| Network Working Group | M. Pala |
| Internet-Draft | CableLabs |
| Intended status: Standards Track | July 24, 2019 |
| Expires: January 25, 2020 |
Credentials Provisioning and Management via EAP (EAP-CREDS)
draft-pala-eap-creds-04
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.
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This Internet-Draft will expire on January 25, 2020.
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 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
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].
Many environments are, today, moving towards requiring strong authentication when it comes to gain access to networks. The 802.1x architecture provides network administrators with the possibility to check credentials presented by a device even before providing any connectivity or IP services 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. EAP-CREDS cannot be used as a stand-alone method, it is required that EAP-CREDS is used as an inner method of EAP-TLS, EAP-TEAP, or any other tunnelling method that can provide the required secrecy and (at minimum) server-side authentication to make sure that the communication is protected and with the right server.
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: Certificate Management Protocol (CMP) [RFC4210], Certificate Management over CMS (CMC) [RFC5272][RFC6402], Enrollment over Secure Transport (EST) [RFC7030], and Automated Certificate Management Environment (ACME) . 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). 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 selected provisioning protocol.
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, tokens, 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 Simple Provisioning Protocol protocol or SPP.
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.
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, EAP-CREDS assumes that an appropriatly encrypted and authenticated channel 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, or EAP-TEAP are examples of such mechanisms.s
EAP does not directly support handling fragmented packets and it requires the outer method to 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
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 encoding 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, the 'D' bit in the message headers is used for this purpose.
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 managed by the network. In particular, the server provides, at minimum, the ('Protocol') TLV, the ('Action') TLV, and the ('Provisioning-Params') or the ('Credentials-Info') TLV.
After checking the parameters sent by the Server, if the Peer does not support any of the proposed ones, 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 Provisioning messages until an error is detected (and the appropriate error message is sent to the other party) or until Phase Two is successfully completed.
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.
In this document we use the following notation in the diagrams to provide information about the cardinality of the data structures (TLVs) within EAP-CREDS messages:
| Symbol | Example | Usage |
|---|---|---|
| { } | {TLV1} | Curly Brackets are used to indicate a set |
| [ ] | {[TLV2]} | Square Brackets are used to indicate that a field is optional |
| ( ) | {TLV1(=V)} | Round Squares are used to specify a value |
| + | {TLV_2+} | The Plus character indicates that one or more instances are allowed |
In a nutshell, EAP-CREDS provides the abstraction layer on top of which credentials provisioning/managing protocols can be deployed thus enabling their use even before provisioning IP services.
This section outlines the operation of the protocol and message flows. The format of the CREDS messages is given in Section 4.
EAP-CREDS message flow is logically subdivided into three different phases: Initialization, Provisioning, and Validation. EAP-CREDS enforces the order of phases, i.e. it is not possible to move to an earlier phase.
Phase transitioning is controlled by the Server. In particular, the server, after the last message of a phase, it can decide to either (a) start the next phase by sending the first message of the next phase, or (b) continue the same phase by sending another "first" message of the phase (e.g., managing a second set of credentials) - this is allowed only in Phase Two and Phase Three but NOT in Phase One, or (c) terminate the EAP session.
In order to keep track of starting and ending a phase, EAP-CREDS defines several bits and fields in the EAP-CREDS message headers. In particular, as described in Section 4.1, the 'S' bit is used to indicate the beginning (or Start) of a phase, while the 'Phase' field (4 bits) is used to indicate the phase for this message.
In EAP-CREDS, phase transitioning is under the sole control of the Server, therefore the value of the 'S' bit is meaningful only in messages sent by the Server. The value of the 'S' bit in Peer's messages SHALL be set to '0x0' and SHALL be ignored by the server.
When starting a new phase, the Server MUST set the 'S' bit to '1' and the 'Phase' field to the current phase number (e.g., one, two, or three).
