Internet Engineering Task Force (IETF)                          F. MainoRequest for Comments: 9303                                 Cisco SystemsCategory: Standards Track                                     V. ErmaganISSN: 2070-1721                                             Google, Inc.                                                             A. Cabellos                                    Universitat Politecnica de Catalunya                                                               D. Saucez                                                                   Inria                                                            October 2022           Locator/ID Separation Protocol Security (LISP-SEC)Abstract   This memo specifies Locator/ID Separation Protocol Security (LISP-   SEC), a set of security mechanisms that provides origin   authentication, integrity, and anti-replay protection to the LISP's   Endpoint-ID-to-Routing-Locator (EID-to-RLOC) mapping data conveyed   via the mapping lookup process.  LISP-SEC also enables verification   of authorization on EID-Prefix claims in Map-Reply messages.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available in Section 2 of RFC 7841.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained at   https://www.rfc-editor.org/info/rfc9303.Copyright Notice   Copyright (c) 2022 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject to BCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (https://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Revised BSD License text as described in Section 4.e of the   Trust Legal Provisions and are provided without warranty as described   in the Revised BSD License.Table of Contents   1.  Introduction   2.  Requirements Notation   3.  Definitions of Terms   4.  LISP-SEC Threat Model   5.  Protocol Operations   6.  LISP-SEC Control Messages Details     6.1.  Encapsulated Control Message LISP-SEC Extensions     6.2.  Map-Reply LISP-SEC Extensions     6.3.  Map-Register LISP-SEC Extensions     6.4.  ITR Processing: Generating a Map-Request     6.5.  Encrypting and Decrypting an OTK       6.5.1.  Unencrypted OTK     6.6.  Map-Resolver Processing     6.7.  Map-Server Processing       6.7.1.  Generating a LISP-SEC-Protected Encapsulated               Map-Request       6.7.2.  Generating a Proxy Map-Reply     6.8.  ETR Processing     6.9.  ITR Processing: Receiving a Map-Reply       6.9.1.  Map-Reply Record Validation   7.  Security Considerations     7.1.  Mapping System Security     7.2.  Random Number Generation     7.3.  Map-Server and ETR Colocation     7.4.  Deploying LISP-SEC     7.5.  Shared Keys Provisioning     7.6.  Replay Attacks     7.7.  Message Privacy     7.8.  Denial-of-Service and Distributed Denial-of-Service Attacks   8.  IANA Considerations     8.1.  ECM AD Type Registry     8.2.  Map-Reply AD Types Registry     8.3.  HMAC Functions     8.4.  Key Wrap Functions     8.5.  Key Derivation Functions   9.  References     9.1.  Normative References     9.2.  Informative References   Acknowledgments   Authors' Addresses1.  Introduction   The Locator/ID Separation Protocol (LISP) [RFC9300] [RFC9301] is a   network-layer-based protocol that enables separation of IP addresses   into two new numbering spaces: Endpoint Identifiers (EIDs) and   Routing Locators (RLOCs).  EID-to-RLOC mappings are stored in a   database and the LISP Mapping System, and they are made available via   the Map-Request/Map-Reply lookup process.  If these EID-to-RLOC   mappings, carried through Map-Reply messages, are transmitted without   integrity protection, an adversary can manipulate them and hijack the   communication, impersonate the requested EID, or mount Denial-of-   Service (DoS) or Distributed Denial-of-Service (DDoS) attacks.  Also,   if the Map-Reply message is transported unauthenticated, an   adversarial LISP entity can overclaim an EID-Prefix and maliciously   redirect traffic.  The LISP-SEC threat model, described in Section 4,   is built on top of the LISP threat model defined in [RFC7835], which   includes a detailed description of an "overclaiming" attack.   This memo specifies LISP-SEC, a set of security mechanisms that   provides origin authentication, integrity, and anti-replay protection   to LISP's EID-to-RLOC mapping data conveyed via the mapping lookup   process.  LISP-SEC also enables verification of authorization on EID-   Prefix claims in Map-Reply messages, ensuring that the sender of a   Map-Reply that provides the location for a given EID-Prefix is   entitled to do so according to the EID-Prefix registered in the   associated Map-Server.  Map-Register/Map-Notify security, including   the right for a LISP entity to register an EID-Prefix or to claim   presence at an RLOC, is out of the scope of LISP-SEC, as those   protocols are protected by the security mechanisms specified in   [RFC9301].  However, LISP-SEC extends the Map-Register message to   allow an Ingress Tunnel Router (ITR) to downgrade to non-LISP-SEC   Map-Requests.  Additional security considerations are described in   Section 7.2.  Requirements Notation   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and   "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.3.  Definitions of Terms   One-Time Key (OTK):  An ephemeral randomly generated key that must be      used for a single Map-Request/Map-Reply exchange.   ITR One-Time Key (ITR-OTK):  The One-Time Key generated at the      Ingress Tunnel Router (ITR).   MS One-Time Key (MS-OTK):  The One-Time Key generated at the Map-      Server.   Authentication Data (AD):  Metadata that is included either in a LISP      Encapsulated Control Message (ECM) header as defined in [RFC9301],      or in a Map-Reply message to support confidentiality, integrity      protection, and verification of EID-Prefix authorization.   OTK Authentication Data (OTK-AD):  The portion of ECM Authentication      Data that contains a One-Time Key.   EID Authentication Data (EID-AD):  The portion of ECM and Map-Reply      Authentication Data used for verification of EID-Prefix      authorization.   Packet Authentication Data (PKT-AD):  The portion of Map-Reply      Authentication Data used to protect the integrity of the Map-Reply      message.   For definitions of other terms, notably Map-Request, Map-Reply,   Ingress Tunnel Router (ITR), Egress Tunnel Router (ETR), Map-Server   (MS), and Map-Resolver (MR), please consult the LISP specification   [RFC9301].4.  LISP-SEC Threat Model   LISP-SEC addresses the control plane threats, described in Sections   3.7 and 3.8 of [RFC7835], that target EID-to-RLOC mappings, including   manipulations of Map-Request and Map-Reply messages and malicious ETR   EID-Prefix overclaiming.  LISP-SEC makes two main assumptions: (1)   the LISP Mapping System is expected to deliver a Map-Request message   to their intended destination ETR as identified by the EID, and (2)   no on-path attack can be mounted within the LISP Mapping System.  