Credentials Provisioning and Management via EAP (EAP-CREDS)
draft-pala-eap-creds-02
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Author | Massimiliano Pala | ||
| Last updated | 2019-06-04 | ||
| Replaces | draft-pala-eap-cprom | ||
| Replaced by | draft-pala-tian-eap-creds | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-pala-eap-creds-02
Network Working Group M. Pala
Internet-Draft CableLabs
Intended status: Standards Track June 4, 2019
Expires: December 6, 2019
Credentials Provisioning and Management via EAP (EAP-CREDS)
draft-pala-eap-creds-02
Abstract
With the increase number of devices, protocols, and applications that
rely on strong credentials (e.g., digital certificates, keys, or
tokens) for network access, the need for a standardized credentials
provisioning and management framework is paramount. The 802.1x
architecture allows for entities (e.g., devices, applications, etc.)
to authenticate to the network by providing a communication channel
where different methods can be used to exchange different types of
credentials. However, the need for managing these credentials (i.e.,
provisioning and renewal) is still a hard problem to solve.
EAP-CREDS, if implemented in Managed Networks (e.g., Cable Modems),
could enable our operators to offer a registration and credentials
management service integrated in the home WiFi thus enabling
visibility about registered devices. During initialization, EAP-
CREDS also allows for MUD files or URLs to be transferred between the
EAP Peer and the EAP Server, thus giving detailed visibility about
devices when they are provisioned with credentials for accessing the
networks. The possibility provided by EAP-CREDS can help to secure
home or business networks by leveraging the synergies of the security
teams from the network operators thanks to the extended knowledge of
what and how is registered/authenticated.
This specifications define how to support the provisioning and
management of authentication credentials that can be exploited in
different environments (e.g., Wired, WiFi, cellular, etc.) to users
and/or devices by using EAP together with standard provisioning
protocols.
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/.
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 6, 2019.
Copyright Notice
Copyright (c) 2019 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
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. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Overview of existing solutions . . . . . . . . . . . . . . . 4
4. Scope Statement . . . . . . . . . . . . . . . . . . . . . . . 5
5. EAP-CREDS Protocol . . . . . . . . . . . . . . . . . . . . . 5
5.1. EAP-CREDS as tunneled mechanism only . . . . . . . . . . 5
5.2. Message Flow . . . . . . . . . . . . . . . . . . . . . . 6
5.3. Phase One: Initialization . . . . . . . . . . . . . . . . 7
5.4. Phase Two: Provisioning . . . . . . . . . . . . . . . . . 9
5.5. Phase Three: Validation . . . . . . . . . . . . . . . . . 10
6. EAP-CREDS Message Format . . . . . . . . . . . . . . . . . . 12
6.1. Message Header . . . . . . . . . . . . . . . . . . . . . 13
6.2. Message Payload . . . . . . . . . . . . . . . . . . . . . 13
6.2.1. General TLV format . . . . . . . . . . . . . . . . . 13
6.2.2. EAP-CREDS defined TLVs . . . . . . . . . . . . . . . 15
6.2.2.1. The Action TLV . . . . . . . . . . . . . . . . . 15
6.2.2.2. The Certificate-Data TLV . . . . . . . . . . . . 16
6.2.2.3. The Challenge-Data TLV . . . . . . . . . . . . . 17
6.2.2.4. The Challenge-Response TLV . . . . . . . . . . . 17
6.2.2.5. The Credentials-Information TLV . . . . . . . . . 18
6.2.2.6. The Credentials-Data TLV . . . . . . . . . . . . 21
6.2.2.7. The Error TLV . . . . . . . . . . . . . . . . . . 22
6.2.2.8. The Profile TLV . . . . . . . . . . . . . . . . . 23
6.2.2.9. The Protocol TLV . . . . . . . . . . . . . . . . 24
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6.2.2.10. The Provisioning-Data TLV . . . . . . . . . . . . 24
6.2.2.11. The Provisioning-Headers TLV . . . . . . . . . . 25
6.2.2.12. The Provisioning-Params TLV . . . . . . . . . . . 25
6.2.2.13. The Token-Data TLV . . . . . . . . . . . . . . . 28
6.2.2.14. The Version TLV . . . . . . . . . . . . . . . . . 29
7. EAP-CREDS Messages . . . . . . . . . . . . . . . . . . . . . 29
7.1. The EAP-CREDS-Init Message . . . . . . . . . . . . . . . 30
7.1.1. EAP Server's Init Message . . . . . . . . . . . . . . 30
7.1.2. EAP Peer's Init Message . . . . . . . . . . . . . . . 30
7.1.2.1. Bootstrapping Peer's Trustworthiness . . . . . . 31
7.2. The EAP-CREDS-ProtoFlow Message . . . . . . . . . . . . . 31
7.3. The EAP-CREDS-Validate Message . . . . . . . . . . . . . 32
7.3.1. Algorithm Requirements . . . . . . . . . . . . . . . 32
8. Error Handling in EAP-CREDS . . . . . . . . . . . . . . . . . 32
9. Fragmentation . . . . . . . . . . . . . . . . . . . . . . . . 32
10. Encapsulating Provisioning Protocols in EAP-CREDS . . . . . . 33
11. EAP-CREDS and Simple Provisioning Protocol (SPP) . . . . . . 33
11.1. SPP Message Format . . . . . . . . . . . . . . . . . . . 34
11.2. SPP: Registering New Credentials . . . . . . . . . . . . 34
11.3. SPP: Renewing Credentials . . . . . . . . . . . . . . . 35
11.4. SPP: Removing Credentials . . . . . . . . . . . . . . . 35
11.5. SPP Password Provisioning . . . . . . . . . . . . . . . 35
11.6. SPP Certificate Provisioning . . . . . . . . . . . . . . 35
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
12.1. Provisioning Protocols . . . . . . . . . . . . . . . . . 36
12.2. Token Types . . . . . . . . . . . . . . . . . . . . . . 36
12.3. Credentials Types . . . . . . . . . . . . . . . . . . . 36
12.4. Credentials Algorithms . . . . . . . . . . . . . . . . . 37
12.5. Credentials Datatypes . . . . . . . . . . . . . . . . . 37
12.6. Credentials Encoding . . . . . . . . . . . . . . . . . . 38
12.7. Action Types . . . . . . . . . . . . . . . . . . . . . . 38
13. Security Considerations . . . . . . . . . . . . . . . . . . . 39
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 39
15. Normative References . . . . . . . . . . . . . . . . . . . . 39
Appendix A. EAP-CREDS Example Message Flow for Provisioning
Standards . . . . . . . . . . . . . . . . . . . . . 40
A.1. EAP-CREDS and CMP . . . . . . . . . . . . . . . . . . . . 40
A.2. EAP-CREDS and EST . . . . . . . . . . . . . . . . . . . . 40
A.3. EAP-CREDS and CMS . . . . . . . . . . . . . . . . . . . . 40
A.4. EAP-CREDS and ACME . . . . . . . . . . . . . . . . . . . 40
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 40
1. Requirements notation
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].