In case the first message of a phase is to be repeated (e.g., because of processing multiple credentials), the 'S' bit SHALL be set to '0' (i.e., it should be set to '1' only on the first occurrency and set to '0' in subsequent messages).
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+ ], [ Challenge ] } | |Phase One|_\
| <--------------------------------------- |Begins |
| | `-----------'
| [2] EAP-Response/EAP-CREDS(Type=Init) |
| { Protocol+, [ Encoding+ ], |
| [ Format+ ] , [ Version ] | ,---------!.
| [ Creds-Info+ ], [ Storage-Info ]| |Phase One|_\
| [ Net-Usage], [ Token ], | |Ends |
| [ Challenge-Rsp ], [ Profile+ ] }| `-----------'
| --------------------------------------->
| |
| |
EAP-CREDS Phase One Message Flow
[1] Server sends EAP-Request/EAP-CREDS(Type=Init):
[2] The Peer sends EAP-Response/EAP-CREDS(Type=Init)
The Server's state machine is depicted in the following Figure:
+-------------------+
| Start Phase One |
+-------------------+
|
v
+-------------------+
| Send the Init Msg |
+-------------------+
|
v
+-------------------+
| Receives Peer's |
| Init Msg |
+-------------------+
|
v
+------------------+ Yes +---------------------+
| Checks for Error |------->| Send Error Msg |
+------------------+ +---------------------+
| No |
v v
+-------------------+ No +---------------------+
| Provisioning ? |------->| End EAP Session |
+-------------------+ +---------------------+
| Yes
v
+-------------------+
| Start Phase Two |
+-------------------+
EAP Creds Phase One State Machine
The first message from the server starts the phase by using the ('Phase-Control') TLV.
The Server selects the action, the provisioning protocol, and associated parameters. Phase Two officially begins with the next message exchanged (i.e. an EAP-Request/EAP-CREDS(Type=Provisioning)),which MUST include the ('Phase-Control') TLV with the 'S' bit set to '1' and the value set to '2'. The message MUST also includes, at minimum, the selected ('Action') and ('Protocol') TLVs.
When renewing existing credentials or registering new ones, the Server MUST include the ('Provisioning-Params') TLVs.
When removing or renewing existing credentials, the Server MUST include the ('Credentials-Info') TLV to identify the set of credentials to which the action applies.
If multiple values are detected in the message, the message shall be discarded and the appropriate error message shall be issued by the Peer.
The following figure provides the message flow for Phase 2:
,--------. ,----------.
|EAP Peer| |EAP Server|
`---+----' `----+-----'
| [1] EAP-Request/EAP-CREDS(Type=Provisioning) |
| { Protocol, Action, | ,---------!.
| [ CredInfo ], [ Params ], | |Phase Two|_\
| [ ProtoData ], [ ProtoHeaders ] } | |Begins |
| <---------------------------------------------- `-----------'
| |
| [2] EAP-Response/EAP-CREDS(Type=Provisioning) |
| { ProtoData, [ ProtoHeaders ] } |
| ---------------------------------------------->
| |
. .
. .
. .
. .
| [N] EAP-Response/EAP-CREDS(Type=Provisioning) |
| { [ CredInfo ], [ ProtoData ], |
| [ ProtoHeaders ] } |
| <----------------------------------------------
| |
| [N+1] EAP-Request/EAP-CREDS(Type=Provisioning)| ,---------!.
| { [ ProtoData ], [ ProtoHeaders ] } | |Phase Two|_\
| ----------------------------------------------> |Ends |
| | `-----------'
| |
EAP-CREDS Phase Two Message Flow
[1] The Server sends EAP-Request/EAP-CREDS(Type=Init)
[2] The Peer sends EAP-Response/EAP-CREDS(Type=Init)
[3] The Server sends EAP-Request/EAP-CREDS(Type=Init)
[N] The Server sends EAP-Request/EAP-CREDS(Type=Provisioning)
[N+1] The Peer sends EAP-Request/EAP-CREDS(Type=Provisioning)
At this point, the Server can decide to provision (or manage) another set of credentials by issuing a new ('Provisioning') message, or it can decide to start Phase Three by sending its first ('Validate') message, or it can terminate the EAP session.
