping of TEEP Message Parameters to CBOR Labels . . . . . . 15 5. Mapping of TEEP Message Parameters to CBOR Labels . . . . . . 17
6. Ciphersuites . . . . . . . . . . . . . . . . . . . . . . . . 15 6. Ciphersuites . . . . . . . . . . . . . . . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16 7. Security Considerations . . . . . . . . . . . . . . . . . . . 18
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
8.1. Media Type Registration . . . . . . . . . . . . . . . . . 18 8.1. Media Type Registration . . . . . . . . . . . . . . . . . 20
8.2. Error Code Registry . . . . . . . . . . . . . . . . . . . 19 8.2. Error Code Registry . . . . . . . . . . . . . . . . . . . 21
8.3. Ciphersuite Registry . . . . . . . . . . . . . . . . . . 19 8.3. Ciphersuite Registry . . . . . . . . . . . . . . . . . . 21
8.4. CBOR Tag Registry . . . . . . . . . . . . . . . . . . . . 19 8.4. CBOR Tag Registry . . . . . . . . . . . . . . . . . . . . 21
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.1. Normative References . . . . . . . . . . . . . . . . . . 20 9.1. Normative References . . . . . . . . . . . . . . . . . . 22
9.2. Informative References . . . . . . . . . . . . . . . . . 21 9.2. Informative References . . . . . . . . . . . . . . . . . 23
A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 21 A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 24
B. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21 B. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24
C. Complete CDDL . . . . . . . . . . . . . . . . . . . . . . . . 21 C. Complete CDDL . . . . . . . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 D. Examples of Diagnostic Notation and Binary Representation . . 27
D.1. Some assumptions in examples . . . . . . . . . . . . . . 27
D.2. QueryRequest Message . . . . . . . . . . . . . . . . . . 28
D.2.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 28
D.2.2. CBOR Binary Representation . . . . . . . . . . . . . 28
D.3. QueryResponse Message . . . . . . . . . . . . . . . . . . 29
D.3.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 29
D.3.2. CBOR Binary Representation . . . . . . . . . . . . . 29
D.4. Install Message . . . . . . . . . . . . . . . . . . . . . 29
D.4.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 29
D.4.2. CBOR Binary Representation . . . . . . . . . . . . . 30
D.5. Success Message (for Install) . . . . . . . . . . . . . . 30
D.5.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 30
D.5.2. CBOR Binary Representation . . . . . . . . . . . . . 30
D.6. Error Message (for Install) . . . . . . . . . . . . . . . 30
D.6.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 30
D.6.2. CBOR binary Representation . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction 1. Introduction
The Trusted Execution Environment (TEE) concept has been designed to The Trusted Execution Environment (TEE) concept has been designed to
separate a regular operating system, also referred as a Rich separate a regular operating system, also referred as a Rich
Execution Environment (REE), from security-sensitive applications. Execution Environment (REE), from security-sensitive applications.
In an TEE ecosystem, device vendors may use different operating In a TEE ecosystem, device vendors may use different operating
systems in the REE and may use different types of TEEs. When systems in the REE and may use different types of TEEs. When TA
application providers or device administrators use Trusted Developers or Device Administrators use Trusted Application Managers
Application Managers (TAMs) to install, update, and delete Trusted (TAMs) to install, update, and delete Trusted Applications (TAs) on a
Applications (TAs) on a wide range of devices with potentially wide range of devices with potentially different TEEs then an
different TEEs then an interoperability need arises. interoperability need arises.
This document specifies the protocol for communicating between a TAM This document specifies the protocol for communicating between a TAM
and a TEEP Agent, involving a TEEP Broker. and a TEEP Agent.
The Trusted Execution Environment Provisioning (TEEP) architecture The Trusted Execution Environment Provisioning (TEEP) architecture
document [I-D.ietf-teep-architecture] has set to provide a design document [I-D.ietf-teep-architecture] provides design guidance and
guidance for such an interoperable protocol and introduces the introduces the necessary terminology.
necessary terminology. Note that the term Trusted Application may
include more than code; it may also include configuration data and
keys needed by the TA to operate correctly.
2. Requirements Language 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This specification re-uses the terminology defined in This specification re-uses the terminology defined in
[I-D.ietf-teep-architecture]. [I-D.ietf-teep-architecture].
As explained in Section 4.4 of that document, the TEEP protocol
treats each TA, any dependencies the TA has, and personalization data
as separate components that are expressed in SUIT manifests, and a
SUIT manifest might contain or reference multiple binaries (see
[I-D.ietf-suit-manifest] for more details).
As such, the term Trusted Component in this document refers to a set
of binaries expressed in a SUIT manifest, to be installed in a TEE.
Note that a Trusted Component may include one or more TAs and/or
configuration data and keys needed by a TA to operate correctly.
Each Trusted Component is uniquely identified by a "component-id"
byte string, such as a 16-byte UUID [RFC4122]. If Concise Software
Identifiers [I-D.ietf-sacm-coswid] are used (e.g., in the suit-coswid
field of SUIT manifests), the component-id value is the CoSWID tag-id
value.
3. Message Overview 3. Message Overview
The TEEP protocol consists of a couple of messages exchanged between The TEEP protocol consists of messages exchanged between a TAM and a
a TAM and a TEEP Agent via a TEEP Broker. The messages are encoded TEEP Agent. The messages are encoded in CBOR and designed to provide
in CBOR and designed to provide end-to-end security. TEEP protocol end-to-end security. TEEP protocol messages are signed by the
messages are signed by the endpoints, i.e., the TAM and the TEEP endpoints, i.e., the TAM and the TEEP Agent, but Trusted Applications
Agent, but trusted applications may as well be encrypted and signed may also be encrypted and signed by a TA Developer or Device
by the service provider. The TEEP protocol not only re-use CBOR but Administrator. The TEEP protocol not only uses CBOR but also the
also the respective security wrapper, namely COSE [RFC8152]. respective security wrapper, namely COSE [RFC8152]. Furthermore, for
Furthermore, for attestation the Entity Attestation Token (EAT) software updates the SUIT manifest format [I-D.ietf-suit-manifest] is
[I-D.ietf-rats-eat] and for software updates the SUIT manifest format used, and for attestation the Entity Attestation Token (EAT)
[I-D.ietf-suit-manifest] are re-used. [I-D.ietf-rats-eat] format is supported although other attestation
formats are also permitted.
This specification defines six messages. This specification defines six messages.
A TAM queries a device's current state with a QueryRequest message. A TAM queries a device's current state with a QueryRequest message.
A TEEP Agent will, after authenticating and authorizing the request, A TEEP Agent will, after authenticating and authorizing the request,
report attestation information, list all TAs, and provide information report attestation information, list all Trusted Components, and
about supported algorithms and extensions in a QueryResponse message. provide information about supported algorithms and extensions in a
An error message is returned if the request could not be processed. QueryResponse message. An error message is returned if the request
A TAM will process the QueryResponse message and determine whether could not be processed. A TAM will process the QueryResponse message
subsequent message exchanges to install, update, or delete trusted and determine whether to initiate subsequent message exchanges to
applications shall be initiated. install, update, or delete Trusted Applications.
+------------+ +-------------+ +------------+ +-------------+
| TAM | |TEEP Agent | | TAM | |TEEP Agent |
+------------+ +-------------+ +------------+ +-------------+
QueryRequest -------> QueryRequest ------->
QueryResponse QueryResponse
<------- or <------- or
Error Error
With the TrustedAppInstall message a TAM can instruct a TEEP Agent to With the Install message a TAM can instruct a TEEP Agent to install a
install a TA. The TEEP Agent will process the message, determine Trusted Component. The TEEP Agent will process the message,
whether the TAM is authorized and whether the TA has been signed by determine whether the TAM is authorized and whether the Trusted
an authorized SP. In addition to the binary, the TAM may also Component has been signed by an authorized TA Signer. If the Install
provide personalization data. If the TrustedAppInstall message was message was processed successfully then a Success message is returned
processed successfully then a Success message is returned to the TAM, to the TAM, or an Error message otherwise.
an Error message otherwise.