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2. Introduction
Many environments are, today, moving towards requiring strong
authentication when it comes to gain access to networks. The .1x
architecture provides the network administrators with the possibility
to check credentials presented by a device even before providing any
IP service to it.
However, the provisioning and management of these credentials is a
hard problem to solve and many vendors opt for long-lived credentials
that can not be easily revoked, replaced, or simply renewed.
This specification addresses the problem of providing a simple-to-use
and simple-to-deploy conduit for credentials management by extending
the EAP protocol to support credentials provisioning and management
functionality. In particular, the EAP-CREDS method defined here
provides a generic framework that can carry the messages for
provisioning different types of credentials. The method can be use
as a stand-alone method or it can be used as an inner methods of EAP-
TTLS, EAP-TEAP, or any other tunnelling method that can provide the
required encryption and (at minimum) server-side authentication to
deliver server-side generated secrets (e.g., private keys, passwords,
secret keys, etc.)
3. Overview of existing solutions
Currently there are many protocols that address credentials lifecycle
management. In particular, when it comes to digital certificates,
some of the most deployed management protocols are:
o Certificate Management Protocol (CMP) [RFC4210]
o Certificate Management over CMS (CMC) [RFC5272][RFC6402]
o Enrollment over Secure Transport (EST) [RFC7030]
o Automated Certificate Management Environment
However, none of these protocols provide native support for client
that do not have IP connectivity yet (e.g., because they do not have
network-access credentials, yet). The EAP-CREDS provides the
possibility to use such protocols (i.e., message-based) by defining a
series of messages that can be used to encapsulate the provisioning
messages for the specified protocol. In particular, examples of the
message flow for the major provisioning protocols are provided in
Annex Appendix A.
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In addition to these protocols, EAP-CREDS also defines a series of
simple messages that provide a generic enrollment protocol that
allows not only certificates but also other types of credentials
(e.g., username/password pairs or symmetric secrets) to be delivered
to the client as part of the provisioning and/or renewal process.
The set of messages that make up the generic provisioning protocol is
referred to as the CREDS protocol (not to be confused with the EAP-
CREDS).
4. Scope Statement
This document focuses on the definition of the EAP-CREDS method to
convey credentials provisioning and managing messages between the
client and the AAA server. Moreover, the document defines how to
encode messages for the main IETF provisioning protocols.
This document, however, does not provide specifications for how and
where the credentials are generated. In particular, the credentials
could be generated directly within the AAA server or at a different
location (i.e., the Certificate Service Provider or CSP) site.
Different authentication mechanisms (e.g., TLS, etc.) can be used to
secure the communication between the server's endpoint and the CSP.
5. EAP-CREDS Protocol
This section outlines the operation of the protocol and message
flows. The format of the CREDS messages is given in Section 6.
5.1. EAP-CREDS as tunneled mechanism only
EAP-CREDS requires that an outer mechanism is in place between the
Peer and the Server in order to provide authentication and
confidentiality of the messages exchanged via EAP-CREDS.
In other words, the EAP-CREDS method assumes that an appropriate
protection outer layer has been established to prevent the
possibility to leak information or to allow man-in-the-middle
attacks.
This choice was taken to simplify the message flow between Peer and
Server, and to abstract EAP-CREDS from the secure-channel
establishment mechanism. EAP-TLS, EAP-TTLS, and EAP-TEAP are
examples of such mechanisms.s
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5.2. Message Flow
EAP-CREDS message flow is logically subdivided into three different
phases:
Phase One (Required). CREDS Initialization. During this phase the
Peer and the Server exchange the information needed to select the
appropriate credentials management protocol. In particular, the
Sever sends its initial message of type ('Init') and the client
replies with the details about what protocols are supported, and
additional information such as the version of EAP-CREDS and the
supported profiles identifiers.
Phase Two (Required). Provisioning Protocol Flow. In this phase,
the Peer and the Server exchange the provisioning protocol's
messages encapsulated in a EAP-CREDS message of type ProtoFlow.
The messages use two main TLVs: the first one is the Provisioning
Protocol Headers TLV (optional) that carries information that
might be normally coveyed via the transport protocol (e.g., HTTP
headers), while the second one is the Provisioning Protocol Data
(required) and it carries the provisioning protocol's messages.
Phase Two terminates with the Peer sending an empty ProtoFlow
message to the Server. The server can decide to repeat phase two
again to register new credentials or to renew a separate set of
credentials. When no more credentials have to be managed, the
Server can start phase three or simply issue an EAP-SUCCESS
message that terminates the EAP session.
Phase Three (Optional). Credentials Validation. This optional phase
can be initiated by the server and it is used to validate that the
Peer has properly installed the credentials and can use them to
authenticate itself. Depending on the credentials' type, the
messages can carry a challenge/nonce, the value of the secret/
token, or other information. The format of the credentials is
supposed to be known by the provider and the device.
In this document we use the following notation in the diagrams to
provide information about the cardinality of a data structure (TLV)
within a single EAP-CREDS message:
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+--------+---------------+------------------------------------------+
| Symbol | Example | Usage |
+--------+---------------+------------------------------------------+
| { } | { TLV1, TLV2 | Curly Brackets are used to indicate a |
| | } | set |
| [ ] | { TLV1, [ | Square Brackets are used to indicate |
| | TLV2 ] } | that a field is optional |
| ( ) | { | Round Squares are used to specify a |
| | TLV1(=VALUE) | value |
| | } | |
| + | { TLV1, [ | The Plus character indicates that one or |
| | TLV_2+ ] } | more instances are allowed |
+--------+---------------+------------------------------------------+
Table 1: EAP-CREDS Notation
5.3. Phase One: Initialization
The following figure provides the message flow for Phase One:
,--------. ,----------.
|EAP Peer| |EAP Server|
`---+----' `----+-----'
| Outer Tunnel Established |
| <--------------------------------------->
| |
| [1] EAP-Request/EAP-CREDS(Type=Init) | ,---------!.
| { [ Version+ ] } | |Phase One|_\
| <---------------------------------------- |Begins |
| | `-----------'
| [2] EAP-Response/EAP-CREDS(Type=Init) |
| { [ Version ], Protocol+, | ,---------!.
| [ CredInfo+ ], [ Token ] | |Phase One|_\
| [ Challenge ], [ Challenge-Rsp ] }| |Ends |
| ----------------------------------------> `-----------'
| |
| |
During the CREDS initialization, after the establishment of the outer
mechanism (e.g., EAP-TLS, EAP-TEAP, EAP-TTLS, etc.), the server MAY
decide to start a credentials management session. In order to do
that, it sends an empty message to the Client. In particular, it
sends a EAP-Request/EAP-CREDS(Type=Init) message with the list of
supported EAP-CREDS version via the (possibly multiple) Supported-
Version TLV.
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The client, sends back a message that carries one ('Supported-
Version') TLV to indicate the selected version of EAP-CREDS (i.e.
from the list provided by the server) (optional), one or more
('Supported-Protocol') TLV to indicate the list of supported
provisioning protocols, followed by the ('CredInfo') TLVs (one or
more) that provide the status of the credentials (one or more) that
the Network is responsible for. If multiple credentials are
configured on the Peer for this Network, then the Peer MUST include
one CredInfo TLV for each available credential.
