Internet DRAFT - draft-tschofenig-teep-protocol
draft-tschofenig-teep-protocol
TEEP H. Tschofenig
Internet-Draft Arm Ltd.
Intended status: Standards Track M. Pei
Expires: May 20, 2020 Broadcom
D. Wheeler
Intel
D. Thaler
Microsoft
November 17, 2019
Trusted Execution Environment Provisioning Protocol (teep-p)
draft-tschofenig-teep-protocol-01
Abstract
This document specifies a protocol that installs, updates, and
deletes Trusted Applications (TAs) in a device with a Trusted
Execution Environment (TEE). This specification defines an
interoperable protocol for managing the lifecycle of TAs.
The protocol name is teep-p, pronounced teepee. This conjures an
image of a wedge-shaped protective covering for one's belongings,
which sort of matches the intent of this protocol.
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 May 20, 2020.
Copyright Notice
Copyright (c) 2019 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Message Overview . . . . . . . . . . . . . . . . . . . . . . 3
4. Detailed Messages Specification . . . . . . . . . . . . . . . 5
4.1. QueryRequest . . . . . . . . . . . . . . . . . . . . . . 5
4.2. QueryResponse . . . . . . . . . . . . . . . . . . . . . . 7
4.3. TrustedAppInstall . . . . . . . . . . . . . . . . . . . . 9
4.4. TrustedAppDelete . . . . . . . . . . . . . . . . . . . . 9
4.5. Success . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.6. Error . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Ciphersuites . . . . . . . . . . . . . . . . . . . . . . . . 12
6. Security Consideration . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
7.1. Media Type Registration . . . . . . . . . . . . . . . . . 14
7.2. Error Code Registry . . . . . . . . . . . . . . . . . . . 16
7.3. Ciphersuite Registry . . . . . . . . . . . . . . . . . . 17
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Normative References . . . . . . . . . . . . . . . . . . 17
8.2. Informative References . . . . . . . . . . . . . . . . . 18
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 19
Appendix B. Contributors . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
The Trusted Execution Environment (TEE) concept has been designed to
separate a regular operating system, also referred as a Rich
Execution Environment (REE), from security-sensitive applications.
In an TEE ecosystem, different device vendors may use different
operating systems in the REE and may use different types of TEEs.
When application providers or device administrators use Trusted
Application Managers (TAMs) to install, update, and delete Trusted
Applications (TAs) on a wide range of devices with potentially
different TEEs then an interoperability need arises.
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This document specifies the protocol for communicating between a TAM
and a TEEP Agent, involving a TEEP Broker.
The Trusted Execution Environment Provisioning (TEEP) architecture
document [I-D.ietf-teep-architecture] has set to provide a design
guidance for such an interoperable protocol and introduces the
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
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
This specification re-uses the terminology defined in
[I-D.ietf-teep-architecture].
3. Message Overview
The TEEP protocol consists of a couple of messages exchanged between
a TAM and a TEEP Agent via a TEEP Broker. The messages are encoded
either in JSON or CBOR and designed to provide end-to-end security.
TEEP protocol messages are signed and/or encrypted by the endpoints,
i.e., the TAM and the TEEP Agent, but trusted applications may as
well be encrypted and signed by the service provider. The TEEP
protocol not only re-use JSON and CBOR but also the respective
security wrappers, namely JOSE (JWS [RFC7515] and JWE [RFC7516], to
be more specific) and COSE [RFC8152]. Furthermore, for attestation
the Entity Attestation Token (EAT) [I-D.ietf-rats-eat] and for
software updates the SUIT manifest format [I-D.ietf-suit-manifest]
are re-used.
This specification defines six messages.
A TAM queries a device's current state with a QueryRequest message.
A TEEP Agent will, after authenticating and authorizing the request,
report attestation information, list all TAs, and provide information
about supported algorithms and extensions in a QueryResponse message.
An error message is returned if the request could not be processed.
A TAM will process the QueryResponse message and determine whether
subsequent message exchanges to install, update, or delete trusted
applications shall be initiated.