+------------+ +-------------+ +------------+ +-------------+
| TAM | |TEEP Agent | | TAM | |TEEP Agent |
+------------+ +-------------+ +------------+ +-------------+
TrustedAppInstall ----> Install ---->
Success Success
<---- or <---- or
Error Error
With the TrustedAppDelete message a TAM can instruct a TEEP Agent to With the Delete message a TAM can instruct a TEEP Agent to delete one
delete one or multiple TA(s). A Success message is returned when the or multiple Trusted Components. A Success message is returned when
operation has been completed successfully, and an Error message the operation has been completed successfully, or an Error message
otherwise. otherwise.
+------------+ +-------------+ +------------+ +-------------+
| TAM | |TEEP Agent | | TAM | |TEEP Agent |
+------------+ +-------------+ +------------+ +-------------+
TrustedAppDelete ----> Delete ---->
Success Success
<---- or <---- or
Error Error
4. Detailed Messages Specification 4. Detailed Messages Specification
TEEP messages are protected by the COSE_Sign1 structure. The TEEP TEEP messages are protected by the COSE_Sign1 structure. The TEEP
protocol messages are described in CDDL format [RFC8610] below. protocol messages are described in CDDL format [RFC8610] below.
teep-message => (QueryRequest / {
QueryResponse / teep-message => (query-request /
TrustedAppInstall / query-response /
TrustedAppDelete / install /
Error / delete /
Success ), teep-success /
teep-error ),
} }
4.1. Creating and Validating TEEP Messages 4.1. Creating and Validating TEEP Messages
4.1.1. Creating a TEEP message 4.1.1. Creating a TEEP message
To create a TEEP message, the following steps are performed. To create a TEEP message, the following steps are performed.
1. Create a TEEP message according to the description below and 1. Create a TEEP message according to the description below and
populate it with the respective content. populate it with the respective content.
skipping to change at page 6, line 30 skipping to change at page 7, line 17
supported or that are specified as being ignored when not supported or that are specified as being ignored when not
understood. understood.
5. Follow the steps specified in Section 4 of [RFC8152] ("Signing 5. Follow the steps specified in Section 4 of [RFC8152] ("Signing
Objects") for validating a COSE_Sign1 object. The COSE_Sign1 Objects") for validating a COSE_Sign1 object. The COSE_Sign1
payload is the content of the TEEP message. payload is the content of the TEEP message.
6. Verify that the TEEP message is a valid CBOR map and verify the 6. Verify that the TEEP message is a valid CBOR map and verify the
fields of the TEEP message according to this specification. fields of the TEEP message according to this specification.
4.2. QueryRequest 4.2. QueryRequest Message
A QueryRequest message is used by the TAM to learn information from A QueryRequest message is used by the TAM to learn information from
the TEEP Agent. The TAM can learn the features supported by the TEEP the TEEP Agent, such as the features supported by the TEEP Agent,
Agent, including ciphersuites, and protocol versions. Additionally, including ciphersuites, and protocol versions. Additionally, the TAM
the TAM can selectively request data items from the TEEP Agent via can selectively request data items from the TEEP Agent via the
the request parameter. Currently, the following features are request parameter. Currently, the following features are supported:
supported:
o Request for attestation information, o Request for attestation information,
o Listing supported extensions, o Listing supported extensions,
o Querying installed software (trusted apps), and o Querying installed Trusted Components, and
o Listing supporting SUIT commands. o Listing supporting SUIT commands.
Like other TEEP messages, the QueryRequest message is signed, and the Like other TEEP messages, the QueryRequest message is signed, and the
relevant CDDL snippet is shown below. The complete CDDL structure is relevant CDDL snippet is shown below. The complete CDDL structure is
shown in [CDDL]. shown in [CDDL].
query-request = [ query-request = [
type: TEEP-TYPE-query-request, type: TEEP-TYPE-query-request,
token: uint, token: uint,
options: { options: {
? supported-cipher-suites => suite, ? supported-cipher-suites => [ + suite ],
? nonce => bstr .size (8..64), ? challenge => bstr .size (8..64),
? version => [ + version ], ? versions => [ + version ],
? oscp-data => bstr, ? ocsp-data => bstr,
* $$query-request-extensions * $$query-request-extensions
* $$teep-option-extensions * $$teep-option-extensions
}, },
data-item-requested data-item-requested
] ]
The message has the following fields: The message has the following fields:
type type
The value of (1) corresponds to a QueryRequest message sent from The value of (1) corresponds to a QueryRequest message sent from
the TAM to the TEEP Agent. the TAM to the TEEP Agent.
token token
The value in the token parameter is used to match responses to The value in the token parameter is used to match responses to
requests. This is particualrly useful when a TAM issues multiple requests. This is particularly useful when a TAM issues multiple
concurrent requests to a TEEP Agent. concurrent requests to a TEEP Agent.
request data-item-requested
The request parameter indicates what information the TAM requests The data-item-requested parameter indicates what information the
from the TEEP Agent in form of a bitmap. Each value in the bitmap TAM requests from the TEEP Agent in the form of a bitmap. Each
corresponds to an IANA registered information element. This value in the bitmap corresponds to an IANA registered information
specification defines the following initial set of information element. This specification defines the following initial set of
elements: information elements:
attestation (1) With this value the TAM requests the TEEP Agent attestation (1) With this value the TAM requests the TEEP Agent
to return an entity attestation token (EAT) in the response. to return attestation evidence (e.g., an EAT) in the response.
If the TAM requests an attestation token to be returned by the
TEEP Agent then it MUST also include the nonce in the message.
The nonce is subsequently placed into the EAT token for replay
protection.
trusted_apps (2) With this value the TAM queries the TEEP Agent trusted-components (2) With this value the TAM queries the TEEP
for all installed TAs. Agent for all installed Trusted Components.
extensions (4) With this value the TAM queries the TEEP Agent for extensions (4) With this value the TAM queries the TEEP Agent for
supported capabilities and extensions, which allows a TAM to supported capabilities and extensions, which allows a TAM to
discover the capabilities of a TEEP Agent implementation. discover the capabilities of a TEEP Agent implementation.
suit_commands (8) With this value the TAM queries the TEEP Agent suit-commands (8) With this value the TAM queries the TEEP Agent
for supported commands offered by the SUIT manifest for supported commands offered by the SUIT manifest
implementation. implementation.
Further values may be added in the future via IANA registration. Further values may be added in the future via IANA registration.
cipher-suites supported-cipher-suites
The cipher-suites parameter lists the ciphersuite(s) supported by The supported-cipher-suites parameter lists the ciphersuite(s)
the TAM. Details about the ciphersuite encoding can be found in supported by the TAM. Details about the ciphersuite encoding can
Section 6. be found in Section 6.
nonce challenge
The none field is an optional parameter used for ensuring the The challenge field is an optional parameter used for ensuring the
refreshness of the Entity Attestation Token (EAT) returned with a refreshness of the attestation evidence returned with a
QueryResponse message. When a nonce is provided in the QueryResponse message. When a challenge is provided in the
QueryRequest and an EAT is returned with the QueryResponse message QueryRequest and an EAT is returned with the QueryResponse message
then the nonce contained in this request MUST be copied into the then the challenge contained in this request MUST be copied into
nonce claim found in the EAT token. the nonce claim found in the EAT. If any format other than EAT is
used, it is up to that format to define the use of the challenge
field.
version versions
The version field parameter the version(s) supported by the TAM. The versions parameter enumerates the TEEP protocol version(s)
For this version of the specification this field can be omitted. supported by the TAM A value of 0 refers to the current version of
the TEEP protocol. If this field is not present, it is to be
treated the same as if it contained only version 0.