How   the Mapping System is protected from on-path attacks depends on the   particular Mapping System used and is out of the scope of this memo.   Furthermore, while LISP-SEC enables detection of EID-Prefix   overclaiming attacks, it assumes that Map-Servers can verify the EID-   Prefix authorization at registration time.   According to the threat model described in [RFC7835], LISP-SEC   assumes that any kind of attack, including on-path attacks, can be   mounted outside of the boundaries of the LISP Mapping System.  An on-   path attacker outside of the LISP Mapping System can, for example,   hijack Map-Request and Map-Reply messages, spoofing the identity of a   LISP node.  Another example of an on-path attack, called an   overclaiming attack, can be mounted by a malicious ETR by   overclaiming the EID-Prefixes for which it is authoritative.  In this   way, the ETR can maliciously redirect traffic.5.  Protocol Operations   The goal of the security mechanisms defined in [RFC9301] is to   prevent unauthorized insertion of mapping data by providing origin   authentication and integrity protection for the Map-Register and by   using the nonce to detect an unsolicited Map-Reply sent by off-path   attackers.   LISP-SEC builds on top of the security mechanisms defined in   [RFC9301] to address the threats described in Section 4 by leveraging   the trust relationships existing among the LISP entities [RFC9301]   participating in the exchange of the Map-Request/Map-Reply messages.   Those trust relationships (see also Section 7 and [RFC9301]) are used   to securely distribute, as described in Section 8.4, a per-message   One-Time Key (OTK) that provides origin authentication, integrity,   and anti-replay protection to mapping data conveyed via the mapping   lookup process and that effectively prevents overclaiming attacks.   The processing of security parameters during the Map-Request/Map-   Reply exchange is as follows:   *  Per each Map-Request message, a new ITR-OTK is generated and      stored at the ITR and is securely transported to the Map-Server.   *  The Map-Server uses the ITR-OTK to compute a Hashed Message      Authentication Code (HMAC) [RFC2104] that protects the integrity      of the mapping data known to the Map-Server to prevent      overclaiming attacks.  The Map-Server also derives a new OTK, the      MS-OTK, that is passed to the ETR by applying a Key Derivation      Function (KDF) (e.g., [RFC5869]) to the ITR-OTK.   *  The ETR uses the MS-OTK to compute an HMAC that protects the      integrity of the Map-Reply sent to the ITR.   *  Finally, the ITR uses the stored ITR-OTK to verify the integrity      of the mapping data provided by both the Map-Server and the ETR,      and to verify that no overclaiming attacks were mounted along the      path between the Map-Server and the ITR.   Section 6 provides the detailed description of the LISP-SEC control   messages and their processing, while the rest of this section   describes the flow of LISP protocol operations at each entity   involved in the Map-Request/Map-Reply exchange:   1.  The ITR, upon needing to transmit a Map-Request message,       generates and stores an OTK (ITR-OTK).  This ITR-OTK is encrypted       and included into the Encapsulated Control Message (ECM) that       contains the Map-Request sent to the Map-Resolver.   2.  The Map-Resolver decapsulates the ECM, decrypts the ITR-OTK (if       needed), and forwards through the Mapping System the received       Map-Request and the ITR-OTK, as part of a new ECM.  The LISP       Mapping System delivers the ECM to the appropriate Map-Server, as       identified by the EID destination address of the Map-Request.   3.  The Map-Server is configured with the location mappings and       policy information for the ETR responsible for the EID       destination address.  Using this preconfigured information, the       Map-Server, after the decapsulation of the ECM, finds the       longest-match EID-Prefix that covers the requested EID in the       received Map-Request.  The Map-Server adds this EID-Prefix,       together with an HMAC computed using the ITR-OTK, to a new ECM       that contains the received Map-Request.   4.  The Map-Server derives a new OTK, the MS-OTK, by applying a KDF       to the ITR-OTK.  This MS-OTK is included in the ECM that the Map-       Server uses to forward the Map-Request to the ETR.   5.  If the Map-Server is acting in proxy mode, as specified in       [RFC9301], the ETR is not involved in the generation of the Map-       Reply and steps 6 and 7 are skipped.  In this case, the Map-       Server generates the Map-Reply on behalf of the ETR, as described       in Section 6.7.2.   6.  The ETR, upon receiving the ECM-Encapsulated Map-Request from the       Map-Server, decrypts the MS-OTK (if needed), and originates a       Map-Reply that contains the EID-to-RLOC mapping information as       specified in [RFC9301].   7.  The ETR computes an HMAC over the Map-Reply, keyed with MS-OTK to       protect the integrity of the whole Map-Reply.  The ETR also       copies the EID-Prefix authorization data that the Map-Server       included in the ECM-Encapsulated Map-Request into the Map-Reply       message.  The ETR then sends the complete Map-Reply message to       the requesting ITR.   8.  The ITR, upon receiving the Map-Reply, uses the locally stored       ITR-OTK to verify the integrity of the EID-Prefix authorization       data included in the Map-Reply by the Map-Server.  The ITR       computes the MS-OTK by applying the same KDF (as specified in the       ECM-Encapsulated Map-Reply) used by the Map-Server and verifies       the integrity of the Map-Reply.6.  LISP-SEC Control Messages Details   LISP-SEC metadata associated with a Map-Request is transported within   the Encapsulated Control Message that contains the Map-Request.   LISP-SEC metadata associated with the Map-Reply is transported within   the Map-Reply itself.   These specifications use an HMAC in various places (as described in   the following).  The HMAC function AUTH-HMAC-SHA-256-128 [RFC6234]   MUST be supported in LISP-SEC implementations.  LISP-SEC deployments   SHOULD use the AUTH-HMAC-SHA-256-128 HMAC function, except when   communicating with older implementations that only support AUTH-HMAC-   SHA-1-96 [RFC2104].6.1.  Encapsulated Control Message LISP-SEC Extensions   LISP-SEC uses the ECM defined in [RFC9301] with the S-bit set to 1 to   indicate that the LISP header includes Authentication Data (AD).  The   format of the LISP-SEC ECM AD is defined in Figure 1.  OTK-AD stands   for One-Time Key Authentication Data and EID-AD stands for EID   Authentication Data.  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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |  ECM AD Type  |   Unassigned  |        Requested HMAC ID      | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\ |              OTK Length       |     Key ID    | OTK Wrap. ID  | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |                       One-Time-Key Preamble ...               | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+OTK-AD |                   ... One-Time-Key Preamble                   | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ~                      One-Time Key (128 bits)                  ~/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+ |           EID-AD Length       |           KDF ID              |     | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+     | | Record Count  |E| Unassigned  |         EID HMAC ID           |EID-AD +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\    | |  Unassigned   | EID mask-len  |           EID-AFI             | |   | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rec | ~                          EID-Prefix ...                       ~ |   | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/    | ~                            EID HMAC                           ~     | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+               Figure 1: LISP-SEC ECM Authentication Data   ECM AD Type:  1 (LISP-SEC Authentication Data).  See Section 8.   Unassigned:  Set to 0 on transmission and ignored on receipt.   Requested HMAC ID:  The HMAC algorithm, which will be used to protect      the mappings, requested by the ITR.  Permitted values are      registered in the LISP-SEC Authentication Data HMAC ID (see      Section 8.3).  Refer to Section 6.4 for more details.   OTK Length:  The length (in bytes) of the OTK Authentication Data      (OTK-AD), which contains the OTK Preamble and the OTK.   Key ID:  The identifier of the pre-shared secret shared by an ITR and      the Map-Resolver, and by the Map-Server and an ETR.  Per-message      keys are derived from the pre-shared secret to encrypt,      authenticate the origin, and protect the integrity of the OTK.      The Key ID allows to rotate between multiple pre-shared secrets in      a nondisruptive way.   OTK Wrapping ID (OTK Wrap. ID):  The identifier of the Key Derivation      Function and of the key wrapping algorithm used to encrypt the      One-Time-Key. Permitted values are registered in the LISP-SEC      Authentication Data Key Wrap ID (see Section 8.4).  Refer to      Section 6.5 for more details.   One-Time-Key Preamble:  Set to 0 if the OTK is not encrypted.  When      the OTK is encrypted, this field MAY carry additional metadata      resulting from the key wrapping operation.  When a 128-bit OTK is      sent unencrypted by a Map-Resolver, the OTK Preamble is set to      0x0000000000000000 (64 bits).  See Section 6.5.1 for details.   One-Time-Key:  The OTK wrapped as specified by OTK Wrapping ID.  See      Section 6.5 for details.   EID-AD Length:  Length (in bytes) of the EID Authentication Data      (EID-AD).  The ITR MUST set the EID-AD Length to 4 bytes, as it      only fills the 'KDF ID' field, and all the remaining fields part      of the EID-AD are not present.  An EID-AD MAY contain multiple      EID-Records.  Each EID-Record is 4 bytes long, plus the length of      the AFI-encoded EID-Prefix.   KDF ID:  Identifier of the Key Derivation Function used to derive the      MS-OTK.  Permitted values are registered in the LISP-SEC      Authentication Data Key Derivation Function ID (see Section 8.5).      Refer to Section 6.7 for more details.   Record Count:  As defined in Section 5.2 of [RFC9301].   E:  ETR-Cant-Sign bit.  If this bit is set to 1, it signals to the      ITR that at least one of the ETRs that is authoritative for the      EID-Prefixes of this Map-Reply has not enabled LISP-SEC.  Only a      Map-Server can set this bit.  See Section 6.7 for more details.   Unassigned:  Set to 0 on transmission and ignored on receipt.   EID HMAC ID:  Identifier of the HMAC algorithm used to protect the      integrity of the EID-AD.  This field is filled by the Map-Server      that computed the EID-Prefix HMAC.  See Section 6.7.1 for more      details.   EID mask-len:  As defined in Section 5.2 of [RFC9301].   EID-AFI:  As defined in Section 5.2 of [RFC9301].   EID-Prefix:  As defined in Section 5.2 of [RFC9301].   EID HMAC:  HMAC of the EID-AD computed and inserted by a Map-Server.      See Section 6.7.1 for more details.6.2.  Map-Reply LISP-SEC Extensions   LISP-SEC uses the Map-Reply defined in [RFC9301], with Type set to 2   and S-bit set to 1 to indicate that the Map-Reply message includes   Authentication Data (AD).  The format of the LISP-SEC Map-Reply   Authentication Data is defined in Figure 2.  PKT-AD is the Packet   Authentication Data that covers the Map-Reply payload.  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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |  MR AD Type   |                Unassigned                     | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+ |           EID-AD Length       |           KDF ID              |     | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+     | | Record Count  |   Unassigned  |         EID HMAC ID           |EID-AD +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\    | |  Unassigned   | EID mask-len  |           EID-AFI             | |   | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rec | ~                          EID-Prefix ...                       ~ |   | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/    | ~                            EID HMAC                           ~     | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+ |         PKT-AD Length         |         PKT HMAC ID           |\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ~                            PKT HMAC                           ~PKT-AD +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/            Figure 2: LISP-SEC Map-Reply Authentication Data   MR AD Type:  1 (LISP-SEC Authentication Data).  See Section 8.   EID-AD Length:  Length (in bytes) of the EID-AD (see Section 6.1).   KDF ID:  Identifier of the Key Derivation Function used to derive MS-      OTK (see Section 6.1).   Record Count:  The number of records in this Map-Reply message (see      Section 6.1).   Unassigned:  Set to 0 on transmission and ignored on receipt.   EID HMAC ID:  Identifier of the HMAC algorithm used to protect the      integrity of the EID-AD (see Section 6.1).   EID mask-len:  Mask length for EID-Prefix (see Section 6.1).   EID-AFI:  See Section 6.1.   EID-Prefix:  See Section 6.1.   EID HMAC:  See Section 6.1.   PKT-AD Length:  Length (in bytes) of the Packet Authentication Data      (PKT-AD).   PKT HMAC ID:  Identifier of the HMAC algorithm used to protect the      integrity of the Map-Reply (see Section 6.5).   PKT HMAC:  HMAC of the whole Map-Reply packet to protect its      integrity, including the LISP-SEC Authentication Data (from the      'Map-Reply Type' field to the 'PKT HMAC' field), which allow      message authentication.6.3.  Map-Register LISP-SEC Extensions   The S-bit in the Map-Register message (see [RFC9301]) indicates to   the Map-Server that the registering ETR is LISP-SEC enabled.  