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+------------+ +-------------+
| TAM | |TEEP Agent |
+------------+ +-------------+
QueryRequest ------->
QueryResponse
<------- or
Error
With the TrustedAppInstall message a TAM can instruct a TEEP Agent to
install a TA. The TEEP Agent will process the message, determine
whether the TAM is authorized and whether the TA has been signed by
an authorized SP. In addition to the binary, the TAM may also
provide personalization data. If the TrustedAppInstall message was
processed successfully then a Success message is returned to the TAM,
an Error message otherwise.
+------------+ +-------------+
| TAM | |TEEP Agent |
+------------+ +-------------+
TrustedAppInstall ---->
Success
<---- or
Error
With the TrustedAppDelete message a TAM can instruct a TEEP Agent to
delete one or multiple TA(s). A Success message is returned when the
operation has been completed successfully, and an Error message
otherwise.
+------------+ +-------------+
| TAM | |TEEP Agent |
+------------+ +-------------+
TrustedAppDelete ---->
Success
<---- or
Error
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4. Detailed Messages Specification
For a CBOR-based encoding the following security wrapper is used
(described in CDDL format [I-D.ietf-cbor-cddl]).
Outer_Wrapper = {
msg-authenc-wrapper => bstr .cbor
Msg_AuthEnc_Wrapper / nil,
teep-message => (QueryRequest /
QueryResponse /
TrustedAppInstall /
TrustedAppDelete /
Error /
Success ),
}
msg-authenc-wrapper = 1
teep-message = 2
Msg_AuthEnc_Wrapper = [ * (COSE_Mac_Tagged /
COSE_Sign_Tagged /
COSE_Mac0_Tagged /
COSE_Sign1_Tagged)]
A future version of this specification will also describe the
security wrapper for JSON (in CDDL format).
4.1. QueryRequest
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suite = int
version = int
data_items = (
attestation: 1,
trusted_apps: 2,
extensions: 3,
suit_commands: 4
)
QueryRequest = (
TYPE : int,
TOKEN : bstr,
REQUEST : [+data_items],
? CIPHER_SUITE : [+suite],
? NONCE : bstr,
? VERSION : [+version],
? OCSP_DATA : bstr,
* $$extensions
)
A QueryRequest message is signed by the TAM and has the following
fields:
TYPE TYPE = 1 corresponds to a QueryRequest message sent from the
TAM to the TEEP Agent.
TOKEN The value in the TOKEN field is used to match requests to
responses.
REQUEST The REQUEST field indicates what information the TAM
requests from the TEEP Agent in form of a list of integer values.
Each integer value corresponds to an IANA registered information
element. This specification defines the initial set of
information elements:
attestation (1) With this value the TAM requests the TEEP Agent
to return an entity attestation token (EAT) in the response.
trusted_apps (2) With this value the TAM queries the TEEP Agent
for all installed TAs.
extensions (3) With this value the TAM queries the TEEP Agent for
supported capabilities and extensions, which allows a TAM to
discover the capabilities of a TEEP Agent implementation.
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suit_commands (4) With this value the TAM queries the TEEP Agent
for supported commands offered by the SUIT manifest
implementation.
Further values may be added in the future via IANA registration.
CIPHER_SUITE The CIPHER_SUITE field lists the ciphersuite(s)
supported by the TAM. Details about the ciphersuite encoding can
be found in Section 5.
NONCE NONCE is an optional field used for ensuring the refreshness
of the Entity Attestation Token (EAT) contained in the response.
VERSION The VERSION field lists the version(s) supported by the TAM.
For this version of the specification this field can be omitted.
OCSP_DATA The OCSP_DATA field contains a list of OCSP stapling data
respectively for the TAM certificate and each of the CA
certificates up to the root certificate. The TAM provides OCSP
data so that the TEEP Agent can validate the status of the TAM
certificate chain without making its own external OCSP service
call. OCSP data MUST be conveyed as a DER-encoded OCSP response
(using the ASN.1 type OCSPResponse defined in [RFC2560]). The use
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
functionality via the capability discovery exchange, as described
above.