ocsp_data ocsp-data
The ocsp_data parameter contains a list of OCSP stapling data The ocsp-data parameter contains a list of OCSP stapling data
respectively for the TAM certificate and each of the CA respectively for the TAM certificate and each of the CA
certificates up to the root certificate. The TAM provides OCSP certificates up to the root certificate. The TAM provides OCSP
data so that the TEEP Agent can validate the status of the TAM data so that the TEEP Agent can validate the status of the TAM
certificate chain without making its own external OCSP service certificate chain without making its own external OCSP service
call. OCSP data MUST be conveyed as a DER-encoded OCSP response call. OCSP data MUST be conveyed as a DER-encoded OCSP response
(using the ASN.1 type OCSPResponse defined in [RFC2560]). The use (using the ASN.1 type OCSPResponse defined in [RFC2560]). The use
of OCSP is optional to implement for both the TAM and the TEEP of OCSP is OPTIONAL to implement for both the TAM and the TEEP
Agent. A TAM can query the TEEP Agent for the support of this Agent. A TAM can query the TEEP Agent for the support of this
functionality via the capability discovery exchange, as described functionality via the capability discovery exchange, as described
above. above.
4.3. QueryResponse 4.3. QueryResponse Message
The QueryResponse message is the successful response by the TEEP The QueryResponse message is the successful response by the TEEP
Agent after receiving a QueryRequest message. Agent after receiving a QueryRequest message.
Like other TEEP messages, the QueryResponse message is signed, and Like other TEEP messages, the QueryResponse message is signed, and
the relevant CDDL snippet is shown below. The complete CDDL the relevant CDDL snippet is shown below. The complete CDDL
structure is shown in [CDDL]. structure is shown in [CDDL].
query-response = [ query-response = [
type: TEEP-TYPE-query-response, type: TEEP-TYPE-query-response,
token: uint, token: uint,
options: { options: {
? selected-cipher-suite => suite, ? selected-cipher-suite => suite,
? selected-version => version, ? selected-version => version,
? eat => bstr, ? evidence-format => text,
? ta-list => [ + bstr ], ? evidence => bstr,
? tc-list => [ + tc-info ],
? requested-ta-list => [ + requested-ta-info ],
? unneeded-ta-list => [ + bstr ],
? ext-list => [ + ext-info ], ? ext-list => [ + ext-info ],
* $$query-response-extensions, * $$query-response-extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
The message has the following fields: tc-info = {
component-id: bstr,
? tc-manifest-sequence-number: uint
}
requested-ta-info = {
component-id: bstr,
? tc-manifest-sequence-number: uint,
? have-binary: bool
}
The QueryResponse message has the following fields:
type type
The value of (2) corresponds to a QueryResponse message sent from The value of (2) corresponds to a QueryResponse message sent from
the TEEP Agent to the TAM. the TEEP Agent to the TAM.
token token
The value in the token parameter is used to match responses to The value in the token parameter is used to match responses to
requests. The value MUST correspond to the value received with requests. The value MUST correspond to the value received with
the QueryRequest message. the QueryRequest message.
selected-cipher-suite selected-cipher-suite
The selected-cipher-suite parameter indicates the selected The selected-cipher-suite parameter indicates the selected
ciphersuite. Details about the ciphersuite encoding can be found ciphersuite. Details about the ciphersuite encoding can be found
in Section 6. in Section 6.
selected-version selected-version
The selected-version parameter indicates the protocol version The selected-version parameter indicates the TEEP protocol version
selected by the TEEP Agent. selected by the TEEP Agent. The absense of this parameter
indicates the same as if it was present with a value of 0.
eat evidence-format
The eat parameter contains an Entity Attestation Token following The evidence-format parameter indicates the IANA Media Type of the
the encoding defined in [I-D.ietf-rats-eat]. attestation evidence contained in the evidence parameter. It MUST
be present if the evidence parameter is present and the format is
not an EAT.
ta-list evidence
The ta-list parameter enumerates the trusted applications The evidence parameter contains the attestation evidence. This
installed on the device in form of TA_ID byte strings. parameter MUST be present if the QueryResponse is sent in response
to a QueryRequest with the attestation bit set. If the evidence-
format parameter is absent, the attestation evidence contained in
this parameter MUST be an Entity Attestation Token following the
encoding defined in [I-D.ietf-rats-eat].
tc-list
The tc-list parameter enumerates the Trusted Components installed
on the device in the form of tc-info objects.
requested-ta-list
The requested-ta-list parameter enumerates the Trusted
Applications that are not currently installed in the TEE, but
which are requested to be installed, for example by an installer
of an Untrusted Application that has a TA as a dependency.
Requested TAs are expressed in the form of requested-ta-info
objects.
unneeded-ta-list
The unneeded-ta-list parameter enumerates the Trusted Applications
that are currently installed in the TEE, but which are no longer
needed by any other application. The TAM can use this information
in determining whether a TA can be deleted. Each unneeded TA is
expressed in the form of a component-id byte string.
ext-list ext-list
The ext-list parameter lists the supported extensions. This The ext-list parameter lists the supported extensions. This
document does not define any extensions. document does not define any extensions.
4.4. TrustedAppInstall The tc-info object has the following fields:
The TrustedAppInstall message is used by the TAM to install software component-id
(trusted apps) via the TEEP Agent. A unique identifier encoded as a CBOR bstr.
Like other TEEP messages, the TrustedAppInstall message is signed, tc-manifest-sequence-number
and the relevant CDDL snippet is shown below. The complete CDDL The suit-manifest-sequence-number value from the SUIT manifest for
structure is shown in [CDDL]. the Trusted Component, if a SUIT manifest was used.
trusted-app-install = [ The requested-ta-info message has the following fields:
type: TEEP-TYPE-trusted-app-install,
component-id
A unique identifier encoded as a CBOR bstr.
tc-manifest-sequence-number
The minimum suit-manifest-sequence-number value from a SUIT
manifest for the TA. If not present, indicates that any version
will do.
have-binary
If present with a value of true, indicates that the TEEP agent
already has the TA binary and only needs an Install message with a
SUIT manifest that authorizes installing it. If have-binary is
true, the tc-manifest-sequence-number field MUST be present.
4.4. Install Message
The Install message is used by the TAM to install a Trusted Component
via the TEEP Agent.
Like other TEEP messages, the Install message is signed, and the
relevant CDDL snippet is shown below. The complete CDDL structure is
shown in [CDDL].
install = [
type: TEEP-TYPE-install,
token: uint, token: uint,
option: { option: {
? manifest-list => [ + SUIT_Envelope ], ? manifest-list => [ + SUIT_Envelope ],
* $$trusted-app-install-extensions, * $$install-extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
The TrustedAppInstall message has the following fields: The Install message has the following fields:
type type
The value of (3) corresponds to a TrustedAppInstall message sent The value of (3) corresponds to an Install message sent from the
from the TAM to the TEEP Agent. In case of successful processing, TAM to the TEEP Agent. In case of successful processing, a
an Success message is returned by the TEEP Agent. In case of an Success message is returned by the TEEP Agent. In case of an
error, an Error message is returned. Note that the error, an Error message is returned. Note that the Install
TrustedAppInstall message is used for initial TA installation but message is used for initial Trusted Component installation as well
also for TA updates. as for updates.
token token
The value in the token field is used to match responses to The value in the token field is used to match responses to
requests. requests.
manifest-list manifest-list
The manifest-list field is used to convey one or multiple SUIT The manifest-list field is used to convey one or multiple SUIT
manifests. A manifest is a bundle of metadata about the trusted manifests. A manifest is a bundle of metadata about a TA, such as
app, where to find the code, the devices to which it applies, and where to find the code, the devices to which it applies, and
cryptographic information protecting the manifest. The manifest cryptographic information protecting the manifest. The manifest
may also convey personalization data. TA binaries and may also convey personalization data. TA binaries and
personalization data is typically signed and encrypted by the SP. personalization data can be signed and encrypted by the same TA
Other combinations are, however, possible as well. For example, Signer. Other combinations are, however, possible as well. For
it is also possible for the TAM to sign and encrypt the example, it is also possible for the TAM to sign and encrypt the
personalization data and to let the SP sign and/or encrypt the TA personalization data and to let the TA Developer sign and/or
binary. encrypt the TA binary.
