Problem Description for Authorization in Constrained Environments
draft-seitz-ace-problem-description-02
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| Authors | Ludwig Seitz , Göran Selander | ||
| Last updated | 2014-10-27 | ||
| Replaced by | draft-ietf-ace-actors | ||
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draft-seitz-ace-problem-description-02
ACE Working Group L. Seitz
Internet-Draft SICS Swedish ICT
Intended Status: Informational G. Selander
Expires: April 30, 2015 Ericsson
October 27, 2014
Problem Description for Authorization in Constrained Environments
draft-seitz-ace-problem-description-02
Abstract
We present a problem description for authentication and authorization
in constrained-node networks, i.e. networks where some devices have
severe constraints on memory, processing, power and communication
bandwidth.
Status of this Memo
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Copyright and License Notice
Copyright (c) 2014 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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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem Description . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Authorization . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Authentication . . . . . . . . . . . . . . . . . . . . . . 7
3.3. Communication Security . . . . . . . . . . . . . . . . . . 8
3.4. Cryptographic Keys . . . . . . . . . . . . . . . . . . . . 8
4. Assumptions and Requirements . . . . . . . . . . . . . . . . . 9
4.1 Architecture . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2 Constrained Devices . . . . . . . . . . . . . . . . . . . . 10
4.3 Authorization . . . . . . . . . . . . . . . . . . . . . . . 11
4.4 Authorization information . . . . . . . . . . . . . . . . . 11
4.5 Access to authorization information . . . . . . . . . . . . 12
4.6 Resource access . . . . . . . . . . . . . . . . . . . . . . 12
4.7 Keys and cipher suites . . . . . . . . . . . . . . . . . . . 13
4.8 Communication security paradigm . . . . . . . . . . . . . . 13
4.9 Network considerations . . . . . . . . . . . . . . . . . . . 13
4.10 Legacy considerations . . . . . . . . . . . . . . . . . . . 14
4.11 Open issues . . . . . . . . . . . . . . . . . . . . . . . . 14
5. Security Considerations . . . . . . . . . . . . . . . . . . . 14
5.1 Physical attacks on sensor and actuator networksmirror . . . 15
5.2 Time measurements . . . . . . . . . . . . . . . . . . . . . 16
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1 Normative References . . . . . . . . . . . . . . . . . . . 17
8.2 Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
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1. Introduction
Authorization is the process of deciding what an entity ought to be
allowed to do. This memo is about properties of security protocols
to enable explicit and dynamic authorization of clients to access a
resource at a server, in particular in constrained environments when
the client and/or server are constrained nodes.
Relevant use cases are provided in [I-D.seitz-ace-usecases], which
also lists some requirements derived from the use cases. In this
memo we present a more specific problem description for
authentication and authorization in constrained RESTful environments
together with a more detailed set of assumptions and requirements
(cf. section 4).
1.1 Terminology
Certain security-related terms are to be understood in the sense
defined in [RFC4949]. These terms include, but are not limited to,
"authentication", "authorization", "confidentiality", "(data)
integrity", "message authentication code", and "verify".
RESTful terms including "resource", "representation", etc. are to be
understood as used in HTTP [RFC7231] and CoAP [RFC7252].
Terminology for constrained environments including "constrained
device", "constrained-node network", "class 1", etc. are defined in
[RFC7228].
"Explicit" authorization is used here to describe the ability to
specify in some detail which entity has access to what and under what
conditions, as opposed to "implicit" authorization where an entity is
either allowed to access everything or nothing.
"Dynamic" authorization means that the access control polices and the
parameters on which they are evaluated may change during normal
operations, as opposed to "static" authorization meaning that access
control policies cannot be changed during normal operations and may
require some special procedure such as out-of-band provision.
2. Background
We assume a client-server setting, where a client wishes to access
some resource hosted by a server. Such resources may e.g. be sensor
data, configuration data, or actuator settings. Thus access to a
resource could be by different methods, some of which change the
state of the resource. In this memo, we consider the REST setting
i.e. GET, POST, PUT and DELETE, and application protocols in scope
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are HTTP [RFC7231] and CoAP [RFC7252].
We assume that the roles of client and server are not fixed, i.e. a
node which is client could very well be server in some other context
and vice-versa. Further we assume that in some cases, clients are
not previously known to servers, thus we cannot assume that the
server has access control policies specific to that client when the
client initiates communication.
