< draft-ietf-6lo-ap-nd-21.txt   draft-ietf-6lo-ap-nd-22.txt >
6lo P. Thubert, Ed. 6lo P. Thubert, Ed.
Internet-Draft Cisco Internet-Draft Cisco
Updates: 8505 (if approved) B. Sarikaya Updates: 8505 (if approved) B. Sarikaya
Intended status: Standards Track Intended status: Standards Track
Expires: 22 October 2020 M. Sethi Expires: 29 October 2020 M. Sethi
Ericsson Ericsson
R. Struik R. Struik
Struik Security Consultancy Struik Security Consultancy
20 April 2020 27 April 2020
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-21 draft-ietf-6lo-ap-nd-22
Abstract Abstract
This document updates the 6LoWPAN Neighbor Discovery (ND) protocol This document updates the 6LoWPAN Neighbor Discovery (ND) protocol
defined in RFC 6775 and RFC 8505. The new extension is called defined in RFC 6775 and RFC 8505. The new extension is called
Address Protected Neighbor Discovery (AP-ND) and it protects the Address Protected Neighbor Discovery (AP-ND) and it protects the
owner of an address against address theft and impersonation attacks owner of an address against address theft and impersonation attacks
in a low-power and lossy network (LLN). Nodes supporting this in a low-power and lossy network (LLN). Nodes supporting this
extension compute a cryptographic identifier (Crypto-ID) and use it extension compute a cryptographic identifier (Crypto-ID) and use it
with one or more of their Registered Addresses. The Crypto-ID with one or more of their Registered Addresses. The Crypto-ID
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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 22 October 2020. This Internet-Draft will expire on 29 October 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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4.2. Updated EARO . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Updated EARO . . . . . . . . . . . . . . . . . . . . . . 7
4.3. Crypto-ID Parameters Option . . . . . . . . . . . . . . . 8 4.3. Crypto-ID Parameters Option . . . . . . . . . . . . . . . 8
4.4. NDP Signature Option . . . . . . . . . . . . . . . . . . 10 4.4. NDP Signature Option . . . . . . . . . . . . . . . . . . 10
4.5. Extensions to the Capability Indication Option . . . . . 11 4.5. Extensions to the Capability Indication Option . . . . . 11
5. Protocol Scope . . . . . . . . . . . . . . . . . . . . . . . 12 5. Protocol Scope . . . . . . . . . . . . . . . . . . . . . . . 12
6. Protocol Flows . . . . . . . . . . . . . . . . . . . . . . . 13 6. Protocol Flows . . . . . . . . . . . . . . . . . . . . . . . 13
6.1. First Exchange with a 6LR . . . . . . . . . . . . . . . . 14 6.1. First Exchange with a 6LR . . . . . . . . . . . . . . . . 14
6.2. NDPSO generation and verification . . . . . . . . . . . . 16 6.2. NDPSO generation and verification . . . . . . . . . . . . 16
6.3. Multihop Operation . . . . . . . . . . . . . . . . . . . 17 6.3. Multihop Operation . . . . . . . . . . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 18 7. Security Considerations . . . . . . . . . . . . . . . . . . . 18
7.1. Inheriting from RFC 3971 . . . . . . . . . . . . . . . . 18 7.1. Brown Field . . . . . . . . . . . . . . . . . . . . . . . 18
7.2. Related to 6LoWPAN ND . . . . . . . . . . . . . . . . . . 19 7.2. Inheriting from RFC 3971 . . . . . . . . . . . . . . . . 18
7.3. ROVR Collisions . . . . . . . . . . . . . . . . . . . . . 20 7.3. Related to 6LoWPAN ND . . . . . . . . . . . . . . . . . . 19
7.4. Implementation Attacks . . . . . . . . . . . . . . . . . 20 7.4. Compromised 6LR . . . . . . . . . . . . . . . . . . . . . 20
7.5. Cross-Algorithm and Cross-Protocol Attacks . . . . . . . 21 7.5. ROVR Collisions . . . . . . . . . . . . . . . . . . . . . 20
7.6. Compromised 6LR . . . . . . . . . . . . . . . . . . . . . 21 7.6. Implementation Attacks . . . . . . . . . . . . . . . . . 21
7.7. Correlating Registrations . . . . . . . . . . . . . . . . 21 7.7. Cross-Algorithm and Cross-Protocol Attacks . . . . . . . 21
7.8. Public Key Validation . . . . . . . . . . . . . . . . . . 22
7.9. Correlating Registrations . . . . . . . . . . . . . . . . 22
8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 22 8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 22
8.1. CGA Message Type . . . . . . . . . . . . . . . . . . . . 22 8.1. CGA Message Type . . . . . . . . . . . . . . . . . . . . 22
8.2. IPv6 ND option types . . . . . . . . . . . . . . . . . . 22 8.2. Crypto-Type Subregistry . . . . . . . . . . . . . . . . . 23
8.3. Crypto-Type Subregistry . . . . . . . . . . . . . . . . . 22 8.3. IPv6 ND option types . . . . . . . . . . . . . . . . . . 24
8.4. New Codepoints Associated to JWK Encoding . . . . . . . . 23 8.4. New 6LoWPAN Capability Bit . . . . . . . . . . . . . . . 24
8.4.1. JOSE Elliptic Curves Registration . . . . . . . . . . 23
8.4.2. JOSE Algorithms Registration . . . . . . . . . . . . 24
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24
10. Normative References . . . . . . . . . . . . . . . . . . . . 24 10. Normative References . . . . . . . . . . . . . . . . . . . . 24
11. Informative references . . . . . . . . . . . . . . . . . . . 26 11. Informative references . . . . . . . . . . . . . . . . . . . 26
Appendix A. Requirements Addressed in this Document . . . . . . 28 Appendix A. Requirements Addressed in this Document . . . . . . 28
Appendix B. Representation Conventions . . . . . . . . . . . . . 29 Appendix B. Representation Conventions . . . . . . . . . . . . . 28
B.1. Signature Schemes . . . . . . . . . . . . . . . . . . . . 29 B.1. Signature Schemes . . . . . . . . . . . . . . . . . . . . 28
B.2. Integer Representation for ECDSA signatures . . . . . . . 30 B.2. Representation of ECDSA Signatures . . . . . . . . . . . 29
B.3. Alternative Representations of Curve25519 . . . . . . . . 30 B.3. Representation of Public Keys Used with ECDSA . . . . . . 30
B.4. Alternative Representations of Curve25519 . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
1. Introduction 1. Introduction
Neighbor Discovery Optimizations for 6LoWPAN networks [RFC6775] Neighbor Discovery Optimizations for 6LoWPAN networks [RFC6775]
(6LoWPAN ND) adapts the original IPv6 Neighbor Discovery (IPv6 ND) (6LoWPAN ND) adapts the original IPv6 Neighbor Discovery (IPv6 ND)
protocols defined in [RFC4861] and [RFC4862] for constrained low- protocols defined in [RFC4861] and [RFC4862] for constrained low-
power and lossy network (LLN). In particular, 6LoWPAN ND introduces power and lossy network (LLN). In particular, 6LoWPAN ND introduces
a unicast host Address Registration mechanism that reduces the use of a unicast host Address Registration mechanism that reduces the use of
multicast compared to the Duplicate Address Detection (DAD) mechanism multicast compared to the Duplicate Address Detection (DAD) mechanism
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SLAAC: Stateless Address Autoconfiguration SLAAC: Stateless Address Autoconfiguration
TID: Transaction ID TID: Transaction ID
3. Updating RFC 8505 3. Updating RFC 8505
Section 5.3 of [RFC8505] introduces the ROVR that is used to detect Section 5.3 of [RFC8505] introduces the ROVR that is used to detect
and reject duplicate registrations in the DAD process. The ROVR is a and reject duplicate registrations in the DAD process. The ROVR is a
generic object that is designed for both backward compatibility and generic object that is designed for both backward compatibility and
the capability to introduce new computation methods in the future. the capability to introduce new computation methods in the future.
Using a Crypto-ID per this specification is the RECOMMENDED method. Using a Crypto-ID per this specification is the RECOMMENDED method.
Section 7.3 discusses collisions when heterogeneous methods to Section 7.5 discusses collisions when heterogeneous methods to
compute the ROVR field coexist inside a same network. compute the ROVR field coexist inside a same network.
This specification introduces a new token called a cryptographic This specification introduces a new token called a cryptographic
identifier (Crypto-ID) that is transported in the ROVR field and used identifier (Crypto-ID) that is transported in the ROVR field and used
to prove indirectly the ownership of an address that is being to prove indirectly the ownership of an address that is being
registered by means of [RFC8505]. The Crypto-ID is derived from a registered by means of [RFC8505]. The Crypto-ID is derived from a
cryptographic public key and additional parameters. cryptographic public key and additional parameters.
The overall mechanism requires the support of Elliptic Curve The overall mechanism requires the support of Elliptic Curve
Cryptography (ECC) and of a hash function as detailed in Section 6.2. Cryptography (ECC) and of a hash function as detailed in Section 6.2.
To enable the verification of the proof, the registering node needs To enable the verification of the proof, the registering node needs
to supply certain parameters including a nonce and a signature that to supply certain parameters including a nonce and a signature that
will demonstrate that the node possesses the private-key will demonstrate that the node possesses the private-key
corresponding to the public-key used to build the Crypto-ID. corresponding to the public-key used to build the Crypto-ID.