4.5. TrustedAppDelete 4.5. Delete Message
The TrustedAppDelete message is used by the TAM to remove software The Delete message is used by the TAM to remove a Trusted Component
(trust apps) from the device. from the device.
Like other TEEP messages, the TrustedAppDelete message is signed, and Like other TEEP messages, the Delete message is signed, and the
the relevant CDDL snippet is shown below. The complete CDDL relevant CDDL snippet is shown below. The complete CDDL structure is
structure is shown in [CDDL]. shown in [CDDL].
trusted-app-delete = [ delete = [
type: TEEP-TYPE-trusted-app-delete, type: TEEP-TYPE-delete,
token: uint, token: uint,
option: { option: {
? ta-list => [ + bstr ], ? tc-list => [ + bstr ],
* $$trusted-app-delete-extensions, * $$delete-extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
The TrustedAppDelete message has the following fields: The Delete message has the following fields:
type type
The value of (4) corresponds to a TrustedAppDelete message sent The value of (4) corresponds to a Delete message sent from the TAM
from the TAM to the TEEP Agent. In case of successful processing, to the TEEP Agent. In case of successful processing, a Success
an Success message is returned by the TEEP Agent. In case of an message is returned by the TEEP Agent. In case of an error, an
error, an Error message is returned. Error message is returned.
token token
The value in the token parameter is used to match responses to The value in the token parameter is used to match responses to
requests. requests.
ta-list tc-list
The ta-list parameter enumerates the TAs to be deleted. The tc-list parameter enumerates the Trusted Components to be
deleted, in the form of component-id byte strings.
4.6. Success 4.6. Success Message
The TEEP protocol defines two implicit success messages and this The TEEP protocol defines two implicit success messages and this
explicit Success message for the cases where the TEEP Agent cannot explicit Success message for the cases where the TEEP Agent cannot
return another reply, such as for the TrustedAppInstall and the return another reply, such as for the Install and the Delete
TrustedAppDelete messages. messages.
Like other TEEP messages, the Success message is signed, and the Like other TEEP messages, the Success message is signed, and the
relevant CDDL snippet is shown below. The complete CDDL structure is relevant CDDL snippet is shown below. The complete CDDL structure is
shown in [CDDL]. shown in [CDDL].
teep-success = [ teep-success = [
type: TEEP-TYPE-teep-success, type: TEEP-TYPE-teep-success,
token: uint, token: uint,
option: { option: {
? msg => text, ? msg => text,
? suit-reports => [ + suit-report ],
* $$teep-success-extensions, * $$teep-success-extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
The Success message has the following fields: The Success message has the following fields:
type type
The value of (5) corresponds to corresponds to a Success message The value of (5) corresponds to corresponds to a Success message
sent from the TEEP Agent to the TAM. sent from the TEEP Agent to the TAM.
token token
The value in the token parameter is used to match responses to The value in the token parameter is used to match responses to
requests. requests.
msg msg
The msg parameter contains optional diagnostics information The msg parameter contains optional diagnostics information
encoded in UTF-8 [RFC3629] returned by the TEEP Agent. encoded in UTF-8 [RFC3629] returned by the TEEP Agent.
4.7. Error suit-reports
If present, the suit-reports parameter contains a set of SUIT
Reports as defined in Section 4 of [I-D.moran-suit-report].
4.7. Error Message
The Error message is used by the TEEP Agent to return an error. The Error message is used by the TEEP Agent to return an error.
Like other TEEP messages, the Error message is signed, and the Like other TEEP messages, the Error message is signed, and the
relevant CDDL snippet is shown below. The complete CDDL structure is relevant CDDL snippet is shown below. The complete CDDL structure is
shown in [CDDL]. shown in [CDDL].
teep-error = [ teep-error = [
type: TEEP-TYPE-teep-error, type: TEEP-TYPE-teep-error,
token: uint, token: uint,
err-code: uint, err-code: uint,
options: { options: {
? err-msg => text, ? err-msg => text,
? cipher-suites => [ + suite ], ? supported-cipher-suites => [ + suite ],
? versions => [ + version ], ? versions => [ + version ],
? suit-reports => [ + suit-report ],
* $$teep-error--extensions, * $$teep-error--extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
The Error message has the following fields: The Error message has the following fields:
type type
The value of (6) corresponds to an Error message sent from the The value of (6) corresponds to an Error message sent from the
TEEP Agent to the TAM. TEEP Agent to the TAM.
token token
The value in the token parameter is used to match responses to The value in the token parameter is used to match responses to
requests. requests.
err-code err-code
The err-code parameter is populated with values listed in a The err-code parameter contains one of the values listed in the
registry (with the initial set of error codes listed below). Only registry defined in Section 8.2 (with the initial set of error
selected messages are applicable to each message. codes listed below). Only selected values are applicable to each
message.
err-msg err-msg
The err-msg parameter is a human-readable diagnostic text that The err-msg parameter is human-readable diagnostic text that MUST
MUST be encoded using UTF-8 [RFC3629] using Net-Unicode form be encoded using UTF-8 [RFC3629] using Net-Unicode form [RFC5198].
[RFC5198].
cipher-suites supported-cipher-suites
The cipher-suites parameter lists the ciphersuite(s) supported by The supported-cipher-suites parameter lists the ciphersuite(s)
the TEEP Agent. This field is optional but MUST be returned with supported by the TEEP Agent. Details about the ciphersuite
the ERR_UNSUPPORTED_CRYPTO_ALG error message. encoding can be found in Section 6. This field is optional but
MUST be returned with the ERR_UNSUPPORTED_CRYPTO_ALG error
message.
versions versions
The version parameter enumerates the protocol version(s) supported The versions parameter enumerates the TEEP protocol version(s)
by the TEEP Agent. This otherwise optional parameter MUST be supported by the TEEP Agent. This otherwise optional parameter
returned with the ERR_UNSUPPORTED_MSG_VERSION error message. MUST be returned with the ERR_UNSUPPORTED_MSG_VERSION error
message.
suit-reports
If present, the suit-reports parameter contains a set of SUIT
Reports as defined in Section 4 of [I-D.moran-suit-report].
This specification defines the following initial error messages: This specification defines the following initial error messages:
ERR_ILLEGAL_PARAMETER (1) ERR_ILLEGAL_PARAMETER (1)
The TEEP Agent sends this error message when a request contains The TEEP request contained incorrect fields or fields that are
incorrect fields or fields that are inconsistent with other inconsistent with other fields.
fields.
ERR_UNSUPPORTED_EXTENSION (2) ERR_UNSUPPORTED_EXTENSION (2)
The TEEP Agent sends this error message when it recognizes an The TEEP Agent does not support the request message or an
unsupported extension or unsupported message. extension it indicated.
ERR_REQUEST_SIGNATURE_FAILED (3) ERR_REQUEST_SIGNATURE_FAILED (3)
The TEEP Agent sends this error message when it fails to verify The TEEP Agent could not verify the signature of the request
the signature of the message. message.
ERR_UNSUPPORTED_MSG_VERSION (4) ERR_UNSUPPORTED_MSG_VERSION (4)
The TEEP Agent receives a message but does not support the The TEEP Agent does not support the TEEP protocol version
indicated version. indicated in the request message.
