Network Working Group G. Selander
Internet-Draft J. Mattsson
Intended status: Informational Ericsson AB
Expires: November 5, 2021 M. Vucinic
INRIA
M. Richardson
Sandelman Software Works
A. Schellenbaum
Institute of Embedded Systems, ZHAW
May 04, 2021
Lightweight Authorization for Authenticated Key Exchange.
draft-selander-ace-ake-authz-03
Abstract
This document describes a procedure for augmenting the authenticated
Diffie-Hellman key exchange EDHOC with third party assisted
authorization targeting constrained IoT deployments (RFC 7228).
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
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on November 5, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Description . . . . . . . . . . . . . . . . . . . . . 3
3. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Device . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Domain Authenticator . . . . . . . . . . . . . . . . . . 4
3.3. Authorization Server . . . . . . . . . . . . . . . . . . 5
4. The Protocol . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Device <-> Authorization Server . . . . . . . . . . . . . 7
4.2. Device <-> Authenticator . . . . . . . . . . . . . . . . 10
4.3. Authenticator <-> Authorization Server . . . . . . . . . 12
5. ACE Profile . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1. Protocol Overview . . . . . . . . . . . . . . . . . . . . 15
5.2. AS Request Creation Hints . . . . . . . . . . . . . . . . 15
5.3. Client-to-AS Request . . . . . . . . . . . . . . . . . . 16
5.4. AS-to-Client Response . . . . . . . . . . . . . . . . . . 16
6. Security Considerations . . . . . . . . . . . . . . . . . . . 17
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8. Informative References . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
For constrained IoT deployments [RFC7228] the overhead contributed by
security protocols may be significant which motivates the
specification of lightweight protocols that are optimizing, in
particular, message overhead (see [I-D.ietf-lake-reqs]). This
document describes a procedure for augmenting the lightweight
authenticated Diffie-Hellman key exchange EDHOC [I-D.ietf-lake-edhoc]
with third party assisted authorization.
The procedure involves a device, a domain authenticator and an
authorization server. The device and authenticator perform mutual
authentication and authorization, assisted by the authorization
server which provides relevant authorization information to the
device (a "voucher") and to the authenticator.
The protocol assumes that authentication between device and
authenticator is performed with EDHOC, and defines the integration of
a lightweight authorization procedure using the Auxiliary Data
defined in EDHOC.
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In this document we consider the target interaction to be
"enrollment", for example certificate enrollment (such as
[I-D.selander-ace-coap-est-oscore]) or joining a network for the
first time (e.g. [I-D.ietf-6tisch-minimal-security]), but it can be
applied to authorize other target interactions.
The protocol enables a low message count by performing authorization
and enrollment in parallel with authentication, instead of in
sequence which is common for network access. It further reuses
protocol elements from EDHOC leading to reduced message sizes on
constrained links.
This protocol is applicable to a wide variety of settings, and can be
mapped to different authorization architectures. This document
specifies a profile of the ACE framework [I-D.ietf-ace-oauth-authz].
Other settings such as EAP [RFC3748] are out of scope for this
specification.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Problem Description
The (potentially constrained) device wants to enroll into a domain
over a constrained link. The device authenticates and enforces
authorization of the (non-constrained) domain authenticator with the
help of a voucher, and makes the enrollment request. The domain
authenticator authenticates the device and authorizes its enrollment.
Authentication between device and domain authenticator is made with
the lightweight authenticated Diffie-Hellman key exchange protocol
EDHOC [I-D.ietf-lake-edhoc]. The procedure is assisted by a (non-
constrained) authorization server located in a non-constrained
network behind the domain authenticator providing information to the
device and to the domain authenticator as part of the protocol.
The objective of this document is to specify such a protocol which is
lightweight over the constrained link and reuses elements of EDHOC.
See illustration in Figure 1.
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Voucher
EDHOC Info
+----------+ | | +---------------+ Voucher +---------------+
| | | | | | Request | |
| Device |--|----o-->| Domain |---------->| Authorization |
| |<-|---o----| Authenticator |<----------| Server |
| (U) |--|---|--->| (V) | Voucher | (W) |
| | | | | Response | |
+----------+ | +---------------+ +---------------+
Voucher
Figure 1: Overview of message flow. Link between U anv V is
constrained but link between V and W is not. Voucher Info and
Voucher are sent in EDHOC Auxiliary Data.