An ETR   that supports LISP-SEC MUST set the S-bit in its Map-Register   messages.6.4.  ITR Processing: Generating a Map-Request   Upon creating a Map-Request, the ITR generates a random ITR-OTK that   is stored locally, until the corresponding Map-Reply is received (see   Section 6.9), together with the nonce generated as specified in   [RFC9301].   The ITR MAY use the 'KDF ID' field to indicate the recommended KDF   algorithm according to local policy.  The Map-Server can overwrite   the KDF ID if it does not support the KDF ID recommended by the ITR   (see Section 6.7).  A KDF value of NOPREF (0) may be used to specify   that the ITR has no preferred KDF ID.   ITR-OTK confidentiality and integrity protection MUST be provided in   the path between the ITR and the Map-Resolver.  This can be achieved   either by encrypting the ITR-OTK with the pre-shared secret known to   the ITR and the Map-Resolver (see Section 6.5) or by enabling DTLS   [RFC9147] between the ITR and the Map-Resolver.   The Map-Request (as defined in [RFC9301]) MUST be encapsulated as a   LISP Control Message in an ECM, with the S-bit set to 1, to indicate   the presence of Authentication Data.  Such a message is also called a   "Protected Map-Request" in this memo.   The ITR-OTK is wrapped with the algorithm specified by the 'OTK   Wrapping ID' field.  See Section 6.5 for further details on OTK   encryption.  If the NULL-KEY-WRAP-128 algorithm (see Section 8.4) is   selected, and no other encryption mechanism (e.g., DTLS) is enabled   in the path between the ITR and the Map-Resolver, the Map-Request   MUST be dropped, and an appropriate log action SHOULD be taken.   Implementations may include mechanisms (which are beyond the scope of   this document) to avoid log resource exhaustion attacks.   The 'Requested HMAC ID' field contains the suggested HMAC algorithm   to be used by the Map-Server and the ETR to protect the integrity of   the ECM Authentication Data and of the Map-Reply.  A HMAC ID value of   NONE (0) MAY be used to specify that the ITR has no preferred HMAC   ID.   The 'KDF ID' field specifies the suggested Key Derivation Function to   be used by the Map-Server to derive the MS-OTK.  A KDF value of NONE   (0) may be used to specify that the ITR has no preferred KDF ID.   The EID-AD Length is set to 4 bytes, since the Authentication Data   does not contain EID-Prefix Authentication Data, and the EID-AD   contains only the 'KDF ID' field.   If the ITR is directly connected to a Mapping System, such as   LISP+ALT [RFC6836], it performs the functions of both the ITR and the   Map-Resolver, forwarding the Protected Map-Request as described in   Section 6.6.   The processing performed by Proxy ITRs (PITRs) is equivalent to the   processing of an ITR; hence, the procedure described above applies.6.5.  Encrypting and Decrypting an OTK   MS-OTK confidentiality and integrity protection MUST be provided in   the path between the Map-Server and the ETR.  This can be achieved   either by enabling DTLS between the Map-Server and the ETR or by   encrypting the MS-OTK with the pre-shared secret known to the Map-   Server and the ETR [RFC9301].   Similarly, ITR-OTK confidentiality and integrity protection MUST be   provided in the path between the ITR and the Map-Resolver.  This can   be achieved either by enabling DTLS between the Map-Server and the   ITR or by encrypting the ITR-OTK with the pre-shared secret known to   the ITR and the Map-Resolver.  The ITR/Map-Resolver pre-shared key is   similar to the Map-Server/ETR pre-shared key.   This section describes OTK processing in the ITR/Map-Resolver path,   as well as in the Map-Server/ETR path.   It's important to note that, to prevent ETR's overclaiming attacks,   the ITR/Map-Resolver pre-shared secret MUST be independent from the   Map-Server/ETR pre-shared secret.   The OTK is wrapped using the algorithm specified in the 'OTK Wrapping   ID' field.  This field identifies both the:   *  Key Encryption Algorithm used to encrypt the wrapped OTK and   *  Key Derivation Function used to derive a per-message encryption      key.   Implementations of this specification MUST support the OTK Wrapping   ID AES-KEY-WRAP-128+HKDF-SHA256, which specifies the use of the HKDF-   SHA256 Key Derivation Function specified in [RFC5869] to derive a   per-message encryption key (per-msg-key), as well as the AES-KEY-   WRAP-128 key wrap algorithm used to encrypt a 128-bit OTK, according   to [RFC3394].   Implementations of this specification MUST support OTK Wrapping NULL-   KEY-WRAP-128.  NULL-KEY-WRAP-128 is used to carry an unencrypted   128-bit OTK, with a 64-bit preamble set to 0x0000000000000000 (64   bits).   The key wrapping process for OTK Wrapping ID AES-KEY-WRAP-128+HKDF-   SHA256 is described below:   1.  The KDF and key wrap algorithms are identified by the value of       the 'OTK Wrapping ID' field.  The initial values are documented       in Table 5.   2.  If the NULL-KEY-WRAP-128 algorithm (see Section 8.4) is selected       and DTLS is not enabled, the Map-Request MUST be dropped and an       appropriate log action SHOULD be taken.  Implementations may       include mechanisms (which are beyond the scope of this document)       to avoid log resource exhaustion attacks.   3.  The pre-shared secret used to derive the per-msg-key is       represented by PSK[Key ID], which is the pre-shared secret       identified by the 'Key ID'.   4.  The 128-bit-long per-message encryption key is computed as:          per-msg-key = KDF( nonce + s + PSK[Key ID] )       where the nonce is the value in the 'Nonce' field of the Map-       Request, 's' is the string "OTK-Key-Wrap", and the operation'+'       just indicates string concatenation.   5.  The per-msg-key is then used to wrap the OTK with AES-KEY-WRAP-       128, as specified in Section 2.2.1 of [RFC3394].  The AES Key       Wrap Initialization Value MUST be set to 0xA6A6A6A6A6A6A6A6 (64       bits).  The output of the AES key wrap operation is 192 bits       long.  The most significant 64 bits are copied in the 'One-Time       Key Preamble' field, while the 128 least significant bits are       copied in the 'One-Time Key' field of the LISP-SEC Authentication       Data.   When decrypting an encrypted OTK, the receiver MUST verify that the   Initialization Value resulting from the AES key wrap decryption   operation is equal to 0xA6A6A6A6A6A6A6A6.  If this verification   fails, the receiver MUST discard the entire message.6.5.1.  Unencrypted OTK   However, when DTLS is enabled, the OTK MAY be sent unencrypted as   transport layer security is providing confidentiality and integrity   protection.   When a 128-bit OTK is sent unencrypted, the OTK Wrapping ID is set to   NULL_KEY_WRAP_128, and the OTK Preamble is set to 0x0000000000000000   (64 bits).6.6.  Map-Resolver Processing   Upon receiving a Protected Map-Request, the Map-Resolver decapsulates   the ECM.  The ITR-OTK, if encrypted, is decrypted as specified in   Section 6.5.   