ERR_UNSUPPORTED_CRYPTO_ALG (5) ERR_UNSUPPORTED_CRYPTO_ALG (5)
The TEEP Agent receives a request message encoded with an The TEEP Agent does not support the cryptographic algorithm
unsupported cryptographic algorithm. indicated in the request message.
ERR_BAD_CERTIFICATE (6) ERR_BAD_CERTIFICATE (6)
The TEEP Agent returns this error when processing of a certificate Processing of a certificate failed. For diagnosis purposes it is
failed. For diagnosis purposes it is RECOMMMENDED to include RECOMMMENDED to include information about the failing certificate
information about the failing certificate in the error message. in the error message.
ERR_UNSUPPORTED_CERTIFICATE (7) ERR_UNSUPPORTED_CERTIFICATE (7)
The TEEP Agent returns this error when a certificate was of an A certificate was of an unsupported type.
unsupported type.
ERR_CERTIFICATE_REVOKED (8) ERR_CERTIFICATE_REVOKED (8)
The TEEP Agent returns this error when a certificate was revoked A certificate was revoked by its signer.
by its signer.
ERR_CERTIFICATE_EXPIRED (9) ERR_CERTIFICATE_EXPIRED (9)
The TEEP Agent returns this error when a certificate has expired A certificate has expired or is not currently valid.
or is not currently valid.
ERR_INTERNAL_ERROR (10) ERR_INTERNAL_ERROR (10)
The TEEP Agent returns this error when a miscellaneous internal A miscellaneous internal error occurred while processing the
error occurred while processing the request. request message.
ERR_RESOURCE_FULL (11)
This error is reported when a device resource isn't available
anymore, such as storage space is full.
ERR_TA_NOT_FOUND (12)
This error will occur when the target TA does not exist. This
error may happen when the TAM has stale information and tries to
delete a TA that has already been deleted.
ERR_TA_ALREADY_INSTALLED (13)
While installing a TA, a TEE will return this error if the TA has
already been installed.
ERR_TA_UNKNOWN_FORMAT (14)
The TEEP Agent returns this error when it does not recognize the
format of the TA binary.
ERR_TA_DECRYPTION_FAILED (15)
The TEEP Agent returns this error when it fails to decrypt the TA
binary.
ERR_TA_DECOMPRESSION_FAILED (16) ERR_TC_NOT_FOUND (12)
The TEEP Agent returns this error when it fails to decompress the The target Trusted Component does not exist. This error may
TA binary. happen when the TAM has stale information and tries to delete a
Trusted Component that has already been deleted.
ERR_MANIFEST_PROCESSING_FAILED (17) ERR_MANIFEST_PROCESSING_FAILED (17)
The TEEP Agent returns this error when manifest processing The TEEP Agent encountered one or more manifest processing
failures occur that are less specific than ERR_TA_UNKNOWN_FORMAT, failures. If the suit-reports parameter is present, it contains
ERR_TA_UNKNOWN_FORMAT, and ERR_TA_DECOMPRESSION_FAILED. the failure details.
ERR_PD_PROCESSING_FAILED (18)
The TEEP Agent returns this error when it fails to process the
provided personalization data.
Additional error code can be registered with IANA. Additional error codes can be registered with IANA.
5. Mapping of TEEP Message Parameters to CBOR Labels 5. Mapping of TEEP Message Parameters to CBOR Labels
In COSE, arrays and maps use strings, negative integers, and unsigned In COSE, arrays and maps use strings, negative integers, and unsigned
integers as their keys. Integers are used for compactness of integers as their keys. Integers are used for compactness of
encoding. Since the word "key" is mainly used in its other meaning, encoding. Since the word "key" is mainly used in its other meaning,
as a cryptographic key, this specification uses the term "label" for as a cryptographic key, this specification uses the term "label" for
this usage as a map key. this usage as a map key.
This specification uses the following mapping: This specification uses the following mapping:
+-----------------------+-------+ +-----------------------------+-------+
| Name | Label | | Name | Label |
+-----------------------+-------+ +-----------------------------+-------+
| cipher-suites | 1 | | supported-cipher-suites | 1 |
| nonce | 2 | | challenge | 2 |
| version | 3 | | version | 3 |
| ocsp-data | 4 | | ocsp-data | 4 |
| selected-cipher-suite | 5 | | selected-cipher-suite | 5 |
| selected-version | 6 | | selected-version | 6 |
| eat | 7 | | evidence | 7 |
| ta-list | 8 | | tc-list | 8 |
| ext-list | 9 | | ext-list | 9 |
| manifest-list | 10 | | manifest-list | 10 |
| msg | 11 | | msg | 11 |
| err-msg | 12 | | err-msg | 12 |
+-----------------------+-------+ | evidence-format | 13 |
| requested-tc-list | 14 |
| unneeded-tc-list | 15 |
| component-id | 16 |
| tc-manifest-sequence-number | 17 |
| have-binary | 18 |
| suit-reports | 19 |
+-----------------------------+-------+
6. Ciphersuites 6. Ciphersuites
A ciphersuite consists of an AEAD algorithm, a HMAC algorithm, and a A ciphersuite consists of an AEAD algorithm, an HMAC algorithm, and a
signature algorithm. Each ciphersuite is identified with an integer signature algorithm. Each ciphersuite is identified with an integer
value, which corresponds to an IANA registered ciphersuite. This value, which corresponds to an IANA registered ciphersuite (see
document specifies two ciphersuites. Section 8.3. This document specifies two ciphersuites.
+-------+------------------------------------------------+ +-------+------------------------------------------------+
| Value | Ciphersuite | | Value | Ciphersuite |
+-------+------------------------------------------------+ +-------+------------------------------------------------+
| 1 | AES-CCM-16-64-128, HMAC 256/256, X25519, EdDSA | | 1 | AES-CCM-16-64-128, HMAC 256/256, X25519, EdDSA |
| 2 | AES-CCM-16-64-128, HMAC 256/256, P-256, ES256 | | 2 | AES-CCM-16-64-128, HMAC 256/256, P-256, ES256 |
+-------+------------------------------------------------+ +-------+------------------------------------------------+
7. Security Considerations 7. Security Considerations
This section summarizes the security considerations discussed in this This section summarizes the security considerations discussed in this
specification: specification:
Cryptographic Algorithms Cryptographic Algorithms
TEEP protocol messages exchanged between the TAM and the TEEP TEEP protocol messages exchanged between the TAM and the TEEP
Agent are protected using COSE. This specification relies on the Agent are protected using COSE. This specification relies on the
cryptographic algorithms provided by COSE. Public key based cryptographic algorithms provided by COSE. Public key based
authentication is used to by the TEEP Agent to authenticate the authentication is used by the TEEP Agent to authenticate the TAM
TAM and vice versa. and vice versa.
Attestation Attestation
A TAM may rely on the attestation information provided by the TEEP A TAM can rely on the attestation evidence provided by the TEEP
Agent and the Entity Attestation Token is re-used to convey this Agent. To sign the attestation evidence, it is necessary for the
information. To sign the Entity Attestation Token it is necessary device to possess a public key (usually in the form of a
for the device to possess a public key (usually in the form of a
certificate) along with the corresponding private key. Depending certificate) along with the corresponding private key. Depending
on the properties of the attestation mechanism it is possible to on the properties of the attestation mechanism, it is possible to
uniquely identify a device based on information in the attestation uniquely identify a device based on information in the attestation
information or in the certificate used to sign the attestation evidence or in the certificate used to sign the attestation
token. This uniqueness may raise privacy concerns. To lower the evidence. This uniqueness may raise privacy concerns. To lower
privacy implications the TEEP Agent MUST present its attestation the privacy implications the TEEP Agent MUST present its
information only to an authenticated and authorized TAM and SHOULD attestation evidence only to an authenticated and authorized TAM
use encryption in EATs as discussed in [I-D.ietf-rats-eat] since and when using EATS, it SHOULD use encryption as discussed in
confidentiality is not provided by the TEEP protocol itself, and [I-D.ietf-rats-eat], since confidentiality is not provided by the
the transport protocol under the TEEP protocol might be TEEP protocol itself and the transport protocol under the TEEP
implemented outside of any TEE. protocol might be implemented outside of any TEE. If any
mechanism other than EATs is used, it is up to that mechanism to
specify how privacy is provided.