The elliptic curves and the hash functions listed in Table 2 in The elliptic curves and the hash functions listed in Table 1 in
Section 8.3 can be used with this specification; more may be added in Section 8.2 can be used with this specification; more may be added in
the future to the IANA registry. The signature scheme that specifies the future to the IANA registry. The signature scheme that specifies
which combination is used (including the curve and the representation which combination is used (including the curve and the representation
conventions) is signaled by a Crypto-Type in a new IPv6 ND Crypto-ID conventions) is signaled by a Crypto-Type in a new IPv6 ND Crypto-ID
Parameters Option (CIPO, see Section 4.3) that contains the Parameters Option (CIPO, see Section 4.3) that contains the
parameters that are necessary for the proof, a Nonce option parameters that are necessary for the proof, a Nonce option
([RFC3971]) and a NDP Signature option (Section 4.4). The NA(EARO) ([RFC3971]) and a NDP Signature option (Section 4.4). The NA(EARO)
is modified to enable a challenge and transport a Nonce option. is modified to enable a challenge and transport a Nonce option.
4. New Fields and Options 4. New Fields and Options
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ownership of the Registered Address can be ascertained. ownership of the Registered Address can be ascertained.
A node in possession of the necessary cryptographic primitives SHOULD A node in possession of the necessary cryptographic primitives SHOULD
use Crypto-ID by default as ROVR in its registrations. Whether a use Crypto-ID by default as ROVR in its registrations. Whether a
ROVR is a Crypto-ID is indicated by a new "C" flag in the NS(EARO) ROVR is a Crypto-ID is indicated by a new "C" flag in the NS(EARO)
message. message.
The Crypto-ID is derived from the public key and a modifier as The Crypto-ID is derived from the public key and a modifier as
follows: follows:
1. The hash function indicated by the Crypto-Type is applied to the 1. The hash function used by the signature scheme indicated by the
CIPO. Note that all the reserved and padding bits MUST be set to Crypto-Type is applied to the CIPO. Note that all the reserved
zero. and padding bits MUST be set to zero.
2. The leftmost bits of the resulting hash, up to the desired size, 2. The leftmost bits of the resulting hash, up to the desired size,
are used as the Crypto-ID. are used as the Crypto-ID.
At the time of this writing, a minimal size for the Crypto-ID of 128 At the time of this writing, a minimal size for the Crypto-ID of 128
bits is RECOMMENDED unless backward compatibility is needed bits is RECOMMENDED unless backward compatibility is needed
[RFC8505]. This value is bound to augment in the future. [RFC8505]. This value is bound to augment in the future.
4.2. Updated EARO 4.2. Updated EARO
This specification updates the EARO option to enable the use of the This specification updates the EARO option to enable the use of the
skipping to change at page 8, line 11 skipping to change at page 8, line 11
"Validation Failed", which are defined in [RFC8505]. "Validation Failed", which are defined in [RFC8505].
this specification does not define any new Status value. this specification does not define any new Status value.
4.3. Crypto-ID Parameters Option 4.3. Crypto-ID Parameters Option
This specification defines the Crypto-ID Parameters Option (CIPO). This specification defines the Crypto-ID Parameters Option (CIPO).
The CIPO carries the parameters used to form a Crypto-ID. The CIPO carries the parameters used to form a Crypto-ID.
In order to provide cryptographic agility [BCP 201], this In order to provide cryptographic agility [BCP 201], this
specification supports different elliptic curves, indicated by a specification supports different elliptic-curve based signature
Crypto-Type field: schemes, indicated by a Crypto-Type field:
* NIST P-256 [FIPS186-4] MUST be supported by all implementations. * The ECDSA256 signature scheme, which uses ECDSA with the NIST
P-256 curve [FIPS186-4] and the hash function SHA-256 [RFC6234],
MUST be supported by all implementations.
* The Edwards-Curve Digital Signature Algorithm (EdDSA) curve * The Ed25519 signature scheme, which uses the Pure Edwards-Curve
Ed25519 (PureEdDSA) [RFC8032] MAY be supported as an alternative. Digital Signature Algorithm (PureEdDSA) [RFC8032] with the twisted
Edwards curve Edwards25519 [RFC7748] and the hash function SHA-512
[RFC6234] internally, MAY be supported as an alternative.
* This specification uses signature schemes that target similar * The ECDSA25519 signature scheme, which uses ECDSA [FIPS186-4] with
cryptographic strength but rely on different curves, hash the Weierstrass curve Wei25519 (see Appendix B.4) and the hash
functions, signature algorithms, and/or representation function SHA-256 [RFC6234], MAY be supported as an alternative.
conventions. Future specification may extend this to different
cryptographic algorithms and key sizes, e.g., to provide better This specification uses signature schemes that target similar
security properties or a simpler implementation. cryptographic strength but rely on different curves, hash functions,
signature algorithms, and/or representation conventions. Future
specification may extend this to different cryptographic algorithms
and key sizes, e.g., to provide better security properties or a
simpler implementation.
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 |Reserved1| Public Key Length | | Type | Length |Reserved1| Public Key Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Crypto-Type | Modifier | EARO Length | Reserved2 | | Crypto-Type | Modifier | EARO Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
. . . .
. Public Key (variable length) . . Public Key (variable length) .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Padding . . Padding .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Crypto-ID Parameters Option Figure 2: Crypto-ID Parameters Option
Type: 8-bit unsigned integer. to be assigned by IANA, see Table 1. Type: 8-bit unsigned integer. to be assigned by IANA, see Table 2.
Length: 8-bit unsigned integer. The length of the option in units Length: 8-bit unsigned integer. The length of the option in units
of 8 octets. of 8 octets.
Reserved1: 5-bit unsigned integer. It MUST be set to zero by the Reserved1: 5-bit unsigned integer. It MUST be set to zero by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
Public Key Length: 11-bit unsigned integer. The length of the Public Key Length: 11-bit unsigned integer. The length of the
Public Key field in bytes. Public Key field in bytes. The actual length depends on the
Crypto Type and on whether the compressed or uncompressed form is
used. The valid values at provided in Table 1.
Crypto-Type: 8-bit unsigned integer. The type of cryptographic Crypto-Type: 8-bit unsigned integer. The type of cryptographic
algorithm used in calculation Crypto-ID indexed by IANA in the algorithm used in calculation Crypto-ID indexed by IANA in the
"Crypto-Type Subregistry" in the "Internet Control Message "Crypto-Type Subregistry" in the "Internet Control Message
Protocol version 6 (ICMPv6) Parameters" (see Section 8.3). Protocol version 6 (ICMPv6) Parameters" (see Section 8.2).
Modifier: 8-bit unsigned integer. Set to an arbitrary value by the Modifier: 8-bit unsigned integer. Set to an arbitrary value by the
creator of the Crypto-ID. The role of the modifier is to enable creator of the Crypto-ID. The role of the modifier is to enable
the formation of multiple Crypto-IDs from a same key pair, which the formation of multiple Crypto-IDs from a same key pair, which
reduces the traceability and thus improves the privacy of a reduces the traceability and thus improves the privacy of a
constrained node that could not maintain many key-pairs. constrained node that could not maintain many key-pairs.
EARO Length: 8-bit unsigned integer. The option length of the EARO EARO Length: 8-bit unsigned integer. The option length of the EARO
that contains the Crypto-ID associated with the CIPO. that contains the Crypto-ID associated with the CIPO.
Reserved2: 8-bit unsigned integer. It MUST be set to zero by the
sender and MUST be ignored by the receiver.
Public Key: A variable-length field, size indicated in the Public Public Key: A variable-length field, size indicated in the Public
Key Length field. JWK-encoded Public Key [RFC7517]. Key Length field.
Padding: A variable-length field completing the Public Key field to Padding: A variable-length field completing the Public Key field to
align to the next 8-bytes boundary. It MUST be set to zero by the align to the next 8-bytes boundary. It MUST be set to zero by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
The implementation of multiple hash functions in a constrained The implementation of multiple hash functions in a constrained device
devices may consume excessive amounts of program memory. This may consume excessive amounts of program memory. This specification
specification enables the use of SHA-256 [RFC6234] for all the enables the use of the same hash function SHA-256 [RFC6234] for two
supported ECC curves. of the three supported ECC-based signature schemes. Some code
factorization is also possible for the ECC computation itself.
Some code factorization is also possible for the ECC computation [CURVE-REPR] provides information on how to represent Montgomery
itself. [CURVE-REPR] provides information on how to represent curves and (twisted) Edwards curves as curves in short-Weierstrass
Montgomery curves and (twisted) Edwards curves as curves in short- form and illustrates how this can be used to implement elliptic curve
Weierstrass form and illustrates how this can be used to implement computations using existing implementations that already provide,
elliptic curve computations using existing implementations that e.g., ECDSA and ECDH using NIST [FIPS186-4] prime curves. For more
already provide, e.g., ECDSA and ECDH using NIST [FIPS186-4] prime details on representation conventions, we refer to Appendix B.
curves. For more details on representation conventions, we refer to
Appendix B.