When there are no abailable credentials, the Peer MAY include an
authorization token that can be consumed by the Server for
registering new credentials. In particular, the Peer can include the
('Token-Data') TLV to convey the value of the token. The
('Challenge-Data') and ('Challenge-Response') TLVs, instead, can be
used to convey a challenge and the response to that challenge based
on the authorization information (e.g., maybe a public key hash is
present in the Token, then the peer can generate some random data -
or use the one from the Server - and generate a signature on that:
the value of the signature shall be in the ('Challenge-Response') TLV
and should be calculated over the values of the ('Challenge-Data')
TLV and the ('Token-Data') TLV).
The server checks that the Peer's selected protocol, version, and
parameters are supported and, if not (or if the server detects an
error), it can (a) send a non-recoverable error message to the peer,
notify the outer (tunneling) layer, and terminate the EAP-CREDS
session, or (b) start phase one again by sending a new ('EAP-CREDS-
Init') message that will also carry an ERROR TLV that provides the
Peer with the reason the initial response was not acceptable. The
server and the peer can repeat phase one until they reach an
agreement or the session is terminated.
On the other hand, in case the server can serve the request from the
client, EAP-CREDS continues by starting the provisioning process.
The determination of the need to start phase two or not is based on
the contents of the CredInfo sent by the Peer (e.g., a credential is
about to expire or a credential is simply missing). The Server can
repeat phase two as many times as needed: each time, the combination
of the ('Credentials-Info') TLV (a.k.a. CredInfo) and the ('Action')
TLV shall be unique for each session to repeat the same operation on
the same credential. In case all credentials for the Network do not
need maintenance at this time, the Server can decide to end the EAP-
CREDS session (no actions to be taken) and successfully complete the
session.
In order to move to phase two (if the server needs to perform
management operations on the credentials exposed by the peer), the
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Server selects the version, the provisioning protocol, associated
parameters, and, optionally, the provider and sends it back to the
Peer. Phase Two officially begins with the next message exchanged by
the two parties which is an EAP-Request/EAP-CREDS(Type=ProtoFlow)
message to the client which includes the selected ('Version'),
('Action'), ('Protocols'), ('CredInfo'), and optionally the
('Provider') TLVs with only one value each. The TLVs cannot be
repeated within the same message. If multiple values are detected in
the message, the message shall be discarded and the appropriate error
message shall be issued by the Peer.
5.4. Phase Two: Provisioning
The following figure provides the message flow for Phase 2:
,--------. ,----------.
|EAP Peer| |EAP Server|
`---+----' `----+-----'
| [3] EAP-Request/EAP-CREDS(Type=ProtoFlow) |
| { [ Version ], Protocol, Action, | ,---------!.
| [ CredInfo ], [ ProvParams ], | |Phase Two|_\
| [ ProtoData ] } | |Begins |
| <------------------------------------------ `-----------'
| |
| [4] EAP-Response/EAP-CREDS(Type=ProtoFlow)|
| { ProtoData, [ ProtoHeaders ] } |
| ------------------------------------------>
| |
. .
. .
. .
. .
| [5] EAP-Request/EAP-CREDS(Type=ProtoFlow) |
| { ProtoData, [ ProtoHeaders ] } |
| <------------------------------------------
| |
| [6] EAP-Response/EAP-CREDS(Type=ProtoFlow)| ,---------!.
| { << Empty Body >> } | |Phase Two|_\
| ------------------------------------------> |Ends |
| | `-----------'
| |
The server starts phase two of the EAP-CREDS protocol by sending an
EAP-Request/EAP-CREDS(Type=ProtoFlow) message with the selected
protocol's details to the Peer. This indicates that the Server is
ready to initiate the provisioning protocol.
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Specifically, the Server MUST include the 'Version' and 'Protocol'
TLVs to indicate the EAP-CREDS version agreed upon by the parties and
the specific provisioning protocol to use. The 'provider' TLV is
optional and MUST be included if a selection was made by the Peer.
The 'provider' TLV MAY be included in the message even if the Peer
did not make a selection.
After that, the Peer sends its first message to the Server by sending
the EAP-Response/EAP-CREDS(Type=ProtoFlow) message. This message
contains the selected provisioning protocol's message data and some
extra fields (e.g., transport-protocol headers) in the Protocol-Data
and Protocol-Headers TLVs respectively.
The Server replies to the Peer's message with EAP-Request/EAP-
CREDS(Type=ProtoFlow) messages until the provisioning protocol
reaches an end (the client will send a 'ProtoFlow' message with an
empty body) or an error condition (the party that detected the error
condition will use a 'ProtoFlow' message with an 'Error' TLV to
convey the issue and terminate the protocol).
After the Peer sends the final empty message, the server can start
phase three of EAP-CREDS or it can repeat phase two by issuing a new
ProtoFlow message with the appropriate TLVs to idicate the target
credential and action to perform.
5.5. Phase Three: Validation
The following figure provides the message flow for Phase 3:
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,--------. ,----------.
|EAP Peer| |EAP Server|
`---+----' `----+-----'
| [1] EAP-Request/EAP-CREDS(Type=Validate) | ,-----------!.
| { CredInfo, Challenge } | |Phase Three|_\
| <----------------------------------------- |Begins |
| | `-------------'
| [2] EAP-Response/EAP-CREDS(Type=Validate)|
| { Challenge, ChallengeResponse, |
| [ ExtraChallenge ] } |
| ----------------------------------------->
| |
| [3] EAP-Request/EAP-CREDS(Type=Validate) |
| { Challenge, ChallengeResponse } |
| <-----------------------------------------
| |
| [4] EAP-Response/EAP-CREDS(Type=Validate)| ,-----------!.
| { << Empty Body >> } | |Phase Three|_\
| -----------------------------------------> |Ends |
| | `-------------'
| |
Phase three is optional and it is used by the server to request the
client to validate (proof) that the new credentials have been
installed correctly before issuing the final Success message.
NOTE WELL: Phase Three introduces the dependency on a hashing
algorithm to provide an easy way to check the integrity and
functionality of a newly installed credentials. This requirement
might be updated should the security properties of the selected
algorithm be weakened.
In order to do that, the server and the client exchange two messages,
i.e. one EAP-Request/EAP-CREDS(Type=Validate) and one EAP-Response/
EAP-CREDS(Type=Validate). These messages are used to verify the
correctness of the exchanged credentials and the ability by the Peer
to use the credentials. The server must include the ('Credentials-
Info') TLV to provide the indication about which credential the
Server intends to validate. The Server MUST also include a randomly
generated challenge in the message to the client.
When the client receives the Validate message from the server, it
calculates the response to the challenge (based on the type of
credentials and the protocol itself) and sends the response back to
the server. The Peer MUST calculate the response as follows:
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Public-Key - For any public-key based credentials (e.g.,
certificates or raw keys), the response to the challenge is
calculated by generating a signature over the hashed value of the
challenge. The hashing algorithm to be used for this purpose is
specified in Section 7.3.1.