4.2. QueryResponse
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ta_id = (
Vendor_ID = bstr,
Class_ID = bstr,
Device_ID = bstr,
* $$extensions
)
ext_info = int
QueryResponse = (
TYPE : int,
TOKEN : bstr,
? SELECTED_CIPHER_SUITE : suite,
? SELECTED_VERSION : version,
? EAT : bstr,
? TA_LIST : [+ta_id],
? EXT_LIST : [+ext_info],
* $$extensions
)
The QueryResponse message is signed and encrypted by the TEEP Agent
and returned to the TAM. It has the following fields:
TYPE TYPE = 2 corresponds to a QueryResponse message sent from the
TEEP Agent to the TAM.
TOKEN The value in the TOKEN field is used to match requests to
responses. The value MUST correspond to the value received with
the QueryRequest.
SELECTED_CIPHER_SUITE The SELECTED_CIPHER_SUITE field indicates the
selected ciphersuite. Details about the ciphersuite encoding can
be found in Section 5.
SELECTED_VERSION The SELECTED_VERSION field indicates the protocol
version selected by the TEEP Agent.
EAT The EAT field contains an Entity Attestation Token following the
encoding defined in [I-D.ietf-rats-eat].
TA_LIST The TA_LIST field enumerates the trusted applications
installed on the device in form of ta_ids, i.e., a vendor id/class
id/device id triple.
EXT_LIST The EXT_LIST field lists the supported extensions. This
document does not define any extensions.
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4.3. TrustedAppInstall
TrustedAppInstall = (
TYPE : int,
TOKEN : bstr,
? MANIFEST_LIST : [+ SUIT_Outer_Wrapper],
* $$extensions
)
The TrustedAppInstall message is MACed and encrypted by the TAM and
has the following fields:
TYPE TYPE = 3 corresponds to a TrustedAppInstall message sent from
the TAM to the TEEP Agent. In case of successful processing, an
Success message is returned by the TEEP Agent. In case of an
error, an Error message is returned. Note that the
TrustedAppInstall message is used for initial TA installation but
also for TA updates.
TOKEN The value in the TOKEN field is used to match requests to
responses.
TA The MANIFEST_LIST field is used to convey one or multiple SUIT
manifests. A manifest is a bundle of metadata about the trusted
app, where to find the code, the devices to which it applies, and
cryptographic information protecting the manifest. The manifest
may also convey personalization data. TA binaries and
personalization data is typically signed and encrypted by the SP.
Other combinations are, however, possible as well. For 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
binary.
4.4. TrustedAppDelete
TrustedAppDelete = (
TYPE : int,
TOKEN : bstr,
? TA_LIST : [+ta_id],
* $$extensions
)
The TrustedAppDelete message is MACed and encrypted by the TAM and
has the following fields:
TYPE TYPE = 4 corresponds to a TrustedAppDelete message sent from
the TAM to the TEEP Agent. In case of successful processing, an
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Success message is returned by the TEEP Agent. In case of an
error, an Error message is returned.
TOKEN The value in the TOKEN field is used to match requests to
responses.
TA_LIST The TA_LIST field enumerates the TAs to be deleted.
4.5. Success
Success = (
TYPE : int,
TOKEN : bstr,
? MSG : tstr,
* $$extensions
)
The Success message is MACed and encrypted by the TEEP Agent and has
the following fields:
TYPE TYPE = 5 corresponds to a Error message sent from the TEEP
Agent to the TAM.
TOKEN The value in the TOKEN field is used to match requests to
responses.
MSG The MSG field contains optional diagnostics information encoded
in UTF-8 [RFC3629] returned by the TEEP Agent.
4.6. Error
Error = (
TYPE : int,
TOKEN : bstr,
ERR_CODE : int,
? ERR_MSG : tstr,
? CIPHER_SUITE : [+suite],
? VERSION : [+version],
* $$extensions
)
If possible, the Error message is MACed and encrypted by the TEEP
Agent. Unprotected Error messages MUST be handled with care by the
TAM due to possible downgrading attacks. It has the following
fields:
TYPE TYPE = 6 corresponds to a Error message sent from the TEEP
Agent to the TAM.
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TOKEN The value in the TOKEN field is used to match requests to
responses.
ERR_CODE The ERR_CODE field is populated with values listed in a
registry (with the initial set of error codes listed below). Only
selected messages are applicable to each message.
ERR_MSG The ERR_MSG message is a human-readable diagnostic message
that MUST be encoded using UTF-8 [RFC3629] using Net-Unicode form
[RFC5198].