4.4. NDP Signature Option 4.4. NDP Signature Option
This specification defines the NDP Signature Option (NDPSO). The This specification defines the NDP Signature Option (NDPSO). The
NDPSO carries the signature that proves the ownership of the Crypto- NDPSO carries the signature that proves the ownership of the Crypto-
ID. The format of the NDPSO is illustrated in Figure 3. ID. The format of the NDPSO is illustrated in Figure 3.
As opposed to the RSA Signature Option (RSAO) defined in section 5.2. As opposed to the RSA Signature Option (RSAO) defined in section 5.2.
of SEND [RFC3971], the NDPSO does not have a key hash field. of SEND [RFC3971], the NDPSO does not have a key hash field.
Instead, the leftmost 128 bits of the ROVR field in the EARO are used Instead, the leftmost 128 bits of the ROVR field in the EARO are used
skipping to change at page 11, line 5 skipping to change at page 11, line 5
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Padding . . Padding .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: NDP signature Option Figure 3: NDP signature Option
Type: to be assigned by IANA, see Table 1. Type: to be assigned by IANA, see Table 2.
Length: 8-bit unsigned integer. The length of the option in units Length: 8-bit unsigned integer. The length of the option in units
of 8 octets. of 8 octets.
Reserved1: 5-bit unsigned integer. It MUST be set to zero by the Reserved1: 5-bit unsigned integer. It MUST be set to zero by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
Digital Signature Length: 11-bit unsigned integer. The length of Digital Signature Length: 11-bit unsigned integer. The length of
the Digital Signature field in bytes. the Digital Signature field in bytes.
Reserved2: 32-bit unsigned integer. It MUST be set to zero by the Reserved2: 32-bit unsigned integer. It MUST be set to zero by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
Digital Signature: A variable-length field containing the JWS- Digital Signature: A variable-length field containing the digital
encoded digital signature[RFC7515]. The length and computation of signature. The length and computation of the digital signature
the digital signature both depend on the Crypto-Type which is both depend on the Crypto-Type which is found in the associated
found in the associated CIPO, see Appendix B.2. For the values of CIPO, see Appendix B. For the values of the Crypto-Type defined
the Crypto-Type defined in this specification, and for future in this specification, and for future values of the Crypto-Type
values of the Crypto-Type unless specified otherwise, the unless specified otherwise, the signature is computed as detailed
signature is computed as detailed in Section 6.2. in Section 6.2.
Padding: A variable-length field completing the Digital Signature Padding: A variable-length field completing the Digital Signature
field to align to the next 8-bytes boundary. It MUST be set to field to align to the next 8-bytes boundary. It MUST be set to
zero by the sender and MUST be ignored by the receiver. zero by the sender and MUST be ignored by the receiver.
4.5. Extensions to the Capability Indication Option 4.5. Extensions to the Capability Indication Option
This specification defines 2 new capability bits in the 6CIO, defined This specification defines one new capability bits in the 6CIO,
by [RFC7400] for use by the 6LR and 6LBR in IPv6 ND RA messages. defined by [RFC7400] for use by the 6LR and 6LBR in IPv6 ND RA
messages.
The "A" flag indicates that AP-ND is enabled in the network. It is
set by the 6LBR that serves the network and propagated by the 6LRs.
The "J" flag indicates that the 6LR supports JWK-encoded keys in the
CIPO option.
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 = 1 | Reserved |J|A|D|L|B|P|E|G| | Type | Length = 1 | Reserved |A|D|L|B|P|E|G|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: New Capability Bits in the 6CIO Figure 4: New Capability Bit in the 6CIO
New Option Fields: New Option Field:
J: 1-bit flag. This 6LR supports AP-ND with JWK encoding A: 1-bit flag. Set to indicate that AP-ND is globally activated in
the network.
A: 1-bit flag. This network supports AP-ND The "A" flag is set by the 6LBR that serves the network and
propagated by the 6LRs. It is typically turned on when all 6LRs are
migrated to this specification.
5. Protocol Scope 5. Protocol Scope
The scope of the protocol specified here is a 6LoWPAN LLN, typically The scope of the protocol specified here is a 6LoWPAN LLN, typically
a stub network connected to a larger IP network via a Border Router a stub network connected to a larger IP network via a Border Router
called a 6LBR per [RFC6775]. A 6LBR has sufficient capability to called a 6LBR per [RFC6775]. A 6LBR has sufficient capability to
satisfy the needs of duplicate address detection. satisfy the needs of duplicate address detection.
The 6LBR maintains registration state for all devices in its attached The 6LBR maintains registration state for all devices in its attached
LLN. Together with the first-hop router (the 6LR), the 6LBR assures LLN. Together with the first-hop router (the 6LR), the 6LBR assures
skipping to change at page 12, line 35 skipping to change at page 12, line 33
---+-------- ............ ---+-------- ............
| 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 (6LN) o o o(6LR)
^
o o | LLN link
o o v
o(6LN)
o
Figure 5: Basic Configuration Figure 5: 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 mandates 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. 6LRs.
This specification mandates that a chain of trust is established so This specification mandates that all the LLN links between the 6LR
that a packet that was validated by the first 6LR can be safely and the 6LBR are protected so that a packet that was validated by the
routed by other on-path 6LRs to the 6LBR. first 6LR can be safely routed by other on-path 6LRs to the 6LBR.
6. Protocol Flows 6. Protocol Flows
The 6LR/6LBR ensures first-come/first-serve by storing the ROVR The 6LR/6LBR ensures first-come/first-serve by storing the ROVR
associated to the address being registered upon the first associated to the address being registered upon the first
registration and rejecting a registration with a different ROVR registration and rejecting a registration with a different ROVR
value. A 6LN can claim any address as long as it is the first to value. A 6LN can claim any address as long as it is the first to
make that claim. After a successful registration, the 6LN becomes make that claim. After a successful registration, the 6LN becomes
the owner of the registered address and the address is bound to the the owner of the registered address and the address is bound to the
ROVR value in the 6LR/6LBR registry. ROVR value in the 6LR/6LBR registry.
This specification protects the ownership of the address. Its use in This specification protects the ownership of the address at the first
a network is signaled by the 6LBR by setting the 'A' flag in the hop (the edge). Its use in a network is signaled by the "A" flag in
6CIO. This is echoed by the 6LRs, that also indicate the key the 6CIO. The flag is set by the 6LBR and propagated unchanged by
encoding format that they support in another 6CIO flag, currently the the 6LRs. The "A" flag enables to migrate a network with the
'J' flag for JWK. protection off and then turn it on globally.
When using a ROVR that is a Crypto-ID, a 6LN MUST use a 6LR that The 6LN places a cryptographic token, the Crypto-ID, in the ROVR that
supports the key encoding used in the CIPO. If the 6LR does not is associated with the address at the first registration, enabling
support the Crypto-Type, it MUST reply with an EARO Status 10 the 6LR to later challenge it to verify that it is the original
"Validation Failed" without a challenge. In that case, the 6LN may Registering Node. The challenge may happen at any time at the
try another Crypto-Type until it falls back to Crypto-Type 0 that discretion of the 6LR and the 6LBR. A valid registration in the 6LR
MUST be supported by all 6LRs. or the 6LBR MUST NOT be altered until the challenge is complete.
This specification enables the 6LR to challenge the 6LN to verify its When the "A" flag is on, the 6LR MUST challenge the 6LN when it
ownership of the binding by placing a Crypto-ID in the ROVR. The creates a binding with the "C" flag set in the ROVR and when a new
challenge can happen at any time at the discretion of the 6LR. The registration attempts to change a parameter of that binding that
6LR MUST challenge the 6LN when it creates a binding and when a new
registration attempts to change a parameter of the binding that
identifies the 6LN, for instance its Source Link-Layer Address. The identifies the 6LN, for instance its Source Link-Layer Address. The
verification protects against a rogue that would steal an address and verification protects against a rogue that would steal an address and
attract its traffic, or use it as source address. attract its traffic, or use it as source address.
The challenge can also triggered by the 6LBR, e.g., to enforce a The 6LR MUST also challenge the 6LN if the 6LBR directly signals to
global policy. In that case, the 6LBR returns a status of do so, using an EDAC Message with a "Validation Requested" status.
"Validation Requested" in the DAR/DAC exchange, which is echoed by The EDAR is echoed by the 6LR in the NA (EARO) back to the
the 6LR in the NA (EARO) back to the registering node. A valid registering node. The 6LR SHOULD also challenge all its attached
registration in the 6LR or the 6LBR MUST NOT be altered until the 6LNs at the time the 6LBR turns the "A" flag on in the 6CIO, to
challenge is complete. detect an issue immediately.
If the 6LR does not support the Crypto-Type, it MUST reply with an
EARO Status 10 "Validation Failed" without a challenge. In that
case, the 6LN may try another Crypto-Type until it falls back to
Crypto-Type 0 that MUST be supported by all 6LRs.
A node may use more than one IPv6 address at the same time. The A node may use more than one IPv6 address at the same time. The
separation of the address and the cryptographic material avoids the separation of the address and the cryptographic material avoids the
need for the constrained device to compute multiple keys for multiple need for the constrained device to compute multiple keys for multiple
addresses. The 6LN MAY use the same Crypto-ID to prove the ownership addresses. The 6LN MAY use the same Crypto-ID to prove the ownership
of multiple IPv6 addresses. The 6LN MAY also derive multiple Crypto- of multiple IPv6 addresses. The 6LN MAY also derive multiple Crypto-
IDs from a same key. IDs from a same key.