Finally we also assume that in a significant number of cases, the
server and/or the client are too constrained to handle the
authorization policies and related configuration on their own. Many
authorization solutions involve a centralized, trusted third party,
supporting the client and/or resource server. A trusted third party
provides a more scalable way to centrally manage authorization
policies, in order to ensure consistent authorization decisions. The
physical separation of policy decision and policy enforcement is an
established principle in policy based management, e.g. [RFC2748].
Borrowing from OAuth 2.0 [RFC6749] terminology we name the entities:
client (C), resource server (RS), authorization server (AS - the
third party), and resource owner (RO). RO does not need to be active
in an constrained device access control setting, so interactions with
the RO are out of scope for this memo. In the target setting RS is
typically constrained, C may be constrained, whereas AS is not
assumed to be constrained.
Since RS is constrained, we assume that it needs to offload
authorization policy management and/or authorization decision making
to AS. This means that some authorization information needs to be
transferred from AS to RS. This information may for example be
specific access control decisions such as "client C has the right to
access this URI with this RESTful method, this payload value, under
these local conditions", "client C has the right to access these
URIs" or more indirect information "client C is in this access
group". In the latter it is assumed that RS knows what rights are
associated to a particular access group. As mentioned above, since
RS is constrained, it needs to offload authorization policy
management and/or authorization decision making to AS, and thus some
authorization information needs to be transferred from AS to RS.
This information may for example be specific access control decisions
such as "client C has the right to access this URI with this RESTful
method, this payload value, under these local conditions", "client C
has the right to access these URIs", or more indirect information
"client C is in this access group". In the latter it is assumed that
RS knows what rights are associated to a particular access group.
Protecting information carried between AS and RS, requires some a
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priori established cryptographic keys. How those keys are
established is out of scope for this problem description. However,
cryptographic keys that are used to protect information between AS
and C are in scope: The reason being that dynamic access control is
one of the use cases to be supported, and this may involve granting
access to a client previously unknown to the server. An RS may have
multiple trusted ASs corresponding to resources of different ROs, in
which case it requires a key for each AS. This is a straightforward
extension and is not further elaborated in this memo.
AS may for example be implemented as a cloud service, in a home
server, or in a smartphone. C and RS may or may not have
connectivity to AS (e.g. because AS is switched off), or may only
have intermittent connectivity, where a connection at the time of
access request cannot be guaranteed. Another reason for intermittent
connectivity may be that constant connectivity is not affordable
(e.g. due to limited battery power, or a sensor mobility business
case for which cellular connectivity cost too much or is not
available). Obviously, in order for a client request to reach RS
there must be connectivity between C and RS, but that could be a
short range technology such as Bluetooth, ZigBee, NFC, etc.
Furthermore, if there is not sufficient authorization information
about C in RS, and neither C nor RS can access AS, access requests
will be denied. Therefore we assume that either C or RS can access
AS at some point in time, prior to the client's request.
As a summary, there are potentially a number of information flows
that needs to be secured:
a. The transfer of authorization information from AS to RS
b. The transfer of cryptographic keys or credentials from AS to RS
and C, respectively
c. The access request/response procedure between C and RS
3. Problem Description
From the background described in the previous section, we see the
following problems that need to be solved in order to achieve
explicit and dynamic authorization:
o Authorization
RS must have access to authorization information.
Given that the relevant information has been provided to RS, it
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must be able to handle an access request from C (match request
against authorization information, grant or deny the request,
and in the case of grant perform what is requested).
o Authentication
Some property of C needs to be authenticated to bind
authorization information to it.
RS needs to establish the authenticity of authorization
information, and that it comes from a trusted AS.
Finally some property of RS needs to be authenticated to C, so
that C can verify that it is communicating with the intended RS.
o Communication Security
Communication security is needed to protect the integrity, and
sometimes the secrecy of information flows between the parties.
This includes the flow of authentication and authorization
information, but also the actual request and response upon which
access control is performed.
o Key establishment
C and RS need to establish cryptographic keys in order to set up
secure communications
Clearly, these problems are interconnected and need to take into
account the involved constrained devices.
3.1. Authorization
The core problem we are trying to solve is authorization.
o AS needs to transfer authorization information to RS. This can
be done with or without involvement of C. In the case of C
involvement there are three different message sequences: Agent,
Pull or Push [RFC2904].