Protecting the confidentiality of the ITR-OTK and, in general, the   security of how the Map-Request is handed by the Map-Resolver to the   Map-Server is specific to the particular Mapping System used and is   outside of the scope of this memo.   In Mapping Systems where the Map-Server is compliant with [RFC9301],   the Map-Resolver originates a new ECM header with the S-bit set,   which contains the unencrypted ITR-OTK, as specified in Section 6.5,   and the other data derived from the ECM Authentication Data of the   received Encapsulated Map-Request.   The Map-Resolver then forwards to the Map-Server the received Map-   Request, which is encapsulated in the new ECM header that includes   the newly computed 'Authentication Data' fields.6.7.  Map-Server Processing   Upon receiving a Protected Map-Request, the Map-Server processes it   according to the setting of the S-bit and the P-bit in the Map-   Register received from the ETRs authoritative for that prefix, as   described below.   While processing the Map-Request, the Map-Server can overwrite the   'KDF ID' field if it does not support the KDF ID recommended by the   ITR.  Processing of the Map-Request MUST proceed in the order   described in the table below, applying the process corresponding to   the first rule that matches the conditions indicated in the first   column:    +=================+==============================================+    | Matching        | Processing                                   |    | Condition       |                                              |    +=================+==============================================+    | 1.  At least    | The Map-Server MUST generate a LISP-SEC-     |    | one of the ETRs | protected Map-Reply, as specified in         |    | authoritative   | Section 6.7.2.  The ETR-Cant-Sign E-bit in   |    | for the EID-    | the EID Authentication Data (EID-AD) MUST be |    | Prefix included | set to 0.                                    |    | in the Map-     |                                              |    | Request         |                                              |    | registered with |                                              |    | the P-bit set   |                                              |    | to 1            |                                              |    +-----------------+----------------------------------------------+    | 2.  At least    | The Map-Server MUST generate a LISP-SEC-     |    | one of the ETRs | protected Encapsulated Map-Request (as       |    | authoritative   | specified in Section 6.7.1) to be sent to    |    | for the EID-    | one of the authoritative ETRs that           |    | Prefix included | registered with the S-bit set to 1 (and the  |    | in the Map-     | P-bit set to 0).  If there is at least one   |    | Request         | ETR that registered with the S-bit set to 0, |    | registered with | the ETR-Cant-Sign E-bit of the EID-AD MUST   |    | the S-bit set   | be set to 1 to signal the ITR that a non-    |    | to 1            | LISP-SEC Map-Request might reach additional  |    |                 | ETRs that have LISP-SEC disabled.            |    +-----------------+----------------------------------------------+    | 3.  All the     | The Map-Server MUST send a Negative Map-     |    | ETRs            | Reply protected with LISP-SEC, as described  |    | authoritative   | in Section 6.7.2.  The ETR-Cant-Sign E-bit   |    | for the EID-    | MUST be set to 1 to signal the ITR that a    |    | Prefix included | non-LISP-SEC Map-Request might reach         |    | in the Map-     | additional ETRs that have LISP-SEC disabled. |    | Request         |                                              |    | registered with |                                              |    | the S-bit set   |                                              |    | to 0            |                                              |    +-----------------+----------------------------------------------+                     Table 1: Map-Request Processing   In this way, the ITR that sent a LISP-SEC-protected Map-Request   always receives a LISP-SEC-protected Map-Reply.  However, the ETR-   Cant-Sign E-bit set to 1 specifies that a non-LISP-SEC Map-Request   might reach additional ETRs that have LISP-SEC disabled.  This   mechanism allows the ITR to downgrade to non-LISP-SEC requests, which   does not protect against threats described in Section 4.6.7.1.  Generating a LISP-SEC-Protected Encapsulated Map-Request   The Map-Server decapsulates the ECM and generates new ECM   Authentication Data.  The Authentication Data includes the OTK-AD and   the EID-AD, which contains EID-Prefix authorization information that   are eventually received by the requesting ITR.   The Map-Server updates the OTK-AD by deriving a new OTK (MS-OTK) from   the ITR-OTK received with the Map-Request.  MS-OTK is derived by   applying the Key Derivation Function specified in the 'KDF ID' field.   If the algorithm specified in the 'KDF ID' field is not supported,   the Map-Server uses a different algorithm to derive the key and   updates the 'KDF ID' field accordingly.   The Map-Request MUST be encapsulated in an ECM, with the S-bit set to   1, to indicate the presence of Authentication Data.   MS-OTK is wrapped with the algorithm specified by the 'OTK Wrapping   ID' field.  See Section 6.5 for further details on OTK encryption.   If the NULL-KEY-WRAP-128 algorithm is selected and DTLS is not   enabled in the path between the Map-Server and the ETR, the Map-   Request MUST be dropped and an appropriate log action SHOULD be   taken.   In the EID-AD, the Map-Server includes in the EID-AD the longest-   match-registered EID-Prefix for the destination EID and an HMAC of   this EID-Prefix.  The HMAC is keyed with the ITR-OTK contained in the   received ECM Authentication Data, and the HMAC algorithm is chosen   according to the 'Requested HMAC ID' field.  If the Map-Server does   not support this algorithm, the Map-Server uses a different algorithm   and specifies it in the 'EID HMAC ID' field.  The scope of the HMAC   operation MUST cover the entire EID-AD, from the 'EID-AD Length'   field to the 'EID HMAC' field, which MUST be set to 0 before the   computation.   The Map-Server then forwards the updated ECM-Encapsulated Map-   Request, which contains the OTK-AD, the EID-AD, and the received Map-   Request to an authoritative ETR as specified in [RFC9301].6.7.2.  Generating a Proxy Map-Reply   A LISP-SEC proxy Map-Reply is generated according to [RFC9301], with   the Map-Reply S-bit set to 1.  The Map-Reply includes the   Authentication Data that contains the EID-AD computed as specified in   Section 6.7.1, as well as the PKT-AD computed as specified in   Section 6.8.6.8.  ETR Processing   Upon receiving an ECM-Encapsulated Map-Request with the S-bit set,   the ETR decapsulates the ECM.  The 'OTK' field, if encrypted, is   decrypted as specified in Section 6.5 to obtain the unencrypted MS-   OTK.   