6.1. First Exchange with a 6LR 6.1. First Exchange with a 6LR
skipping to change at page 14, line 23 skipping to change at page 14, line 23
then it replies with a challenge NA (EARO, status=Validation then it replies with a challenge NA (EARO, status=Validation
Requested) that contains a Nonce Option (shown as NonceLR in Requested) that contains a Nonce Option (shown as NonceLR in
Figure 6). Figure 6).
6LN 6LR 6LN 6LR
| | | |
|<------------------------- RA -------------------------| |<------------------------- RA -------------------------|
| | ^ | | ^
|---------------- NS with EARO (Crypto-ID) ------------>| | |---------------- NS with EARO (Crypto-ID) ------------>| |
| | option | | option
|<- NA with EARO (status=Validation Requested), NonceLR-| | |<- NA with EARO(status=Validation Requested), NonceLR | |
| | v | | v
|------- NS with EARO, CIPO, NonceLN and NDPSO -------->| |------- NS with EARO, CIPO, NonceLN and NDPSO -------->|
| | | |
|<------------------- NA with EARO ---------------------| |<------------------- NA with EARO ---------------------|
| | | |
... ...
| | | |
|--------------- NS with EARO (Crypto-ID) ------------->| |--------------- NS with EARO (Crypto-ID) ------------->|
| | | |
|<------------------- NA with EARO ---------------------| |<------------------- NA with EARO ---------------------|
skipping to change at page 15, line 23 skipping to change at page 15, line 23
the signed material. This provides a "contributory behavior", so the signed material. This provides a "contributory behavior", so
that either party that knows it generates a good quality nonce knows that either party that knows it generates a good quality nonce knows
that the protocol will be secure. that the protocol will be secure.
The 6LR MUST store the information associated to a Crypto-ID on the The 6LR MUST store the information associated to a Crypto-ID on the
first NS exchange where it appears in a fashion that the CIPO first NS exchange where it appears in a fashion that the CIPO
parameters can be retrieved from the Crypto-ID alone. parameters can be retrieved from the Crypto-ID alone.
The steps for the registration to the 6LR are as follows: The steps for the registration to the 6LR are as follows:
* Upon the first exchange with a 6LR, a 6LN will be challenged to Upon the first exchange with a 6LR, a 6LN will be challenged to prove
prove ownership of the Crypto-ID and the Target Address being ownership of the Crypto-ID and the Target Address being registered in
registered in the Neighbor Solicitation message. When a 6LR the Neighbor Solicitation message. When a 6LR receives a NS(EARO)
receives a NS(EARO) registration with a new Crypto-ID as a ROVR, registration with a new Crypto-ID as a ROVR, and unless the
and unless the registration is rejected for another reason, it registration is rejected for another reason, it MUST challenge by
MUST challenge by responding with a NA(EARO) with a status of responding with a NA(EARO) with a status of "Validation Requested".
"Validation Requested".
* Upon receiving a first NA(EARO) with a status of "Validation Upon receiving a first NA(EARO) with a status of "Validation
Requested" from a 6LR, the registering node SHOULD retry its Requested" from a 6LR, the registering node SHOULD retry its
registration with a Crypto-ID Parameters Option (CIPO) registration with a Crypto-ID Parameters Option (CIPO) (Section 4.3)
(Section 4.3) that contains all the necessary material for that contains all the necessary material for building the Crypto-ID,
building the Crypto-ID, the NonceLN that it generated, and the NDP the NonceLN that it generated, and the NDP signature (Section 4.4)
signature (Section 4.4) option that proves its ownership of the option that proves its ownership of the Crypto-ID and intent of
Crypto-ID and intent of registering the Target Address. In registering the Target Address. In subsequent revalidation with the
subsequent revalidation with the same 6LR, the 6LN MAY try to omit same 6LR, the 6LN MAY try to omit the CIPO to save bandwidth, with
the CIPO to save bandwidth, with the expectation that the 6LR the expectation that the 6LR saved it. If the validation fails and
saved it. If the validation fails and it gets challenged again, it gets challenged again, then it SHOULD add the CIPO again.
then it SHOULD add the CIPO again.
* In order to validate the ownership, the 6LR performs the same In order to validate the ownership, the 6LR performs the same steps
steps as the 6LN and rebuilds the Crypto-ID based on the as the 6LN and rebuilds the Crypto-ID based on the parameters in the
parameters in the CIPO. If the rebuilt Crypto-ID matches the CIPO. If the rebuilt Crypto-ID matches the ROVR, the 6LN also
ROVR, the 6LN also verifies the signature contained in the NDPSO verifies the signature contained in the NDPSO option. If at that
option. If at that point the signature in the NDPSO option can be point the signature in the NDPSO option can be verified, then the
verified, then the validation succeeds. Otherwise the validation validation succeeds. Otherwise the validation fails.
fails.
* If the 6LR fails to validate the signed NS(EARO), it responds with If the 6LR fails to validate the signed NS(EARO), it responds with a
a status of "Validation Failed". After receiving a NA(EARO) with status of "Validation Failed". After receiving a NA(EARO) with a
a status of "Validation Failed", the registering node SHOULD try status of "Validation Failed", the registering node SHOULD try and
and alternate Crypto-Type and if even Crypto-Type 0 fails, it may alternate Crypto-Type and if even Crypto-Type 0 fails, it may try to
try to register a different address in the NS message. register a different address in the NS message.
6.2. NDPSO generation and verification 6.2. NDPSO generation and verification
The signature generated by the 6LN to provide proof-of-ownership of The signature generated by the 6LN to provide proof-of-ownership of
the private-key is carried in the NDP Signature Option (NDPSO). It the private-key is carried in the NDP Signature Option (NDPSO). It
is generated by the 6LN in a fashion that depends on the Crypto-Type is generated by the 6LN in a fashion that depends on the Crypto-Type
(see Table 2 in Section 8.3) chosen by the 6LN as follows: (see Table 1 in Section 8.2) chosen by the 6LN as follows:
* Concatenate the following in the order listed: * Form the message to be signed, by concatenating the following
byte-strings in the order listed:
1. The 128-bit Message Type tag [RFC3972] (in network byte 1. The 128-bit Message Type tag [RFC3972] (in network byte
order). For this specification the tag is 0x8701 55c8 0cca order). For this specification the tag is given in
dd32 6ab7 e415 f148 84d0. (The tag value has been generated Section 8.1. (The tag value has been generated by the editor
by the editor of this specification on random.org). of this specification on random.org).
2. the CIPO 2. the CIPO
3. the 16-byte Target Address (in network byte order) sent in the 3. the 16-byte Target Address (in network byte order) sent in the
Neighbor Solicitation (NS) message. It is the address which Neighbor Solicitation (NS) message. It is the address which
the 6LN is registering with the 6LR and 6LBR. the 6LN is registering with the 6LR and 6LBR.
4. NonceLR received from the 6LR (in network byte order) in the 4. NonceLR received from the 6LR (in network byte order) in the
Neighbor Advertisement (NA) message. The nonce is at least 6 Neighbor Advertisement (NA) message. The nonce is at least 6
bytes long as defined in [RFC3971]. bytes long as defined in [RFC3971].
5. NonceLN sent from the 6LN (in network byte order). The nonce 5. NonceLN sent from the 6LN (in network byte order). The nonce
is at least 6 bytes long as defined in [RFC3971]. is at least 6 bytes long as defined in [RFC3971].
6. 1-byte Option Length of the EARO containing the Crypto-ID. 6. 1-byte Option Length of the EARO containing the Crypto-ID.
* Apply the hash function (if any) specified by the Crypto-Type to * Apply the signature algorithm specified by the Crypto-Type using
the concatenated data, e.g., hash the resulting data using SHA- the private key.
256.
* Apply the signature algorithm specified by the Crypto-Type, e.g.,
sign the hash output with ECDSA (if curve P-256 is used) or sign
the hash with EdDSA (if curve Ed25519 (PureEdDSA)).
The 6LR on receiving the NDPSO and CIPO options first checks that the The 6LR on receiving the NDPSO and CIPO options first checks that the
EARO Length in the CIPO matches the length of the EARO. If so it EARO Length in the CIPO matches the length of the EARO. If so it
regenerates the Crypto-ID based on the CIPO to make sure that the regenerates the Crypto-ID based on the CIPO to make sure that the
leftmost bits up to the size of the ROVR match. leftmost bits up to the size of the ROVR match.
If and only if the check is successful, it tries to verify the If and only if the check is successful, it tries to verify the
signature in the NDPSO option using the following: signature in the NDPSO option using the following:
* Concatenate the following in the order listed: * Form the message to be verified, by concatenating the following
byte-strings in the order listed:
1. The 128-bit Message Type tag specified above (in network byte 1. The 128-bit Message Type tag given in Section 8.1 (in network
order) byte order)
2. the CIPO 2. the CIPO
3. the 16-byte Target Address (in network byte order) received in 3. the 16-byte Target Address (in network byte order) received in
the Neighbor Solicitation (NS) message. It is the address the Neighbor Solicitation (NS) message. It is the address
which the 6LN is registering with the 6LR and 6LBR. which the 6LN is registering with the 6LR and 6LBR.