(i) In the agent sequence, C submits its request to AS and AS
contacts RS to execute the request on C's behalf.
(ii) When using the pull sequence, C contacts RS and RS pulls
authorization information directly from AS as a reaction
to C's request (as e.g. in RADIUS [RFC2865]).
(iii) In the push sequence, C is used as intermediary between AS
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and RS, and authorization information is transferred in
the form of some token (as e.g. in OAuth [RFC6749]).
o What does the transferred authorization information contain and
how should it be formatted/encoded? This must be efficient for
constrained devices, considering size of authorization
information and parser complexity.
o How does RS verify the authenticity of the authorization
information? There is a trade-off between processing complexity
and deployment complexity in using digital signatures with
asymmetric keys or message authentication codes with symmetric
keys.
o How does RS enforce authorization decisions of AS? Does the
authorization information it obtained from AS require additional
policy evaluation (e.g. matching against local access control
lists, evaluating local conditions)? What kind of "policy
evaluation" can we assume a constrained device to be capable of?
o Finally, as is indicated in the previous bullet, for a
particular authorization decision there may be different kinds
of authorization information needed, and these pieces of
information may be transferred to RS at different times and in
different ways prior to or during the client request. For
example, local access control lists for particular access groups
may be pushed from AS to RS without involvement of C at regular
intervals, whereas an assertion of group membership (client
attribute) of a particular C can be pushed involving C as in
(iii) above.
3.2. Authentication
The following problems need to be addressed, when considering
authentication:
o RS needs to authenticate some property of C, in order to bind it
to the relevant authorization information. This could e.g. be a
digital signature or a message authentication codes performed by
C where a corresponding cryptographic key is contained in the
authorization information.
o In many use cases C wants to authenticate RS, in order to ensure
that it is interacting with the right resources.
o AS needs to authenticate its communication partner (either C or
RS), in order to ensure it serves the correct device.
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o Since AS has a trust relation to both C and RS, it could also
provide them with the means of mutual authentication (similar to
a Kerberos [RFC4120] server). This would make it possible for
RS to authenticate previously unknown clients.
3.3. Communication Security
There are different alternatives to provide communication security.
o One is session-based security at transport layer such as DTLS
[RFC6347], which offers security, including integrity and
confidentiality protection, for the whole application layer
exchange. One cost of DTLS is the handshake protocol, which may
be expensive for constrained devices especially in terms of
memory and power consumption for message transmissions.
o An alternative is data object security at application layer,
e.g. using JWE [I-D.ietf-jose-json-web-encryption]. Secure
objects can be stored or cached in network nodes and provide
security for a more flexible communication model such as
publish/subscribe (compare e.g. CoRE Mirror Server [I-D.vial-
core-mirror-proxy]). However, data object security only may not
provide confidentiality for the message headers. For example,
information such as the RESTful method, the host address, and
the resource URI may be revealed.
o A solution to the overall authorization problem may be based on
session-based security only, data object security only or a
hybrid. An example of a hybrid is where authorization
information and cryptographic keys are provided by AS in the
format of secure data objects, but where the resource access is
protected by session-based security. (For secure objects
containing authorization information, compare e.g. OAuth 2.0 MAC
Tokens [I-D.ietf-oauth-v2-http-mac].)
o A hybrid solution may also be useful to support a flexible trust
model, e.g. a resource representation wrapped end-to-end in JWE
sent over DTLS hop-by-hop in a case where an intermediary is
allowed to read the header but not the payload.
o A detailed analysis how different use cases benefit from
different communication security paradigms is beyond the scope
of this memo. Current Internet standards support both
approaches, and this should be possible to leverage also in
constrained environments.
3.4. Cryptographic Keys
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With respect to cryptographic keys, we see the following
problems that need to be addressed:
o Symmetric vs Asymmetric Keys
Do we want to support solutions based on asymmetric keys or
symmetric keys, or both? The question applies both to
protection of resource access and to protection of
authentication and authorization information.
There are classes of devices that can easily perform symmetric
cryptography, but consume considerably more time/battery for
asymmetric operations. On the other hand asymmetric
cryptography has benefits e.g. in terms of deployment.
o Key Establishment
How are the corresponding cryptographic keys established?
Considering section 3.1 there must be a binding between these
keys and the authorization information, at least in the sense
that AS must be able to specify a unique client identifier which
RS can verify (using an associated key).