The Server's state machine for Phase Two is depicted in the following Figure:
+-------------------+
| Start Phase Two |
+-------------------+
|
v
+-------------------+
+----------------->| New Credentials |
| +----<| Available ? |>-----+
| | Yes +-------------------+ No |
| | ^ |
| v | v
| +-------------------+ | +-------------------+
| | Action Needed for |>----+ | Register New |
| | Credentials ? | No | Credentials |
| +-------------------+ +-------------------+
| v Yes Yes v v No
| | | |
| | +-------------------+ | |
| +---->| Provisioning |<--+ |
| | Protocol | |
| +-------------------+ |
| | |
| v |
| No +------------------+ |
+-----------------<| End of Provision | |
+------------------+ |
Yes | |
v |
+------------------+ |
| End of Phase Two |<-----------+
+------------------+
EAP-CREDS Phase Two State Machine
The Server can decide to 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 MUST be unique for each session to make sure notto repeat the same operation on the same credential over and over again. 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 EAP session.
The following figure provides the message flow for Phase 3:
,--------. ,----------.
|EAP Peer| |EAP Server|
`---+----' `----+-----'
| [1] EAP-Request/EAP-CREDS(Type=Validate) | ,-----------!.
| { Cred-Info, Challenge } | |Phase Three|_\
| <----------------------------------------- |Begins |
| | `-------------'
| [2] EAP-Response/EAP-CREDS(Type=Validate)| ,-----------!.
| { Challenge-Response } | |Phase Three|_\
| -----------------------------------------> |Ends |
| | `-------------'
| |
EAP-CREDS Phase Three Message Flow
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.
[1] The Server sends EAP-Request/EAP-CREDS(Type=Validate)
[2] The Peer sends EAP-Response/EAP-CREDS(Type=Validate)
The Server's state machine for Phase Three is depicted in the following Figure:
+-------------------+
| Start Phase Three |
+-------------------+
|
v
+---------------------+ No
+------------------------------->| New Credentials |>-------+
| +------------------->| Available ? |<---+ |
| | +---------------------+ | |
| | Yes | ^ | |
| | v | | |
| | +-------------------+ | | |
| | | Validate |>-----+ | |
| | | Credentials ? | No | |
| | +-------------------+ | |
| | v Yes | |
| | | | |
| | | +---------------------+ | |
| | +----->| Send Validate | | |
| | | Messsage | | |
| | +---------------------+ | |
| | | | |
| | v | |
| +---------------------+ No +---------------------+ | |
| | Report the Error |<----<| Response Error? |----+ |
| +---------------------+ +---------------------+ No |
| Yes | |
| v |
| No +---------------------+ |
+------------------------------<| End Validation ? | |
+---------------------+ |
Yes | |
v |
+---------------------+ |
| End Phase Three |<--------+
+---------------------+
EAP-CREDS Phase Three State Machine
The EAP-CREDS defines the following message types:
Each of these message types have the basic structure as identified in Section 4.1. EAP-CREDS messages contain zero, one, or more TLVs. The internal structure of the different types of TLVs is described in Section 4.2, while a detailed description of the EAP-CREDS message types is provided in Section 5.
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 |J|S|F|D| Phase | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Length | Data ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-.
Where the Code, Identifier, Length, and Type fields are all part of the EAP header as defined in [RFC3748]. Since EAP-CREDS can only be used as a tunneled mechanism, the presence of these fields is only for backward compatibility with existing parsers. In particular, the 'Length' field is not used (can be ignored): the message length is carried in the 'Message Length' field instead.
The Type field in the EAP header is <TBD> for EAP-CREDS.