TA Binaries TA Binaries
TA binaries are provided by the SP. It is the responsibility of Each TA binary is signed by a TA Signer. It is the responsibility
the TAM to relay only verified TAs from authorized SPs. Delivery of the TAM to relay only verified TAs from authorized TA Signers.
of that TA to the TEEP Agent is then the responsibility of the TAM Delivery of a TA to the TEEP Agent is then the responsibility of
and the TEEP Broker, using the security mechanisms provided by the the TAM, using the security mechanisms provided by the TEEP
TEEP protocol. To protect the TA binary the SUIT manifest is re- protocol. To protect the TA binary, the SUIT manifest format is
used and it offers a varity of security features, including used and it offers a variety of security features, including
digitial signatures and symmetric encryption. digitial signatures and symmetric encryption.
Personalization Data Personalization Data
An SP or a TAM can supply personalization data along with a TA. A TA Signer or TAM can supply personalization data along with a
This data is also protected by a SUIT manifest. The TA. This data is also protected by a SUIT manifest.
personalization data may be opaque to the TAM. Personalization data signed and encrypted by a TA Signer other
than the TAM is opaque to the TAM.
TEEP Broker TEEP Broker
The TEEP protocol relies on the TEEP Broker to relay messages As discussed in section 6 of [I-D.ietf-teep-architecture], the
TEEP protocol typically relies on a TEEP Broker to relay messages
between the TAM and the TEEP Agent. When the TEEP Broker is between the TAM and the TEEP Agent. When the TEEP Broker is
compromised it can drop messages, delay the delivery of messages, compromised it can drop messages, delay the delivery of messages,
and replay messages but it cannot modify those messages. (A and replay messages but it cannot modify those messages. (A
replay would be, however, detected by the TEEP Agent.) A replay would be, however, detected by the TEEP Agent.) A
compromised TEEP Broker could reorder messages in an attempt to compromised TEEP Broker could reorder messages in an attempt to
install an old version of a TA. Information in the manifest install an old version of a TA. Information in the manifest
ensures that the TEEP Agents are protected against such ensures that TEEP Agents are protected against such downgrade
downgrading attacks based on features offered by the manifest attacks based on features offered by the manifest itself.
itself.
CA Compromise TA Signer Compromise
The QueryRequest message from a TAM to the TEEP Agent may include The QueryRequest message from a TAM to the TEEP Agent can include
OCSP stapling data for the TAM's signer certificate and for OCSP stapling data for the TAM's certificate and for intermediate
intermediate CA certificates up to the root certificate so that CA certificates up to the root certificate so that the TEEP Agent
the TEEP Agent can verify the certificate's revocation status. A can verify the certificate's revocation status. A certificate
certificate revocation status check on a TA signer certificate is revocation status check on a TA Signer certificate is OPTIONAL by
OPTIONAL by a TEEP Agent. A TAM is responsible for vetting a TA a TEEP Agent. A TAM is responsible for vetting a TA and before
and before distributing them to TEEP Agents. TEEP Agents will distributing them to TEEP Agents, so TEEP Agents can instead
trust a TA signer certificate's validation status done by a TAM. simply trust that a TA Signer certificate's status was done by the
TAM.
CA Compromise CA Compromise
The CA issuing certificates to a TAM or an SP may get compromised. The CA issuing certificates to a TAM or a TA Signer might get
A compromised intermediate CA certificates can be detected by a compromised. A compromised intermediate CA certificate can be
TEEP Agent by using OCSP information, assuming the revocation detected by a TEEP Agent by using OCSP information, assuming the
information is available. Additionally, it is RECOMMENDED to revocation information is available. Additionally, it is
provide a way to update the trust anchor store used by the device, RECOMMENDED to provide a way to update the trust anchor store used
for example using a firmware update mechanism. If the CA issuing by the TEE, for example using a firmware update mechanism. If the
certificates to devices gets compromised then these devices might CA issuing certificates to devices gets compromised then these
be rejected by a TAM, if revocation is available to the TAM. devices might be rejected by a TAM, if revocation is available to
the TAM.
Compromised TAM Compromised TAM
The TEEP Agent SHOULD use OCSP information to verify the validity The TEEP Agent SHOULD use OCSP information to verify the validity
of the TAM-provided certificate (as well as the validity of of the TAM's certificate (as well as the validity of intermediate
intermediate CA certificates). The integrity and the accuracy of CA certificates). The integrity and the accuracy of the clock
the clock within the TEE determines the ability to determine an within the TEE determines the ability to determine an expired or
expired or revoked certificate since OCSP stapling includes revoked certificate. OCSP stapling data includes signature
signature generation time, certificate validity dates are compared generation time, allowing certificate validity dates to be
to the current time. compared to the current time.
Compromised Time Source
As discussed above, certificate validity checks rely on comparing
validity dates to the current time, which relies on having a
trusted source of time, such as [RFC8915]. A compromised time
source could thus be used to subvert such validity checks.
8. IANA Considerations 8. IANA Considerations
8.1. Media Type Registration 8.1. Media Type Registration
IANA is requested to assign a media type for application/teep+cbor. IANA is requested to assign a media type for application/teep+cbor.
Type name: application Type name: application
Subtype name: teep+cbor Subtype name: teep+cbor
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Same as encoding considerations of Encoding considerations: Same as encoding considerations of
application/cbor application/cbor.
Security considerations: See Security Considerations Section of this Security considerations: See Security Considerations Section of this
document. document.
Interoperability considerations: Same as interoperability Interoperability considerations: Same as interoperability
considerations of application/cbor as specified in [RFC7049] considerations of application/cbor as specified in [RFC7049].
Published specification: This document. Published specification: This document.
Applications that use this media type: TEEP protocol implementations Applications that use this media type: TEEP protocol implementations
Fragment identifier considerations: N/A Fragment identifier considerations: N/A
Additional information: Additional information:
Deprecated alias names for this type: N/A Deprecated alias names for this type: N/A
skipping to change at page 19, line 46 skipping to change at page 22, line 4
defined in Section 6. defined in Section 6.
8.4. CBOR Tag Registry 8.4. CBOR Tag Registry
IANA is requested to register a CBOR tag in the "CBOR Tags" registry IANA is requested to register a CBOR tag in the "CBOR Tags" registry
for use with TEEP messages. for use with TEEP messages.
The registry contents is: The registry contents is:
o CBOR Tag: TBD1 o CBOR Tag: TBD1
o Data Item: TEEP Message o Data Item: TEEP Message
o Semantics: TEEP Message, as defined in [[TBD: This RFC]] o Semantics: TEEP Message, as defined in [[TBD: This RFC]]
o Reference: [[TBD: This RFC]] o Reference: [[TBD: This RFC]]
o Point of Contact: TEEP working group (teep@ietf.org) o Point of Contact: TEEP working group (teep@ietf.org)
9. References 9. References
9.1. Normative References 9.1. Normative References
[I-D.ietf-rats-eat] [I-D.ietf-rats-eat]
Mandyam, G., Lundblade, L., Ballesteros, M., and J. Mandyam, G., Lundblade, L., Ballesteros, M., and J.
O'Donoghue, "The Entity Attestation Token (EAT)", draft- O'Donoghue, "The Entity Attestation Token (EAT)", draft-
ietf-rats-eat-03 (work in progress), February 2020. ietf-rats-eat-04 (work in progress), August 2020.