One of the use cases of [I-D.seitz-ace-usecases] describes
spontaneous change of access policies - e.g. giving a hitherto
unknown client the right to temporarily unlock your house door.
In this case C is not previously known to RS and a key must be
provisioned by AS.
o Revocation and Expiration
How are keys replaced and how is a key that has been compromised
revoked in a manner that reaches all affected parties, also
keeping in mind scenarios with intermittent connectivity?
4. Assumptions and Requirements
In this section we list a set of candidate assumptions and
requirements to make the problem description in the previous sections
more concise and precise.
4.1 Architecture
The architecture consists of at least the following types of nodes:
o RS hosting resources, and responding to access requests
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o C requesting access to resources
o AS supporting the access request/response procedure by providing
authorization information to RS.
- AS may also provide other services such as authenticating C
on behalf of RS, or providing cryptographic keys or
credentials to C and/or RS to secure the request/response
procedure.
o The architecture may contain intermediary nodes between any pair
of C, RS and AS, such as e.g. forward/reverse proxies in the
CoRE architecture. The solution shall not unduly restrict the
use of intermediaries.
4.2 Constrained Devices
o C and/or RS may be constrained in terms of power, processing,
communication bandwidth, memory and storage space, and moreover
- unable to manage complex authorization policies
- unable to manage a large number of secure connections
- without user interface
- without constant network connectivity
- unable to precisely measure time
- required to save on wireless communication due to high power
consumption
o C and RS may be class 1 (potentially with large effort) or more
powerful devices.
o AS is not a constrained device.
o All devices can process symmetric cryptography without incurring
an excessive performance penalty.
- We assume the use of a standardized symmetric key algorithm,
such as AES.
- Except for the most constrained devices we assume the use of
a standardized cryptographic hash function such as SHA-256.
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o Public key cryptography requires additional resources (e.g. RAM,
ROM, power).
o A DTLS handshake with public key cryptography involves
significant computation, communication, and memory overheads in
the context of constrained devices.
- The RAM requirements of DTLS handshake with public key
cryptography may be prohibitive for constrained devices.
- Certificate-based DTLS handshake requires extensive resources
e.g. in terms of ROM.
o The solution shall support a simple scheme for expiring
authentication and authorization information on devices which
are unable to measure time (cf. section 5.2).
4.3 Authorization
o The authorization decision may be based on credentials presented
by C, resource, RESTful method and local context in RS at the
time of the request.
o The authorization decision may be taken either by AS or RS.
o The authorization decision is enforced by RS.
- RS needs to have access to authorization information in order
to verify that C is allowed to access the resource as
requested.
- RS needs to make sure that it provides resource access only
to authorized clients.
o Apart from authorization for access to a resource, authorization
may also be required for access to information about a resource.
o The solution may be able to support authorizing the delegation
of access rights.
4.4 Authorization information
o Authorization information is information that allows RS to
verify that a requesting C is authorized.
o Authorization information includes self-contained information
such as authorization decisions or client capability lists which
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allows RS to directly match against a request.
o Authorization information includes also such information that RS
may need to combine, in order to verify that a requesting C is
authorized, including client attributes and authorization
polices (e.g. access control lists) based on client attributes.
4.5 Access to authorization information
o Authorization information may a priori be transferred directly
between AS and RS, or via C; using Agent, Push or Pull
mechanisms [RFC2904].
o RS shall authenticate that the authorization information is
coming from AS.
o The authorization information may also be encrypted end-to-end
between AS and RS.
o RS may not be able to communicate with AS at the time of the
request from C.
o RS may store or cache authorization information.
o Authorization information may be pre-configured in RS.
o Authorization information stored or cached in RS shall be
possible to change. The change of such information shall be
subject to authorization.
o Authorization policies stored on RS may be handled as a
resource, i.e. information located at a particular URI, accessed
with RESTful methods, and the access being subject to the same
authorization mechanics. AS may have special privileges when
requesting access to the authorization policy resources on RS.
o There may be mechanisms for C to look up the AS which provides
authorization information about a particular resource.
4.6 Resource access
o Resources are accessed in a RESTful manner using GET, PUT, POST,
DELETE.
o By default, the resource request shall be integrity protected
and may be encrypted end-to-end from C to RS. It shall be
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possible for RS to detect a replayed request. (DTLS supports
this.)
o By default, the response to a request shall be integrity
protected and may be encrypted end-to-end from RS to C. It
shall be possible for C to detect a replayed invalid response.