The Flags bitfield is used to convey status information (e.g., extra long message, phase number, phase transitioning state). The transition-control bit (i.e., the 'S' bit) are set in Server's messages and are ignored in Peer's messages (the Server is the entity that unilaterally controls the phase transition process). The meanins of the bits in the 'Flags' field are as follows:
The Phase field is a 4-bits value and identifies the EAP-CREDS phase for the current message. The version of EAP-CREDS described in this document supports three values for this field:
A detailed explanation of the 'Phase' and 'Flags' fields of the message headers is provided in Section 3.1.1.
The Data field is the message payload. The full description of this field is provided in the next section.
The Data part of the message is organized as zero, one, or more TLV objects whose structure is defined in this section.
Each TLV object has the same basic structure that is defined as follows:
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)
Length (uint24)
| TLV Name | TLV Type | Scope/Usage |
|---|---|---|
| <TBD> | Action TLV | Phase Two |
| <TBD> | Certificate-Data TLV | Phase Two/SPP |
| <TBD> | Challenge-Data TLV | Phase Two, Phase Three |
| <TBD> | Challenge-Response TLV | Phase Two, Phase Three |
| <TBD> | Credentials-Data TLV | Phase Two/SPP |
| <TBD> | Credentials-Info TLV | Phase Two, Phase Three |
| <TBD> | Error TLV | All Phases |
| <TBD> | Network-Usage TLV | Phase One |
| <TBD> | Profile TLV | Phase Two |
| <TBD> | Protocol TLV | Phase One, Phase Two |
| <TBD> | Provisioning-Data TLV | Phase Two |
| <TBD> | Provisioning-Headers TLV | Phase Two |
| <TBD> | Provisioning-Params TLV | Phase Two |
| <TBD> | Certificate-Request TLV | SPP |
| <TBD> | Storage-Info TLV | SPP |
| <TBD> | Supported-Format TLV | SPP |
| <TBD> | Supported-Encoding TLV | SPP |
| <TBD> | Token-Data TLV | Phase One |
| <TBD> | Version TLV | Phase One |
TLV Value ( > 1 octet )
The rest of this section describes the structure of the different supported TLVs and their usage in the different messages.
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.
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 | Action Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
TLV Length (uint24)
Flags (uint8)
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)
Length (uint24)
Flags (uint8)
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).
Format (uint8)
Encoding (uint8)
Value (octet string)
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ch. Type | Challenge Data ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
Length (uint24)
Challenge Type (uint8)
Challenge Data (> 1 octet)
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)
Length (uint24)
Challenge Response (> 1 octet)
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 ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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.
For example, when a set of credentials need to be renewed, the server checks the ('Credentials-Info') from the Peer and eventually selects the right one for renewal. The TLV structure is as follows:
TLV Type (uint8)
Length (uint24)
Flags (uint8)
CredType (uint8)
ProtoID (uint16)
IssuedOn (16 octets)
ExpiresOn (16 octets)
Credentials Length (uint16)
CredIDValue (> 1 octet)
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)
Length (uint24)
Cred Type (uint8)
Format (uint8)
Encoding (uint8)
Value (octet string)
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)
Length (uint24)
EAP-CREDS Error Code (2 octets)
Secondary Error Code (2 octets)
Description ( > 1 octet)
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U| Desc Format | Encoding | Network-Usage Data ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
Length (uint24)
Description Format (uint8)
Encoding (uint8)
The 'U' field (1 bit)
Desc Format (7 bits)
Network-Usage Data (octet string)
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)
Length (uint24)
Profile Identifying Data (octet string)
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Protocol ID | Version | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
TLV Length (uint24)
Protocol ID (uint16)
Version (uint16)
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)
Length (uint24)
Headers Data (> 1 octet)
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)
Length (uint24)
Headers Data (> 1 octet)
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)