3. Assumptions
3.1. Device
The device is pre-provisioned with an identity ID_U and asymmetric
key credentials: a private key, a public key (PK_U), and optionally a
public key certificate (Cert_PK_U), issued by a trusted third party
such as e.g. the device manufacturer, used to authenticate to the
domain authenticator. ID_U may be a reference or pointer to the
certificate.
The device is also provisioned with information about its
authorization server:
o At least one static public DH key of the authorization server
(G_W) used to ensure secure communication with the device (see
Section 4.1).
o Location information about the authorization server (LOC_W), e.g.
its domain name. This information may be available in the device
certificate Cert_PK_U.
3.2. Domain Authenticator
The domain authenticator has a private key and a corresponding public
key PK_V used to authenticate to the device.
The domain authenticator needs to be able to locate the authorization
server of the device for which LOC_W is expected to be sufficient.
The communication between domain authenticator and authorization
server is assumed to be mutually authenticated and protected;
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authentication credentials and communication security is out of
scope, except for as specified below in this section.
The domain authenticator may in principle use differents credentials
for authenticating to the authorization server and to the device, for
which PK_V is used. However, the domain authenticator MUST prove
possession of private key of PK_V to the authorization server since
the authorization server is asserting (by means of the voucher to the
device) that this credential belongs to the domain authenticator.
In this version of the draft it is assumed that the domain
authenticator authenticates to the authorization server with PK_V
using some authentication protocol providing proof of possession of
the private key, for example TLS 1.3 [RFC8446]. A future version of
this draft may specify explicit proof of possession of the private
key of PK_V in the voucher request, e.g., by including a signature of
the voucher request with the private key corresponding to PK_V.
3.3. Authorization Server
The authorization server has the private DH key corresponding to G_W,
which is used to secure the communication with the device (see
Section 4.1).
Authentication credentials and communication security used with the
domain authenticator is out of scope, except for the need to verify
the possession of the private key of PK_V as specified in
Section 3.2.
The authorization server provides to the device the authorization
decision for enrollment with the domain authenticator in the form of
a voucher. The authorization server provides information to the
domain authenticator about the device, such as the the device's
certificate Cert_PK_U.
The authorization server needs to be available during the execution
of the protocol.
4. The Protocol
Three security sessions are going on in parallel (as detailed in the
subsections):
o Between device (U) and (domain) authenticator (V),
o between authenticator and authorization server (W), and
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o between device and authorization server mediated by the
authenticator.
The most relevant message fields of EDHOC [I-D.ietf-lake-edhoc] in
this specification are shown within brackets { ... } (see Figure 2):
o G_X: the x-coordinate of the ephemeral public Diffie-Hellman key
of party U
o AD_1: Auxiliary Data of message_1
o AD_2: Auxiliary Data of message_2
o ID_CRED_R: data enabling the party U to obtain the credentials
containing the public authentication key of the responder V
o ID_CRED_I: data enabling the party V to obtain the credentials
containing the public authentication key of the initiator U
o Sig_or_MAC_2: a signature or MAC made by party V with use of the
private key of V
o Sig_or_MAC_3: a signature or MAC made by party U with use of the
private key of U
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U V W
| | |
| {G_X, AD_1} | |
+----------------------------------->| |
| EDHOC message_1 | G_X, CC, AEAD(K_1; ID_U) |
| +----------------------------->|
| | Voucher Request (VREQ) |
| | |
| | G_X, CERT_PK_U, Voucher |
| |<-----------------------------+
| | Voucher Response (VRES) |
| {ID_CRED_R, Sig_or_MAC_2, AD_2} | |
|<-----------------------------------+ |
| EDHOC message_2 | |
| | |
| {ID_CRED_I, Sig_or_MAC_3} | |
+----------------------------------->| |
| EDHOC message_3 | |
where
AD_1 = (T0, LOC_W, CC, AEAD(K1; ID_U))
AD_2 = (T1, Voucher)
Voucher = AEAD(K_2; V_TYPE, PK_V, G_X, ID_U)
Figure 2: W-assisted authorization of AKE between U and V: EDHOC
between U and V, and Voucher Request/Response between V and W.
4.1. Device <-> Authorization Server
The communication between device and authorization server is carried
out via the authenticator protected between the endpoints (protocol
between U and W in Figure 2) using an ECIES hybrid encryption scheme
(see [I-D.irtf-cfrg-hpke]): The device uses the private key
corresponding to its ephemeral DH key G_X generated for EDHOC
message_1 (see Section 4.2) together with the static public DH key of
the authorization server G_W to generate a shared secret G_XW. The
shared secret is used to derive AEAD encryption keys to protect data
between device and authorization server. The data is carried in AD_1
and AD_2 (between device and authenticator) and in Voucher Request/
Response (between authenticator and authorization server).