The ETR then generates a Map-Reply as specified in [RFC9301] and   includes the Authentication Data that contains the EID-AD, as   received in the Encapsulated Map-Request, as well as the PKT-AD.   The EID-AD is copied from the Authentication Data of the received   Encapsulated Map-Request.   The PKT-AD contains the HMAC of the whole Map-Reply packet, keyed   with the MS-OTK and computed using the HMAC algorithm specified in   the 'Requested HMAC ID' field of the received Encapsulated Map-   Request.  If the ETR does not support the Requested HMAC ID, it uses   a different algorithm and updates the 'PKT HMAC ID' field   accordingly.  The HMAC operation MUST cover the entire Map-Reply,   where the 'PKT HMAC' field MUST be set to 0 before the computation.   Finally, the ETR sends the Map-Reply to the requesting ITR as   specified in [RFC9301].6.9.  ITR Processing: Receiving a Map-Reply   In response to a Protected Map-Request, an ITR expects a Map-Reply   with the S-bit set to 1, including an EID-AD and a PKT-AD.  The ITR   MUST discard the Map-Reply otherwise.   Upon receiving a Map-Reply, the ITR must verify the integrity of both   the EID-AD and the PKT-AD and MUST discard the Map-Reply if one of   the integrity checks fails.  After processing the Map-Reply, the ITR   MUST discard the <nonce,ITR-OTK> pair associated to the Map-Reply.   The integrity of the EID-AD is verified using the ITR-OTK (stored   locally for the duration of this exchange) to recompute the HMAC of   the EID-AD using the algorithm specified in the 'EID HMAC ID' field.   If the ITR did indicate a Requested HMAC ID in the Map-Request and   the PKT HAMC ID in the corresponding Map-Reply is different, or if   the ITR did not indicate a Requested HMAC ID in the Map-Request and   the PKT HMAC ID in the corresponding Map-Reply is not supported, then   the ITR MUST discard the Map-Reply and send, according to rate-   limitation policies defined in [RFC9301], a new Map-Request with a   different 'Requested HMAC ID' field, according to ITR's local policy.   The scope of the HMAC operation covers the entire EID-AD, from the   'EID-AD Length' field to the 'EID HMAC' field.   ITR MUST set the 'EID HMAC ID' field to 0 before computing the HMAC.   To verify the integrity of the PKT-AD, first the MS-OTK is derived   from the locally stored ITR-OTK using the algorithm specified in the   'KDF ID' field.  This is because the PKT-AD is generated by the ETR   using the MS-OTK.  If the ITR did indicate a recommended KDF ID in   the Map-Request and the KDF ID in the corresponding Map-Reply is   different or if the ITR did not indicate a recommended KDF ID in the   Map-Request and the KDF ID in the corresponding Map-Reply is not   supported, then the ITR MUST discard the Map-Reply and send,   according to rate-limitation policies defined in [RFC9301], a new   Map-Request with a different KDF ID, according to ITR's local policy.   The Key Derivation Function HKDF-SHA256 MUST be supported in LISP-SEC   implementations.  LISP-SEC deployments SHOULD use the HKDF-SHA256   HKDF function, unless older implementations using HKDF-SHA1-128 are   present in the same deployment.  Without consistent configuration of   involved entities, extra delays may be experienced.  However, since   HKDF-SHA1-128 and HKDF-SHA256 are supported, the process will   eventually converge.   The derived MS-OTK is then used to recompute the HMAC of the PKT-AD   using the algorithm specified in the 'PKT HMAC ID' field.  If the   'PKT HMAC ID' field does not match the Requested HMAC ID, the ITR   MUST discard the Map-Reply and send, according to rate-limitation   policies defined in [RFC9301], a new Map-Request with a different   Requested HMAC ID, according to ITR's local policy or until all HMAC   IDs supported by the ITR have been attempted.  When the 'PKT HMAC ID'   field does not match the Requested HMAC ID, it is not possible to   validate the Map-Reply.   Each individual Map-Reply EID-Record is considered valid only if: (1)   both EID-AD and PKT-AD are valid and (2) the intersection of the EID-   Prefix in the Map-Reply EID-Record with one of the EID-Prefixes   contained in the EID-AD is not empty.  After identifying the Map-   Reply record as valid, the ITR sets the EID-Prefix in the Map-Reply   record to the value of the intersection set computed before and adds   the Map-Reply EID-Record to its EID-to-RLOC Map-Cache, as described   in [RFC9301].  An example of Map-Reply record validation is provided   in Section 6.9.1.   [RFC9301] allows ETRs to send Solicit-Map-Requests (SMRs) directly to   the ITR.  The corresponding SMR-invoked Map-Request will be sent   through the Mapping System, hence, secured with the specifications of   this memo if in use.  If an ITR accepts Map-Replies piggybacked in   Map-Requests and its content is not already present in its EID-to-   RLOC Map-Cache, it MUST send a Map-Request over the Mapping System in   order to verify its content with a secured Map-Reply before using the   content.6.9.1.  Map-Reply Record Validation   The payload of a Map-Reply may contain multiple EID-Records.  The   whole Map-Reply is signed by the ETR, with the PKT HMAC, to provide   integrity protection and origin authentication to the EID-Prefix   records claimed by the ETR.  The 'Authentication Data' field of a   Map-Reply may contain multiple EID-Records in the EID-AD.  The EID-AD   is signed by the Map-Server, with the EID HMAC, to provide integrity   protection and origin authentication to the EID-Prefix records   inserted by the Map-Server.   Upon receiving a Map-Reply with the S-bit set, the ITR first checks   the validity of both the EID HMAC and of the PKT-AD HMAC.  If either   one of the HMACs is not valid, a log action SHOULD be taken and the   Map-Reply MUST NOT be processed any further.  Implementations may   include mechanisms (which are beyond the scope of this document) to   avoid log resource exhaustion attacks.  If both HMACs are valid, the   ITR proceeds with validating each individual EID-Record claimed by   the ETR by computing the intersection of each one of the EID-Prefixes   contained in the payload of the Map-Reply, with each one of the EID-   Prefixes contained in the EID-AD.  An EID-Record is valid only if at   least one of the intersections is not the empty set; otherwise, a log   action MUST be taken and the EID-Record MUST be discarded.   Implementations may include mechanisms (which are beyond the scope of   this document) to avoid log resource exhaustion attacks.   For instance, the Map-Reply payload contains 3 mapping record EID-   Prefixes:      2001:db8:102::/48      2001:db8:103::/48      2001:db8:200::/40   The EID-AD contains two EID-Prefixes:      2001:db8:103::/48      2001:db8:203::/48   The EID-Record with EID-Prefix 2001:db8:102::/48 is not eligible to   be used by the ITR, since it is not included in any of the EID-ADs   signed by the Map-Server.  A log action MUST be taken, and the EID-   Record MUST be discarded.  