Length (uint24)
Min Length (uint16)
Max Length (uint16)
Flags (uint8)
Algorithm (uint8)
Object Identifier (binary; > 1 octet)
| OID Name | Dotted Representation | Binary Encoding |
|---|---|---|
| secp256r1 curve | 1.2.840.10045.3.1.7 | 06 08 2A 86 48 CE 3D 03 01 07 |
| secp384r1 curve | 1.2.840.10045.3.1.34 | 06 08 2A 86 48 CE 3D 03 01 22 |
| secp521r1 curve | 1.2.840.10045.3.1.35 | 06 08 2A 86 48 CE 3D 03 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 |
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Encoding | Format | Value ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
TLV Length (uint24)
Encoding (uint8)
Format (uint8)
Value (octet string)
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 | Spare Slots | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available Memory | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Type (uint8)
Flags (8 bits)
Spare Slots (uint16)
Available Memory (uint32)
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Format | +-+-+-+-+-+-+-+-+
TLV Type (uint8)
TLV Length (uint24)
Format (uint8)
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Encoding | +-+-+-+-+-+-+-+-+
TLV Type (uint8)
TLV Length (uint24)
Encoding (uint8)
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)
TLV Length (uint24)
Token Type (uint8)
Encoding (uint8)
Value (octet string)
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | +-+-+-+-+-+-+-+-+
TLV Type (uint8)
TLV Length (uint24)
Version (uint8)
This section describes each message and what TLVs are allowed or required. EAP-CREDS defines the following values for the Message Type (Type):
| Message Type | Name | Description |
|---|---|---|
| 0 | EAP-CREDS-Init | Initialization Phase |
| 1 | EAP-CREDS-Provisioning | Carries Provisioning Protocol Messages |
| 2 | EAP-CREDS-Validate | Validates newly installed credentials |
The EAP-CREDS-Init message type is used in Phase One only of EAP-CREDS. The message flow is depicted in Section 3.2. This message supports the following TLVs: Version, Protocol, Credentials-Info, and Error.
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 first message from the server is the one that starts Phase One, therefore the Server MUST set the headers' 'S' bit to '1' (Start) and the headers' 'Phase' value to '1' (Phase One).
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 MUST include, in its Init message, a ('Challenge-Data') field that can be used by the client to provide challenge data for proof-of-possession of secrets.
The Peer MUST reply to the Server's ('EAP-CREDS-Init') message with its own ('EAP-CREDS-Init') one. The Peer SHOULD include one ('Version') TLV in its first 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 one or more 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) via the ('Token-Data') and ('Challenge-Response') TLV.
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 and selected depending on the location and other factors (e.g., X.509 certificate and username/password combination).
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. In this case, the Peer SHOULD include authorization information via the ('Token-Data') TLV as described in Section 5.1.2.1. Additionally, the Peer can add the ('Profile') TLV to indicate a preferred profile for the credentials.
When the Peer does not have any valid credentials for the Network that it is authenticating to, it does not provide any ('Credentials-Info') TLV. This indicates to the Server that new credentials MUST be registered before the Peer is allowed on the network.
The Registration process might rely on information exchanged during the Provisioning Process in Phase Two. However, if an authorization mechanism is not available from the supported provisioning protocol and no credentials are available on the Peer, EAP-CREDS provides a simple machanism for the Peer to leverage an out-of-band token/passphrase/ott that may be already available on the Peer (e.g., a device certificate or a 'spendable' credentials token like a kerberos ticket or a crypto-currency transaction) 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 additional authorization data) 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.
The EAP-CREDS-Provisioning message type is used in Phase Two only of EAP-CREDS. The message flow is depicted in Section 3.3. This message type supports the following TLVs: Protocol, Profile, Credentials-Info, Provisioning-Headers, Provisioning-Data, Token-Data, and Error.
