draft-ietf-6lo-ap-nd-06.txt   draft-ietf-6lo-ap-nd-07.txt 
6lo P. Thubert, Ed. 6lo P. Thubert, Ed.
Internet-Draft Cisco Internet-Draft Cisco
Updates: 6775 (if approved) B. Sarikaya Updates: 6775 (if approved) B. Sarikaya
Intended status: Standards Track Intended status: Standards Track
Expires: August 27, 2018 M. Sethi Expires: March 7, 2019 M. Sethi
Ericsson Ericsson
February 23, 2018 September 3, 2018
Address Protected Neighbor Discovery for Low-power and Lossy Networks Address Protected Neighbor Discovery for Low-power and Lossy Networks
draft-ietf-6lo-ap-nd-06 draft-ietf-6lo-ap-nd-07
Abstract Abstract
This document defines an extension to 6LoWPAN Neighbor Discovery (ND) This document defines an extension to 6LoWPAN Neighbor Discovery (ND)
[RFC6775][I-D.ietf-6lo-rfc6775-update] called Address Protected ND [RFC6775] [I-D.ietf-6lo-rfc6775-update] called Address Protected ND
(AP-ND); AP-ND protects the owner of an address against address theft (AP-ND); AP-ND protects the owner of an address against address theft
and impersonation inside a low-power and lossy network (LLN). Nodes and impersonation inside a low-power and lossy network (LLN). Nodes
supporting this extension compute a cryptographic Owner Unique supporting this extension compute a cryptographic Owner Unique
Interface ID and associate it with one or more of their Registered Interface ID and associate it with one or more of their Registered
Addresses. The Cryptographic ID uniquely identifies the owner of the Addresses. The Cryptographic ID identifies the owner of the
Registered Address and can be used for proof-of-ownership. It is Registered Address and can be used for proof-of-ownership. It is
used in 6LoWPAN ND in place of the EUI-64-based unique ID that is used in 6LoWPAN ND in place of the EUI-64-based unique ID that is
associated with the registration. Once an address is registered with associated with the registration. Once an address is registered with
a Cryptographic ID, only the owner of that ID can modify the anchor a Cryptographic ID, only the owner of that ID can modify the
state information of the Registered Address, and Source Address registration information of the Registered Address, and Source
Validation can be enforced. Address Validation can be enforced.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 27, 2018. This Internet-Draft will expire on March 7, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 5 2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. New Fields and Options . . . . . . . . . . . . . . . . . . . 5 2.2. References . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Encoding the Public Key . . . . . . . . . . . . . . . . . 5 2.3. 6LoWPAN sub-glossary . . . . . . . . . . . . . . . . . . 5
4.2. New Crypto-ID . . . . . . . . . . . . . . . . . . . . . . 6 2.4. Crypto-ID . . . . . . . . . . . . . . . . . . . . . . . . 6
4.3. Updated EARO . . . . . . . . . . . . . . . . . . . . . . 6 3. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 6
4.4. Crypto-ID Parameters Option . . . . . . . . . . . . . . . 8 4. New Fields and Options . . . . . . . . . . . . . . . . . . . 6
4.5. Nonce Option . . . . . . . . . . . . . . . . . . . . . . 9 4.1. Encoding the Public Key . . . . . . . . . . . . . . . . . 7
4.6. NDP Signature Option . . . . . . . . . . . . . . . . . . 9 4.2. New Crypto-ID . . . . . . . . . . . . . . . . . . . . . . 7
5. Protocol Scope . . . . . . . . . . . . . . . . . . . . . . . 9 4.3. Updated EARO . . . . . . . . . . . . . . . . . . . . . . 7
6. Protocol Flows . . . . . . . . . . . . . . . . . . . . . . . 10 4.4. Crypto-ID Parameters Option . . . . . . . . . . . . . . . 9
6.1. First Exchange with a 6LR . . . . . . . . . . . . . . . . 11 4.5. Nonce Option . . . . . . . . . . . . . . . . . . . . . . 10
4.6. NDP Signature Option . . . . . . . . . . . . . . . . . . 10
5. Protocol Scope . . . . . . . . . . . . . . . . . . . . . . . 10
6. Protocol Flows . . . . . . . . . . . . . . . . . . . . . . . 11
6.1. First Exchange with a 6LR . . . . . . . . . . . . . . . . 12
6.2. Multihop Operation . . . . . . . . . . . . . . . . . . . 13 6.2. Multihop Operation . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7.1. Inheriting from RTC 3971 . . . . . . . . . . . . . . . . 15 7.1. Inheriting from RFC 3971 . . . . . . . . . . . . . . . . 15
7.2. Related to 6LoWPAN ND . . . . . . . . . . . . . . . . . . 16 7.2. Related to 6LoWPAN ND . . . . . . . . . . . . . . . . . . 16
7.3. OUID Collisions . . . . . . . . . . . . . . . . . . . . . 16 7.3. ROVR Collisions . . . . . . . . . . . . . . . . . . . . . 16
8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 17 8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 17
8.1. CGA Message Type . . . . . . . . . . . . . . . . . . . . 17 8.1. CGA Message Type . . . . . . . . . . . . . . . . . . . . 17
8.2. Crypto-Type Subregistry . . . . . . . . . . . . . . . . . 17 8.2. Crypto-Type Subregistry . . . . . . . . . . . . . . . . . 17
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . 18 10.1. Normative References . . . . . . . . . . . . . . . . . . 18
10.2. Informative references . . . . . . . . . . . . . . . . . 19 10.2. Informative references . . . . . . . . . . . . . . . . . 19
Appendix A. Requirements Addressed in this Document . . . . . . 21 Appendix A. Requirements Addressed in this Document . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
"Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775] "Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775]
(6LoWPAN ND) adapts the classical IPv6 ND protocol [RFC4861][RFC4862] (6LoWPAN ND) adapts the IPv6 ND (NDv6) protocol [RFC4861][RFC4862]
(IPv6 ND) for operations over a constrained low-power and lossy (IPv6 ND) for operations over a constrained low-power and lossy
network (LLN). In particular, 6LoWPAN ND introduces a unicast host network (LLN). In particular, 6LoWPAN ND introduces a unicast host
address registration mechanism that contributes to reduce the use of address registration mechanism that reduces the use of multicast
multicast messages that are present in the classical IPv6 ND messages that are present in the NDv6 protocol. 6LoWPAN ND defines a
protocol. 6LoWPAN ND defines a new Address Registration Option (ARO) new Address Registration Option (ARO) that is carried in the unicast
that is carried in the unicast Neighbor Solicitation (NS) and Neighbor Solicitation (NS) and Neighbor Advertisement (NA) messages
Neighbor Advertisement (NA) messages between the 6LoWPAN Node (6LN) exchanged between a 6LoWPAN Node (6LN) and a 6LoWPAN Router (6LR).
and the 6LoWPAN Router (6LR). Additionally, it also defines the It also defines the Duplicate Address Request (DAR) and Duplicate
Duplicate Address Request (DAR) and Duplicate Address Confirmation Address Confirmation (DAC) messages between the 6LR and the 6LoWPAN
(DAC) messages between the 6LR and the 6LoWPAN Border Router (6LBR). Border Router (6LBR). In LLN networks, the 6LBR is the central
In LLN networks, the 6LBR is the central repository of all the repository of all the registered addresses in its domain.
registered addresses in its domain.
