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Versions: 00 01 02 03 04 05 06 07 08 09 10 RFC 6518

   KARP Working Group                                      G. Lebovitz
   Internet Draft
   Intended status: Informational                            M. Bhatia
   Expires: January, 2012                               Alcatel-Lucent
                                                        September 2011
           Keying and Authentication for Routing Protocols (KARP)
                              Design Guidelines
   Status of this Memo
      This Internet-Draft is submitted to IETF in full conformance
      with the provisions of BCP 78 and BCP 79.
      Internet-Drafts are working documents of the Internet
      Engineering Task Force (IETF), its areas, and its working
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      The list of current Internet-Drafts can be accessed at
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      This Internet-Draft will expire on August 2011.
   Copyright Notice
      Copyright (c) 2011 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
      (http://trustee.ietf.org/license-info) in effect on the date of
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      in Section 4.e of the Trust Legal Provisions and are provided
      without warranty as described in the Simplified BSD License.
      This document is one of a series concerned with defining a
      roadmap of protocol specification work for the use of modern
      cryptographic mechanisms and algorithms for message
      authentication in routing protocols.  In particular, it defines
      the framework for a key management protocol that may be used to
      create and manage session keys for message authentication and
   Conventions used in this document
      The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
      "OPTIONAL" in this document are to be interpreted as described
      in RFC 2119. [RFC2119]
   Table of Contents
      1. Introduction..................................................3
      2. Categorizing Routing Protocols................................4
         2.1. Category: Message Transaction Type.......................4
         2.2. Category: Peer vs Group Keying...........................6
      3. Consider the future existence of a Key Management Protocol....6
         3.1. Consider Asymmetric Keys.................................6
         3.2. Cryptographic Keys Life Cycle............................8
      4. RoadMap.......................................................9
         4.1. Work Phases on any Particular Protocol...................9
         4.2. Work Items Per Routing Protocol.........................11
      5. Routing Protocols in Categories..............................13
      6. Gap Analysis.................................................16
      7. Security Considerations......................................19
         7.1. Use Strong Keys.........................................19
         7.2. Internal vs. External Operation.........................20
         7.3. Unique versus Shared Keys...............................21
         7.4. Out-of-Band External Configuration vs. Peer-to-Peer Key
      8. Acknowledgments..............................................25
      9. IANA Considerations..........................................25
      10. References..................................................25
         10.1. Normative References...................................25
         10.2. Informative References.................................26
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   1. Introduction
      In March 2006 the Internet Architecture Board (IAB) held a
      workshop on the topic of "Unwanted Internet Traffic".  The
      report from that workshop is documented in RFC 4948 [RFC4948].
      Section 8.1 of that document states that "A simple risk
      analysis would suggest that an ideal attack target of minimal
      cost but maximal disruption is the core routing
      infrastructure."  Section 8.2 calls for "[t]ightening the
      security of the core routing infrastructure."  Four main steps
      were identified for that tightening:
      o  Increased security mechanisms and practices for operating
         routers. This work is being addressed in the OPSEC Working
      o  Cleaning up the Internet Routing Registry repository [IRR],
         and securing both the database and the access, so that it
         can be used for routing verifications.  This work should be
         addressed through liaisons with those running the IRR's
      o  Specifications for cryptographic validation of routing
      message content.  This work is being addressed in the
      SIDR Working Group.
      o  Securing the routing protocols' packets on the wire
      This document addresses the last bullet, securing the packets
      on the wire of the routing protocol exchanges.  Thus, it is
      concerned with guidelines for describing issues and techniques
      for protecting the messages between directly communicating
      peers.  This may overlap with, but is strongly distinct from,
      protection designed to ensure that routing information is
      properly authorized relative to sources of this information.
      Such assurances are provided by other mechanisms and are
      outside the scope of this document and work that relies on it.
      This document uses the terminology "on the wire" to talk about
      the information used by routing systems.  This term is widely
      used in IETF RFCs, but is used in several different ways.  In
      this document, it is used to refer both to information
      exchanged between routing protocol instances, and to underlying
      protocols that may also need to be protected in specific
      circumstances.  Individual protocol analysis documents will
      need to be more specific in their usage.