After the exchange of phase one messages, the Server MAY start phase two by issuing an ('EAP-CREDS-Provisioning') 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'), and metadata to the client in a EAP-Request/EAP-CREDS(Type=Provisioning) message. The header's 'S' bit MUST be set to '1' (Start) and the 'Phase' value set to '2' (Phase Two begins).
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-Provisioning') 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.
If no other actions, the server MAY continue with phase three or issue a success message and terminate the EAP session.
The EAP-CREDS-Validate message type is used in Phase Three only of EAP-CREDS. The message flow is depicted in Section 3.4. This message type supports the following TLVs: Protocol, Credentials-Info, Provisioning-Headers, Provisioning-Data, Token-Data, and Error.
After Phase One (and/or Phase Two) ends, the Server MAY start phase three by issuing an ('EAP-CREDS-Validate') message for the Peer where it encodes all the required details for starting the validation process. In particular, the server sends the ('Credentials-Info'), a ('Challenge'), and the ('Phase-Control') TLVs in a EAP-Request/EAP-CREDS(Type=Validate) message. The ('Phase-Control') TLV should carry the '1' value for the 'S' bit (Start) and the number '3' for its value (Phase Three begins).
The Peer generates the answer to the Challenge and sends back a EAP-Response/EAP-CREDS(Type=Validate) message with the ('Challenge-Response') and an optional ('Challenge') field (only for server-side validation of the symmetric credentials). If the Peer requested server-side validation of the credentials, the Server MUST include (if a symmetric secret) the response to the Peer-issued ('Challenge') TLV by computing the response and adding it to the ('Challenge-Response') TLV in its reply.
Finally, in the last message, the Server (if Phase Three is to be ended) SHALL include the ('Phase-Control') TLV with the 'S' bit set to '0' (end of phase) and the value set to '3' (Phase Three ended).
At this point, EAP-CREDS has terminated all possible operations and can be terminated. The Server can now terminate the EAP session successfully. In case the Peer was not authenticated during the tunnel establishment (i.e., no credentials were already available on the Peer), the Server should terminate the EAP session with a Failure (thus requiring the device to re-attach and authenticate to the network - phase two should have provided the Peer with the credentials to use for authenticating to the Network).
This section provides a description of the error handling by using the CREDS-Error-TLV in a CREDS message.
EAP-CREDS supports a Simple Provisioning Protocol (SPP) which comprises of a series of messages that enable 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 encapsulated in the ('Provisioning-Data') TLVs in the second phase of the protocol. SPP does not make use of any ('Provisioning-Headers') TLVs because its messages are all self-contained (no transport-protocol specific options are needed).
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 SHOULD NOT try to interpret or parse its contents).
In the case where an authorization token is used, different usage patterns are supported. For tokens that require an associated verifiable proof-of-possession, the Peer can include a ('Challenge-Response') TLVs.
The ('Challenge-Data') TLV provided by the Server MUST be used to convey the challenge data (usually some random value) to compute the contents of the ('Challenge-Response') TLV.
The ('Challenge-Response') TLV is used, instead, to encode the response to the challenge data. The ('Challenge-Response') TLV is generated by the Peer and verified by the Server. At minimum, the ('Challenge-Response') TLV SHOULD be calculated over the values of the ('Token-Data') and the ('Challenge-Data') TLVs to make sure that the authentication covers the token's data as well.
The SPP Messages are constructed with zero, one, or more TLVs and encoded in the ('Provisioning-Data') TLV in EAP-CREDS/Provisioning message types. The size of the encpasulating ('Provisioning-Data') TLV provides the size of the whole message.