The registration mechanism in 6LoWPAN ND [RFC6775] prevents the use The registration mechanism in 6LoWPAN ND [RFC6775] prevents the use
of an address if that address is already present in the subnet (first of an address if that address is already registered in the subnet
come first serve). In order to validate address ownership, the (first come first serve). In order to validate address ownership,
registration mechanism enables the 6LR and 6LBR to validate claims the registration mechanism enables the 6LR and 6LBR to validate the
for a registered address with an associated Owner Unique Interface association between a registered address and a Registration Ownership
IDentifier (OUID). 6LoWPAN ND specifies that the OUID is derived from Verifier (ROVR). 6LoWPAN ND specifies that the ROVR is derived from
the MAC address of the device (using the 64-bit Extended Unique the MAC address of the device (using the 64-bit Extended Unique
Identifier EUI-64 address format specified by IEEE), which can be Identifier EUI-64 address format specified by IEEE), which can be
spoofed. Therefore, any node connected to the subnet and aware of a spoofed. Therefore, any node connected to the subnet and aware of a
registered-address-to-OUID mapping could effectively fake the OUID, registered-address-to-ROVR mapping could effectively fake the ROVR,
steal the address and redirect traffic for that address towards a steal the address and redirect traffic for that address towards a
different 6LN. The "Update to 6LoWPAN ND" different 6LN. The "Registration Extensions for 6LoWPAN Neighbor
[I-D.ietf-6lo-rfc6775-update] defines an Extended ARO (EARO) option Discovery" [I-D.ietf-6lo-rfc6775-update] defines an Extended ARO
that allows to transport alternate forms of OUIDs, and is a (EARO) option that allows to transport alternate forms of ROVRs, and
prerequisite for this specification. is a prerequisite for this specification.
According to this specification, a 6LN generates a cryptographic ID According to this specification, a 6LN generates a cryptographic ID
(Crypto-ID) and places it in the OUID field in the registration of (Crypto-ID) and places it in the ROVR field in the registration of
one (or more) of its addresses with the 6LR(s) that the 6LN uses as one (or more) of its addresses with the 6LR(s) that the 6LN uses as
default router(s). Proof of ownership of the cryptographic ID default router(s). Proof of ownership of the cryptographic ID
(Crypto-ID) is passed with the first registration exchange to a new (Crypto-ID) is passed with the first registration exchange to a new
6LR, and enforced at the 6LR. The 6LR validates ownership of the 6LR, and enforced at the 6LR. The 6LR validates ownership of the
cryptographic ID before it can create a registration state, or a cryptographic ID before it can create a registration, or a change the
change the anchor information, that is the Link-Layer Address and information, that is the Link-Layer Address and associated
associated parameters, in an existing registration state. parameters, in an existing registration state.
The protected address registration protocol proposed in this document The protected address registration protocol proposed in this document
enables the enforcement of Source Address Validation (SAVI) enables Source Address Validation (SAVI) [RFC7039], which ensures
[RFC7039], which ensures that only the correct owner uses a that only the owner uses a registered address in the source address
registered address in the source address field in IPv6 packets. field in IPv6 packets. Consequently, a 6LN that sources a packet has
Consequently, a 6LN that sources a packet has to use a 6LR to which to use a 6LR to which the source address of the packet is registered
the source address of the packet is registered to forward the packet. to forward the packet. The 6LR maintains state information for the
The 6LR maintains state information for the registered addressed, registered addressed, including the MAC address, and a link-layer
including the MAC address, and a link-layer cryptographic key cryptographic key associated with the 6LN. In SAVI-enforcement mode,
associated with the 6LN. In SAVI-enforcement mode, the 6LR allows the 6LR allows only packets from a connected Host if the connected
only packets from a connected Host if the connected Host owns the Host owns the registration of the source address of the packet.
registration of the source address of the packet.
The 6lo adaptation layer framework ([RFC4944], [RFC6282]) expects The 6lo adaptation layer framework ([RFC4944], [RFC6282]) specifies
that a device forms its IPv6 addresses based on Layer-2 address, so that a device forms its IPv6 addresses based on Layer-2 address, so
as to enable a better compression. This is incompatible with "Secure as to enable a better compression. This is incompatible with "Secure
Neighbor Discovery (SeND)" [RFC3971] and "Cryptographically Generated Neighbor Discovery (SeND)" [RFC3971] and "Cryptographically Generated
Addresses (CGAs)" [RFC3972], which derive the Interface ID (IID) in Addresses (CGAs)" [RFC3972], which derive the Interface ID (IID) in
the IPv6 addresses from cryptographic material. "Privacy the IPv6 addresses from key material. "Privacy Considerations for
Considerations for IPv6 Address Generation Mechanisms" [RFC7721] IPv6 Address Generation Mechanisms" [RFC7721] places additional
places additional recommendations on the way addresses should be recommendations on the way addresses should be formed and renewed.
formed and renewed.
This document specifies that a device may form and register addresses This document specifies that a device may form and register addresses
at will, without a constraint on the way the address is formed or the at will, without a constraint on the way the address is formed or the
number of addresses that are registered in parallel. It enables to number of addresses that are registered in parallel, Multiple
protect multiple addresses with a single cryptographic material and addresses with a single ROVR, which only needs to be sent once to a
to send the proof only once to a given 6LR for multiple addresses and given 6LR for multiple addresses and registration updates.
refresher registrations.
2. Terminology 2. Terminology
2.1. BCP 14
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Readers are expected to be familiar with all the terms and concepts 2.2. References
that are discussed in [RFC3971], [RFC3972], [RFC4861], [RFC4919],
[RFC6775], and [I-D.ietf-6lo-backbone-router] which proposes an
evolution of [RFC6775] for wider applicability.