(DTLS supports this.)
o C shall be able to verify that the response to a request comes
from the intended RS. (DTLS supports this.)
o RS shall be able to verify that the request comes from an
authorized client
o There may be resources whose access need not be protected (e.g.
for discovery of the responsible AS).
4.7 Keys and cipher suites
o AS and RS have established cryptographic keys. Either AS and RS
share a secret key or each have the other's public key.
o The transfer of authorization information is protected with
symmetric and/or asymmetric keys.
o The access request/response may be protected with symmetric
and/or asymmetric keys. (DTLS supports this.)
o There must be a mechanism for RS to establish the necessary
key(s) to verify and decrypt the request. (DTLS supports this.)
o There must be a mechanism for C to establish the necessary
key(s) to verify and decrypt the response. (DTLS supports
this.)
o There may be a mechanism for C to look up the supported cipher
suites of a RS. (DTLS supports this.)
4.8 Communication security paradigm
o The solution shall support session based security and/or data
object security.
4.9 Network considerations
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o The solution shall prevent network overload due to avoidable
communication with AS.
o The solution shall prevent network overload by compact
authorization information representation.
o The solution shall optimize the case where authorization
information does not change often.
o The solution where possible shall support an efficient mechanism
for providing authorization information to multiple RSs, for
example when multiple entities need to be configured or change
state.
4.10 Legacy considerations
o The solution shall work with existing infrastructure.
o The solution shall support authorization of access to legacy
devices.
4.11 Open issues
The section lists some known open issues
o What is the level of functionality that can be achieved with
class 1 devices
- with off-the-shelf software?
- using heroic efforts?
o Is authorization for network access in scope?
o Should the model of draft-gerdes-ace-actors [I-D.gerdes-ace-
actors] (in particular the Authorization Manager) be included in
the default architecture?
o Should the requirements include cross-domain authorization?
5. Security Considerations
The entire document is about security. Security considerations
applicable to authentication and authorization in RESTful
environments are provided in e.g. OAuth 2.0 [RFC6749].
In this section we focus on specific security aspects related to
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authorization in constrained-node networks.
5.1 Physical attacks on sensor and actuator networksmirror
The focus of this work is on constrained-node networks consisting of
connected sensors and actuators. The main function of such devices
is to interact with the physical world by gathering information or
performing an action. We now discuss attacks performed with physical
access to such devices.
The main threats to sensors and actuator networks are:
o Unauthorized access to data to and from sensors and actuators,
including eavesdropping and manipulation of data.
o Denial-of-service making the sensor/actuator unable to perform
its intended task correctly.
A number of attacks can be made with physical access to a device
including probing attacks, timing attacks, power attacks, etc.
However, with physical access to a sensor or actuator device it is
possible to directly perform attacks equivalent of eavesdropping,
manipulating data or denial of service. For example:
o Instead of eavesdropping the sensor data or attacking the
authorization system to gain access to the data, the attacker
could make its own measurements on the physical object.
o Instead of manipulating the sensor data the attacker could
change the physical object which the sensor is measuring,
thereby changing the payload data which is being sent.
o Instead of manipulating data for an actuator or attacking the
authorization system, the attacker could perform an unauthorized
action directly on the physical object.
o A denial-of-service attack could be performed physically on the
object or device.
All these attacks are possible by having physical access to the
device, since the assets are related to the physical world.
Moreover, this kind of attacks are in many cases straightforward
(requires no special competence or tools, low cost given physical
access, etc.)
As a conclusion, if an attacker has physical access to a sensor or
actuator device, then much of the security functionality elaborated
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in this draft is not effective to protect the asset during the
physical attack.
Since it does not make sense to design a solution for a situation
that cannot be protected against we assume there is no need to
protect assets which are exposed during a physical attack. In other
words, either an attacker does not have physical access to the sensor
or actuator device, or if it has, the attack shall only have effect
during the period of physical attack.
5.2 Time measurements
Measuring time with certain accuracy is important to achieve certain
security properties, for example to determine whether a public key
certificate, access token or some other assertion is valid.
Dynamic authorization in itself requires the ability to handle expiry
or revocation of authorization decisions or to distinguish new
authorization decisions from old.
For certain categories of devices we can assume that there is an
internal clock which is sufficiently accurate to handle the time
measurement requirements. If RS can connect directly to AS it could
get updated in terms of time as well as revocation information.