TODO: Reference relevant ECIES scheme in [I-D.irtf-cfrg-hpke].
TODO: Define derivation of encryption keys (K_1, K_2) and nonces
(N_1, N_2) for the both directions
AD_1 SHALL be the following CBOR sequence:
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AD_1 = (
T0: int,
LOC_W: tstr,
CC: bstr,
CIPHERTEXT_RQ: bstr
)
where
o T0 is the Auxiliary Data Type (TBD in relevant IANA registry)
and the rest is Voucher Info:
o LOC_W is location information about the authorization server
o CC is a crypto context identifier for the security context between
the device and the authorization server
o 'CIPHERTEXT_RQ' is the authenticated encrypted identity of the
device with CC as Additional Data, more specifically:
'CIPHERTEXT_RQ' is 'ciphertext' of COSE_Encrypt0 (Section 5.2-5.3 of
[RFC8152]) computed from the following:
o the secret key K_1
o the nonce N_1
o 'protected' is a byte string of size 0
o 'plaintext and 'external_aad' as below:
plaintext = (
ID_U: bstr
)
external_aad = (
CC: bstr
)
where
o ID_U is the identity of the device, for example a reference or
pointer to the device certificate
o CC is defined above.
AD_2 SHALL be the following CBOR sequence:
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AD_2 = (
T1: int,
Voucher: bstr
)
where
o T1 is the Auxiliary Data Type (TBD in relevant IANA registry)
and 'Voucher' is defined in Section 4.1.1.
4.1.1. Voucher
The voucher is an assertion by the authorization server to the device
that the authorization server has performed the relevant
verifications and that the device is authorized to continue the
protocol with the authenticator. The voucher consists essentially of
a message authentication code which binds the identity of the
authenticator to message_1 of EDHOC.
More specifically 'Voucher' is the 'ciphertext' of COSE_Encrypt0
(Section 5.2 of [RFC8152]) computed from the following:
o the secret key K_2
o the nonce N_2
o 'protected' is a byte string of size 0
o 'plaintext' is empty (plaintext = nil)
o 'external_aad' as below:
external_aad = bstr .cbor external_aad_array
external_aad_array = [
V_TYPE: int,
PK_V: bstr,
G_X: bstr,
CC: bstr,
ID_U: bstr
]
where
o 'V_TYPE' indicates the type of voucher used
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o PK_V is a COSE_Key containing the public authentication key of the
authenticator. The public key MUST be an Elliptic Curve Diffie-
Hellman key, COSE key type 'kty' = 'EC2' or 'OKP'.
* COSE_Keys of type OKP SHALL only include the parameters 1
(kty), -1 (crv), and -2 (x-coordinate). COSE_Keys of type EC2
SHALL only include the parameters 1 (kty), -1 (crv), -2
(x-coordinate), and -3 (y-coordinate). The parameters SHALL be
encoded in decreasing order.
o G_X is the ephemeral key of the device sent in EDHOC message_1
o CC and ID_U are defined in Section 4.1
All parameters, except 'V_TYPE', are as received in the voucher
request (see Section 4.3).
TODO: Consider making the voucher a CBOR Map to indicate type of
voucher, to indicate the feature (cf. Section 4.3). Alternatively,
include V_TYPE in 'unprotected'.
4.2. Device <-> Authenticator
The device and authenticator run the EDHOC protocol authenticated
with public keys (PK_U and PK_V) of the device and the authenticator,
see protocol between U and V in Figure 2. The normal EDHOC
processing is omitted here.
4.2.1. Message 1
4.2.1.1. Device processing
The device composes EDHOC message_1 with specific parameters pre-
configured, such as EDHOC method. The correlation properties (see
Section 3.1 of [I-D.ietf-lake-edhoc]) are defined by the transport of
the messages. The static public DH key G_W of the authorization
server defines the ECDH curve of the selected cipher suite in
SUITES_I. As part of the normal EDHOC processing, the device
generates the ephemeral public key G_X. A new G_X MUST be generated
for each execution of the protocol. The ephemeral key G_X is reused
in the ECIES scheme, see Section 4.1.