This document defines Crypto-ID as an identifier of variable size In this document, readers will encounter terms and concepts that are
which in most cases is 64 bits long. It is generated using discussed in the following documents:
o "SEcure Neighbor Discovery (SEND)" [RFC3971],
o "Cryptographically Generated Addresses (CGA)" [RFC3972],
o "Neighbor Discovery for IP version 6" [RFC4861],
o "IPv6 Stateless Address Autoconfiguration" [RFC4862],
o "Problem Statement and Requirements for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606],
o "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals" [RFC4919],
o "Neighbor Discovery Optimization for Low-power and Lossy Networks"
[RFC6775],
o "Terms Used in Routing for Low-Power and Lossy Networks (LLNs)"
[RFC7102],
o "Terminology for Constrained-Node Networks" [RFC7228], and
o "Registration Extensions for 6LoWPAN Neighbor Discovery"
[I-D.ietf-6lo-rfc6775-update]
2.3. 6LoWPAN sub-glossary
This document often uses the following acronyms:
6BBR: 6LoWPAN Backbone Router (proxy for the registration)
[I-D.ietf-6lo-backbone-router]
6LBR: 6LoWPAN Border Router
6LN: 6LoWPAN Node
6LR: 6LoWPAN Router (relay to the registration process)
CIPO: Crypto-ID Parameters Option
(E)ARO: (Extended) Address Registration Option
DAD: Duplicate Address Detection
LLN: Low-Power and Lossy Network (a typical IoT network)
NA: Neighbor Advertisement
ND: Neighbor Discovery
NDP: Neighbor Discovery Protocol
NDPSO: NDP Signature Option
NS: Neighbor Solicitation
ROVR: Registration Ownership Verifier (pronounced rover)
RA: Router Advertisement
RS: Router Solicitation
RSAO: RSA Signature Option
TID: Transaction ID (a sequence counter in the EARO)
2.4. Crypto-ID
This document defines a new Crypto-ID as an identifier of variable
size which is 64 to 256 bits long. It is generated using
cryptographic means explained later in this document Section 4.2. cryptographic means explained later in this document Section 4.2.
"Elliptic Curves for Security" [RFC7748] and "Edwards-Curve Digital "Elliptic Curves for Security" [RFC7748] and "Edwards-Curve Digital
Signature Algorithm (EdDSA)" [RFC8032] provides information on Signature Algorithm (EdDSA)" [RFC8032] provides information on
Elliptic Curve Cryptography (ECC) and a (twisted) Edwards curve, Elliptic Curve Cryptography (ECC) and a (twisted) Edwards curve,
Ed25519, which can be used with this specification. "Alternative Ed25519, which can be used with this specification. "Alternative
Elliptic Curve Representations" Elliptic Curve Representations"
[I-D.struik-lwig-curve-representations] provides additional [I-D.struik-lwig-curve-representations] provides additional
information on how to represent Montgomery curves and (twisted) information on how to represent Montgomery curves and (twisted)
Edwards curves as curves in short-Weierstrass form and illustrates Edwards curves as curves in short-Weierstrass form and illustrates
how this can be used to implement elliptic curve computations using how this can be used to implement elliptic curve computations using
existing implementations that already implement, e.g., ECDSA and ECDH existing implementations that already implement, e.g., ECDSA and ECDH
using NIST [FIPS-186-4] prime curves. using NIST [FIPS-186-4] prime curves.
The document also conforms to the terms and models described in
[RFC5889] and uses the vocabulary and the concepts defined in
[RFC4291] for the IPv6 Architecture. Finally, common terminology
related to Low power And Lossy Networks (LLN) defined in [RFC7102] is
also used.
3. Updating RFC 6775 3. Updating RFC 6775
This specification defines a cryptographic identifier (Crypto-ID) This specification defines a cryptographic identifier (Crypto-ID)
that can be used as a replacement to the MAC address in the OUID that can be used as a replacement to the MAC address in the ROVR
field of the EARO option; the computation of the Crypto-ID is field of the EARO option; the computation of the Crypto-ID is
detailed in Section 4.2. A node in possession of the necessary detailed in Section 4.2. A node in possession of the necessary
cryptographic material SHOULD use Crypto-ID by default as OUID in its cryptographic material SHOULD use Crypto-ID by default as ROVR in its
registration. Whether a OUID is a Crypto-ID is indicated by a new registration. Whether a ROVR is a Crypto-ID is indicated by a new
"C" flag in the NS(EARO) message. "C" flag in the NS(EARO) message.
In order to prove its ownership of a Crypto-ID, the registering node In order to prove its ownership of a Crypto-ID, the registering node
needs to produce the parameters that where used to build it, as well needs to supply certain parameters including a nonce and a signature
as a nonce and a signature that will prove that it has the private that will prove that the node has the private key corresponding to
key that corresponds to the public key that was used to build the the public key used to build the Crypto-ID. This specification adds
Crypto-ID. This specification adds the capability to carry new the capability to carry new options in the NS(EARO) and the NA(EARO).
options in the NS(EARO) and the NBA(EARO). These options are a The NS(EARO) carries a variation of the CGA Option (Section 4.4), a
variation of the CGA Option Section 4.4, a Nonce option and a Nonce option and a variation of the RSA Signature option
variation of the RSA Signature option Section 4.6 in the NS(EARO) and (Section 4.6) in the NS(EARO). The NA(EARO) carries a Nonce option.
a Nonce option in the NA(EARO).
4. New Fields and Options 4. New Fields and Options
In order to avoid an inflation of ND option types, this specification In order to avoid the need for new ND option types, this
reuses / extends options defined in SEND [RFC3971] and 6LoWPAN ND specification reuses / extends options defined in SEND [RFC3971] and
[RFC6775][I-D.ietf-6lo-rfc6775-update]. This applies in particular 6LoWPAN ND [RFC6775] [I-D.ietf-6lo-rfc6775-update]. This applies in
to the CGA option and the RSA Signature Option. This specification particular to the CGA option and the RSA Signature Option. This
provides aliases for the specific variations of those options as used specification provides aliases for the specific variations of those
in AP-ND. The presence of the EARO option in the NS/NA messages options as used in AP-ND. The presence of the EARO option in the NS/
indicates that the options are to be understood as specified in this NA messages indicates that the crypto options are to be processed as
document. A router that would receive a NS(EARO) and try to process specified in this document, not as a SEND message.
it as a SEND message will find that the signature does not match and
drop the packet.
4.1. Encoding the Public Key 4.1. Encoding the Public Key
Public Key is the most important parameter in CGA Parameters (sent by A 6LN provides its public key in an NS message. The public key could
6LN in an NS message). ECC Public Key could be in uncompressed form be in uncompressed form or in compressed form where the first octet
or in compressed form where the first octet of the OCTET STRING is of the OCTET STRING is 0x04 and 0x02 or 0x03, respectively. Point
0x04 and 0x02 or 0x03, respectively. Point compression can further compression can further reduce the key size by about 32 octets.
reduce the key size by about 32 octets.
4.2. New Crypto-ID 4.2. New Crypto-ID
Elliptic Curve Cryptography (ECC) is used to calculate the Crypto-ID.
Each 6LN using a Crypto-ID for registration MUST have a public/ Each 6LN using a Crypto-ID for registration MUST have a public/
private key pair. The digital signature is constructed by using the private key pair.
6LN's private key over its EUI-64 (MAC) address. The signature value
is computed using the ECDSA signature algorithm and the hash function
used is SHA-256 [RFC6234].
NIST P-256 [FIPS186-4] that MUST be supported by all implementations.
To support cryptographic algorithm agility [RFC7696], Edwards-Curve
Digital Signature Algorithm (EdDSA) curve Ed25519ph (pre-hashing)
[RFC8032] MAY be supported as an alternate.