4. NonceLR sent in the Neighbor Advertisement (NA) message. The 4. NonceLR sent in the Neighbor Advertisement (NA) message. The
nonce is at least 6 bytes long as defined in [RFC3971]. nonce is at least 6 bytes long as defined in [RFC3971].
5. NonceLN received from the 6LN (in network byte order) in the 5. NonceLN received from the 6LN (in network byte order) in the
NS message. The nonce is at least 6 bytes long as defined in NS message. The nonce is at least 6 bytes long as defined in
[RFC3971]. [RFC3971].
6. 1-byte EARO Length received in the CIPO. 6. 1-byte EARO Length received in the CIPO.
* Apply the hash function (if any) specified by the Crypto-Type * Verify the signature on this message with the public-key in the
indicated by the 6LN in the CIPO to the concatenated data. CIPO and the locally computed values using the signature algorithm
specified by the Crypto-Type. If the verification succeeds, the
* Verify the signature with the public-key in the CIPO and the 6LR propagates the information to the 6LBR using a EDAR/EDAC flow.
locally computed values using the signature algorithm specified by
the Crypto-Type. If the verification succeeds, the 6LR propagates
the information to the 6LBR using a EDAR/EDAC flow.
* Due to the first-come/first-serve nature of the registration, if * Due to the first-come/first-serve nature of the registration, if
the address is not registered to the 6LBR, then flow succeeds and the address is not registered to the 6LBR, then flow succeeds and
both the 6LR and 6LBR add the state information about the Crypto- both the 6LR and 6LBR add the state information about the Crypto-
ID and Target Address being registered to their respective ID and Target Address being registered to their respective
abstract database. abstract database.
6.3. Multihop Operation 6.3. Multihop Operation
A new 6LN that joins the network auto-configures an address and A new 6LN that joins the network auto-configures an address and
performs an initial registration to a neighboring 6LR with an NS performs an initial registration to a neighboring 6LR with an NS
message that carries an Address Registration Option (EARO) [RFC8505]. message that carries an Address Registration Option (EARO) [RFC8505].
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 shown in Figure 7, which illustrates the registration flow to 6LBR as shown in Figure 7, which illustrates the registration flow
all the way to a 6LowPAN Backbone Router (6BBR) [BACKBONE-ROUTER]. all the way to a 6LowPAN Backbone Router (6BBR) [BACKBONE-ROUTER].
The 6LR and the 6LBR communicate using ICMPv6 Extended Duplicate
Address Request (EDAR) and Extended Duplicate Address Confirmation
(EDAC) messages [RFC8505] as shown in Figure 7. This specification
extends EDAR/EDAC messages to carry cryptographically generated ROVR.
The assumption is that the 6LR and the 6LBR maintain a security
association to authenticate and protect the integrity of the EDAR and
EDAC messages, so there is no need to propagate the proof of
ownership to the 6LBR. The 6LBR implicitly trusts that the 6LR
performs the verification when the 6LBR requires it, and if there is
no further exchange from the 6LR to remove the state, that the
verification succeeded.
6LN 6LR 6LBR 6BBR 6LN 6LR 6LBR 6BBR
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | | |--------------->| | |
| | Extended DAR | | | | Extended DAR | |
| |-------------->| | | |-------------->| |
| | | |
| | | proxy NS(EARO) | | | | proxy NS(EARO) |
| | |--------------->| | | |--------------->|
| | | | NS(DAD) | | | | NS(DAD)
| | | | ------> | | | | ------>
| | | | | | | |
| | | | <wait> | | | | <wait>
| | | | | | | |
| | | proxy NA(EARO) | | | | proxy NA(EARO) |
| | |<---------------| | | |<---------------|
| | Extended DAC | | | | Extended DAC | |
| |<--------------| | | |<--------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
| | | | | | | |
Figure 7: (Re-)Registration Flow Figure 7: (Re-)Registration Flow
The 6LR and the 6LBR communicate using ICMPv6 Extended Duplicate
Address Request (EDAR) and Extended Duplicate Address Confirmation
(EDAC) messages [RFC8505] as shown in Figure 7. This specification
extends EDAR/EDAC messages to carry cryptographically generated ROVR.
The assumption is that the 6LR and the 6LBR maintain a security
association to authenticate and protect the integrity of the EDAR and
EDAC messages, so there is no need to propagate the proof of
ownership to the 6LBR. The 6LBR implicitly trusts that the 6LR
performs the verification when the 6LBR requires it, and if there is
no further exchange from the 6LR to remove the state, that the
verification succeeded.
7. Security Considerations 7. Security Considerations
7.1. Inheriting from RFC 3971 7.1. Brown Field
Only 6LRs that are upgraded to this specification are capable to
challenge a registration and repel an attack. In a brown (mixed)
network, an attacker may attach to a legacy 6LR and fool the 6LBR.
So even if the "A" flag could be set at any time to test the protocol
operation, the security will only be effective when the all the 6LRs
are upgraded.
7.2. Inheriting from RFC 3971
Observations regarding the following threats to the local network in Observations regarding the following threats to the local network in
[RFC3971] also apply to this specification. [RFC3971] also apply to this specification.
Neighbor Solicitation/Advertisement Spoofing: Threats in section Neighbor Solicitation/Advertisement Spoofing: Threats in section
9.2.1 of RFC3971 apply. AP-ND counters the threats on NS(EARO) 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 messages by requiring that the NDP Signature and CIPO options be
present in these solicitations. present in these solicitations.
Duplicate Address Detection DoS Attack: Inside the LLN, Duplicate Duplicate Address Detection DoS Attack: Inside the LLN, Duplicate
skipping to change at page 19, line 36 skipping to change at page 19, line 26
Neighbor Discovery DoS Attack: A rogue node that managed to access Neighbor Discovery DoS Attack: A rogue node that managed to access
the L2 network may form many addresses and register them using AP- 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 ND. The perimeter of the attack is all the 6LRs in range of the
attacker. The 6LR MUST protect itself against overflows and attacker. The 6LR MUST protect itself against overflows and
reject excessive registration with a status 2 "Neighbor Cache reject excessive registration with a status 2 "Neighbor Cache
Full". This effectively blocks another (honest) 6LN from Full". This effectively blocks another (honest) 6LN from
registering to the same 6LR, but the 6LN may register to other 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. 6LRs that are in its range but not in that of the rogue.
7.2. Related to 6LoWPAN ND 7.3. Related to 6LoWPAN ND
The threats and mediations discussed in 6LoWPAN ND [RFC6775][RFC8505] The threats and mediations discussed in 6LoWPAN ND [RFC6775][RFC8505]
also apply here, in particular denial-of-service attacks against the also apply here, in particular denial-of-service attacks against the
registry at the 6LR or 6LBR. registry at the 6LR or 6LBR.
Secure ND [RFC3971] forces the IPv6 address to be cryptographic since Secure ND [RFC3971] forces the IPv6 address to be cryptographic since
it integrates the CGA as the IID in the IPv6 address. In contrast, it integrates the CGA as the IID in the IPv6 address. In contrast,
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
skipping to change at page 20, line 15 skipping to change at page 20, line 5
short cycles for privacy reasons [RFC8064][RFC8065], that cannot be short cycles for privacy reasons [RFC8064][RFC8065], that cannot be
compressed. compressed.
This specification provides added protection for addresses that are This specification provides added protection for addresses that are
obtained following due procedure [RFC8505] but does not constrain the obtained following due procedure [RFC8505] but does not constrain the
way the addresses are formed or the number of addresses that are used way the addresses are formed or the number of addresses that are used
in parallel by a same entity. A rogue may still perform denial-of- in parallel by a same entity. A rogue may still perform denial-of-
service attack against the registry at the 6LR or 6LBR, or attempt to service attack against the registry at the 6LR or 6LBR, or attempt to
deplete the pool of available addresses at Layer-2 or Layer-3. deplete the pool of available addresses at Layer-2 or Layer-3.
7.3. ROVR Collisions 7.4. Compromised 6LR
This specification distributes the challenge and its validation at
the edge of the network, between the 6LN and its 6LR. This protects
against DOS attacks targeted at that central 6LBR. This also saves
back and forth exchanges across a potentially large and constrained
network.
The downside is that the 6LBR needs to trust the 6LR for performing
the checking adequately, and the communication between the 6LR and
the 6LBR must be protected to avoid tempering with the result of the
test.
If a 6LR is compromised, and provided that it knows the ROVR field
used by the real owner of the address, the 6LR may pretend that the
owner has moved, is now attached to it and has successfully passed
the Crpto-ID validation. The 6LR may then attract and inject traffic
at will on behalf of that address or let a rogue take ownership of
the address.
7.5. ROVR Collisions
A collision of Registration Ownership Verifiers (ROVR) (i.e., the A collision of Registration Ownership Verifiers (ROVR) (i.e., the
Crypto-ID in this specification) is possible, but it is a rare event. Crypto-ID in this specification) is possible, but it is a rare event.