Symmetric Secret - For any symmetric based credentials (e.g.,
password or Key), the response to the challenge is calculated by
using the selected hash function Section 7.3.1 on the
concatenation of (a) the value carried in the corresponding
('Challenge-Data') TLV, and (b) the secret value itself.
Optionally, the client can optionally add a new ('Challenge-Data')
TLV in its reply to request that the network proves it can calculate
responses. This extra challenge is only available for symmetric
secrets (it is not used to verify again the identity of the server,
but it is used for the server to prove it does have the right
symmetric data on its side). This 'extra' challenge carries the
Peer-Generated challenge information that the server MUST use to
calculate the corresponding ('Challenge-Response') TLV.
When the server receives the EAP-Response/EAP-CREDS(Type=Validate)
with the Challenge TLV in it, it MUST calculate the response to the
challenge and send back the response to the client in an EAP-Request/
EAP-CREDS(Type=Validate) with the ChallengeResponse TLV.
In case of issues with the validation of the newly deployed
credentials, both the client and the server should consider those
credentials invalid (or unusable) and should issue the required
failure message(s).
6. EAP-CREDS Message Format
The EAP-CREDS defines the following message types:
EAP-CREDS/Init
EAP-CREDS/ProtoFlow
EAP-CREDS/Validate
Each of these message types have the basic structure as identified in
Section 6.1 and in Section 6.2 and contain zero, one, or more TLVs.
The allowed TLVs for the different types of messages are described in
Section 7. The internal structure of the different types of TLVs is
described in Section 6.2.1.
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6.1. Message Header
The EAP-CREDS messages consist of the standard EAP header (see
Section 4 of [RFC3748]), followed by the version of the EAP-CREDS (4
bits) and a field (4 bits) reserved for future use. The header has
the following structure:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Flags | Ver | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length | Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-.
Where the Code, Identifier, Length, and Type fields are all part of
the EAP header as defined in [RFC3748].
The Type field in the EAP header is <TBD> for EAP-CREDS.
The Ver (Version) bitfield (4 bits) identifies the version of the
EAP-CREDS protocol used for the exchange. This document defines the
value to use for this field as '0x1' (0001).
The Flags bitfield (4 bits) is currently not used and it is reserved
for future use. The value of the bitfield shall be ignored when the
Version ('Ver') field is set to '0x1' (0001).
6.2. Message Payload
The Data part of the message is organized as zero, one, or more TLV
objects whose structure is defined in this section. In particular,
the general structure of a TLV is described in Section 6.2.1, while
the specific structures for the supported TLVs is provided in
Section 6.2.2.
6.2.1. General TLV format
Each TLV object has the same basic structure that is defined as
follows:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
TLV-Type (uint8)
This field is used to indicate the type of data that the TLV
carries. The type of TLV determines its internal structure. The
supported values for this fields are provided in the following
table:
Length (uint24)
This field carries the size of the value of the TLV. In
particular, the overall size of a TLV (i.e., the header plus the
value) can be calculated by adding the size of the header (6
octects) to the value of the Length field (i.e., the size of the
TLV's value).
+--------------+--------------------------+
| Message Type | Purpose |
+--------------+--------------------------+
| 0 | Action TLV |
| 1 | Challenge-Data TLV |
| 2 | Challenge-Response TLV |
| 3 | Credentials-Data TLV |
| 4 | Credentials-Info TLV |
| 5 | Error TLV |
| 6 | Profile TLV |
| 7 | Protocol TLV |
| 8 | Provisioning-Headers TLV |
| 9 | Provisioning-Data TLV |
| 10 | Provisioning-Params TLV |
| 11 | Token-Data TLV |
| 12 | Version TLV |
+--------------+--------------------------+
Table 2: EAP-CREDS Supported TLVs Types
TLV Value ( > 1 octet )
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This field carries data for the identified TLV. The internal
structure is determined by the TLV Type field.
6.2.2. EAP-CREDS defined TLVs
EAP-CREDS messages's payload comprieses zero, one, or more TLVs that
are encoded in a single EAP-CREDS message. The values for the TLV
Type that are supported by this specifications are listed in Table 2.
This section describes the structure of the different supported TLVs
and their usage in the different messages.
6.2.2.1. The Action TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | Flags | Action Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Action TLV
Flags (uint8)
Reserved
Action Type (uint16)
Provides the indication of the type of action to be performed in
the current run of the phase two of EAP-CREDS. The values for
this field are provided in Table 11.
Encoding (uint8)
Provides the indication of the Encoding the credentials are in.
The allowed values for this field are listed in Table 10.
Value (octet string)
This field carries the data for the credentials.
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6.2.2.2. The Certificate-Data TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Format | Encoding | Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Certificate-Data TLV
Length (uint24)
Provides the length of the TLV (> 3 octets)
Flags (uint8)
Provides a BITMASK that can be used to provide additional
information related to the encapsulated certificate. The bits
have the following meaning:
Bit 0 - If set, the certificate is trusted (Trust Anchor)
Bit 1 - If set, the certificate is a CA certificate
Bit 2 - If set, the certificate is self-signed
Bit 3 - If set, the certificate is a proxy certificate
Bit 4 - If set, the certificate is an attributes certificate
Bit 5 - Reserved
Bit 6 - Reserved
Bit 7 - Reserved
For a Trusted Root CA, the value of the flags shall be 0x7 (0000
0111). For an intermediate CA certificate that is not implicitly
trusted, the value of the flags field should be set to 0x02 (0000
0010). For an End-Entity certificate, the value of the Flags will be
0x0 (0000 0000).
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Format (uint8)
Provides the indication of the Format the certificate is in. The
allowed values for this field are listed in Section 12.5.
Encoding (uint8)
Provides the indication of the Encoding the certificate is in.
The allowed values for this field are listed in Table 10.
Value (octet string)
This field carries the data for the certificate.
6.2.2.3. The Challenge-Data TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Challenge Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Challenge-Data TLV
Length (uint24)
3 octets
Challenge Data (> 1 octet)
This field carries the data to be used as a challenge when
validating newly deployed credentials
6.2.2.4. The Challenge-Response TLV
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Challenge Response ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Challenge-Response TLV
Length (uint24)
3 octets
Challenge Response (> 1 octet)
This field carries the data that resulted from the use of the
credentials to be validated.
6.2.2.5. The Credentials-Information TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | CredsType | ProtoID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IssuedOn (GMT) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Expires On (GMT) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credentials Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CredIDValue ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The Credential-Information TLV is used by the Peer to provide a
description of the installed credentials that are relevant for the
network that is being accessed. The TLV is also used by the server
to provide indication to the Peer about the required parameters when
requesting/updating credentials.
For example, when a set of credentials need to be renewed, the server
checks the CredInfo from the Peer and eventually selects the right
one for renewal - in the first message of Phase Two, the CredInfo TLV
is used by the server to convey (let's say that the credentials to
renew are X.509 based) the requirements for generating the X.509
PKCS#10 request, such as the algorithm (RSA, ECDSA, etc.) further
parameters (e.g., the specific curve to use or the Key Size) and the
indication if the credentials are to be generated on the server or on
the client.