[I-D.ietf-suit-manifest] [I-D.ietf-suit-manifest]
Moran, B., Tschofenig, H., Birkholz, H., and K. Zandberg, Moran, B., Tschofenig, H., Birkholz, H., and K. Zandberg,
"A Concise Binary Object Representation (CBOR)-based "A Concise Binary Object Representation (CBOR)-based
Serialization Format for the Software Updates for Internet Serialization Format for the Software Updates for Internet
of Things (SUIT) Manifest", draft-ietf-suit-manifest-08 of Things (SUIT) Manifest", draft-ietf-suit-manifest-09
(work in progress), July 2020. (work in progress), July 2020.
[I-D.moran-suit-report]
Moran, B., "Secure Reporting of Update Status", draft-
moran-suit-report-00 (work in progress), October 2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc- DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
editor.org/info/rfc2119>. editor.org/info/rfc2119>.
[RFC2560] Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. [RFC2560] Myers, M., Ankney, R., Malpani, A., Galperin, S., and C.
Adams, "X.509 Internet Public Key Infrastructure Online Adams, "X.509 Internet Public Key Infrastructure Online
Certificate Status Protocol - OCSP", RFC 2560, Certificate Status Protocol - OCSP", RFC 2560,
DOI 10.17487/RFC2560, June 1999, <https://www.rfc- DOI 10.17487/RFC2560, June 1999, <https://www.rfc-
editor.org/info/rfc2560>. editor.org/info/rfc2560>.
skipping to change at page 21, line 7 skipping to change at page 23, line 19
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017, RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>. <https://www.rfc-editor.org/info/rfc8152>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 9.2. Informative References
[I-D.ietf-sacm-coswid]
Birkholz, H., Fitzgerald-McKay, J., Schmidt, C., and D.
Waltermire, "Concise Software Identification Tags", draft-
ietf-sacm-coswid-15 (work in progress), May 2020.
[I-D.ietf-teep-architecture] [I-D.ietf-teep-architecture]
Pei, M., Tschofenig, H., Thaler, D., and D. Wheeler, Pei, M., Tschofenig, H., Thaler, D., and D. Wheeler,
"Trusted Execution Environment Provisioning (TEEP) "Trusted Execution Environment Provisioning (TEEP)
Architecture", draft-ietf-teep-architecture-11 (work in Architecture", draft-ietf-teep-architecture-12 (work in
progress), July 2020. progress), July 2020.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005, <https://www.rfc-
editor.org/info/rfc4122>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data [RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>. June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC8915] Franke, D., Sibold, D., Teichel, K., Dansarie, M., and R.
Sundblad, "Network Time Security for the Network Time
Protocol", RFC 8915, DOI 10.17487/RFC8915, September 2020,
<https://www.rfc-editor.org/info/rfc8915>.
A. Contributors A. Contributors
We would like to thank Brian Witten (Symantec), Tyler Kim (Solacia), We would like to thank Brian Witten (Symantec), Tyler Kim (Solacia),
Nick Cook (Arm), and Minho Yoo (IoTrust) for their contributions to Nick Cook (Arm), and Minho Yoo (IoTrust) for their contributions to
the Open Trust Protocol (OTrP), which influenced the design of this the Open Trust Protocol (OTrP), which influenced the design of this
specification. specification.
B. Acknowledgements B. Acknowledgements
We would like to thank Eve Schooler for the suggestion of the We would like to thank Eve Schooler for the suggestion of the
skipping to change at page 22, line 16 skipping to change at page 24, line 46
token: uint, token: uint,
options: { * teep-option }, options: { * teep-option },
* int; further integers, e.g. for data-item-requested * int; further integers, e.g. for data-item-requested
] ]
teep-option = (uint => any) teep-option = (uint => any)
; messages defined below: ; messages defined below:
$teep-message-type /= query-request $teep-message-type /= query-request
$teep-message-type /= query-response $teep-message-type /= query-response
$teep-message-type /= trusted-app-install $teep-message-type /= install
$teep-message-type /= trusted-app-delete $teep-message-type /= delete
$teep-message-type /= teep-error
$teep-message-type /= teep-success $teep-message-type /= teep-success
$teep-message-type /= teep-error
; message type numbers ; message type numbers
TEEP-TYPE-query-request = 1 TEEP-TYPE-query-request = 1
TEEP-TYPE-query-response = 2 TEEP-TYPE-query-response = 2
TEEP-TYPE-trusted-app-install = 3 TEEP-TYPE-install = 3
TEEP-TYPE-trusted-app-delete = 4 TEEP-TYPE-delete = 4
TEEP-TYPE-teep-success = 5 TEEP-TYPE-teep-success = 5
TEEP-TYPE-teep-error = 6 TEEP-TYPE-teep-error = 6
version = uint .size 4 version = uint .size 4
ext-info = uint ext-info = uint
; data items as bitmaps ; data items as bitmaps
data-item-requested = $data-item-requested .within uint .size 8 data-item-requested = $data-item-requested .within uint .size 8
attestation = 1 attestation = 1
$data-item-requested /= attestation $data-item-requested /= attestation
trusted-apps = 2 trusted-components = 2
$data-item-requested /= trusted-apps $data-item-requested /= trusted-components
extensions = 4 extensions = 4
$data-item-requested /= extensions $data-item-requested /= extensions
suit-commands = 8 suit-commands = 8
$data-item-requested /= suit-commands $data-item-requested /= suit-commands
query-request = [ query-request = [
type: TEEP-TYPE-query-request, type: TEEP-TYPE-query-request,
token: uint, token: uint,
options: { options: {
? supported-cipher-suites => suite, ? supported-cipher-suites => [ + suite ],
? nonce => bstr .size (8..64), ? challenge => bstr .size (8..64),
? version => [ + version ], ? versions => [ + version ],
? oscp-data => bstr, ? ocsp-data => bstr,
* $$query-request-extensions * $$query-request-extensions
* $$teep-option-extensions * $$teep-option-extensions
}, },
data-item-requested data-item-requested
] ]
; ciphersuites as bitmaps ; ciphersuites as bitmaps
suite = $TEEP-suite .within uint .size 8 suite = $TEEP-suite .within uint .size 8
TEEP-AES-CCM-16-64-128-HMAC256--256-X25519-EdDSA = 1 TEEP-AES-CCM-16-64-128-HMAC256--256-X25519-EdDSA = 1
skipping to change at page 23, line 24 skipping to change at page 26, line 5
$TEEP-suite /= TEEP-AES-CCM-16-64-128-HMAC256--256-X25519-EdDSA $TEEP-suite /= TEEP-AES-CCM-16-64-128-HMAC256--256-X25519-EdDSA
$TEEP-suite /= TEEP-AES-CCM-16-64-128-HMAC256--256-P-256-ES256 $TEEP-suite /= TEEP-AES-CCM-16-64-128-HMAC256--256-P-256-ES256
query-response = [ query-response = [
type: TEEP-TYPE-query-response, type: TEEP-TYPE-query-response,
token: uint, token: uint,
options: { options: {
? selected-cipher-suite => suite, ? selected-cipher-suite => suite,