Assuming in the calculations/discussion below that the hash used for Assuming in the calculations/discussion below that the hash used for
calculating the Crypto-ID is a well-behaved cryptographic hash and calculating the Crypto-ID is a well-behaved cryptographic hash and
thus that random collisions are the only ones possible, the formula thus that random collisions are the only ones possible, the formula
(birthday paradox) for calculating the probability of a collision is (birthday paradox) for calculating the probability of a collision is
1 - e^{-k^2/(2n)} where n is the maximum population size (2^64 here, 1 - e^{-p^2/(2n)} where n is the maximum population size (2^64 here,
1.84E19) and k is the actual population (number of nodes, assuming 1.84E19) and p is the actual population (number of nodes, assuming
one Crypto-ID per node). one Crypto-ID per node).
If the Crypto-ID is 64-bits (the least possible size allowed), the If the Crypto-ID is 64-bits (the least possible size allowed), the
chance of a collision is 0.01% for network of 66 million nodes. chance of a collision is 0.01% for network of 66 million nodes.
Moreover, the collision is only relevant when this happens within one Moreover, the collision is only relevant when this happens within one
stub network (6LBR). In the case of such a collision, a third party stub network (6LBR). In the case of such a collision, a third party
node would be able to claim the registered address of an another node would be able to claim the registered address of an another
legitimate node, provided that it wishes to use the same address. To legitimate node, provided that it wishes to use the same address. To
prevent address disclosure and avoid the chances of collision on both prevent address disclosure and avoid the chances of collision on both
the ROVR and the address, it is RECOMMENDED that nodes do not derive the ROVR and the address, it is RECOMMENDED that nodes do not derive
the address being registered from the ROVR. the address being registered from the ROVR.
7.4. Implementation Attacks 7.6. Implementation Attacks
The signature schemes referenced in this specification comply with The signature schemes referenced in this specification comply with
NIST [FIPS186-4] or Crypto Forum Research Group (CFRG) standards NIST [FIPS186-4] or Crypto Forum Research Group (CFRG) standards
[RFC8032] and offer strong algorithmic security at roughly 128-bit [RFC8032] and offer strong algorithmic security at roughly 128-bit
security level. These signature schemes use elliptic curves that security level. These signature schemes use elliptic curves that
were either specifically designed with exception-free and constant- were either specifically designed with exception-free and constant-
time arithmetic in mind [RFC7748] or where one has extensive time arithmetic in mind [RFC7748] or where one has extensive
implementation experience of resistance to timing attacks implementation experience of resistance to timing attacks
[FIPS186-4]. However, careless implementations of the signing [FIPS186-4].
operations could nevertheless leak information on private keys. For
example, there are micro-architectural side channel attacks that
implementors should be aware of [breaking-ed25519]. Implementors
should be particularly aware that a secure implementation of Ed25519
requires a protected implementation of the hash function SHA-512,
whereas this is not required with implementations of SHA-256 used
with ECDSA.
7.5. Cross-Algorithm and Cross-Protocol Attacks However, careless implementations of the signing operations could
nevertheless leak information on private keys. For example, there
are micro-architectural side channel attacks that implementors should
be aware of [breaking-ed25519]. Implementors should be particularly
aware that a secure implementation of Ed25519 requires a protected
implementation of the hash function SHA-512, whereas this is not
required with implementations of the hash function SHA-256 used with
ECDSA256 and ECDSA25519.
7.7. Cross-Algorithm and Cross-Protocol Attacks
The keypair used in this specification can be self-generated and the The keypair used in this specification can be self-generated and the
public key does not need to be exchanged, e.g., through certificates, public key does not need to be exchanged, e.g., through certificates,
with a third party before it is used. New keypairs can be formed for with a third party before it is used.
new registration as the node desires. On the other hand, it is safer
to allocate a keypair that is used only for the address protection
and only for one instantiation of the signature scheme (which
includes choice of elliptic curve domain parameters, used hash
function, and applicable representation conventions). The same
private key MUST NOT be reused with more than one instantiation of
the signature scheme in this specification. The same private key
MUST NOT be used for anything other than computing NDPSO signatures
per this specification.
7.6. Compromised 6LR New keypairs can be formed for new registration as the node desires.
On the other hand, it is safer to allocate a keypair that is used
only for the address protection and only for one instantiation of the
signature scheme (which includes choice of elliptic curve domain
parameters, used hash function, and applicable representation
conventions).
This specification distributes the challenge and its validation at The same private key MUST NOT be reused with more than one
the edge of the network, between the 6LN and its 6LR. This protects instantiation of the signature scheme in this specification. The
against DOS attacks targeted at that central 6LBR. This also saves same private key MUST NOT be used for anything other than computing
back and forth exchanges across a potentially large and constrained NDPSO signatures per this specification.
network. The downside is that the 6LBR needs to trust the 6LR for
performing the checking adequately, and the communication between the
6LR and the 6LBR must be protected to avoid tempering with the result
of the test. If a 6LR is compromised, and provided that it knows the
ROVR field used by the real owner of the address, the 6LR may pretend
that the owner has moved, is now attached to it and has successfully
passed the Crpto-ID validation. The 6LR may then attract and inject
traffic at will on behalf of that address or let a rogue take
ownership of the address.
7.7. Correlating Registrations ECDSA shall be used strictly as specified in [FIPS186-4]. In
particular, each signing operation of ECDSA MUST use randomly
generated ephemeral private keys and MUST NOT reuse these ephemeral
private keys accross signing operations. This precludes the use of
deterministic ECDSA without a random input for determination of 'k',
which is deemed dangerous for the intended applications this document
aims to serve.
7.8. Public Key Validation
Public keys contained in the CIPO field (which are used for signature
verification) shall be verified to be correctly formed, by checking
that this public key is indeed a point of the elliptic curve
indicated by the Crypto-Type and that this point does have the proper
order.
For points used with the signature scheme Ed25519, one MUST check
that this point is not a point in the small subgroup (see
Appendix B.1 of [CURVE-REPR]); for points used with the signature
scheme ECDSA (i.e., both ECDSA256 and ECDSA25519), one MUST check
that the point has the same order as the base point of the curve in
question. This is commonly called full public key validation (again,
see Appendix B.1 of [CURVE-REPR]).
7.9. Correlating Registrations
The ROVR field in the EARO introduced in [RFC8505] extends the EUI-64 The ROVR field in the EARO introduced in [RFC8505] extends the EUI-64
field of the ARO defined in [RFC6775]. One of the drawbacks of using field of the ARO defined in [RFC6775]. One of the drawbacks of using
an EUI-64 as ROVR is that an attacker that is aware of the an EUI-64 as ROVR is that an attacker that is aware of the
registrations can correlate traffic for a same 6LN across multiple registrations can correlate traffic for a same 6LN across multiple
addresses. Section 3 of [RFC8505] indicates that the ROVR and the addresses. Section 3 of [RFC8505] indicates that the ROVR and the
address being registered are decoupled. A 6LN may use a same ROVR address being registered are decoupled. A 6LN may use a same ROVR
for multiple registrations or a different ROVR per registration, and for multiple registrations or a different ROVR per registration, and
the IID must not derive from the ROVR. In theory different 6LNs the IID must not derive from the ROVR. In theory different 6LNs
could use a same ROVR as long as they do not attempt to register the could use a same ROVR as long as they do not attempt to register the
skipping to change at page 22, line 18 skipping to change at page 22, line 47
expense of storage in the 6LR, which will need to store multiple expense of storage in the 6LR, which will need to store multiple
CIPOs that contain the same public key. Note that if the attacker is CIPOs that contain the same public key. Note that if the attacker is
the 6LR, then the Modifier alone does not provide a protection, and the 6LR, then the Modifier alone does not provide a protection, and
the 6LN would need to use different keys and MAC addresses in an the 6LN would need to use different keys and MAC addresses in an
attempt to obfuscate its multiple ownership. attempt to obfuscate its multiple ownership.
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 of a Message Type tag under
[RFC3972] name space: 0x8701 55c8 0cca dd32 6ab7 e415 f148 84d0. the CGA Message Type [RFC3972] name space: 0x8701 55c8 0cca dd32 6ab7
e415 f148 84d0.
8.2. IPv6 ND option types
This document registers two new ND option types under the subregistry
"IPv6 Neighbor Discovery Option Formats":
+------------------------------+-----------------+---------------+
| Option Name | Suggested Value | Reference |
+==============================+=================+===============+
| NDP Signature Option (NDPSO) | 38 | This document |
+------------------------------+-----------------+---------------+
| Crypto-ID Parameters Option | 39 | This document |
| (CIPO) | | |
+------------------------------+-----------------+---------------+
Table 1: New ND options
8.3. Crypto-Type Subregistry 8.2. Crypto-Type Subregistry
IANA is requested to create a new subregistry "Crypto-Type IANA is requested to create a new subregistry "Crypto-Type
Subregistry" in the "Internet Control Message Protocol version 6 Subregistry" in the "Internet Control Message Protocol version 6
(ICMPv6) Parameters". The registry is indexed by an integer in the (ICMPv6) Parameters". The registry is indexed by an integer in the
interval 0..255 and contains an Elliptic Curve, a Hash Function, a interval 0..255 and contains an Elliptic Curve, a Hash Function, a
Signature Algorithm, and Representation Conventions, as shown in Signature Algorithm, Representation Conventions, Public key size, and
Table 2, which together specify a signature scheme. The following Signature size, as shown in Table 1, which together specify a
Crypto-Type values are defined in this document: signature scheme (and which are fully specified in Appendix B).