The Crypto-ID is computed as follows: The Crypto-ID is computed as follows:
1. An 8-bits modifier is selected, for instance, but not 1. An 8-bit modifier is selected, enabling a device to form multiple
necessarily, randomly; the modifier enables a device to form Crypto-IDs with a single key pair. This is useful for privacy
multiple Crypto-IDs with a single key pair. This may be useful reasons in order to avoid the correlation of addresses based on
for privacy reasons in order to avoid the correlation of their Crypto-ID;
addresses based on their Crypto-ID;
2. the modifier value and the DER-encoded public key (Section 4.1) 2. the modifier value and the DER-encoded public key (Section 4.1)
are concatenated from left to right; are concatenated from left to right;
3. Digital signature (SHA-256 then either NIST P-256 or EdDSA) is 3. The digital signature is constructed by using the 6LN's private
executed on the concatenation key over its EUI-64 (MAC) address. The signature value is
computed using the ECDSA signature algorithm and the hash
4. the leftmost bits of the resulting signature are used as the function used is SHA-256 [RFC6234].
Crypto-ID;
With this specification, only 64 bits are retained, but it could be 4. the leftmost bits of the resulting hash are used as the Crypto-
expanded to more bits in the future by increasing the size of the ID, up to the size of the ROVR field.
OUID field.
4.3. Updated EARO 4.3. Updated EARO
This specification updates the EARO option as follows: This specification updates the EARO option as follows:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Status | Reserved | | Type | Length | Status | Opaque |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved|C|R|T| TID | Registration Lifetime | |Rsvd |C| I |R|T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Owner Unique ID (EUI-64 or Crypto-ID) + ... Registration Ownership Verifier (ROVR) ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Enhanced Address Registration Option Figure 1: Enhanced Address Registration Option
Type: 33 Type: 33
Length: 8-bit unsigned integer. The length of the option Length: 8-bit unsigned integer. The length of the option
(including the type and length fields) in units of 8 (including the type and length fields) in units of 8
bytes. bytes.
Status: 8-bit unsigned integer. Indicates the status of a Status: 8-bit unsigned integer. Indicates the status of a
registration in the NA response. MUST be set to 0 in registration in the NA response. MUST be set to 0 in
NS messages. This specification uses values NS messages.
introduced in the update to 6LoWPAN ND
[I-D.ietf-6lo-rfc6775-update], such as "Validation
Requested" and "Validation Failed". No additional
value is defined.
Reserved: This field is unused. It MUST be initialized to zero Opaque: Defined in [I-D.ietf-6lo-rfc6775-update].
by the sender and MUST be ignored by the receiver.
Rsvd (Reserved): This field is unused. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
C: This "C" flag is set to indicate that the Owner C: This "C" flag is set to indicate that the Owner
Unique ID field contains a Crypto-ID and that the 6LN Unique ID field contains a Crypto-ID and that the 6LN
MAY be challenged for ownership as specified in this MAY be challenged for ownership as specified in this
document. document.
I: Defined in [I-D.ietf-6lo-rfc6775-update].
R: Defined in [I-D.ietf-6lo-rfc6775-update]. R: Defined in [I-D.ietf-6lo-rfc6775-update].
T and TID: Defined in [I-D.ietf-6lo-rfc6775-update]. T and TID: Defined in [I-D.ietf-6lo-rfc6775-update].
Owner Unique ID: When the "C" flag is set, this field contains a Registration Ownership Verifier (ROVR): When the "C" flag is set,
Crypto-ID. this field contains a Crypto-ID.
This specification uses Status values "Validation Requested" and
"Validation Failed", which are defined in 6LoWPAN ND
[I-D.ietf-6lo-rfc6775-update]. No other new Status values is
defined.
4.4. Crypto-ID Parameters Option 4.4. Crypto-ID Parameters Option
This specification defines the Crypto-ID Parameters Option (CIPO), as This specification defines the Crypto-ID Parameters Option (CIPO), as
a variation of the CGA Option that carries the parameters used to a variation of the CGA Option that carries the parameters used to
form a Crypto-ID. In order to provide cryptographic agility, AP-ND form a Crypto-ID. In order to provide cryptographic agility
supports two possible signature algorithms, indicated by a Crypto- [RFC7696], AP-ND supports two possible signature algorithms,
Type field. A value of 0 indicates that NIST P-256 is used for the indicated by a Crypto-Type field. Elliptic Curve Cryptography (ECC)
signature operation and SHA-256 as the hash algorithm. NIST P-256 is used to calculate the Crypto-ID. NIST P-256 [FIPS186-4] MUST be
MUST be supported by all implement A value of 1 indicates that supported by all implementations. The Edwards-Curve Digital
Ed25519ph is used for the signature operation and SHA-256 as the hash Signature Algorithm (EdDSA) curve Ed25519ph (pre-hashing) [RFC8032]
algorithm. MAY be supported as an alternate.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Pad Length | Reserved | | Type | Length | Pad Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Crypto-Type | Modifier | Reserved | | Crypto-Type | Modifier | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| | | |
skipping to change at page 9, line 6 skipping to change at page 10, line 6
Length: 8-bit unsigned integer. The length of the option in Length: 8-bit unsigned integer. The length of the option in
units of 8 octets. units of 8 octets.
Modifier: 8-bit unsigned integer. Modifier: 8-bit unsigned integer.
Pad Length: 8-bit unsigned integer. The length of the Padding Pad Length: 8-bit unsigned integer. The length of the Padding
field. field.
Crypto-Type: The type of cryptographic algorithm used in Crypto-Type: The type of cryptographic algorithm used in
calculation Crypto-ID. Default value of all zeros calculation Crypto-ID. A value of 0 indicates NIST
indicate NIST P-256. A value of 1 is assigned for P-256, with SHA-256 as the hash algorithm. A value
Ed25519ph. New values may be defined later. of 1 is assigned for Ed25519ph, with SHA-256 as the
hash algorithm.
Public Key: Public Key of 6LN. Public Key: DER-Encoded Public Key.
Padding: A variable-length field making the option length a Padding: A variable-length field making the option length a
multiple of 8, containing as many octets as specified multiple of 8, containing as many octets as specified
in the Pad Length field. in the Pad Length field.
4.5. Nonce Option 4.5. Nonce Option
This document reuses the Nonce Option defined in section 5.3.2. of This document reuses the Nonce Option defined in section 5.3.2. of
SEND [RFC3971] without a change. SEND [RFC3971] without a change.
4.6. NDP Signature Option 4.6. NDP Signature Option
This document reuses the RSA Signature Option (RSAO) defined in This document reuses the RSA Signature Option (RSAO) defined in
section 5.2. of SEND [RFC3971]. Admittedly, the name is ill-chosen section 5.2. of SEND [RFC3971]. Admittedly, the name is ill-chosen
since the option is extended for non-RSA Signatures and this since the option is extended for non-RSA Signatures and this
specification defines an alias to avoid the confusion. specification defines an alias to avoid the confusion.
The description of the operation on the option detailed in section The description of the operation on the option detailed in section
skipping to change at page 9, line 46 skipping to change at page 10, line 47
signature indicated in the Crypto-Type field of the CIPO option signature indicated in the Crypto-Type field of the CIPO option
using the private key associated with the public key in the CIPO. using the private key associated with the public key in the CIPO.
o The alias NDP Signature Option (NDPSO) can be used to refer to the o The alias NDP Signature Option (NDPSO) can be used to refer to the
RSAO when used as described in this specification. RSAO when used as described in this specification.
