DOTS R. Moskowitz
Internet-Draft L. Xia
Intended status: Standards Track Huawei
Expires: May 3, 2017 D. Migault
Ericsson
A. Mortensen
Arbor Networks, Inc.
October 30, 2016
Strong Identities for DOTS Agents
draft-moskowitz-dots-identities-00.txt
Abstract
DOTS communications are machine-to-machine oriented communications.
In addition DOTS agents are expected to end up in a large number of
entities. As a result, in addition to secure, the naming scheme to
identify all DOTS agents must be scalable. For these reasons this
document recommends the use of cryptographic identifiers or strong
Identities as opposed to human readable identifiers for example.
This document proposes two forms of strong Identities for the
registration and operation of DOTS Agents. One is 802.1AR LDevID
[Std-802.1AR-2009] X.509 certificates. The other is raw public keys
as in HIP [RFC7401] or TLS/DTLS Raw Public Keys [RFC7250].
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on May 3, 2017.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. X.509 LDevID . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Raw Public Key . . . . . . . . . . . . . . . . . . . . . 3
2. Terms and Definitions . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements Terminology . . . . . . . . . . . . . . . . 4
2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
3. Problem Space . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Trusted Identities . . . . . . . . . . . . . . . . . . . 5
3.2. Managing the scope of Trust . . . . . . . . . . . . . . . 5
4. Effectively Managing Identity Trust . . . . . . . . . . . . . 5
4.1. The IEEE 802.1AR Device Identity Certificate Model . . . 5
4.2. The Raw Public Key Model . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
DOTS communications are machine-to-machine oriented communications.
In addition DOTS agents are expected to end up in a large number of
entities. As a result, in addition to secure, the naming scheme to
identify all DOTS agents must be scalable. For these reasons the
document recommend the use of cryptographic identifiers or strong
Identities as opposed to human readable identifiers for example.
Human readable identifiers are very helpful to represent a resource
for human. A typical example is the use of First Name and Last Name
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which is easier for human beings to remember than a phone number.
The same occurs for web sites where FQDNs are easier to remember than
the IPv6 addresses. However the human readable representation also
comes with some issues.
First human readable identifiers have very little entropy which means
that when the number of identifiers grow, collision are likely to
happen. The likelihood of identifier collision may be limited at the
expense of management complexity whose complexity grows with the
number of identifiers. Second, human readable identifiers are only
meaningful when used by humans who are only able to handle a limited
numbers of identifiers. Third the identifier needs to be securely
bound to additional element such as security elements - a public key
- or routing elements - an IP address - in order to enable a
communication.
As a result, human readable identifiers do not scale to meet the need
of DOTs identifiers and the management overhead complexity to make
identifiers human readable becomes meaningless in a automated machine
to machine environment. A DOTS is intended for machine to machine
-like communication, there is no reason for using human readable
identifiers. DOTS recommends the use of cryptographic identifiers to
avoid an additional and unnecessary cryptographic binding between the
identifier and the security material.
This document describes two forms of strong Identities for the
registration and operation of DOTS Agents.
1.1. X.509 LDevID
The first is the X.509 LDevID defined in 802.1AR [Std-802.1AR-2009].
The methodology proposed herein expects the DOTS mitigation provider
to provide a PKI that will issue LDevID certificates to its
customers. This provides a strong "domain of trust" to the
identities of its customers. Inter provider trust can be established
through any of the multi-PKI trust models in use today.
Customer LDevID registration may be based on an "Owner Certificate",
allocated to the device during a NETCONF zerotouch registration
[I-D.ietf-netconf-zerotouch]. Or the IDevID could be used directly
in some registration process.
1.2. Raw Public Key
The second form of Identity is a Raw Public Key.
One type of Raw Public Key is a HIP [RFC7401] Host Identity (HI).
The customer may use HIP DNS Extension [RFC8005] to assert its HI to
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the DOTS mitigation provider and then use HIP to prove ownership of
the HI.