,--------. ,----------.
|EAP Peer| |EAP Server|
`---+----' `----+-----'
| [1] EAP-Request/EAP-CREDS(Type=Provisioning) |
| { Protocol(=SPP), Action, |
| [ CredsInfo ] [ Params ], |
| [ ProvData(=CredsData) ] } |
| <------------------------------------------
| |
| [2] EAP-Response/EAP-CREDS(Type=Provisioning)|
| { [ ProvData(=CredsData) ] } |
| ------------------------------------------>
| |
| [3] EAP-Response/EAP-CREDS(Type=Provisioning)|
| { [ ProvData(=CredsData) ] } |
| <------------------------------------------
| |
| |
SPP was designed to provide an easy alternative to more complex provisioning protocols. When no extra flexibility is needed, SPP provides an easy-to-implement alternative that can handle not only certificates, but also symmetric secrets and access tokens provisioning. In this section we provide the generic flow of messages for SPP and specific examples for certificates, username/password, and token provisioning.
EAP-CREDS defines several actions for a set of credentials and they are listed in Section 8.9.
When a Peer wants to join a network it may or may not have have the needed credentials to do so. In case the Peer does not have valid credentials yet, the Server MAY start Phase Two with the intention of registering a new set of credentials. Alternatively, the Server MAY start Phase Two when the presented credentials information from the Peer triggers the Renew or the Remove action.
[1] The Server sends EAP-Request/EAP-CREDS(Type=Provisioning)
[2] The Peer sends EAP-Response/EAP-CREDS(Type=Provisioning)
[3] The Server sends EAP-Request/EAP-CREDS(Type=Provisioning)
,--------. ,----------.
|EAP Peer| |EAP Server|
`---+----' `----+-----'
| [1] EAP-Request/EAP-CREDS(Type=Provisioning) |
| { Protocol(=SPP), Action, [ Creds-Info ], |
| [ Prov-Params ], [ Profile ] |
| [ Prov-Data(=[Creds-Info],[Creds-Data]) ] }|
| <-----------------------------------------------
| |
| [2] EAP-Response/EAP-CREDS(Type=Provisioning) |
| { [ Prov-Data(=[Creds-Data]) ] } |
| ----------------------------------------------->
| |
| [3] EAP-Response/EAP-CREDS(Type=Provisioning) |
| { [ Prov-Data(=Creds-Info,[Creds-Data]) ] } |
| <-----------------------------------------------
| |
| |
EAP-CREDS/SPP can provision symmetric secrets (e.g, username/password, API keys, or SIM-based keys), tokens (e.g., username/password OAuth or Kerberos tokens), or asymmetric credentials (e.g., X.509 certificates or Key Pairs). This section focuses on provisioning symmetric secrets only. The message flow is provided in Section 7.2.1
EAP-CREDS/SPP provides the possibility for shared secret to be generated in different ways: Section 4.2.1.13).
In particular, when initiating the second phase of the protocol, the ('Provisioning-Params') TLV is used to specify how to generate the secret (see
[ TO BE EDITED ]
Figure 1: SPP Message Flow for Server-Side only secrets provisioning
The message flow for deploying a server-side only credential (i.e., during registration or renewal) consists of only one message from the server. The flow is depicted in Figure 1.
In this case, the Server sends the first Provisioning message (which is also the last one), which MUST carry, the following data:
The Server also includes, encoded in the ('Provisioning-Data') TLV, the following data:
Server-side secrets' generation can be used to generate username/password combinations, API Keys, SIM-based credentials, or tokens.
[ TO BE EDITED ]
Figure 2: SPP Message Flow for Client-Side only secrets provisioning
The message flow for deploying a client-side only credential (i.e., during registration or renewal) consists of the full three messages exchange. The flow is depicted in Figure 2.
In this case, the Server MUST include, in its first Provisioning message and encoded in the ('Provisioning-Data') TLV, the following data:
Notice that the Server does not include any ('Credentials-Data') TLV in its first message because the Server is not involved in the secret generation (client-side only).
The Peer MUST reply with its own Provisioning message where the Peer MUST encode the following data in the ('Provisioning-Data') TLV:
The credentials data MUST conform to the specifications the Server provided in the ('Provisioning-Params') TLV.