VERSION The VERSION field enumerates the protocol version(s)
supported by the TEEP Agent. This field is optional but MUST be
returned with the ERR_UNSUPPORTED_MSG_VERSION error message.
CIPHER_SUITE The CIPHER_SUITE field lists the ciphersuite(s)
supported by the TEEP Agent. This field is optional but MUST be
returned with the ERR_UNSUPPORTED_CRYPTO_ALG error message.
This specification defines the following initial error messages.
Additional error code can be registered with IANA.
ERR_ILLEGAL_PARAMETER The TEEP Agent sends this error message when a
request contains incorrect fields or fields that are inconsistent
with other fields.
ERR_UNSUPPORTED_EXTENSION The TEEP Agent sends this error message
when it recognizes an unsupported extension or unsupported
message.
ERR_REQUEST_SIGNATURE_FAILED The TEEP Agent sends this error message
when it fails to verify the signature of the message.
ERR_UNSUPPORTED_MSG_VERSION The TEEP Agent receives a message but
does not support the indicated version.
ERR_UNSUPPORTED_CRYPTO_ALG The TEEP Agent receives a request message
encoded with an unsupported cryptographic algorithm.
ERR_BAD_CERTIFICATE The TEEP Agent returns this error when
processing of a certificate failed. For diagnosis purposes it is
RECOMMMENDED to include information about the failing certificate
in the error message.
ERR_UNSUPPORTED_CERTIFICATE The TEEP Agent returns this error when a
certificate was of an unsupported type.
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ERR_CERTIFICATE_REVOKED The TEEP Agent returns this error when a
certificate was revoked by its signer.
ERR_CERTIFICATE_EXPIRED The TEEP Agent returns this error when a
certificate has expired or is not currently valid.
ERR_INTERNAL_ERROR The TEEP Agent returns this error when a
miscellaneous internal error occurred while processing the
request.
ERR_RESOURCE_FULL This error is reported when a device resource
isn't available anymore, such as storage space is full.
ERR_TA_NOT_FOUND 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 While installing a TA, a TEE will return
this error if the TA has already been installed.
ERR_TA_UNKNOWN_FORMAT The TEEP Agent returns this error when it does
not recognize the format of the TA binary.
ERR_TA_DECRYPTION_FAILED The TEEP Agent returns this error when it
fails to decrypt the TA binary.
ERR_TA_DECOMPRESSION_FAILED The TEEP Agent returns this error when
it fails to decompress the TA binary.
ERR_MANIFEST_PROCESSING_FAILED The TEEP Agent returns this error
when manifest processing failures occur that are less specific
than ERR_TA_UNKNOWN_FORMAT, ERR_TA_UNKNOWN_FORMAT, and
ERR_TA_DECOMPRESSION_FAILED.
ERR_PD_PROCESSING_FAILED The TEEP Agent returns this error when it
fails to process the provided personalization data.
5. Ciphersuites
A ciphersuite consists of an AEAD algorithm, a HMAC algorithm, and a
signature algorithm. Each ciphersuite is identified with an integer
value, which corresponds to an IANA registered ciphersuite. This
document specifies two ciphersuites.
Value | Ciphersuite
------+------------------------------------------------
0 | AES-CCM-16-64-128, HMAC 256/256, X25519, EdDSA
1 | AES-CCM-16-64-128, HMAC 256/256, P-256, ES256
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6. Security Consideration
This section summarizes the security considerations discussed in this
specification:
Cryptographic Algorithms This specification relies on the
cryptographic algorithms provided by the security wrappers JOSE
and COSE, respectively. A companion document makes algorithm
recommendations but this document is written in an algorithm-
agnostic way. TEEP protocol messages exchanged between the TAM
and the TEEP Agent are protected using JWS and JWE (for JSON-
encoded messages) and COSE (for CBOR-encoded messages). Public
key based authentication is used to by the TEEP Agent to
authenticate the TAM and vice versa.
Attestation A TAM may rely on the attestation information provided
by the TEEP Agent and the Entity Attestation Token is re-used to
convey this information. To sign the Entity Attestation Token it
is necessary for the device to possess a public key (usually in
the form of a certificate) along with the corresponding private
key. Depending on the properties of the attestation mechanism it
is possible to uniquely identify a device based on information in
the attestation information or in the certificate used to sign the
attestation token. This uniqueness may raise privacy concerns.