The TLV structure is as follows:
TLV Type (uint8)
<TBD> - Credentials-Information TLV
Length (uint24)
Provides the total length of the body of the Credential-
Information TLV.
Flags (uint8)
Provides a BITMASK that can be used to provide information about
the status of the credentials (e.g., if the use marks the
credentials to be compromised). The bits have the following
meaning:
Bit 0 - If set, the credential is marked as compromised
Bit 1 - If set, the credential is immutable and cannot be
updated
Bit 2 - Private Key or Secret Immutable, the public part of the
credential (e.g., a certificate) can still be updated
Bit 3 - If set, the credential cannot be updated (both public
and private parts)
Bit 4 - If set, the credential is ready to be used
Bit 5 - If set, the credential was generated on the server
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Bit 6 - If set, the Peer would like to update the credential
even if they are not expired
Bit 7 - Reserved
CredType (uint8)
This field provides the description of the type of credential.
The type of credentials are listed in Table 7
ProtoID (uint16)
This field indicates the protocol that was used to retrieve the
target credential. When the TLV is used in a Request by the
Server, this field specifies which protocol should be used for its
management. The values for this field are listed in Table 5.
IssuedOn (16 octets)
This field carries the GMT date for when this credential was
issued. This field is 16 bytes long (the last byte must be set to
'0x00') and contains the NULL-terminated ASCII string that
represents the timestamp where the credential was issued. When
the value is not set, the field should be set to { 0x00 }. The
format of the string is as follows:
YYYYMMDDHHmmssZ
Where:
YYYY - is the 4 digits representation of the year
MM - is the 2 digits representation of the month
DD - is the 2 digits representation of the day of the month
HH - is the 2 digits representation of the hour of the day (24
hour format)
mm - is the 2 digits representation of the minutes of the hour
ss - is the 2 digits representation of the seconds of the
minute
Z - is the character 'Z'
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ExpiresOn (16 octets)
This field carries the GMT date for when this credential is to be
considered expired. This field is 16 bytes long (the last byte
must be set to '0x00') and contains the NULL-terminated ASCII
string that represents the timestamp where the credential was
issued. The format is the same as the ('IssuedOn') field. When
the value is not set, the field should be set to { 0x00 }.
Credentials Length (uint16)
Length (in bytes) of the Credentials value. When used with a
public-key type of credentials, this is the size of the key (e.g.,
for an RSA 2048 bit keys, this field should carry the value of
256). When used with a symmetric secret, this field carries the
size of the secred (in bytes).
CredIDValue (> 1 octet)
The binary value of the credentials' identifier. This identifier
can be the binary value of the SHA-256 calculated over the
certificate, a username, or it could be a simple random handle.
As long as the ID allows the server to uniquely (in its context)
identify the credentials, the value of this field can be
calculated in any way.
6.2.2.6. The Credentials-Data TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cred Type | Format | Encoding | Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Credentials-Data TLV
Length (uint24)
Provides the length of the TLV (> 3 octets)
Cred Type (uint8)
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Provides the indication of the type of credentials. The allowed
values for this field are listed in Table 7.
Format (uint8)
Provides the indication of the Format the credentials are in. The
allowed values for this field are listed in Section 12.5.
Encoding (uint8)
Provides the indication of the Encoding the credentials are in.
The allowed values for this field are listed in Table 10.
Value (octet string)
This field carries the data for the credentials.
6.2.2.7. The Error TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EAP-CREDS Error Code | Secondary Error Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Description ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Challenge-Response-Data TLV
Length (uint24)
3 octets
EAP-CREDS Error Code (2 octets)
This field carries the EAP-CREDS error code. These code are
related to the EAP-CREDS operations only and it should not be used
to carry the Provisioning-Protocol specific error codes.
Secondary Error Code (2 octets)
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This field is used to convery an error at the encapsulation layer
(i.e., the provisioning protocol error). Do not use this field to
convery EAP-CREDS specific errors.
Description ( > 1 octet)
The Description field is optional (i.e., when the Description Size
is set to zero) and carries information about the error that
occurred. The message may or may not be used by a user or an
automated process for debugging purposes.
6.2.2.8. The Profile TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Profile Identifying Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Profile Identifying Data TLV
Length (uint24)
4 octets
Profile Identifying Data (octet string)
The Profile Identifying Data is used to provide indication to the
other party about which profiles are supported when requesting
credentials management.
Also in this case, the data used in this field is left to be
interpreted by the end-point and it is orthogonal to EAP-CREDS
data types.
An example of values for this field, an end-point could use the
string representation (i.e., dotted representation) of the Object
Identifier (OID) of the specific profile supported (e.g., could be
defined in the Certificate Policy of the credentials' provider).
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6.2.2.9. The Protocol TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | Protocol ID | Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Protocol TLV
Protocol ID (uint16)
The Protocol ID value carries the id of a supported provisioning
protocol. The initial values for the provisioning protocol
identifiers can be found in Section 12.1.
Version
The Version (Protocol Version) value represents the specific
version of the identified provisioning protocol. When no version
is specified for a protocol (i.e., either it does not support
multiple versions or it does not matter), the value of this field
should be set to '0x0'.
6.2.2.10. The Provisioning-Data TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Provisioning Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Provisioning-Data TLV
Length (uint24)
3 octets
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Headers Data (> 1 octet)
This field carries the provisioning protocol's messages.
6.2.2.11. The Provisioning-Headers TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Headers Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Provisioning-Headers TLV
Length (uint24)
3 octets
Headers Data (> 1 octet)
This field carries the meta-data (if any) that might be associated
with the transport-layer normally used with the provisioning
protocol. For example, this TLV can carry the set of HTTP headers
required by EST or ACME.
6.2.2.12. The Provisioning-Params TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Min Length | Max Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Algorithm | Flags | OBJECT IDENTIFIER (DER) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Provisioning-Params TLV
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Length (uint24)
Provides the length of the TLV (>= 4 octets)
Min Length (uint16)
Provides the indication minimum size of the credentials. This
value has meaning depending on the context of the credentials,
however sizes are always expressed in bytes.
For example, when used with a symmetric key or a password, the
('Min Length') and ('Max Length') refer to the minimum and maximum
size of the password data. The ('Algor OID') field can be omitted
in this case.
On the other hand, when referring public-key credentials, this
field should carry the size of the modulus of the key. For
example, for an RSA 2048 bit keys, the field should carry the
value of 256. For an ECDSA that uses the prime256r1 curve, this
field should carry the value of 32 and the Algor OID should be the
DER representation of the specific value of the curve (i.e., the
DER representation of '1.2.840.10045.3.1.7').
Max Length (uint16)
Provides the indication maximum size of the credentials. This
value has meaning depending on the context of the credentials,
however sizes are always expressed in bytes.
The same considerations apply to this field as well as the ('Min
Length') one discussed above.
Flags (uint8)
Provides a BITMASK that can be used to provide information about
the status of the credentials (e.g., if the use marks the
credentials to be compromised). The bits have the following
meaning:
Bit 0 - Credentials (or part of it) are to be generated on the
server
Bit 1 - Credentials (or part of it) are to be generated on the
peer
Bit 2 - Reserved
Bit 3 - Reserved
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Bit 4 - Reserved
Bit 5 - Reserved
Bit 6 - Reserved
Bit 7 - Reserved
When using public-key based credentials, the bits 0 and 1 are
mutually exclusive.