5. Protocol Scope 5. Protocol Scope
The scope of the present work is a 6LoWPAN Low Power Lossy Network The scope of the present work is a 6LoWPAN Low Power Lossy Network
(LLN), typically a stub network connected to a larger IP network via (LLN), typically a stub network connected to a larger IP network via
a Border Router called a 6LBR per [RFC6775]. a Border Router called a 6LBR per [RFC6775]. A 6LBR has sufficient
capability to satisfy the needs of DAD.
The 6LBR maintains a registration state for all devices in the The 6LBR maintains registration state for all devices in its attached
attached LLN, and, in conjunction with the first-hop router (the LLN. Together with the first-hop router (the 6LR), the 6LBR assures
6LR), is in a position to validate uniqueness and grant ownership of uniqueness and grants ownership of an IPv6 address before it can be
an IPv6 address before it can be used in the LLN. This is a used in the LLN. This is in contrast to a traditional network that
fundamental difference with a classical network that relies on IPv6 relies on IPv6 address auto-configuration [RFC4862], where there is
address auto-configuration [RFC4862], where there is no guarantee of no guarantee of ownership from the network, and each IPv6 Neighbor
ownership from the network, and any IPv6 Neighbor Discovery packet Discovery packet must be individually secured [RFC3971].
must be individually secured [RFC3971].
---+-------- ............ ---+-------- ............
| External Network | External Network
| |
+-----+ +-----+
| | 6LBR | | 6LBR
+-----+ +-----+
o o o o o o
o o o o o o o o
o o LLN o o o o o LLN o o o
o o o (6LR) o o o (6LR)
o (6LN) o (6LN)
Figure 3: Basic Configuration Figure 3: Basic Configuration
In a mesh network, the 6LR is directly connected to the host device. In a mesh network, the 6LR is directly connected to the host device.
This specification expects that the peer-wise layer-2 security is This specification mandates that the peer-wise layer-2 security is
deployed so that all the packets from a particular host are securely deployed so that all the packets from a particular host are securely
identifiable by the 6LR. The 6LR may be multiple hops away from the identifiable by the 6LR. The 6LR may be multiple hops away from the
6LBR. Packets are routed between the 6LR and the 6LBR via other 6LBR. Packets are routed between the 6LR and the 6LBR via other
6LRs. This specification expects that a chain of trust is 6LRs. This specification mandates that a chain of trust is
established so that a packet that was validated by the first 6LR can established so that a packet that was validated by the first 6LR can
be safely routed by the next 6LRs to the 6LBR. be safely routed by the next 6LRs to the 6LBR.
6. Protocol Flows 6. Protocol Flows
The 6LR/6LBR ensures first-come/first-serve by storing the EARO The 6LR/6LBR ensures first-come/first-serve by storing the EARO
information including the Crypto-ID correlated to the node being information including the Crypto-ID associated to the node being
registered. The node is free to claim any address it likes as long registered. The node can claim any address as long as it is the
as it is the first to make such a claim. After a successful first to make such a claim. After a successful registration, the
registration, the node becomes the owner of the registered address node becomes the owner of the registered address and the address is
and the address is bound to the Crypto-ID in the 6LR/6LBR registry. bound to the Crypto-ID in the 6LR/6LBR registry.
This specification enables to verify the ownership of the binding at This specification enables the 6LR to verify the ownership of the
any time assuming that the "C" flag is set. If it is not set, then binding at any time assuming that the "C" flag is set. The
the verification methods presented in this specification cannot be verification prevents other nodes from stealing the address and
applied. The verification prevents other nodes from stealing the trying to attract traffic for that address or use it as their source
address and trying to attract traffic for that address or use it as address.
their source address.
A node may use multiple IPv6 addresses at the same time. The node A node may use multiple IPv6 addresses at the same time. The node
may use a same Crypto-ID, or multiple crypto-IDs derived from a same may use a same Crypto-ID, or multiple crypto-IDs derived from a same
key pair, to protect multiple IPv6 addresses. The separation of the key pair, to protect multiple IPv6 addresses. The separation of the
address and the cryptographic material avoids the constrained device address and the cryptographic material avoids the constrained device
to compute multiple keys for multiple addresses. The registration to compute multiple keys for multiple addresses. The registration
process allows the node to bind all of its addresses to the same process allows the node to use the same Crypto-ID for all of its
Crypto-ID. addresses.
6.1. First Exchange with a 6LR 6.1. First Exchange with a 6LR
A 6LN registers to a 6LR that is one hop away from it with the "C" A 6LN registers to a 6LR that is one hop away from it with the "C"
flag set in the EARO, indicating that the Owner Unique ID field flag set in the EARO, indicating that the ROVR field contains a
contains a Crypto-ID. The on-link (local) protocol interactions are Crypto-ID. The on-link (local) protocol interactions are shown in
shown in Figure 4 If the 6LR does not have a state with the 6LN that Figure 4 If the 6LR does not have a state with the 6LN that is
is consistent with the NS(EARO), then it replies with a challenge NA consistent with the NS(EARO), then it replies with a challenge NA
(EARO, status=Validation Requested) that contains a Nonce Option. (EARO, status=Validation Requested) that contains a Nonce Option.
The Nonce option MUST contain a Nonce value that was never used with The Nonce option MUST contain a Nonce value that was never used with
this device. this device.
The 6LN replies to the challenge with a proof-of-ownership NS(EARO) The 6LN replies to the challenge with an NS(EARO) that includes the
that includes the echoed Nonce option, the CIPO with all the echoed Nonce option, the CIPO Section 4.4, and the NDPSO with the
parameters that where used to build EARO with a Crypto-ID, and as the signature. The information associated to a crypto-ID stored by the
last option the NDPSO with the signature. The information associated 6LR on the first NS exchange where it appears. The 6LR SHOULD store
to a crypto-ID is passed to and stored by the 6LR on the first NS the CIPO parameters associated with the crypto-ID so it can be used
exchange where it appears. The 6LR SHOULD store the CIPO information for more than one address.
associated with the crypto-ID so it can be used for more than one
address.