The final message is from the Server and it MUST contain (if no errors were detected), the following TLVs encoded, as usual, in the ('Provisioning-Data') TLV:
Client-side secrets' generation should be used with caution and an evaluation of the quality of the generated credentials MUST be performed to make sure that the security of the generated secret is adequate for accessing the network. Since evaluating the quality of a secret is quite a difficult tasks, the use of this generation mode MUST be evaluated carefully and selected accordingly to acceptable risk profiles.
When registering or renewing credentials and the secret generation is split between the Server (1st share) and the Peer (2nd share), the message flow is the same as Section 7.2.1.2 with the following exceptions:
All other parameters remain the same.
Co-generation of the secret is the most secure option because both parties can provide the required randomness in their own share of the secret.
EAP-CREDS/SSP defines the following flow of messages for requesting the provisioning of key pairs (public and private keys).
[ This case covers the server-side generation of KeyPair and Certificate ]
[ This case covers the registration of a self-signed or already available (e.g., device) certificate ]
This use-case is not supported. In other words, for the provisioning of Key Pairs, the ('Provisioning-Params') can not have both the peer-generation and server-generation bits set.
EAP-CREDS/SSP defines the following flow of messages for requesting the provisioning of credentials.
[ This case covers the server-side generation of KeyPair and Certificate ]
[ This case covers the registration of a self-signed or already available (e.g., device) certificate ]
[ This case covers the generation of the KeyPair on the Peer and the generation of the certificate on the Server ]
EAP-CREDS/SSP defines the following flow of messages for requesting the provisioning of token-based credentials.
[ This case covers the server-side generation of the Token and possibly associated key ]
[ This case covers the registration of a self-signed or already available (e.g., device) certificate ]
[ This case covers the generation of the KeyPair on the Peer and the generation of the Token that cointains the reference to the key on the Server ]
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.
| 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 |
Assignment of new values for new cryptosuites MUST be done through IANA with "Specification Required" and "IESG Approval" as defined in [RFC8126].
| Token Type | Description |
|---|---|
| 0 | Unspecified |
| 1 | JWT |
| 2 | Kerberos |
| 3 | OAuth |
| 200..254 | Vendor Specific |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
| 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 |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
| ID | Algorithm |
|---|---|
| 0 | None |
| 1 | RSA |
| 2 | ECDSA |
| 3 | XMMS |
| 4 | AKA Subscriber Key |
| 5 | OAuth |
| 6 | Kerberos4 |
| 7 | Kerberos5 |
| 200-254 | Reserved |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
| ID | Data Type |
|---|---|
| 0 | None (Binary) |
| 1 | PKCS#8 |
| 2 | PKCS#10 |
| 3 | PKCS#12 |
| 4 | PublicKeyInfo |
| 200-254 | Reserved |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
| ID | Data Type |
|---|---|
| 0 | Not Specified |
| 1 | EAP-CREDS-ASYMMETRIC |
| 2 | EAP-CREDS-SYMMETRIC |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
| ID | Data Type |
|---|---|
| 0 | Vendor-Specific |
| 1 | Manufacturer Usage Description [RFC8520] |
| 2 | Network Access Granting System |
| 3 | Firmware Manifest |
| 4..127 | Reserved for Future Use |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
| ID | Encoding |
|---|---|
| 0 | None (Raw) |
| 1 | DER |
| 2 | PEM |
| 3 | Base64 |
| 4 | JSON |
| 5 | XML |
| 6 | ASCII |
| 7 | UTF-8 |
| 200-254 | Reserved |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
| 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 |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
| Type | Description |
|---|---|
| 0 | Binary (Unspecified) |
| 1 | MUD File |
| 2 | TEEP Manifest |
Assignment of new values for new Message Types MUST be done through IANA with "Expert Review" as defined in [RFC8126].
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.
The authors would like to thank everybody who provided insightful comments and helped in the definition of the deployment considerations.