When using passwords or shared secrets, if bit 0 is set, then the
secret is generated by the server and then sent to the client. On
the other hand, if bit 1 is set, then the secret is generated by
the peer and then sent to the server. Ultimately, if both bits
are set, then the Peer generates the first part of the password
and sends it to the Server, while the Server generates the second
part of the password and sends it to the Peer. The password to be
used for future authentication is the concatenation of the two
shares of the password: first the one from the Server, then the
one from the Client.
Last but not least, since these passwords/secrets are meant to be
used in a automated fashion, there is no restriction around the
character set to use or their interpretation. Therefore, we
suggest to generate full random passphrases (on client and server)
to maximize the randomness carried within the secret.
Algorithm (uint8)
Provides the indication of the algorithm used for the generation
of the credentials. The allowed values for this field are listed
in Table 8.
Object Identifier (binary; > 1 octet)
Provides the indication of additional parameters that need to be
encoded for the credentials. This value is used only when the
credentials use public-key cryptography - this field carries
additional information about the algorithm to be used. We provide
some useful values that can be used as reference:
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+----------------+----------------------+---------------------------+
| OID Name | Dotted | Binary Encoding |
| | Representation | |
+----------------+----------------------+---------------------------+
| secp256r1 | 1.2.840.10045.3.1.7 | 06 08 2A 86 48 CE 3D 03 |
| curve | | 01 07 |
| secp384r1 | 1.2.840.10045.3.1.34 | 06 08 2A 86 48 CE 3D 03 |
| curve | | 01 22 |
| secp521r1 | 1.2.840.10045.3.1.35 | 06 08 2A 86 48 CE 3D 03 |
| curve | | 01 23 |
| X25519 curve | 1.3.101.110 | 06 03 2B 65 6E |
| X25519 curve | 1.3.101.110 | 06 03 2B 65 6E |
| X448 curve | 1.3.101.111 | 06 03 2B 65 6F |
| Ed25519 curve | 1.3.101.112 | 06 03 2B 65 70 |
| Ed448 curve | 1.3.101.113 | 06 03 2B 65 71 |
+----------------+----------------------+---------------------------+
Table 3: Object Identifiers Examples
6.2.2.13. The Token-Data TLV
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token Type | Encoding | Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Token-Data TLV
Length (uint24)
Provides the length of the TLV (> 3 octets)
Token Type (uint8)
Provides the indication of the type of credentials. The allowed
values for this field are listed in Table 6.
Encoding (uint8)
Provides the indication of the Encoding the credentials are in.
The allowed values for this field are listed in Table 10.
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Value (octet string)
This field carries the data for the credentials.
6.2.2.14. The Version TLV
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
<TBD> - Version TLV
Version (uint8)
The Version field is a uint8 value and represents the specific
version of the EAP-CREDS protocol that are supported by the end
point. When multiple versions of EAP-CREDS are supported,
multiple ('Version') TLVs can be used.
When no version is specified (i.e., either it does not support
multiple versions or it does not matter), the value of this field
should be set to '0x0'.
7. EAP-CREDS Messages
This section describes each message and what TLVs are allowed or
required. EAP-CREDS defines the following values for the Message
Type (Type):
+------------+---------------------+--------------------------------+
| Message | Name | Description |
| Type | | |
+------------+---------------------+--------------------------------+
| 0 | EAP-CREDS-Init | Initialization Phase |
| 1 | EAP-CREDS-ProtoFlow | Carries Provisioning Protocol |
| | | Messages |
| 2 | EAP-CREDS-Validate | Validates newly installed |
| | | credentials |
+------------+---------------------+--------------------------------+
Table 4: EAP-CREDS Message Types
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7.1. The EAP-CREDS-Init Message
The EAP-CREDS-Init message type is used in Phase One only of EAP-
CREDS. The message flow is depicted in Section 5.3. This message
supports the following TLVs: Version, Protocol, Credentials-Info, and
Error.
7.1.1. EAP Server's Init Message
EAP-CREDS starts with an ('EAP-CREDS-Init') message from the server.
This message MAY contain zero, one, or more ('Version') TLVs and,
optionally, a ('Challenge-Data') TLV.
The Server uses one or more ('Version') TLVs in the EAP-Request/EAP-
CREDS(Type=Init) message to provide the Peer with the list of EAP-
CREDS versions supported. If omitted, the implict version of EAP-
CREDS used in the session is one ('0x1'). If the Server detects
multiple occurrences of this TLV in the reply from the Peer, an error
shall be issued and the EAP-CREDS session should be terminated.
In case Token-Based registration is enabled on the Server, the Server
SHOULD include, in its Init message, a ('Challenge-Data') field that
can be used by the client to provide reply protection, and (unique)
challenge data for proof-of-possession of secrets.
7.1.2. EAP Peer's Init Message
The Peer MUST reply to the Server's ('EAP-CREDS-Init') message with
its own ('EAP-CREDS-Init') one. The Peer one Version TLV in the EAP-
Response/EAP-CREDS(Type=Init) message to indicate the version of EAP-
CREDS that the client wants to use for the session. The Peer MUST
also provide the list of supported provisioning protocols (via the
'Protocol' TLV), the list and status of the installed credentials
(via the 'Credentials-Info' TLV). The Peer MAY include authorization
data when registering new credentials (e.g., an authorization token
or a device certifcate).
The Peer MUST include one ('Credentials-Info') TLV for each
credential the Network is authorized to manage. Typically, a Peer
will include only one ('Credentials-Info') TLV in its ('EAP-CREDS-
Init') message, but there might be cases where multiple types of
credentials are available (e.g., X.509 certificate and username/
password combination) and used depending on the location and other
factors.
In case the Peer does not have any credentials available yet, it does
not add any ('Credentials-Info') TLV - leaving the Server with the
only action possible: Registration.
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7.1.2.1. Bootstrapping Peer's Trustworthiness
The Registration process might rely on information exchanged during
the Provisioning Process in Phase Two, however, if an authorization
mechanism is not available, EAP-CREDS provides a simple machanism for
the Peer to leverage an out-of-band token/passphrase/ott that is
available (or can easily be made available) on the Peer and that can
be verified by the Server.
In particular, when the Peer wants to register new credentials (and
the Server requires the use of authorization because, for example,
the Peer does not have any credentials yet) it may need to provide
(a) a Token, (b) a challenge value, and (c) a response to the
challenge value. To do so, the Peer MUST encode the token in a
('Token-Data') TLV, the challenge value in a ('Challenge-Data') TLV,
and, finally, the response to the challenge in the ('Challenge-
Response') TLV.
The use of ('Challenge-Data') and ('Challenge-Response') TLVs is
optional, however it is suggested that if a token is used for
bootstrapping the trust, it should provide a way to verify a secret
associated with it.
It is also very important that the authorization token is disclosed
only to authorized servers - the Peer MUST NOT disclose authorization
tokens that are not meant for the network that is being accessed.