? selected-version => version, ? selected-version => version,
? eat => bstr, ? evidence-format => text,
? ta-list => [ + bstr ], ? evidence => bstr,
? tc-list => [ + tc-info ],
? requested-tc-list => [ + requested-tc-info ],
? unneeded-tc-list => [ + bstr ],
? ext-list => [ + ext-info ], ? ext-list => [ + ext-info ],
* $$query-response-extensions, * $$query-response-extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
trusted-app-install = [ tc-info = {
type: TEEP-TYPE-trusted-app-install, component-id: bstr,
? tc-manifest-sequence-number: uint
}
requested-ta-info = {
component-id: bstr,
? tc-manifest-sequence-number: uint,
? have-binary: bool
}
install = [
type: TEEP-TYPE-install,
token: uint, token: uint,
option: { option: {
? manifest-list => [ + SUIT_Envelope ], ? manifest-list => [ + SUIT_Envelope ],
* $$trusted-app-install-extensions, * $$install-extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
trusted-app-delete = [ delete = [
type: TEEP-TYPE-trusted-app-delete, type: TEEP-TYPE-delete,
token: uint, token: uint,
option: { option: {
? ta-list => [ + bstr ], ? tc-list => [ + bstr ],
* $$trusted-app-delete-extensions, * $$delete-extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
teep-success = [ teep-success = [
type: TEEP-TYPE-teep-success, type: TEEP-TYPE-teep-success,
token: uint, token: uint,
option: { option: {
? msg => text, ? msg => text,
? suit-reports => [ + suit-report ],
* $$teep-success-extensions, * $$teep-success-extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
] ]
teep-error = [ teep-error = [
type: TEEP-TYPE-teep-error, type: TEEP-TYPE-teep-error,
token: uint, token: uint,
err-code: uint,
options: { options: {
? err-msg => text, ? err-msg => text,
? cipher-suites => [ + suite ], ? supported-cipher-suites => [ + suite ],
? versions => [ + version ], ? versions => [ + version ],
? suit-reports => [ + suit-report ],
* $$teep-error--extensions, * $$teep-error--extensions,
* $$teep-option-extensions * $$teep-option-extensions
} }
err-code: uint,
] ]
cipher-suites = 1 supported-cipher-suites = 1
nonce = 2 challenge = 2
versions = 3 versions = 3
oscp-data = 4 ocsp-data = 4
selected-cipher-suite = 5 selected-cipher-suite = 5
selected-version = 6 selected-version = 6
eat = 7 evidence = 7
ta-list = 8 tc-list = 8
ext-list = 9 ext-list = 9
manifest-list = 10 manifest-list = 10
msg = 11 msg = 11
err-msg = 12 err-msg = 12
evidence-format = 13
requested-tc-list = 14
unneeded-tc-list = 15
component-id = 16
tc-manifest-sequence-number = 17
have-binary = 18
suit-reports = 19
D. Examples of Diagnostic Notation and Binary Representation
D.1. Some assumptions in examples
o OCSP stapling data = h'010203'
o TEEP Device will have 2 TAs
* TA-ID: 0x0102030405060708090a0b0c0d0e0f,
0x1102030405060708090a0b0c0d0e0f
o SUIT manifest-list is set empty only for example purposes
o Not including Entity Attestation Token (EAT) parameters for
example purposes
D.2. QueryRequest Message
D.2.1. CBOR Diagnostic Notation
/ query-request = /
[
1, / type : TEEP-TYPE-query-request = 1 (fixed int) /
2004318071, / token : 0x77777777 (uint), generated by TAM /
/ options : /
{
1 : [ 1 ] / supported-cipher-suites = 1 (mapkey) : /
/ TEEP-AES-CCM-16-64-128-HMAC256--256-X25519-EdDSA =
[ 1 ] (array of uint .size 8) /
3 : [ 0 ] / version = 3 (mapkey) :
[ 0 ] (array of uint .size 4) /
4 : h'010203' / ocsp-data = 4 (mapkey) : 0x010203 (bstr) /
},
2 / data-item-requested : trusted-components = 2 (uint) /
]
D.2.2. CBOR Binary Representation
84 # array(4),
01 # unsigned(1)
1A 77777777 # unsigned(2004318071, 0x77777777)
A3 # map(3)
01 # unsigned(1)
81 # array(1)
01 # unsigned(1) within .size 8
03 # unsigned(3)
81 # array(1)
00 # unsigned(0) within .size 4
04 # unsigned(4)
43 # bytes(3)
010203 # "\x01\x02\x03"
02 # unsigned(2)
D.3. QueryResponse Message
D.3.1. CBOR Diagnostic Notation
/ query-response = /
[
2, / type : TEEP-TYPE-query-response = 2 (fixed int) /
2004318071, / token : 0x77777777 (uint), from TAM's QueryRequest
message /
/ options : /
{
5 : 1, / selected-cipher-suite = 5(mapkey) :/
/ TEEP-AES-CCM-16-64-128-HMAC256--256-X25519-EdDSA =
1 (uint .size 8) /
6 : 0, / selected-version = 6 (mapkey) : 0 (uint .size 4) /
8 : [ h'0102030405060708090a0b0c0d0e0f',
h'1102030405060708090a0b0c0d0e0f' ]
/ ta-list = 8 (mapkey) :
[ 0x0102030405060708090a0b0c0d0e0f,
0x1102030405060708090a0b0c0d0e0f ]
(array of bstr) /
}
]
D.3.2. CBOR Binary Representation
83 # array(3)
02 # unsigned(2)
1A 77777777 # unsigned(2004318071, 0x77777777)
A3 # map(3)
05 # unsigned(5)
01 # unsigned(1) within .size 8
06 # unsigned(6)
00 # unsigned(0) within .size 4
08 # unsigned(8)
82 # array(2)
4F # bytes(16)
0102030405060708090A0B0C0D0D0F
4F # bytes(16)
1102030405060708090A0B0C0D0D0F
D.4. Install Message
D.4.1. CBOR Diagnostic Notation
/ install = /
[
3, / type : TEEP-TYPE-install = 3 (fixed int) /
2004318072, / token : 0x777777778 (uint), generated by TAM /
/ options : /
{
10 : [ ] / manifest-list = 10 (mapkey) :
[ ] (array of SUIT_Envelope(any)) /
/ empty, example purpose only /
}
]
D.4.2. CBOR Binary Representation
83 # array(3)
03 # unsigned(3)
1A 77777778 # unsigned(2004318072, 0x77777778)
A1 # map(1)
0A # unsigned(10)
80 # array(0)
D.5. Success Message (for Install)
D.5.1. CBOR Diagnostic Notation
/ teep-success = /
[
5, / type : TEEP-TYPE-teep-success = 5 (fixed int) /
2004318072, / token : 0x777777778 (uint), from Install message /
]
D.5.2. CBOR Binary Representation
83 # array(3)
05 # unsigned(5)
1A 77777778 # unsigned(2004318072, 0x77777778)
D.6. Error Message (for Install)
D.6.1. CBOR Diagnostic Notation
/ teep-error = /
[
6, / type : TEEP-TYPE-teep-error = 6 (fixed int) /
2004318072, / token : 0x777777778 (uint), from Install message /
ERR_MANIFEST_PROCESSING_FAILED,
/ err-code : ERR_MANIFEST_PROCESSING_FAILED = 17 (uint) /
/ options : /
{
12 : "disk-full" / err-msg = 12 (mapkey) :
"disk-full" (UTF-8 string) /
}
]
D.6.2. CBOR binary Representation
83 # array(3)
06 # unsigned(6)
1A 77777778 # unsigned(2004318072, 0x77777778)
11 # unsigned(17)
A1 # map(1)
0B # unsigned(12)
69 # text(9)
6469736b2d66756c6c # "disk-full"
Authors' Addresses Authors' Addresses
Hannes Tschofenig Hannes Tschofenig
Arm Ltd. Arm Ltd.
Absam, Tirol 6067 Absam, Tirol 6067
Austria Austria
Email: hannes.tschofenig@arm.com Email: hannes.tschofenig@arm.com
Mingliang Pei Mingliang Pei
Broadcom Broadcom
350 Ellis St 350 Ellis St
Mountain View, CA 94043 Mountain View, CA 94043
USA USA
Email: mingliang.pei@broadcom.com Email: mingliang.pei@broadcom.com
David Wheeler David Wheeler
Intel Intel
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