To lower the privacy implications the TEEP Agent MUST present its
attestation information only to an authenticated and authorized
TAM.
TA Binaries TA binaries are provided by the SP.It is the
responsibility of the TAM to relay only verified TAs from
authorized SPs. Delivery of that TA to the TEEP Agent is then the
responsibility of the TAM and the TEEP Broker, using the security
mechanisms provided by the TEEP protocol. To protect the TA
binary the SUIT manifest is re-used and it offers a varity of
security features, including digitial signatures and symmetric
encryption.
Personalization Data An SP or a TAM can supply personalization data
along with a TA. This data is also protected by a SUIT manifest.
The personalization data may be itself is (or can be) opaque to
the TAM.
TEEP Broker The TEEP protocol relies on the TEEP Broker to relay
messages between the TAM and the TEEP Agent. When the TEEP Broker
is compromised it can drop messages, delay the delivery of
messages, and replay messages but it cannot modify those messages.
(A replay would be, however, detected by the TEEP Agent.) A
compromised TEEP Broker could reorder messages in an attempt to
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install an old version of a TA. Information in the manifest
ensures that the TEEP Agents are protected against such
downgrading attacks based on features offered by the manifest
itself.
CA Compromise The QueryRequest message from a TAM to the TEEP Agent
may include OCSP stapling data for the TAM's signer certificate
and for intermediate CA certificates up to the root certificate so
that the TEEP Agent can verify the certificate's revocation
status.
A certificate revocation status check on a TA signer certificate
is OPTIONAL by a TEEP Agent. A TAM is responsible for vetting a
TA and before distributing them to TEEP Agents. TEEP Agents will
trust a TA signer certificate's validation status done by a TAM.
CA Compromise The CA issuing certificates to a TAM or an SP may get
compromised. A compromised intermediate CA certificates can be
detected by a TEEP Agent by using OCSP information, assuming the
revocation information is available. Additionally, it is
RECOMMENDED to provide a way to update the trust anchor store used
by the device, for example using a firmware update mechanism.
If the CA issuing certificates to devices gets compromised then
these devices might be rejected by a TAM, if revocation is
available to the TAM.
Compromised TAM The TEEP Agent SHOULD use OCSP information to verify
the validity of the TAM-provided certificate (as well as the
validity of intermediate CA certificates). The integrity and the
accuracy of the clock within the TEE determines the ability to
determine an expired or revoked certificate since OCSP stapling
includes signature generation time, certificate validity dates are
compared to the current time.
7. IANA Considerations
7.1. Media Type Registration
IANA is requested to assign a media type for application/teep-p+json.
Type name: application
Subtype name: teep-p+json
Required parameters: none
Optional parameters: none
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Encoding considerations: Same as encoding considerations of
application/json as specified in Section 11 of [RFC7159]
Security considerations: See Security Considerations Section of this
document.
Interoperability considerations: Same as interoperability
considerations of application/json as specified in [RFC7159]
Published specification: This document.
Applications that use this media type: TEEP protocol implementations
Fragment identifier considerations: N/A
Additional information:
Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): N/A
Macintosh file type code(s): N/A
Person to contact for further information: teep@ietf.org
Intended usage: COMMON
Restrictions on usage: none
Author: See the "Authors' Addresses" section of this document
Change controller: IETF
IANA is requested to assign a media type for application/teep-p+cbor.
Type name: application
Subtype name: teep-p+cbor
Required parameters: none
Optional parameters: none
Encoding considerations: Same as encoding considerations of
application/cbor
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Security considerations: See Security Considerations Section of this
document.
Interoperability considerations: Same as interoperability
considerations of application/cbor as specified in [RFC7049]
Published specification: This document.
Applications that use this media type: TEEP protocol implementations
Fragment identifier considerations: N/A
Additional information:
Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): N/A
Macintosh file type code(s): N/A
Person to contact for further information: teep@ietf.org
Intended usage: COMMON
Restrictions on usage: none
Author: See the "Authors' Addresses" section of this document
Change controller: IETF
7.2. Error Code Registry
IANA is also requested to create a new registry for the error codes
defined in Section 4.