+----------------+----------------+----------------+----------------+ The following Crypto-Type values are defined in this document:
| Crypto-Type | 0 (ECDSA256) | 1 (Ed25519) | 2 |
| value | | | (ECDSA25519) |
+================+================+================+================+
| Elliptic curve | NIST P-256 | Curve25519 | Curve25519 |
| | [FIPS186-4] | [RFC7748] | [RFC7748] |
+----------------+----------------+----------------+----------------+
| Hash function | SHA-256 | SHA-512 | SHA-256 |
| | [RFC6234] | [RFC6234] | [RFC6234] |
+----------------+----------------+----------------+----------------+
| Signature | ECDSA | Ed25519 | ECDSA |
| algorithm | [FIPS186-4] | [RFC8032] | [FIPS186-4] |
+----------------+----------------+----------------+----------------+
| Representation | Weierstrass, | Edwards, | Weierstrass, |
| conventions | uncompressed, | compressed, | compressed, |
| | MSB/msb first, | LSB/lsb first, | MSB/msb |
| | [RFC7518] | [RFC8037] | first, |
| | | | [CURVE-REPR] |
+----------------+----------------+----------------+----------------+
| Defining | This document | This document | This |
| specification | | | document |
+----------------+----------------+----------------+----------------+
Table 2: Crypto-Types +----------------+-----------------+--------------+-----------------+
| Crypto-Type | 0 (ECDSA256) | 1 (Ed25519) | 2 (ECDSA25519) |
| value | | | |
+================+=================+==============+=================+
| Elliptic curve | NIST P-256 | Curve25519 | Curve25519 |
| | [FIPS186-4] | [RFC7748] | [RFC7748] |
+----------------+-----------------+--------------+-----------------+
| Hash function |SHA-256 [RFC6234]| SHA-512 |SHA-256 [RFC6234]|
| | | [RFC6234] | |
+----------------+-----------------+--------------+-----------------+
| Signature |ECDSA [FIPS186-4]| Ed25519 |ECDSA [FIPS186-4]|
| algorithm | | [RFC8032] | |
+----------------+-----------------+--------------+-----------------+
| Representation | Weierstrass, | Edwards, | Weierstrass, |
| conventions | (un)compressed, | compressed, | (un)compressed, |
| | MSB/msb first, |LSB/lsb first,| MSB/msb first, |
| | [RFC7518] | [RFC8037] | [CURVE-REPR] |
+----------------+-----------------+--------------+-----------------+
|Public key size | 33/65 bytes | 32 bytes | 33/65 bytes |
| | (compressed/ | (compressed) | (compressed/ |
| | uncompressed) | | uncompressed) |
+----------------+-----------------+--------------+-----------------+
| Signature size | 64 bytes | 64 bytes | 64 bytes |
+----------------+-----------------+--------------+-----------------+
| Defining | This_RFC | This_RFC | This_RFC |
| specification | | | |
+----------------+-----------------+--------------+-----------------+
Table 1: Crypto-Types
New Crypto-Type values providing similar or better security may be New Crypto-Type values providing similar or better security may be
defined in the future. defined in the future.
Assignment of new values for new Crypto-Type MUST be done through Assignment of new values for new Crypto-Type MUST be done through
IANA with either "Specification Required" or "IESG Approval" as IANA with either "Specification Required" or "IESG Approval" as
defined in BCP 26 [RFC8126]. defined in BCP 26 [RFC8126].
The "Defining specification" column indicates the document that 8.3. IPv6 ND option types
defines the length and computation of the digital signature, which
could be this for values defined through "IESG Approval".
8.4. New Codepoints Associated to JWK Encoding
Code points are requested for curve Wei25519 and its use with ECDSA,
using the representation conventions of this document.
8.4.1. JOSE Elliptic Curves Registration
This section registers the following value in the IANA "JSON Web Key
Elliptic Curve" registry [IANA.JOSE.Curves].
Curve Name: Wei25519
Curve Description: short-Weierstrass curve Wei25519
JOSE Implementation Requirements: Optional
Change Controller: IESG
Reference: Appendix E.3 of [CURVE-REPR]
8.4.2. JOSE Algorithms Registration
This section registers the following value in the IANA "JSON Web
Signature and Encryption Algorithms" registry [IANA.JOSE.Algorithms].
Algorithm Name: ECDSA25519 This document registers two new ND option types under the subregistry
"IPv6 Neighbor Discovery Option Formats":
Algorithm Description: ECDSA using SHA-256 and curve Wei25519 +------------------------------+-----------------+---------------+
| Option Name | Suggested Value | Reference |
+==============================+=================+===============+
| NDP Signature Option (NDPSO) | 38 | This document |
+------------------------------+-----------------+---------------+
| Crypto-ID Parameters Option | 39 | This document |
| (CIPO) | | |
+------------------------------+-----------------+---------------+
Algorithm Usage Locations: alg Table 2: New ND options
JOSE Implementation Requirements: Optional 8.4. New 6LoWPAN Capability Bit
Change Controller: IESG IANA is requested to make additions to the Subregistry for "6LoWPAN
Capability Bits" created for [RFC7400] as follows:
Reference: Section 4.3 of [CURVE-REPR] +----------------+-----------------------+----------+
| Capability Bit | Description | Document |
+================+=======================+==========+
| 09 | AP-ND Enabled (1 bit) | This_RFC |
+----------------+-----------------------+----------+
Algorithm Analysis Document(s): Section 4.3 of [CURVE-REPR] Table 3: New 6LoWPAN Capability Bit
9. Acknowledgments 9. Acknowledgments
Many thanks to Charlie Perkins for his in-depth review and Many thanks to Charlie Perkins for his in-depth review and
constructive suggestions. The authors are also especially grateful constructive suggestions. The authors are also especially grateful
to Robert Moskowitz and Benjamin Kaduk for their comments and to Robert Moskowitz and Benjamin Kaduk for their comments and
discussions that led to many improvements. The authors wish to also discussions that led to many improvements. The authors wish to also
thank Roman Danyliw, Alissa Cooper, Mirja Kuhlewind, Eric Vyncke, thank Shwetha Bhandari for actively shepherding this document and
Vijay Gurbani, Al Morton and Adam Montville for their constructive Roman Danyliw, Alissa Cooper, Mirja Kuhlewind, Eric Vyncke, Vijay
reviews during the IESG process. Gurbani, Al Morton, and Adam Montville for their constructive reviews
during the IESG process. Finally Many thanks to our INT area ADs,
Suresh Krishnan and then Erik Kline, who supported us along the whole
process.
10. Normative References 10. Normative References
[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>.
[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,
skipping to change at page 25, line 21 skipping to change at page 25, line 26
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>.
[RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for [RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for
IPv6 over Low-Power Wireless Personal Area Networks IPv6 over Low-Power Wireless Personal Area Networks
(6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November
2014, <https://www.rfc-editor.org/info/rfc7400>. 2014, <https://www.rfc-editor.org/info/rfc7400>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/info/rfc7517>.
[RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves [RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
for Security", RFC 7748, DOI 10.17487/RFC7748, January for Security", RFC 7748, DOI 10.17487/RFC7748, January
2016, <https://www.rfc-editor.org/info/rfc7748>. 2016, <https://www.rfc-editor.org/info/rfc7748>.
[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital [RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
Signature Algorithm (EdDSA)", RFC 8032, Signature Algorithm (EdDSA)", RFC 8032,
DOI 10.17487/RFC8032, January 2017, DOI 10.17487/RFC8032, January 2017,
<https://www.rfc-editor.org/info/rfc8032>. <https://www.rfc-editor.org/info/rfc8032>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
skipping to change at page 26, line 10 skipping to change at page 26, line 7
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 , July 2013. Technology , July 2013.
[SEC1] SEC1, "SEC 1: Elliptic Curve Cryptography, Version 2.0", [SEC1] SEC1, "SEC 1: Elliptic Curve Cryptography, Version 2.0",
Standards for Efficient Cryptography , June 2009. Standards for Efficient Cryptography , June 2009.
11. Informative references 11. Informative references
[IANA.JOSE.Algorithms]
IANA, "JSON Web Signature and Encryption Algorithms",
IANA,
https://www.iana.org/assignments/jose/jose.xhtml#web-
signature-encryption-algorithms.
[IANA.JOSE.Curves]
IANA, "JSON Web Key Elliptic Curve", IANA,
https://www.iana.org/assignments/jose/jose.xhtml#web-key-
elliptic-curve.
[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>.
[BCP 106] Eastlake 3rd, D., Schiller, J., and S. Crocker, [BCP 106] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, "Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005, DOI 10.17487/RFC4086, June 2005,
<https://www.rfc-editor.org/info/rfc4086>. <https://www.rfc-editor.org/info/rfc4086>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
skipping to change at page 29, line 4 skipping to change at page 28, line 31
to more LLN links than IEEE 802.15.4 only. Support for at least to more LLN links than IEEE 802.15.4 only. Support for at least
the LLN links for which a 6lo "IPv6 over foo" specification the LLN links for which a 6lo "IPv6 over foo" specification
exists, as well as Low-Power Wi-Fi SHOULD be possible. exists, as well as Low-Power Wi-Fi SHOULD be possible.