The device sends EDHOC message_1 with AD_1 as specified in
Section 4.1.
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4.2.1.2. Authenticator processing
The authenticator receives EDHOC message_1 from the device, which
triggers the voucher request to the authorization server as described
in Section 4.3.
4.2.2. Message 2
4.2.2.1. Authenticator processing
The authenticator receives the voucher response from the
authorization server as described in Section 4.3.
The authenticator sends EDHOC message_2 to the device with the
voucher (see Section 4.1) in AD_2. The public key PK_V is carried in
ID_CRED_R of message_2 encoded as a COSE header_map, see Section 4.1
of [I-D.ietf-lake-edhoc]. The Sig_or_MAC_2 field calculated using
the private key corresponding to PK_V is either signature or MAC
depending on EDHOC method.
4.2.2.2. Device processing
In addition to normal EDHOC verifications, the device MUST verify the
voucher by calculating the same message authentication code as when
it was generated (see Section 4.1.1) and compare with what was
received in message_2.
The input in this calculation includes:
o The ephemeral key G_X, sent in message_1.
o The identity ID_U, sent in message_1.
o The public key of the authenticator PK_V, received in message_2.
If the voucher does not verify, the device MUST discontinue the
protocol.
4.2.3. Message 3
4.2.3.1. Device processing
If all verifications are passed, the device sends EDHOC message_3.
The message field ID_CRED_I contains data enabling the authenticator
to retrieve the public key of the device, PK_U. Since the
authenticator before sending message_2 received a certificate of PK_U
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from the authorization server (see Section 4.3), ID_CRED_I SHALL be a
COSE header_map of type 'kid' with the empty byte string as value:
ID_CRED_I =
{
4 : h''
}
The Sig_or_MAC_3 field calculated using the private key corresponding
to PK_U is either signature or MAC depending on EDHOC method.
AD_3 MAY contain an enrolment request, see
[I-D.mattsson-cose-cbor-cert-compress], or other request which the
device is now authorized to make.
EDHOC message_3 may be combined with an OSCORE request, see
[I-D.palombini-core-oscore-edhoc].
4.2.3.2. Authenticator processing
The authenticator performs the normal EDHOC verifications of
message_3, with the exception that the Sig_or_MAC_3 field MUST be
verified using the public key included in Cert_PK_U (see
Section 4.3.2) received from the authorization server. The
authenticator MUST ignore any key related information obtained in
ID_CRED_I.
This enables the authenticator to verify that message_3 was generated
by the device authorized by the authorization server as part of the
associated Voucher Request/Response procedure (see Section 4.3).
4.3. Authenticator <-> Authorization Server
The authenticator and authorization server are assumed to have, or to
be able to, set up a secure connection, for example TLS 1.3
authenticated with certificates. The authenticator is assumed to
authenticate with the public key PK_V, see Section 3.2.
This secure connection protects the Voucher Request/Response Protocol
(see protocol between V and W in Figure 2).
The ephemeral public key G_X sent in EDHOC message_1 from device to
authenticator serves as challenge/response nonce for the Voucher
Request/Response Protocol, and binds together instances of the two
protocols.
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4.3.1. Voucher Request
4.3.1.1. Authenticator processing
Unless already in place, the authenticator and the authorization
server establish a secure connection. The autenticator uses G_X
received from the device as a nonce associated to this connection
with the authorization server. If the same value of the nonce G_X is
already used for a connection with this or other authorization
server, the protocol SHALL be discontinued.
The authenticator sends the voucher request to the authorization
server. The Voucher_Request SHALL be a CBOR array as defined below:
Voucher_Request = [
G_X: bstr,
CC: bstr,
CIPHERTEXT_RQ: bstr
]
where the parameters are defined in Section 4.1.
TODO: Add in VREQ the optional parameters ?PK_V:bstr, and ?PoP:bstr
to support the case when V uses different keys to authenticate to U
and W. One case to study is when V authenticates to U with static DH
and to W with signature.
4.3.1.2. Authorization Server processing
The authorization server receives the voucher request, verifies and
decrypts the identity ID_U of the device, and associates the nonce
G_X to ID_U. If G_X is not unique among nonces associated to this
identity, the protocol SHALL be discontinued.
4.3.2. Voucher Response
4.3.2.1. Authorization Server processing
The authorization server uses the identity of the device, ID_U, to
look up the device certificate, Cert_PK_U.