6LN 6LR 6LN 6LR
| | | |
|<------------------------- RA -------------------------| |<------------------------- RA -------------------------|
| | ^ | | ^
|---------------- NS with EARO (Crypto-ID) ------------>| | |---------------- NS with EARO (Crypto-ID) ------------>| |
| | option | | option
|<- NA with EARO (status=Validation Requested), Nonce --| | |<- NA with EARO (status=Validation Requested), Nonce --| |
| | v | | v
|-------- NS with EARO, CIPO, Nonce and NDPSO --------->| |-------- NS with EARO, CIPO, Nonce and NDPSO --------->|
skipping to change at page 12, line 34 skipping to change at page 13, line 7
| | | |
|--------------- NS with EARO (Crypto-ID) ------------->| |--------------- NS with EARO (Crypto-ID) ------------->|
| | | |
|<------------------- NA with EARO ---------------------| |<------------------- NA with EARO ---------------------|
| | | |
Figure 4: On-link Protocol Operation Figure 4: On-link Protocol Operation
The steps for the registration to the 6LR are as follows: The steps for the registration to the 6LR are as follows:
o Upon the first exchange with a 6LR, a 6LN may be challenged and o Upon the first exchange with a 6LR, a 6LN may be challenged to
have to produce the proof of ownership of the Crypto-ID. However, prove ownership of the Crypto-ID. The proof is not needed again
it is not expected that the proof is needed again in the periodic in later registrations for that address, or when registering other
refresher registrations for that address, or when registering addresses with the same ROVR. When a 6LR receives a NS(EARO)
other addresses with the same OUID. When a 6LR receives a registration with a new Crypto-ID as a ROVR, it SHOULD challenge
NS(EARO) registration with a new Crypto-ID as a OUID, it SHOULD by responding with a NA(EARO) with a status of "Validation
challenge by responding with a NA(EARO) with a status of Requested". This process of validation MAY be skipped in networks
"Validation Requested". This process of validation MAY be skipped where there is no mobility.
in networks where there is no mobility.
o The challenge MUST also be triggered in the case of a registration o The challenge is triggered when the registration for a Source
for which the Source Link-Layer Address is not consistent with a Link-Layer Address is not verifiable either at the 6LR or the
state that already exists either at the 6LR or the 6LBR. In the 6LBR. In the latter case, the 6LBR returns a status of
latter case, the 6LBR returns a status of "Validation Requested" "Validation Requested" in the DAR/DAC exchange, which is echoed by
in the DAR/DAC exchange, which is echoed by the 6LR in the NA the 6LR in the NA (EARO) back to the registering node. The
(EARO) back to the registering node. This flow should not alter a challenge MUST NOT alter a valid registration in the 6LR or the
preexisting state in the 6LR or the 6LBR. 6LBR.
o Upon receiving a NA(EARO) with a status of "Validation Requested", o Upon receiving a NA(EARO) with a status of "Validation Requested",
the registering node SHOULD retry its registration with a Crypto- the registering node SHOULD retry its registration with a Crypto-
ID Parameters Option (CIPO) Section 4.4 that contains all the ID Parameters Option (CIPO) (Section 4.4) that contains all the
necessary material for building the Crypto-ID, the Nonce and the necessary material for building the Crypto-ID, the Nonce and the
NDP signature Section 4.6 options that prove its ownership of the NDP signature (Section 4.6) options that prove its ownership of
Crypto-ID. the Crypto-ID.
o In order to validate the ownership, the 6LR performs the same o In order to validate the ownership, the 6LR performs the same
steps as the 6LN and rebuilds the Crypto-ID based on the steps as the 6LN and rebuilds the Crypto-ID based on the
parameters in the CIPO. If the result is different then the parameters in the CIPO. If the result is different then the
validation fails. Else, the 6LR checks the signature in the NDPSO validation fails. Else, the 6LR checks the signature in the NDPSO
using the public key in the CIPO. If it is correct then the using the public key in the CIPO. If it is correct then the
validation passes, else it fails. validation passes, else it fails.
o If the 6LR fails to validate the signed NS(EARO), it responds with o If the 6LR fails to validate the signed NS(EARO), it responds with
a status of "Validation Failed". After receiving a NA(EARO) with a status of "Validation Failed". After receiving a NA(EARO) with
a status of "Validation Failed", the registering node SHOULD try a status of "Validation Failed", the registering node SHOULD try
an alternate Signature Algorithm and Crypto-ID. In any case, it an alternate Crypto-ID. The registering node MUST NOT use the
MUST NOT use this Crypto-ID for registering with that 6LR again. same Crypto-ID for subsequent registration attempts.
6.2. Multihop Operation 6.2. Multihop Operation
In a multihop 6LoWPAN, the registration with Crypto-ID is propagated In a multihop 6LoWPAN, the registration with Crypto-ID is propagated
to 6LBR as described in Section 6.2. If a chain of trust is present to 6LBR as described in this section. If the 6LR and the 6LBR
between the 6LR and the 6LBR, then there is no need to propagate the maintain a security association, then there is no need to propagate
proof of ownership to the 6LBR. All the 6LBR needs to know is that the proof of ownership to the 6LBR.
this particular OUID is randomly generated, so as to enforce that any
update via a different 6LR is also random.
A new device that joins the network auto-configures an address and A new device that joins the network auto-configures an address and
performs an initial registration to an on-link 6LR with an NS message performs an initial registration to a neighboring 6LR with an NS
that carries an Address Registration Option (EARO) [RFC6775]. The message that carries an Address Registration Option (EARO) [RFC6775].
6LR validates the address with the central 6LBR using a DAR/DAC The 6LR validates the address with an 6LBR using a DAR/DAC exchange,
exchange, and the 6LR confirms (or denies) the address ownership with and the 6LR confirms (or denies) the address ownership with an NA
an NA message that also carries an Address Registration Option. message that also carries an Address Registration Option.
Figure 5 illustrates a registration flow all the way to a 6LowPAN Figure 5 illustrates a registration flow all the way to a 6LowPAN
Backbone Router (6BBR). Backbone Router (6BBR).
6LN 6LR 6LBR 6BBR 6LN 6LR 6LBR 6BBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | | |--------------->| | |
| | Extended DAR | | | | Extended DAR | |
| |-------------->| | | |-------------->| |
skipping to change at page 14, line 37 skipping to change at page 14, line 44
Figure 5: (Re-)Registration Flow Figure 5: (Re-)Registration Flow
In a multihop 6LoWPAN, a 6LBR sends RAs with prefixes downstream and In a multihop 6LoWPAN, a 6LBR sends RAs with prefixes downstream and
the 6LR receives and relays them to the nodes. 6LR and 6LBR the 6LR receives and relays them to the nodes. 6LR and 6LBR
communicate using ICMPv6 Duplicate Address Request (DAR) and communicate using ICMPv6 Duplicate Address Request (DAR) and
Duplicate Address Confirmation (DAC) messages. The DAR and DAC use Duplicate Address Confirmation (DAC) messages. The DAR and DAC use
the same message format as NS and NA, but have different ICMPv6 type the same message format as NS and NA, but have different ICMPv6 type
values. values.
In AP-ND we extend DAR/DAC messages to carry cryptographically In AP-ND we extend DAR/DAC messages to carry cryptographically
generated OUID. In a multihop 6LoWPAN, the node exchanges the generated ROVR. In a multihop 6LoWPAN, the node exchanges the
messages shown in Figure 5. The 6LBR must identify who owns an messages shown in Figure 5. The 6LBR must identify who owns an
address (EUI-64) to defend it, if there is an attacker on another address (EUI-64) to defend it, if there is an attacker on another
6LR. 6LR.