* As part of this extension, a mechanism to compute a unique * As part of this extension, a mechanism to compute a unique
Identifier should be provided with the capability to form a Link Identifier should be provided with the capability to form a Link
Local Address that SHOULD be unique at least within the LLN Local Address that SHOULD be unique at least within the LLN
connected to a 6LBR. connected to a 6LBR.
* The Address Registration Option used in the ND registration SHOULD * The Address Registration Option used in the ND registration SHOULD
be extended to carry the relevant forms of Unique Interface be extended to carry the relevant forms of Unique Interface
Identifier. Identifier.
* The Neighbor Discovery should specify the formation of a site- * The Neighbor Discovery should specify the formation of a site-
local address that follows the security recommendations from local address that follows the security recommendations from
[RFC7217]. [RFC7217].
Appendix B. Representation Conventions Appendix B. Representation Conventions
B.1. Signature Schemes B.1. Signature Schemes
The signature scheme ECDSA256 corresponding to Crypto-Type 0 is The signature scheme ECDSA256 corresponding to Crypto-Type 0 is
ECDSA, as specified in [FIPS186-4], instantiated with the NIST prime ECDSA, as specified in [FIPS186-4], instantiated with the NIST prime
curve P-256, as specified in Appendix B of [FIPS186-4], and the hash curve P-256, as specified in Appendix B of [FIPS186-4], as specified
function SHA-256, as specified in [RFC6234], where points of this in [RFC6234], where points of this NIST curve are represented as
NIST curve are represented as points of a short-Weierstrass curve points of a short-Weierstrass curve (see [FIPS186-4]) and are encoded
(see [FIPS186-4]) and are encoded as octet strings in most- as octet strings in most-significant-bit first (msb) and most-
significant-bit first (msb) and most-significant-byte first (MSB) significant-byte first (MSB) order. The signature itself consists of
order. The signature itself consists of two integers (r and s), two integers (r and s), which are each encoded as fixed-size octet
which are each encoded as fixed-size octet strings in most- strings in most-significant-bit first and most-significant-byte first
significant-bit first and most-significant-byte first order. For order. The hash function is SHA-256. For details on ECDSA, see
details on ECDSA, see [FIPS186-4]; for details on the integer [FIPS186-4]; for details on the encoding of public keys, see
encoding, see Appendix B.2. Appendix B.3; for details on the signature encoding, see
Appendix B.2.
The signature scheme Ed25519 corresponding to Crypto-Type 1 is EdDSA, The signature scheme Ed25519 corresponding to Crypto-Type 1 is EdDSA,
as specified in [RFC8032], instantiated with the Montgomery curve as specified in [RFC8032], instantiated with the Montgomery curve
Curve25519, as specified in [RFC7748], and the hash function SHA-512, Curve25519, as specified in [RFC7748]. , where points of this
as specified in [RFC6234], where points of this Montgomery curve are Montgomery curve are represented as points of the corresponding
represented as points of the corresponding twisted Edwards curve (see twisted Edwards curve Edwards25519 (see Appendix B.4) and are encoded
Appendix B.3) and are encoded as octet strings in least-significant- as octet strings in least-significant-bit first (lsb) and least-
bit first (lsb) and least-significant-byte first (LSB) order. The significant-byte first (LSB) order. The associated hash algorithm,
signature itself consists of a bit string that encodes a point of used internally by Ed25519 but not part of the signature process, is
this twisted Edwards curve, in compressed format, and an integer SHA-512, as specified in [RFC6234]. The signature itself consists of
encoded in least-significant-bit first and least-significant-byte a bit string that encodes a point of this twisted Edwards curve, in
first order. For details on EdDSA and on the encoding conversions, compressed format, and an integer encoded in least-significant-bit
see the specification of pure Ed25519 in [RFC8032]. first and least-significant-byte first order. For details on EdDSA,
the encoding of public keys and that of signatures, see the
specification of pure Ed25519 in [RFC8032].
The signature scheme ECDSA25519 corresponding to Crypto-Type 2 is The signature scheme ECDSA25519 corresponding to Crypto-Type 2 is
ECDSA, as specified in [FIPS186-4], instantiated with the Montgomery ECDSA, as specified in [FIPS186-4], instantiated with the Montgomery
curve Curve25519, as specified in [RFC7748], and the hash function curve Curve25519, as specified in [RFC7748], and the hash function
SHA-256, as specified in [RFC6234], where points of this Montgomery SHA-256, as specified in [RFC6234], where points of this Montgomery
curve are represented as points of a corresponding curve in short- curve are represented as points of the corresponding short-
Weierstrass form (see Appendix B.3) and are encoded as octet strings Weierstrass curve Wei25519 (see Appendix B.4) and are encoded as
in most-significant-bit first and most-significant-byte first order. octet strings in most-significant-bit first and most-significant-byte
The signature itself consists of a bit string that encodes two first order. The signature itself consists of a bit string that
integers, each encoded as fixed-size octet strings in most- encodes two integers, each encoded as fixed-size octet strings in
significant-bit first and most-significant-byte first order. For most-significant-bit first and most-significant-byte first order.
details on ECDSA, see [FIPS186-4]; for details on the integer The hash function is SHA-256. For details on ECDSA, see [FIPS186-4];
encoding, see Appendix B.2 for details on the encoding of public keys, see Appendix B.3; for
details on the signature encoding, see Appendix B.2
B.2. Integer Representation for ECDSA signatures B.2. Representation of ECDSA Signatures
With ECDSA, each signature is an ordered pair (r, s) of integers With ECDSA, each signature is an ordered pair (r, s) of integers
[FIPS186-4]. Each integer is encoded as a fixed-size 256-bit bit [FIPS186-4], where each integer is represented as a 32-octet string
string, where each integer is represented according to the Field according to the Field Element to Octet String conversion rules in
Element to Octet String and Octet String to Bit String conversion [SEC1] and where the ordered pair of integers is represented as the
rules in [SEC1] and where the ordered pair of integers is represented rightconcatenation of these representation values (thereby resulting
as the rightconcatenation of the resulting representation values. in a 64-octet string). The inverse operation checks that the
The inverse operation follows the corresponding Bit String to Octet signature is a 64-octet string and represents the left-side and
String and Octet String to Field Element conversion rules of [SEC1]. right-side halves of this string (each a 32-octet string) as the
integers r and s, respectively, using the Octet String to Field
Element conversion rules in [SEC1].
B.3. Alternative Representations of Curve25519 B.3. Representation of Public Keys Used with ECDSA
ECDSA is specified to be used with elliptic curves in short-
Weierstrass form. Each point of such a curve is represented as an
octet string using the Elliptic Curve Point to Octet String
conversion rules in [SEC1], where point compression may be enabled
(which is indicated by the leftmost octet of this representation).
The inverse operation converts an octet string to a point of this
curve using the Octet String to Elliptic Curve Point conversion rules
in [SEC1], whereby the point is rejected if this is the so-called
point at infinity. (This is the case if the input to this inverse
operation is an octet string of length 1.)
B.4. Alternative Representations of Curve25519
The elliptic curve Curve25519, as specified in [RFC7748], is a so- The elliptic curve Curve25519, as specified in [RFC7748], is a so-
called Montgomery curve. Each point of this curve can also be called Montgomery curve. Each point of this curve can also be
represented as a point of a twisted Edwards curve or as a point of an represented as a point of a twisted Edwards curve or as a point of an
elliptic curve in short-Weierstrass form, via a coordinate elliptic curve in short-Weierstrass form, via a coordinate
transformation (a so-called isomorphic mapping). The parameters of transformation (a so-called isomorphic mapping). The parameters of
the Montgomery curve and the corresponding isomorphic curves in the Montgomery curve and the corresponding isomorphic curves in
twisted Edwards curve and short-Weierstrass form are as indicated twisted Edwards curve and short-Weierstrass form are as indicated
below. Here, the domain parameters of the Montgomery curve below. Here, the domain parameters of the Montgomery curve
Curve25519 and of the twisted Edwards curve Edwards25519 are as Curve25519 and of the twisted Edwards curve Edwards25519 are as
specified in [RFC7748]; the domain parameters of the elliptic curve specified in [RFC7748]; the domain parameters of the elliptic curve
Wei25519 in short-Weierstrass curve comply with Section 6.1.1 of Wei25519 in short-Weierstrass curve comply with Section 6.1.1 of
[FIPS186-4]. For details of the coordinate transformations [FIPS186-4]. For further details on these curves and on the
referenced above, see [RFC7748] and [CURVE-REPR]. coordinate transformations referenced above, see [CURVE-REPR].
General parameters (for all curve models): General parameters (for all curve models):
p 2^{255}-19 p 2^{255}-19
(=0x7fffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff (=0x7fffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff
ffffffed) ffffffed)
h 8 h 8
n n
723700557733226221397318656304299424085711635937990760600195093828 723700557733226221397318656304299424085711635937990760600195093828
5454250989 5454250989
 End of changes. 87 change blocks. 
354 lines changed or deleted 381 lines changed or added

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