The authorization server retrieves the public key of V used to
authenticate the secure connection with the authenticator, and
constructs the corresponding COSE_Key as defined in Section 4.1.1.
The authorization server generates the voucher response and sends it
to the authenticator over the secure connection. The
Voucher_Response SHALL be a CBOR array as defined below:
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Voucher_Response = [
G_X: bstr,
CERT_PK_U: bstr,
Voucher: bstr
]
where
o G_X is copied from the associated voucher request.
o CERT_PK_U is the device certificate of the public key PK_U, issued
by a trusted third party. The format of this certificate is out
of scope.
o The voucher is defined in Section 4.1.1.
4.3.2.2. Authenticator processing
The authenticator receives the voucher response from the
authorization server over the secure connection. If the received G_X
does not match the value of the nonce associated to the secure
connection, the protocol SHALL be discontinued.
The authenticator verifies the certificate CERT_PK_U.
TODO: The voucher response may contain a "Voucher-info" field as an
alternative to make the Voucher a CBOR Map (see Section 4.1)
5. ACE Profile
The messages specified in this document may be carried between the
endpoints in various protocols. This section defines an embedding as
a profile of the ACE framework (see Appendix C of
[I-D.ietf-ace-oauth-authz]).
U plays the role of the ACE Resource Server (RS). V plays the role
of the ACE Client (C). W plays the role of the ACE Authorization
Server (AS).
C and RS use the Auxiliary Data in the EDHOC protocol to communicate.
C and RS use the EDHOC protocol to protect their communication.
EDHOC also provides mutual authentication of C and RS, assisted by
the AS.
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5.1. Protocol Overview
RS C AS
| EDHOC message_1 | |
| AD1=AS Request Creation Hints | |
|-------------------------------->| POST /token |
| |-------------------->|
| | |
| | Access Token + |
| EDHOC message_2 | Access Information |
| AD2=Access Token |<--------------------|
|<--------------------------------| |
| EDHOC message_3 | |
|-------------------------------->| |
Figure 3: Overview of the protocol mapping to ACE
RS proactively sends the AS Request Creation Hints message to C to
signal the information on where C can reach the AS. RS piggybacks
the AS Request Creation Hints message using Auxiliary Data of EDHOC
message_1. Before continuing the EDHOC exchange, based on the AS
Request Creation Hints information, C sends a POST request to the
token endpoint at the AS requesting the access token. The AS issues
an assertion to C that is cryptographically protected based on the
secret shared between the AS and RS. In this profile, the assertion
is encoded as a Bearer Token. C presents this token to RS in the
Auxiliary Data of the EDHOC message_2. RS verifies the token based
on the possession of the shared secret with the AS and authenticates
C.
5.2. AS Request Creation Hints
Parameters that can appear in the AS Request Creation Hints message
are specified in Section 5.1.2. of [I-D.ietf-ace-oauth-authz]. RS
MUST use the "AS" parameter to transport LOC_W, i.e. an absolute URI
where C can reach the AS. RS MUST use the "audience" parameter to
transport the CBOR sequence consisting of two elements: CC, the
crypto context; CIPHERTEXT_RQ, the authenticated encrypted identity
of the RS. The "cnonce" parameter MUST be implied to G_X, i.e. the
ephemeral public key of the RS in the underlying EDHOC exchange. The
"cnonce" parameter is not carried in the AS Request Creation Hints
message for byte saving reasons. AS Request Creation Hints MUST be
carried within Auxiliary Data of the EDHOC message_1 (AD_1).
An example AD_1 value in CBOR diagnostic notation is shown below:
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AD_1:
{
"AS" : "coaps://as.example.com/token",
"audience": << h'73',h'737570657273...' >>
}
5.3. Client-to-AS Request
The protocol that provides the secure connection between C and the AS
is out-of-scope. This can, for example, be TLS 1.3. What is
important is that the two peers are mutually authenticated, and that
the secure connection provides message integrity, confidentiality and
freshness. It is also necessary for the AS to be able to extract the
public key of C used in the underlying security handshake.
C sends the POST request to the token endpoint at the AS following
Section 5.6.1. of [I-D.ietf-ace-oauth-authz]. C MUST set the
"audience" parameter to the value received in AS Request Creation
Hints. C MUST set the "cnonce" parameter to G_X, the ephemeral
public key of RS in the EDHOC exchange.