Implementations may include mechanisms   (which are beyond the scope of this document) to avoid log resource   exhaustion attacks.   The EID-Record with EID-Prefix 2001:db8:103::/48 is eligible to be   used by the ITR because it matches the second EID-Prefix contained in   the EID-AD.   The EID-Record with EID-Prefix 2001:db8:200::/40 is not eligible to   be used by the ITR, since it is not included in any of the EID-ADs   signed by the Map-Server.  A log action MUST be taken and the EID-   Record MUST be discarded.  Implementations may include mechanisms   (which are beyond the scope of this document) to avoid log resource   exhaustion attacks.  In this last example, the ETR is trying to over   claim the EID-Prefix 2001:db8:200::/40, but the Map-Server authorized   only 2001:db8:203::/48; hence, the EID-Record is discarded.7.  Security Considerations   This document extends the LISP control plane defined in [RFC9301];   hence, its security considerations apply to this document as well.7.1.  Mapping System Security   The LISP-SEC threat model described in Section 4 assumes that the   LISP Mapping System is working properly and delivers Map-Request   messages to a Map-Server that is authoritative for the requested EID.   It is assumed that the Mapping System ensures the confidentiality of   the OTK and the integrity of the Map-Reply data.  However, how the   LISP Mapping System is secured is out of the scope of this document.   Similarly, Map-Register security, including the right for a LISP   entity to register an EID-Prefix or to claim presence at an RLOC, is   out of the scope of LISP-SEC.7.2.  Random Number Generation   The ITR-OTK MUST be generated by a properly seeded pseudo-random (or   strong random) source.  See [RFC4086] for advice on generating   security-sensitive random data.7.3.  Map-Server and ETR Colocation   If the Map-Server and the ETR are colocated, LISP-SEC does not   provide protection from overclaiming attacks mounted by the ETR.   However, in this particular case, since the ETR is within the trust   boundaries of the Map-Server, ETR's overclaiming attacks are not   included in the threat model.7.4.  Deploying LISP-SEC   Those deploying LISP-SEC according to this memo should carefully   weigh how the LISP-SEC threat model applies to their particular use   case or deployment.  If they decide to ignore a particular   recommendation, they should make sure the risk associated with the   corresponding threats is well understood.   As an example, in certain other deployments, attackers may be very   sophisticated and force the deployers to enforce very strict policies   in terms of HMAC algorithms accepted by an ITR.   Similar considerations apply to the entire LISP-SEC threat model and   should guide the deployers and implementors whenever they encounter   the key word SHOULD across this memo.7.5.  Shared Keys Provisioning   Provisioning of the keys shared between ITR and Map-Resolver pairs as   well as between ETR and Map-Server pairs should be performed via an   orchestration infrastructure, and is out of the scope of this memo.   It is recommended that both shared keys be refreshed at periodical   intervals to address key aging or attackers gaining unauthorized   access to the shared keys.  Shared keys should be unpredictable   random values.7.6.  Replay Attacks   An attacker can capture a valid Map-Request and/or Map-Reply and   replay it; however, once the ITR receives the original Map-Reply, the   <nonce,ITR-OTK> pair stored at the ITR will be discarded.  If a   replayed Map-Reply arrives at the ITR, there is no <nonce,ITR-OTK>   that matches the incoming Map-Reply and the replayed Map-Reply will   be discarded.   In the case of a replayed Map-Request, the Map-Server, Map-Resolver,   and ETR will have to do a LISP-SEC computation.  This is equivalent,   in terms of resources, to a valid LISP-SEC computation and, beyond a   risk of DoS attack, an attacker does not obtain any additional   effect, since the corresponding Map-Reply is discarded as previously   explained.7.7.  Message Privacy   DTLS [RFC9147] SHOULD be used (conforming to [RFC7525]) to provide   communication privacy and to prevent eavesdropping, tampering, or   message forgery to the messages exchanged between the ITR, Map-   Resolver, Map-Server, and ETR, unless the OTK is encrypted in another   way, e.g., using a pre-shared secret.  DTLS has the responder be   verified by the initiator, which enables an ITR to authenticate the   Map-Resolver and the Map-Server to authenticate the responding ETR.7.8.  Denial-of-Service and Distributed Denial-of-Service Attacks   LISP-SEC mitigates the risks of DoS and DDoS attacks by protecting   the integrity and authenticating the origin of the Map-Request/Map-   Reply messages and by preventing malicious ETRs from overclaiming   EID-Prefixes that could redirect traffic directed to a potentially   large number of hosts.8.  IANA Considerations   IANA has created the subregistries listed in the following sections   in the "Locator/ID Separation Protocol (LISP) Parameters" registry.   For all of the subregistries, new values are assigned according to   the Specification Required policy defined in [RFC8126].  Expert   Review should assess the security properties of newly added functions   so that encryption robustness remains strong.  For instance, at the   time of this writing, the use of SHA-256-based functions is   considered to provide sufficient protection.  Consultation with   security experts may be needed.8.1.  ECM AD Type Registry   IANA has created the "LISP ECM Authentication Data Types" registry   with values 0-255 for use in the ECM LISP-SEC extensions (see   Section 6.1).  Initial allocations are shown in Table 2.                +==================+========+============+                | Name             | Number | Defined in |                +==================+========+============+                | Reserved         |   0    | RFC 9303   |                +------------------+--------+------------+                | LISP-SEC-ECM-EXT |   1    | RFC 9303   |                +------------------+--------+------------+                  Table 2: LISP ECM Authentication Data                                  Types   Values 2-255 are unassigned.8.2.  Map-Reply AD Types Registry   IANA has created the "LISP Map-Reply Authentication Data Types"   registry with values 0-255 for use in the Map-Reply LISP-SEC   extensions (see Section 6.2).  Initial allocations are shown in   Table 3.                 +=================+========+============+                 | Name            | Number | Defined in |                 +=================+========+============+                 | Reserved        |   0    | RFC 9303   |                 +-----------------+--------+------------+                 | LISP-SEC-MR-EXT |   1    | RFC 9303   |                 +-----------------+--------+------------+                     Table 3: Map-Reply Authentication                                 Data Types   Values 2-255 are unassigned.8.3.  