Occasionally, a 6LR might miss the node's OUID (that it received in 7. Security Considerations
ARO). 6LR should be able to ask for it again. This is done by
restarting the exchanges shown in Figure 4. The result enables 6LR
to refresh the information that was lost. The 6LR MUST send DAR
message with ARO to 6LBR. The 6LBR replies with a DAC message with
the information copied from the DAR, and the Status field is set to
zero. With this exchange, the 6LBR can (re)validate and store the
information to make sure that the 6LR is not a fake.
In some cases, the 6LBR may use a DAC message to solicit a Crypto-ID 7.1. Inheriting from RFC 3971
from a 6LR and also requests 6LR to verify the EUI-64 6LR received
from 6LN. This may happen when a 6LN node is compromised and a fake
node is sending the Crypto-ID as if it is the node's EUI-64. Note
that the detection in this case can only be done by 6LBR not by 6LR.
7. Security Considerations Observations regarding the following threats to the local network in
[RFC3971] also apply to this specification.
7.1. Inheriting from RTC 3971 Neighbor Solicitation/Advertisement Spoofing
The observations regarding the threats to the local network in Threats in section 9.2.1 of RFC3971 apply. AP-ND counters the
[RFC3971] also apply to this specification. Considering RFC3971 threats on NS(EARO) messages by requiring that the NDP Signature
security section subsection by subsection: and CIPO options be present in these solicitations.
Neighbor Solicitation/Advertisement Spoofing Threats in section Neighbor Unreachability Detection Failure
9.2.1 of RFC3971 apply. AP-ND counters the threats on NS(EARO)
messages by requiring that the NDP Signature and CIPO options be
present in these solicitations.
Neighbor Unreachability Detection Failure With RFC6775, a NUD can With RFC6775, a NUD can still be used by the endpoint to assess
still be used by the endpoint to assess the liveliness of a the liveness of a device. The NUD request may be protected by
device. The NUD request may be protected by SEND in which case SEND in which case the provision in section 9.2 of RFC 3972
the provision in section 92.2. of RFC 3972 applies. The response applies. The response to the NUD may be proxied by a backbone
to the NUD may be proxied by a backbone router only if it has a router only if it has a fresh registration state for it. For a
fresh registration state for it. The registration being protected registration being protected by this specification, the proxied
by this specification, the proxied NUD response provides a NUD response provides truthful information on the original owner
truthful information on the original owner of the address but it of the address but it cannot be proven using SEND. If the NUD
cannot be proven using SEND. If the NUD response is not proxied, response is not proxied, the 6LR will pass the lookup to the end
the 6LR will pass the lookup to the end device which will respond device which will respond with a traditional NA. If the 6LR does
with a traditional NA. If the 6LR does not have a cache entry not have a registration associated for the device, it can issue a
associated for the device, it can issue a NA with EARO NA with EARO (status=Validation Requested) upon the NA from the
(status=Validation Requested) upon the NA from the device, which device, which will trigger a NS that will recreate and revalidate
will trigger a NS that will recreate and revalidate the ND cache the ND registration.
entry.
Duplicate Address Detection DoS Attack Inside the LLN, Duplicate Duplicate Address Detection DoS Attack
Addresses are sorted out using the OUID, which differentiates it
from a movement. DAD coming from the backbone are not forwarded
over the LLN so the LLN is protected by the backbone routers.
Over the backbone, the EARO option is present in NS/NA messages.
This protects against misinterpreting a movement for a
duplication, and enables to decide which backbone router has the
freshest registration and thus most possibly the device attached
to it. But this specification does not guarantee that the
backbone router claiming an address over the backbone is not an
attacker.
Router Solicitation and Advertisement Attacks This specification Inside the LLN, Duplicate Addresses are sorted out using the ROVR,
does not change the protection of RS and RA which can still be which differentiates it from a movement. DAD coming from the
protected by SEND. backbone are not forwarded over the LLN, which provides some
protection against DoS attacks inside the resource-constrained
part of the network. Over the backbone, the EARO option is
present in NS/NA messages. This protects against misinterpreting
a movement for a duplication, and enables the backbone routers to
determine which one has the freshest registration and is thus the
best candidate to validate the registration for the device
attached to it. But this specification does not guarantee that
the backbone router claiming an address over the backbone is not
an attacker.
Replay Attacks A Nonce given by the 6LR in the NA with EARO Router Solicitation and Advertisement Attacks
(status=Validation Requested) and echoed in the signed NS This specification does not change the protection of RS and RA
guarantees against replay attacks of the NS(EARO). The NA(EARO) which can still be protected by SEND.
is not protected and can be forged by a rogue node that is not the
6LR in order to force the 6LN to rebuild a NS(EARO) with the proof
of ownership, but that rogue node must have access to the L2 radio
network next to the 6LN to perform the attack.
Neighbor Discovery DoS Attack A rogue node that managed to access Replay Attacks
the L2 network may form many addresses and register them using AP-
ND. The perimeter of the attack os all the 6LRs in range of the A Nonce given by the 6LR in the NA with EARO (status=Validation
attacker. The 6LR must protect itself against overflows and Requested) and echoed in the signed NS guarantees against replay
reject excessive registration with a status 2 "Neighbor Cache attacks of the NS(EARO). The NA(EARO) is not protected and can be
Full". This effectively blocks another (honest) 6LN from forged by a rogue node that is not the 6LR in order to force the
registering to the same 6LR, but the 6LN may register to other 6LN to rebuild a NS(EARO) with the proof of ownership, but that
6LRs that are in its range but not in that of the rogue. rogue node must have access to the L2 radio network next to the
6LN to perform the attack.
Neighbor Discovery DoS Attack
A rogue node that managed to access the L2 network may form many
addresses and register them using AP-ND. The perimeter of the
attack is all the 6LRs in range of the attacker. The 6LR must
protect itself against overflows and reject excessive registration
with a status 2 "Neighbor Cache Full". This effectively blocks
another (honest) 6LN from registering to the same 6LR, but the 6LN
may register to other 6LRs that are in its range but not in that
of the rogue.
7.2. Related to 6LoWPAN ND 7.2. Related to 6LoWPAN ND
The threats discussed in 6LoWPAN ND [RFC6775] and its update The threats discussed in 6LoWPAN ND [RFC6775] and its update
[I-D.ietf-6lo-rfc6775-update] also apply here. Compared with SeND, [I-D.ietf-6lo-rfc6775-update] also apply here. Compared with SeND,
this specification saves about 1Kbyte in every NS/NA message. Also, this specification saves about 1Kbyte in every NS/NA message. Also,
this specification separates the cryptographic identifier from the this specification separates the cryptographic identifier from the
registered IPv6 address so that a node can have more than one IPv6 registered IPv6 address so that a node can have more than one IPv6
address protected by the same cryptographic identifier. SeND forces address protected by the same cryptographic identifier. SeND forces
the IPv6 address to be cryptographic since it integrates the CGA as the IPv6 address to be cryptographic since it integrates the CGA as
the IID in the IPv6 address. This specification frees the device to the IID in the IPv6 address. This specification frees the device to
form its addresses in any fashion, so as to enable the classical form its addresses in any fashion, thereby enabling not only 6LoWPAN
6LoWPAN compression which derives IPv6 addresses from Layer-2 compression which derives IPv6 addresses from Layer-2 addresses but
addresses, as well as privacy addresses. The threats discussed in also privacy addresses.