Registration requests are evaluated after a three-week review period
on the teep-reg-review@ietf.org mailing list, on the advice of one or
more Designated Experts [RFC8126]. However, to allow for the
allocation of values prior to publication, the Designated Experts may
approve registration once they are satisfied that such a
specification will be published.
Registration requests sent to the mailing list for review should use
an appropriate subject (e.g., "Request to register an error code:
example"). Registration requests that are undetermined for a period
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longer than 21 days can be brought to the IESG's attention (using the
iesg@ietf.org mailing list) for resolution.
Criteria that should be applied by the Designated Experts includes
determining whether the proposed registration duplicates existing
functionality, whether it is likely to be of general applicability or
whether it is useful only for a single extension, and whether the
registration description is clear.
IANA must only accept registry updates from the Designated Experts
and should direct all requests for registration to the review mailing
list.
7.3. Ciphersuite Registry
IANA is also requested to create a new registry for ciphersuites, as
defined in Section 5.
8. References
8.1. Normative References
[I-D.ietf-rats-eat]
Mandyam, G., Lundblade, L., Ballesteros, M., and J.
O'Donoghue, "The Entity Attestation Token (EAT)", draft-
ietf-rats-eat-01 (work in progress), July 2019.
[I-D.ietf-suit-manifest]
Moran, B., Tschofenig, H., and H. Birkholz, "SUIT CBOR
manifest serialisation format", draft-ietf-suit-
manifest-01 (work in progress), October 2019.
[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/info/rfc2119>.
[RFC2560] Myers, M., Ankney, R., Malpani, A., Galperin, S., and C.
Adams, "X.509 Internet Public Key Infrastructure Online
Certificate Status Protocol - OCSP", RFC 2560,
DOI 10.17487/RFC2560, June 1999,
<https://www.rfc-editor.org/info/rfc2560>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>.
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[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[RFC5198] Klensin, J. and M. Padlipsky, "Unicode Format for Network
Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008,
<https://www.rfc-editor.org/info/rfc5198>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
RFC 7516, DOI 10.17487/RFC7516, May 2015,
<https://www.rfc-editor.org/info/rfc7516>.
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/info/rfc7517>.
[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/info/rfc7518>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
8.2. Informative References
[I-D.ietf-cbor-cddl]
Birkholz, H., Vigano, C., and C. Bormann, "Concise data
definition language (CDDL): a notational convention to
express CBOR and JSON data structures", draft-ietf-cbor-
cddl-08 (work in progress), March 2019.
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[I-D.ietf-teep-architecture]
Pei, M., Tschofenig, H., Wheeler, D., Atyeo, A., and D.
Liu, "Trusted Execution Environment Provisioning (TEEP)
Architecture", draft-ietf-teep-architecture-03 (work in
progress), July 2019.
[I-D.ietf-teep-opentrustprotocol]
Pei, M., Atyeo, A., Cook, N., Yoo, M., and H. Tschofenig,
"The Open Trust Protocol (OTrP)", draft-ietf-teep-
opentrustprotocol-03 (work in progress), May 2019.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
Appendix A. Acknowledgements
This work is based on the initial version of OTrP
[I-D.ietf-teep-opentrustprotocol] and hence credits go to those who
have contributed to it.
We would like to thank Eve Schooler for the suggestion of the
protocol name.
Appendix B. Contributors
We would like to thank the following individuals for their
contributions to an earlier version of this specification.
- Brian Witten
Symantec
brian_witten@symantec.com
- Tyler Kim
Solacia
tylerkim@iotrust.kr
- Nick Cook
Arm Ltd.
nicholas.cook@arm.com
- Minho Yoo
IoTrust
minho.yoo@iotrust.kr
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Authors' Addresses
Hannes Tschofenig
Arm Ltd.
110 Fulbourn Rd
Cambridge, CB1 9NJ
Great Britain
Email: hannes.tschofenig@arm.com
Mingliang Pei
Broadcom
350 Ellis St
Mountain View, CA 94043
USA
Email: mingliang.pei@broadcom.com
David Wheeler
Intel
US
Email: david.m.wheeler@intel.com
Dave Thaler
Microsoft
US
Email: dthaler@microsoft.com
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