This can be done, usually, by verifying the identity of the Server
first (in the outer mechanism) and then verify that the target of the
Token is the Server the Client is talking to.
7.2. The EAP-CREDS-ProtoFlow Message
The EAP-CREDS-ProtoFlow message type is used in Phase Two only of
EAP-CREDS. The message flow is depicted in Section 5.4. This
message type supports the following TLVs: Protocol, Credentials-Info,
Provisioning-Headers, Provisioning-Data, Token-Data, and Error.
After the exchange of the initial two ('EAP-CREDS-Init') messages,
the Server MAY start phase two by issuing an ('EAP-CREDS-ProtoFlow')
message for the Peer where it encodes all the required details for
starting the provisioning process. In particular, the server sends
the selected ('Action'), ('Protocol'), ('Credentials-Info'), and
metadata to the client in a EAP-Request/EAP-CREDS(Type=ProtoFlow)
message.
NOTE WELL: After the initial message, the only TLVs that are
allowed in messages coming from the server are the usual
('Provisioning-Headers') ('Provisioning-Data'), and ('Error').
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The client checks that all the selected parameters are supported for
the selected credentials and, if no errors are detected, it sends its
first ('EAP-CREDS-ProtoFlow') message to the Server with the
('Provisioning-Headers') and ('Provisioning-Data') TLVs only.
From now on, the conversation between the Peer and the Server
continues until an error is detected or the provisioning protocol
completes successfully (the client sends an empty ('EAP-CREDS-
ProtoFlow') message to the Server to indicate that the protocol
completed successfully).
If no other actions, the server MAY continue with phase three or
issue a success message and terminate the EAP session.
NOTE WELL: When the SPP protocol is used, the protocol messages
that are encoded inside the ('Protocol-Data') TLV are composed of
sets of TLVs as defined in this document. The overall message
size is provided by the size of the ('Protocol-Data') TLV that
encapsulates the SPP-specific TLVs. This design choice provides
symmetry in implementing support for SPP when compared to other
(available) provisioning protocols.
7.3. The EAP-CREDS-Validate Message
7.3.1. Algorithm Requirements
EAP-CREDS uses the SHA-256 hashing algorithm to verify credentials in
phase three of the protocol. Peers and Servers MUST support SHA-256
for this purpose.
8. Error Handling in EAP-CREDS
This section provides a description of the error handling by using
the CREDS-Error-TLV in a CREDS message.
9. Fragmentation
Although EAP does not directly support handling of fragmented
packets, EAP-CREDS requires that its messages are encapsulated via an
outer method that MUST provide fragmentation support.
Because of the outer method requirements in particular, removing any
support for fragmented messages in EAP-CREDS removes the duplication
of packets (e.g., Acknowledgment Packets) sent across the Peer and
the Server, thus resulting in a smaller number of exchanged messages
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10. Encapsulating Provisioning Protocols in EAP-CREDS
In order to use EAP-CREDS together with your favorite provisioning
protocol, the messages from the provisioning protcol need to be sent
to the other party. In EAP-CREDS, this is done by putting the
provisioning protocol messages inside the ('Provisioning-Data') TLV.
In case the provisioning protocol uses additional data for its
operations (e.g., uses HTTP Headers), this data can be encoded in a
separate ('Provisioning-Headers') TLV.
Since the implementation of the provisioning endpoint could happen in
a (logically or physically) different component, a method is needed
to identify when a provisioning protocol has actually ended. In EAP-
CREDS, when the provisioning protocol is over, when an empty message
is sent by the Server (not the Peer).
In the first message of Phase Two, the Server provides the client
with all the selected parameters for one specific credential that
needs attention (or for a new credential) to be registered with the
network. In particular, the server provides the ('Version') TLV
(optional), the ('Protocol') TLV, the ('Action') TLV, and the
('Provisioning-Params') TLV.
After checking the parameters sent by the Server, if the Peer does
not support any of them, it MUST send a message with one single
('Error') TLV with the appropriate error code(s). The server, can
then decide if to manage a different set of credentials (if more
where reported by the Peer in its Phase One message) or if to
terminate the EAP session with an error.
The Peer and the Server exchange ProtoFlow messages until an error is
detected and the appropriate error message is sent to the other
party. If the error message was sent by the Peer, then the Server
MAY send an empty message to the Peer and terminate the session, or
it MAY try to restart Phase Two for a different set of credentials or
with a different action (same target and action MUST not be repeated
in the same EAP-CREDS session).
11. EAP-CREDS and Simple Provisioning Protocol (SPP)
EAP-CREDS supports a Simple Provisioning Protocol (SPP) which
comprises a series of messages that enables the management not only
of certificates, but also of other types of credentials like
username/password pairs, asymmetric keys, and symmetric keys.
The Simple Provisioning Protocol (SPP), described in this section,
behaves as any other provisioning protocol: its messages are
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encapsulated in the ('Provisioning-Data') TLVs in the second phase of
the protocol.
When no ('Credentials-Info') TLVs have been provided by the client,
the Server knows that the device does not have valid credentials it
wants to use to access the Network. In this case, EAP-CREDS/SPP
supports the use of Tokens to kick-off the registration process. The
type, format, or encoding of the Token is orthogonal to EAP-CREDS/SPP
which treats the token as a black-box field (i.e., it does not try to
interpret or parse its contents).
NOTE WELL: During Phase One, the Peer MAY include the ('Token-
Data') TLV in its EAP-CREDS-Init message to provide the needed
authorization to register a new set of credentials. The Server
might not allow the registration of new credentials if the
required authorization (i.e., the Token) was not provided during
the initialization phase.
In the case where an authorization Token MUST be used and it is not
just a bearer token but it can be used (or a secret identified in it)
to generate a verifiable proof-of-possession, the Peer can include a
('Challenge-Data') and a ('Challenge-Response') TLVs.
The ('Challenge-Data') TLV MUST be used to convey the challenge data
(usually some random value), if any. If the Server provided a
('Challenge-Data') TLV, then the Peer MUST use the same TLV in its
message (and to calculate the response).
The ('Challenge-Response') TLV is used, instead, to encode the
response to the challenge data that can be generated by the Peer and
verified by the Server.
NOTE WELL: The use of the ('Token-Data'), ('Challenge-Data'), and
('Challenge-Response') TLVs in the Peer's Init message can be used
to bootstrap trust between the server and the client.
11.1. SPP Message Format
The SPP Messages are constructed with zero, one, or more TLVs and
encoded in the ('Provisioning-Data') TLV. The size of the
encpasulating ('Provisioning-Data') TLV provides the size of the
whole message.
11.2. SPP: Registering New Credentials
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11.3. SPP: Renewing Credentials
11.4. SPP: Removing Credentials
11.5. SPP Password Provisioning
EAP-CREDS/SPP defines the following flow of messages for provisioning
symmetric secrets. This method can be used to deliver a username/
password combination, a token, or a symmetric key. The message flow
is provided
EAP-CREDS/SPP provides the possibility for shared secret to be
generated in different ways:
1. Server-Side Generated
2. Client-Side Generated
3. Both Sides Generate a share
In particular, when initiating the second phase of the protocol, the
('Provisioning-Params') TLV is used to specify how to generate the
secret.