Section 9.2 of [RFC3971] are countered by the protocol described in
this document as well.
7.3. OUID Collisions 7.3. ROVR Collisions
Collisions of Owner Unique Interface IDentifier (OUID) (which is the A collision of Registration Ownership Verifiers (ROVR) (i.e., the
Crypto-ID in this specification) is a possibility that needs to be Crypto-ID in this specification) is possible, but it is a rare event.
considered. The formula for calculating the probability of a The formula for calculating the probability of a collision is 1 -
collision is 1 - e^{-k^2/(2n)} where n is the maximum population size e^{-k^2/(2n)} where n is the maximum population size (2^64 here,
(2^64 here, 1.84E19) and K is the actual population (number of 1.84E19) and K is the actual population (number of nodes). If the
nodes). If the Crypto-ID is 64-bit long, then the chance of finding Crypto-ID is 64-bits, the chance of a collision is 0.01% when the
a collision is 0.01% when the network contains 66 million nodes. It network contains 66 million nodes. Moreover, the collision is only
is important to note that the collision is only relevant when this relevant when this happens within one stub network (6LBR). In the
happens within one stub network (6LBR). A collision of Crypto-ID is case of such a collision, an attacker may be able to claim the
a rare event. In the case of a collision, an attacker may be able to registered address of an another legitimate node. However for this
claim the registered address of an another legitimate node. However to happen, the attacker would also need to know the address which was
for this to happen, the attacker would also need to know the address registered by the legitimate node. This registered address is never
which was registered by the legitimate node. This registered address broadcasted on the network and therefore providing an additional
is however never broadcasted on the network and therefore it provides 64-bits that an attacker must correctly guess. To prevent address
an additional entropy of 64-bits that an attacker must correctly disclosure, it is RECOMMENDED that nodes derive the address being
guess. To prevent such a scenario, it is RECOMMENDED that nodes registered independently of the ROVR.
derive the address being registered independently of the OUID.
8. IANA considerations 8. IANA considerations
8.1. CGA Message Type 8.1. CGA Message Type
This document defines a new 128-bit value under the CGA Message Type This document defines a new 128-bit value under the CGA Message Type
[RFC3972] namespace, 0x8701 55c8 0cca dd32 6ab7 e415 f148 84d0. [RFC3972] namespace, 0x8701 55c8 0cca dd32 6ab7 e415 f148 84d0.
8.2. Crypto-Type Subregistry 8.2. Crypto-Type Subregistry
skipping to change at page 18, line 17 skipping to change at page 18, line 17
10.1. Normative References 10.1. Normative References
[FIPS-186-4] [FIPS-186-4]
FIPS 186-4, "Digital Signature Standard (DSS), Federal FIPS 186-4, "Digital Signature Standard (DSS), Federal
Information Processing Standards Publication 186-4", US Information Processing Standards Publication 186-4", US
Department of Commerce/National Institute of Standards and Department of Commerce/National Institute of Standards and
Technology Gaithersburg, MD, July 2013. Technology Gaithersburg, MD, July 2013.
[I-D.ietf-6lo-rfc6775-update] [I-D.ietf-6lo-rfc6775-update]
Thubert, P., Nordmark, E., Chakrabarti, S., and C. Thubert, P., Nordmark, E., Chakrabarti, S., and C.
Perkins, "An Update to 6LoWPAN ND", draft-ietf-6lo- Perkins, "Registration Extensions for 6LoWPAN Neighbor
rfc6775-update-13 (work in progress), February 2018. Discovery", draft-ietf-6lo-rfc6775-update-21 (work in
progress), June 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and
Identifiers for the Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 3279, DOI 10.17487/RFC3279, April
2002, <https://www.rfc-editor.org/info/rfc3279>.
[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971, "SEcure Neighbor Discovery (SEND)", RFC 3971,
DOI 10.17487/RFC3971, March 2005, DOI 10.17487/RFC3971, March 2005,
<https://www.rfc-editor.org/info/rfc3971>. <https://www.rfc-editor.org/info/rfc3971>.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, DOI 10.17487/RFC3972, March 2005, RFC 3972, DOI 10.17487/RFC3972, March 2005,
<https://www.rfc-editor.org/info/rfc3972>. <https://www.rfc-editor.org/info/rfc3972>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007, DOI 10.17487/RFC4862, September 2007,
<https://www.rfc-editor.org/info/rfc4862>. <https://www.rfc-editor.org/info/rfc4862>.
[RFC5758] Dang, Q., Santesson, S., Moriarty, K., Brown, D., and T. [RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem
Polk, "Internet X.509 Public Key Infrastructure: Statement and Requirements for IPv6 over Low-Power
Additional Algorithms and Identifiers for DSA and ECDSA", Wireless Personal Area Network (6LoWPAN) Routing",
RFC 5758, DOI 10.17487/RFC5758, January 2010, RFC 6606, DOI 10.17487/RFC6606, May 2012,
<https://www.rfc-editor.org/info/rfc5758>. <https://www.rfc-editor.org/info/rfc6606>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)", Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012, RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>. <https://www.rfc-editor.org/info/rfc6775>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative references 10.2. Informative references
[FIPS186-4] [FIPS186-4]
"FIPS Publication 186-4: Digital Signature Standard", July "FIPS Publication 186-4: Digital Signature Standard", July
2013, <http://nvlpubs.nist.gov/nistpubs/FIPS/ 2013, <http://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.186-4.pdf>. NIST.FIPS.186-4.pdf>.
[I-D.ietf-6lo-backbone-router] [I-D.ietf-6lo-backbone-router]
Thubert, P., "IPv6 Backbone Router", draft-ietf-6lo- Thubert, P., "IPv6 Backbone Router", draft-ietf-6lo-
backbone-router-05 (work in progress), January 2018. backbone-router-06 (work in progress), February 2018.
[I-D.struik-lwig-curve-representations] [I-D.struik-lwig-curve-representations]
Struik, R., "Alternative Elliptic Curve Representations", Struik, R., "Alternative Elliptic Curve Representations",
draft-struik-lwig-curve-representations-00 (work in draft-struik-lwig-curve-representations-02 (work in
progress), November 2017. progress), July 2018.
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs): over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals", Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, DOI 10.17487/RFC4919, August 2007, RFC 4919, DOI 10.17487/RFC4919, August 2007,
<https://www.rfc-editor.org/info/rfc4919>. <https://www.rfc-editor.org/info/rfc4919>.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4 "Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<https://www.rfc-editor.org/info/rfc4944>. <https://www.rfc-editor.org/info/rfc4944>.
[RFC5889] Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing
Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889,
September 2010, <https://www.rfc-editor.org/info/rfc5889>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234, (SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011, DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/info/rfc6234>. <https://www.rfc-editor.org/info/rfc6234>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011, DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>. <https://www.rfc-editor.org/info/rfc6282>.
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