Although nothing prevents HI/HIT to be assigned by the provider,
there is currently no mechanisms defined for such provisioning. This
might be defined in future work, however, the current use of HI/HIT
is that these identifiers are generated by the owner or the agent.
Another type of Raw Public Key is defined in [RFC7250]. The customer
would use the methods defined in DANE [RFC6698] validate a TLS Raw
Public Key.
2. Terms and Definitions
2.1. Requirements Terminology
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 RFC 2119 [RFC2119].
2.2. Definitions
DOTS Agents: Per [I-D.ietf-dots-requirements], any DOTS-aware
software module capable of participating in a DOTS signaling
session.
Host Identity (HI): The term "HI" is defined in [RFC7401] as "the
public key of the signature algorithm that represents the identity
of the host." In HIP, a host proves its identity by creating a
signature with the private key belonging to its HI.
Initial Secure Device Identifier (IDevID): The term "IDevID" is
defined in [Std-802.1AR-2009] as "the Secure Device Identifier
(DevID) installed on the device by the manufacturer". By example,
an IDevID certificate, signed by the manufacturer may encode a
manufacturer assigned unique identifier (e.g., serial number) and
a public key matching a private key held within a TPM chip
embedded within the device.
Locally Significant Secure Device Identifier (LDevID): The term
"LDevID" is defined in [Std-802.1AR-2009] as "A Secure Device
Identifier credential that is unique in the local administrative
domain in which the device is used.". By example, an LDevID
certificate, signed by the device owner may encode an owner
assigned unique identifier (e.g., installation location) and a
public key matching a private key held within a TPM chip embedded
within the device.
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Owner Certificate: The term "owner certificate" is defined in
[I-D.ietf-netconf-zerotouch] as used in this document to represent
an X.509 certificate, signed by the device's manufacturer or
delegate, that binds an owner identity to the owner's private key,
which the owner can subsequently use to sign artifacts.
TLS Raw Public Key: The term "Raw Public Key" is defined in
[RFC7250]. So a "TLS Raw Public Key" as used in this document to
represent this subset of an X.509 certificate used in the manner
specified in RFC7250.
3. Problem Space
3.1. Trusted Identities
DOTS is meant to be deployed within the context of a business
arrangement between a customer and a DDoS mitigation provider. This
relationship is long-lived over a persistent session. This
relationship and the data communications can best be managed with
trusted identities.
Further, the customer's DDoS mitigation provider may need to enlist
the assistance of a peer provider. A strong trusted identity link
from the requesting provider back to the attacked customer would
benefit the mitigation process.
3.2. Managing the scope of Trust
The web's PKI model is fraught with trust leakage challenges. Why
trust a specific certificate just because some CA within the list of
CAs that must be trusted has signed the certificate? This leads to
independent vetting of each client certificate or applying some rules
as to which CA is accepted for what business arrangement and then
still maintaining a list of accepted client certificates is needed.
This leads to a basic question of what is an X.509 certificate
providing to the business agreement that would not be needed to be
found out independent from the certificate?
4. Effectively Managing Identity Trust
4.1. The IEEE 802.1AR Device Identity Certificate Model
IEEE 802.1AR [Std-802.1AR-2009] defines two important types of X.509
certificates. The IDevID is installed in the device in permanent,
secure storage (e.g. a TPM) and is NEVER replaced. This certificate
is signed by the manufacturer's CA. Typically, its subjectName
contains the device's serial number and other information that
uniquely identifies the device.
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The IDevID is not appropriate to use as an Identifier for any action
other than provisioning another Identifier that is more flexible for
general use. This limitation is based, in part, on the permanency of
IDevIDs and the potential for a large number of CAs 'owning' those
IDevIDs.
The second, more regularly usable, type of certificate is the LDevID.