If RS continuously measures time but can't connect to AS or other
trusted source, time drift may have to be accepted and it may not be
able to manage revocation. However, it may still be able to handle
short lived access rights within some margins, by measuring the time
since arrival of authorization information or request.
Some categories of devices in scope may be unable measure time with
any accuracy (e.g. because of sleep cycles). This category of
devices is not suitable for the use cases which require measuring
validity of assertions and authorizations in terms of absolute time.
However there are simpler schemes to grant certain temporary access
requests in a secure manner. For example, one-time authorization
grants based on some freshness maintained between AS and RS such as
sequence numbers or nonces. For the convenience of the reader we now
outline a very simplistic scheme. AS may keep a counter for each RS,
step the counter for each time it generates new authorization
information and include the counter in the authorization information.
RS accepts as fresh authorization information with a higher counter
compared to highest previously received counter value. If the
authorization information is fresh, RS grants the associated access
request and replaces the old counter value with the new. The
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INTERNET DRAFT Problem description for ACE October 27, 2014
security considerations of this scheme is out of scope for this memo.
6. IANA Considerations
This document has no actions for IANA.
7. Acknowledgements
The authors would like to thank Carsten Bormann, Stefanie Gerdes,
Sandeep Kumar, John Mattson, Corinna Schmitt, Mohit Sethi, Hannes
Tschofenig, Vlasios Tsiatsis and Erik Wahlstroem for contributing to
the discussion, giving helpful input and commenting on the 00-
version. The authors would also like to acknowledge input provided by
draft-gerdes-ace-actors [I-D.gerdes-ace-actors] and Hummen et al
[HUM14delegation].
8. References
8.1 Normative References
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2", FYI
36, RFC 4949, August 2007.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, June 2014.
[RFC7252] Shelby, Z., Hartke K., and C. Bohrmann, "The Constrained
Application Protocol (CoAP)", RFC7252, June 2014
8.2 Informative References
[I-D.seitz-ace-usecases]
Seitz, L., Gerdes, S., and Selander, G., "ACE use cases",
draft-seitz-ace-usecases (work in progress), February
2014.
[I-D.ietf-jose-json-web-encryption]
Jones, M., Hildebrand, J., "JSON Web Encryption (JWE)",
draft-ietf-jose-json-web-encryption (work in progress),
April 2014.
[I-D.vial-core-mirror-proxy]
Vial, M., "CoRE Mirror Server", draft-vial-core-mirror-
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INTERNET DRAFT Problem description for ACE October 27, 2014
proxy (expired), July 2012.
[I-D.ietf-oauth-v2-http-mac]
Richter, J., Mills, W., Tschofenig, H. (Ed.), and P. Hunt,
"OAuth 2.0 Message Authentication Code (MAC) Tokens",
draft-ietf-oauth-v2-http-mac (work in progress), January
2014.
[I-D.gerdes-ace-actors]
Gerdes, S., "Actors in the ACE Architecture", draft-
gerdes-ace-actors-01 (work in progress), July 2014.
[HUM14delegation] Hummen, R., Shafagh, H., Raza, S., Voigt, T.,
Wehrle, K., "Delegation-based Authentication and
Authorization for the IP-based Internet of Things", 11th
IEEE International Conference on Sensing, Communication,
and Networking (SECON'14), June 30 - July 3, 2014.
[RFC2748] Durham, D., Ed., Boyle, J., Cohen, R., Herzog, S., Rajan,
R., and A. Sastry, "The COPS (Common Open Policy Service)
Protocol", RFC 2748, January 2000.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[RFC2904] Vollbrecht, J., Calhoun, P., Farrell, S., Gommans, L.,
Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and
D. Spence, "AAA Authorization Framework", RFC 2904, August
2000.
[RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The
Kerberos Network Authentication Service (V5)", RFC 4120,
July 2005.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, October 2012.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228, May 2014.
[RFC7231] Fielding, R., Ed., and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Semantics and Content",
RFC 7231, June 2014.
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INTERNET DRAFT Problem description for ACE October 27, 2014
Authors' Addresses
Ludwig Seitz
SICS Swedish ICT AB
Scheelevagen 17
22370 Lund
SWEDEN
EMail: ludwig@sics.se
Goeran Selander
Ericsson
Farogatan 6
16480 Kista
SWEDEN
EMail: goran.selander@ericsson.com
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