HMAC Functions   IANA is requested to create the "LISP-SEC Preferred Authentication   Data HMAC IDs" registry with values 0-65535 for use as Requested HMAC   IDs, EID HMAC IDs, and PKT HMAC IDs in the LISP-SEC Authentication   Data.  Initial allocations are shown in Table 4.              +=======================+========+============+              | Name                  | Number | Defined in |              +=======================+========+============+              | NOPREF                |   0    | RFC 9303   |              +-----------------------+--------+------------+              | AUTH-HMAC-SHA-1-96    |   1    | [RFC2104]  |              +-----------------------+--------+------------+              | AUTH-HMAC-SHA-256-128 |   2    | [RFC6234]  |              +-----------------------+--------+------------+                 Table 4: LISP-SEC Preferred Authentication                               Data HMAC IDs   Values 3-65535 are unassigned.8.4.  Key Wrap Functions   IANA has created the "LISP-SEC Authentication Data Key Wrap IDs"   registry with values 0-65535 for use as OTK key wrap algorithm IDs in   the LISP-SEC Authentication Data.  Initial allocations are shown in   Table 5.   +==============================+======+=========+=========+=========+   | Name                         |Number|Key Wrap |KDF      |Reference|   +==============================+======+=========+=========+=========+   | Reserved                     |  0   |None     |None     |RFC 9303 |   +------------------------------+------+---------+---------+---------+   | NULL-KEY-WRAP-128            |  1   |RFC 9303 |None     |RFC 9303 |   +------------------------------+------+---------+---------+---------+   | AES-KEY-WRAP-128+HKDF-SHA256 |  2   |[RFC3394]|[RFC4868]|RFC 9303 |   +------------------------------+------+---------+---------+---------+             Table 5: LISP-SEC Authentication Data Key Wrap IDs   Values 3-65535 are unassigned.8.5.  Key Derivation Functions   IANA has created the "LISP-SEC Authentication Data Key Derivation   Function IDs" registry with values 0-65535 for use as KDF IDs.   Initial allocations are shown in Table 6.                  +===============+========+===========+                  | Name          | Number | Reference |                  +===============+========+===========+                  | NOPREF        |   0    |  RFC 9303 |                  +---------------+--------+-----------+                  | HKDF-SHA1-128 |   1    | [RFC5869] |                  +---------------+--------+-----------+                  | HKDF-SHA256   |   2    | [RFC5869] |                  +---------------+--------+-----------+                     Table 6: LISP-SEC Authentication                     Data Key Derivation Function IDs   Values 3-65535 are unassigned.9.  References9.1.  Normative References   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-              Hashing for Message Authentication", RFC 2104,              DOI 10.17487/RFC2104, February 1997,              <https://www.rfc-editor.org/info/rfc2104>.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels", BCP 14, RFC 2119,              DOI 10.17487/RFC2119, March 1997,              <https://www.rfc-editor.org/info/rfc2119>.   [RFC3394]  Schaad, J. and R. Housley, "Advanced Encryption Standard              (AES) Key Wrap Algorithm", RFC 3394, DOI 10.17487/RFC3394,              September 2002, <https://www.rfc-editor.org/info/rfc3394>.   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-              384, and HMAC-SHA-512 with IPsec", RFC 4868,              DOI 10.17487/RFC4868, May 2007,              <https://www.rfc-editor.org/info/rfc4868>.   [RFC5869]  Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand              Key Derivation Function (HKDF)", RFC 5869,              DOI 10.17487/RFC5869, May 2010,              <https://www.rfc-editor.org/info/rfc5869>.   [RFC6234]  Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms              (SHA and SHA-based HMAC and HKDF)", RFC 6234,              DOI 10.17487/RFC6234, May 2011,              <https://www.rfc-editor.org/info/rfc6234>.   [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,              "Recommendations for Secure Use of Transport Layer              Security (TLS) and Datagram Transport Layer Security              (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May              2015, <https://www.rfc-editor.org/info/rfc7525>.   [RFC7835]  Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID              Separation Protocol (LISP) Threat Analysis", RFC 7835,              DOI 10.17487/RFC7835, April 2016,              <https://www.rfc-editor.org/info/rfc7835>.   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for              Writing an IANA Considerations Section in RFCs", BCP 26,              RFC 8126, DOI 10.17487/RFC8126, June 2017,              <https://www.rfc-editor.org/info/rfc8126>.   [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>.   [RFC9147]  Rescorla, E., Tschofenig, H., and N. Modadugu, "The              Datagram Transport Layer Security (DTLS) Protocol Version              1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,              <https://www.rfc-editor.org/info/rfc9147>.   [RFC9300]  Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.              Cabellos, Ed., "The Locator/ID Separation Protocol              (LISP)", RFC 9300, DOI 10.17487/RFC9300, October 2022,              <https://www.rfc-editor.org/info/rfc9300>.   [RFC9301]  Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,              Ed., "Locator/ID Separation Protocol (LISP) Control              Plane", RFC 9301, DOI 10.17487/RFC9301, October 2022,              <https://www.rfc-editor.org/info/rfc9301>.9.2.  Informative References   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,              "Randomness Requirements for Security", BCP 106, RFC 4086,              DOI 10.17487/RFC4086, June 2005,              <https://www.rfc-editor.org/info/rfc4086>.   [RFC6836]  Fuller, V., Farinacci, D., Meyer, D., and D. Lewis,              "Locator/ID Separation Protocol Alternative Logical              Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836,              January 2013, <https://www.rfc-editor.org/info/rfc6836>.Acknowledgments   The authors would like to acknowledge Luigi Iannone, Pere Monclus,   Dave Meyer, Dino Farinacci, Brian Weis, David McGrew, Darrel Lewis,   and Landon Curt Noll for their valuable suggestions provided during   the preparation of this document.Authors' Addresses   Fabio Maino   Cisco Systems   San Jose, CA   United States of America   Email: fmaino@cisco.com   Vina Ermagan   Google, Inc.   1600 Amphitheatre Parkway   Mountain View, CA 94043   United States of America   Email: ermagan@gmail.com   Albert Cabellos   Universitat Politecnica de Catalunya   c/ Jordi Girona s/n   08034 Barcelona   Spain   Email: acabello@ac.upc.edu   Damien Saucez   Inria   2004 route des Lucioles - BP 93   Sophia Antipolis   France   Email: damien.saucez@inria.fr