An example exchange using CoAP and CBOR diagnostic notation is shown
below:
Header: POST (Code=0.02)
Uri-Host: "as.example.com"
Uri-Path: "token"
Content-Format: "application/ace+cbor"
Payload:
{
"audience" : << h'73',h'737570657273...' >>
"cnonce" : h'756E73686172...'
}
5.4. AS-to-Client Response
Given successful authorization of C at the AS, the AS responds by
issuing a Bearer token and retrieves the certificate of RS on behalf
of C. The access token and the certificate are passed back to C, who
uses it to complete the EDHOC exchange. This document extends the
ACE framework by registering a new Access Information parameter:
rsp_ad: OPTIONAL. Carries additional information from the AS to C
associated with the access token.
When responding to C, the AS MUST set the "ace_profile" parameter to
"edhoc-authz". The AS MUST set the "token_type" parameter to
"Bearer". The access token MUST be formatted as specified in
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Section 4.1.1. The AS MUST set the "rsp_ad" parameter to the
certificate of RS. To be able to do so, AS first needs to decrypt
the audience value, and based on it retrieve the corresponding RS
certificate.
An example AS response to C is shown below:
2.01 Created
Content-Format: application/ace+cbor
Max-Age: 3600
Payload:
{
"ace_profile" : "edhoc-authz",
"token_type" : "Bearer",
"access_token" : h'666F726571756172746572...',
"rsp_ad" : h'61726973746F64656D6F637261746963616C...'
}
TODO: Add cnonce = G_X to this message to match the current version
of the voucher response.
6. Security Considerations
TODO: Identity protection of device
TODO: Use of G_X as ephemeral key between device and authenticator,
and between device and authorization server
7. IANA Considerations
TODO: CC registry
TODO: Voucher type registry
TODO: register rsp_ad ACE parameter
8. Informative References
[I-D.ietf-6tisch-minimal-security]
Vucinic, M., Simon, J., Pister, K., and M. Richardson,
"Constrained Join Protocol (CoJP) for 6TiSCH", draft-ietf-
6tisch-minimal-security-15 (work in progress), December
2019.
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[I-D.ietf-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for
Constrained Environments (ACE) using the OAuth 2.0
Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-40
(work in progress), April 2021.
[I-D.ietf-lake-edhoc]
Selander, G., Mattsson, J., and F. Palombini, "Ephemeral
Diffie-Hellman Over COSE (EDHOC)", draft-ietf-lake-
edhoc-06 (work in progress), April 2021.
[I-D.ietf-lake-reqs]
Vucinic, M., Selander, G., Mattsson, J. P., and D. Garcia-
Carrillo, "Requirements for a Lightweight AKE for OSCORE",
draft-ietf-lake-reqs-04 (work in progress), June 2020.
[I-D.irtf-cfrg-hpke]
Barnes, R. L., Bhargavan, K., Lipp, B., and C. A. Wood,
"Hybrid Public Key Encryption", draft-irtf-cfrg-hpke-08
(work in progress), February 2021.
[I-D.mattsson-cose-cbor-cert-compress]
Raza, S., Hoeglund, J., Selander, G., Mattsson, J. P., and
M. Furuhed, "CBOR Encoded X.509 Certificates (C509
Certificates)", draft-mattsson-cose-cbor-cert-compress-08
(work in progress), February 2021.
[I-D.palombini-core-oscore-edhoc]
Palombini, F., Tiloca, M., Hoeglund, R., Hristozov, S.,
and G. Selander, "Combining EDHOC and OSCORE", draft-
palombini-core-oscore-edhoc-02 (work in progress),
February 2021.
[I-D.selander-ace-coap-est-oscore]
Selander, G., Raza, S., Furuhed, M., Vucinic, M., and T.
Claeys, "Protecting EST Payloads with OSCORE", draft-
selander-ace-coap-est-oscore-04 (work in progress),
November 2020.
[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>.
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[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, Ed., "Extensible Authentication Protocol
(EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
<https://www.rfc-editor.org/info/rfc3748>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
Authors' Addresses
Goeran Selander
Ericsson AB
Email: goran.selander@ericsson.com
John Preuss Mattsson
Ericsson AB
Email: john.mattsson@ericsson.com
Malisa Vucinic
INRIA
Email: malisa.vucinic@inria.fr
Michael Richardson
Sandelman Software Works
Email: mcr+ietf@sandelman.ca
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Aurelio Schellenbaum
Institute of Embedded Systems, ZHAW
Email: aureliorubendario.schellenbaum@zhaw.ch
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