This Locally Significant Secure Device Identifier is expected to be
signed by a PKI appropriate to its use. For example, the DDoS
mitigation provider can maintain its PKI for the signing and
validating the device's LDevID certificate. The methodology for an
IDevID to leverage the creation of an LDevID is left to IETF
protocols. Originally, this meant using PKIX protocols like CMP
[RFC4210]. Recent work with [I-D.ietf-netconf-zerotouch] can lead to
a trusted lDevID request based on the Owner Certificate.
4.2. The Raw Public Key Model
With Raw Public Keys, the trust establishment is left to the
provider. Authentication based on a Raw Public Key assumes the peer
already has the corresponding identifier. Authentication based on
raw keys has been integrated by many protocol such as IKEv2, HIP, and
TLS. However, unless the identifier is known by the peer, such
protocol end with an unauthenticated communication. Provisioning of
the identifier, is usually out of scope of these protocol. The
Identifier may be provided out of band, using leap of faith
mechanisms. Eventually DNSSEC can also be used to bind the
identifier to raw key.
There are some recent developments, like Hierarchical HITs
[I-D.moskowitz-hierarchical-hip] that provide an trusted
infrastructure for Raw Public Keys.
5. IANA Considerations
TBD
6. Security Considerations
TBD
7. Acknowledgments
TBD
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8. References
8.1. 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,
<http://www.rfc-editor.org/info/rfc2119>.
[Std-802.1AR-2009]
IEEE SA-Standards Board, "IEEE Standard for Local and
metropolitan area networks - Secure Device Identity",
December 2009, <http://standards.ieee.org/findstds/
standard/802.1AR-2009.html>.
8.2. Informative References
[I-D.ietf-dots-requirements]
Mortensen, A., Moskowitz, R., and T. Reddy, "Distributed
Denial of Service (DDoS) Open Threat Signaling
Requirements", draft-ietf-dots-requirements-02 (work in
progress), July 2016.
[I-D.ietf-netconf-zerotouch]
Watsen, K. and M. Abrahamsson, "Zero Touch Provisioning
for NETCONF or RESTCONF based Management", draft-ietf-
netconf-zerotouch-09 (work in progress), July 2016.
[I-D.moskowitz-hierarchical-hip]
Moskowitz, R. and X. Xu, "Hierarchical HITs for HIPv2",
draft-moskowitz-hierarchical-hip-02 (work in progress),
October 2016.
[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,
<http://www.rfc-editor.org/info/rfc4210>.
[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
of Named Entities (DANE) Transport Layer Security (TLS)
Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
2012, <http://www.rfc-editor.org/info/rfc6698>.
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[RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
Weiler, S., and T. Kivinen, "Using Raw Public Keys in
Transport Layer Security (TLS) and Datagram Transport
Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
June 2014, <http://www.rfc-editor.org/info/rfc7250>.
[RFC7401] Moskowitz, R., Ed., Heer, T., Jokela, P., and T.
Henderson, "Host Identity Protocol Version 2 (HIPv2)",
RFC 7401, DOI 10.17487/RFC7401, April 2015,
<http://www.rfc-editor.org/info/rfc7401>.
[RFC8005] Laganier, J., "Host Identity Protocol (HIP) Domain Name
System (DNS) Extension", RFC 8005, DOI 10.17487/RFC8005,
October 2016, <http://www.rfc-editor.org/info/rfc8005>.
Authors' Addresses
Robert Moskowitz
Huawei
Oak Park, MI 48237
USA
Email: rgm@labs.htt-consult.com
Liang Xia
Huawei
No. 101, Software Avenue, Yuhuatai District
Nanjing
China
Email: Frank.xialiang@huawei.com
Daniel Migault
Ericsson
8400 boulevard Decarie
Montreal, QC H4P 2N2
Canada
Phone: +1 514-452-2160
Email: daniel.migault@ericsson.com
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Andrew Mortensen
Arbor Networks, Inc.
2727 S. State St
Ann Arbor, MI 48104
United States
Email: amortensen@arbor.net
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