11.6. SPP Certificate Provisioning
EAP-CREDS/SSP defines the following flow of messages for requesting
the provisioning of credentials.
12. IANA Considerations
This document uses a new EAP type, EAP-CREDS, whose value (TBD) MUST
be allocated by IANA from the EAP TYPEs subregistry of the RADIUS
registry. This section provides guidance to the Internet Assigned
Numbers Authority (IANA) regarding registration of values related to
the EAP-CREDS protocol, in accordance with [RFC8126].
The EAP Method Type number for EAP-CREDS needs to be assigned.
This document also requires IANA to create new registries as defined
in the following subsections.
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12.1. Provisioning Protocols
+-----------------+-------------------------------------------------+
| Message Type | Purpose |
+-----------------+-------------------------------------------------+
| 0 | Unspecified |
| 1 | Simple Provisioning Protocol (SPP) |
| 2 | Basic Certificate Management Protocol (CMP-S) |
| 3 | Full Certificate Management Protocol (CMP-F) |
| 4 | Enrollment over Secure Transport (EST) |
| 5 | Certificate Management over CMS (CMC) |
| 6 | Automatic Certificate Management Environment |
| | (ACME) |
| ... | ... |
| 49141 ... 65534 | Vendor Specific |
+-----------------+-------------------------------------------------+
Table 5: EAP-CREDS Inner Protocol Identifiers
Assignment of new values for new cryptosuites MUST be done through
IANA with "Specification Required" and "IESG Approval" as defined in
[RFC8126].
12.2. Token Types
+------------+-----------------+
| Token Type | Description |
+------------+-----------------+
| 0 | Unspecified |
| 1 | JWT |
| 2 | Kerberos |
| 3 | OAuth |
| 200..254 | Vendor Specific |
+------------+-----------------+
Table 6: Token Types
Assignment of new values for new Message Types MUST be done through
IANA with "Expert Review" as defined in [RFC8126].
12.3. Credentials Types
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+------------------+-----------------------+
| Credentials Type | Description |
+------------------+-----------------------+
| 0 | X.509 Certificate |
| 1 | Public Key |
| 2 | Symmetric Key |
| 3 | Username and Password |
| 4 | AKA Subscriber Key |
| 5 | Bearer Token |
| 6 | One-Time Token |
| 7 | API Key |
+------------------+-----------------------+
Table 7: Credentials Types
Assignment of new values for new Message Types MUST be done through
IANA with "Expert Review" as defined in [RFC8126].
12.4. Credentials Algorithms
+---------+--------------------+
| ID | Algorithm |
+---------+--------------------+
| 0 | None |
| 1 | RSA |
| 2 | ECDSA |
| 3 | XMMS |
| 4 | AKA Subscriber Key |
| 5 | OAuth |
| 6 | Kerberos4 |
| 7 | Kerberos5 |
| 200-254 | Reserved |
+---------+--------------------+
Table 8: Credentials Algorithms
Assignment of new values for new Message Types MUST be done through
IANA with "Expert Review" as defined in [RFC8126].
12.5. Credentials Datatypes
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+---------+---------------+
| ID | Data Type |
+---------+---------------+
| 0 | None (Binary) |
| 1 | PKCS#8 |
| 2 | PKCS#12 |
| 3 | PublicKeyInfo |
| 200-254 | Reserved |
+---------+---------------+
Table 9: Credentials Datatypes
Assignment of new values for new Message Types MUST be done through
IANA with "Expert Review" as defined in [RFC8126].
12.6. Credentials Encoding
+---------+------------+
| ID | Encoding |
+---------+------------+
| 0 | None (Raw) |
| 1 | DER |
| 2 | PEM |
| 3 | Base64 |
| 4 | JSON |
| 5 | XML |
| 6 | ASCII |
| 7 | UTF-8 |
| 200-254 | Reserved |
+---------+------------+
Table 10: Credentials Encoding
Assignment of new values for new Message Types MUST be done through
IANA with "Expert Review" as defined in [RFC8126].
12.7. Action Types
+---------+--------------+--------------------------------+
| ID | Data Type | Description |
+---------+--------------+--------------------------------+
| 0 | Registration | Registers New Credentials |
| 1 | Renewal | Renew an Existing Credential |
| 2 | Remove | Removes an Existing Credential |
| 200-254 | n/a | Reserved |
+---------+--------------+--------------------------------+
Table 11: Action Types
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Assignment of new values for new Message Types MUST be done through
IANA with "Expert Review" as defined in [RFC8126].
13. Security Considerations
Several security considerations need to be explicitly considered for
the system administrators and application developers to understand
the weaknesses of the overall architecture.
The most important security consideration when deploying EAP-CREDS is
related to the security of the outer channel. In particular, EAP-
CREDS assumes that the communication channel has been properly
authenticated and that the information exchanged between the Peer and
the Server are protected (i.e., confidentiality and integrity).
For example, if certificate-based authentication is used, the server
presents a certificate to the peer as part of the trust establishment
(or negotiation). The peer SHOULD verify the validity of the EAP
server certificate and SHOULD also examine the EAP server name
presented in the certificate in order to determine whether the EAP
server can be trusted. When performing server certificate
validation, implementations MUST provide support for the rules in
[RFC5280] for validating certificates against a known trust anchor.
14. Acknowledgments
The authors would like to thank everybody who provided insightful
comments and helped in the definition of the deployment
considerations.
15. Normative References
[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>.
[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>.
[RFC4210] Adams, C., Farrell, S., Kause, T., and T. Mononen,
"Internet X.509 Public Key Infrastructure Certificate
Management Protocol (CMP)", RFC 4210,
DOI 10.17487/RFC4210, September 2005,
<https://www.rfc-editor.org/info/rfc4210>.
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[RFC5272] Schaad, J. and M. Myers, "Certificate Management over CMS
(CMC)", RFC 5272, DOI 10.17487/RFC5272, June 2008,
<https://www.rfc-editor.org/info/rfc5272>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>.
[RFC6402] Schaad, J., "Certificate Management over CMS (CMC)
Updates", RFC 6402, DOI 10.17487/RFC6402, November 2011,
<https://www.rfc-editor.org/info/rfc6402>.
[RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
"Enrollment over Secure Transport", RFC 7030,
DOI 10.17487/RFC7030, October 2013,
<https://www.rfc-editor.org/info/rfc7030>.
[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. EAP-CREDS Example Message Flow for Provisioning Standards
A.1. EAP-CREDS and CMP
Describe how to use EAP-CREDS with CMP.
A.2. EAP-CREDS and EST
Describe how to use EAP-CREDS with EST.
A.3. EAP-CREDS and CMS
Describe how to use EAP-CREDS with CMS.
A.4. EAP-CREDS and ACME
Describe how to use EAP-CREDS with ACME.
Author's Address
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Massimiliano Pala
CableLabs
858 Coal Creek Cir
Louisville, CO 80027
US
Email: m.pala@openca.org
URI: http://www.linkedin.com/in/mpala
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