      This document refers to routing transport in order to provide a
      common referent for the varied ways that routing protocols
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      exchange messages.  This can be TCP, UDP, or even direct link
      level messaging in the case of some routing protocols.  The
      term is used here to allow a referent for discussing both
      common and disparate issues that affect or interact with this
      dimension of the routing systems.  The term is used here to
      refer generally to the set of mechanisms and exchanges
      underneath the routing protocol, whatever that is in specific
      Readers must refer to the [I-D.ietf-karp-threats-reqs] for a
      clear definition of the scope, goals, non goals and the
      audience for the design work being undertaken in KARP WG.
   2. Categorizing Routing Protocols
   For the purpose of this security roadmap definition, we categorize
   routing protocols into groups and anticipate that design teams will
   focus on the specification of security mechanisms within each
   group. The protocols will be grouped according to the requirements
   for authentication mechanisms that they are believed to have, and
   it is assumed that reuse of authentication mechanisms will be
   possible and desirable within each group. The work items placed on
   the roadmap will be defined and assigned based on these
   categorizations.  It is also hoped that, down the road we can
   create one Key Management Protocol (KMP) per category (if not for
   several categories) so that the work can be easily leveraged by for
   use in the various Routing Protocol groupings.  KMPs are useful for
   allowing simple, automated updates of the traffic keys used in a
   base protocol.  KMPs replace the need for humans, or OSS routines,
   to periodically replace keys on running systems.  It also removes
   the need for a chain of manual keys to be chosen or configured on
   such systems.  When configured properly, a KMP will enforce the key
   freshness policy among peers by keeping track of the key lifetime
   and negotiating a new key at the defined interval.
   2.1. Category: Message Transaction Type
      The first categorization defines three types of messaging
      transactions used on the wire by the base Routing Protocol.
      They are:
        One peer router directly and intentionally delivers a route
        update specifically to one other peer router. Examples are
        BGP [RFC4271], LDP [RFC5036], BFD [RFC5880] and RSVP-TE
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        [RFC3209] [RFC3473] [RFC4726] [RFC5151]. Point-to-point modes
        of both IS-IS [RFC1195] and OSPF [RFC2328], when sent over
        both traditional point-to-point links and when using multi-
        access layers, may both also fall into this category.
        A router peers with multiple other routers on a single
        network segment -- i.e. on link local -- such that it creates
        and sends one route update message which is intended for
        consumption by multiple peers.  Examples would be OSPF and
        IS-IS in their broadcast, non-point-to-point mode and Routing
        Information Protocol (RIP) [RFC2453].
        Multicast protocols have unique security properties because
        of the fact that they are inherently group-based protocols
        and thus have group keying requirements at the routing level
        where link-local routing messages are multicasted.  Also, at
        least in the case of PIM-SM [RFC4601], some messages are sent
        unicast to a given peer(s), as is the case with router-close-
        to-sender and the "Rendezvous Point".  Some work for
        application layer message security has been done in the
        Multicast Security working group (MSEC,
        http://www.ietf.org/html.charters/msec-charter.html) and may
        be helpful to review, but is not directly applicable.
      These categories affect both the routing protocol view of the
      communication, and the actual message transfer.  As a result,
      some mechanisms for a few routing protocols, may be mixtures,
      for example using broadcast where multicast might be expected,
      or using unicast to deliver what looks to the routing protocol
      like broadcast or multicast.
      This may include any semantics of the communication that impact
      the routing protocol, such as when source identity or path
      properties of the communication path are used by the routing
      algorithm, e.g., as when BGP infers routing table entry quality
      from the persistence of the TCP connection over which they are
      Protocol security analysis documents produced in KARP need to
      pay attention both to the semantics of the communication, and
      the techniques that are used for the message exchanges.
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   2.2. Category: Peer vs Group Keying
      The second axis of categorization groups protocols is by the
      keying mechanism that will be necessary for distributing
      session keys to the actual Routing Protocol transports. They
      Peer keying
      One router sends the keying messages only to one other router,
      such that a one-to-one, uniquely keyed security association
      (SA) is established between the two routers. This would be
      employed by protocols like BGP, BFD and LDP.
      Group Keying
      One router creates and distributes a single keying message to
      multiple peers.  In this case a group SA will be established
      and used among multiple peers simultaneously. Group keying
      exists for protocols like OSPF [RFC2328], and also for
      multicast protocols like PIM-SM [RFC4601].
   3. Consider the future existence of a Key Management Protocol
      When it comes time for the KARP WG to design a re-usable model
      for a Key Management Protocol (KMP), [RFC4107] should be
      When conducting the design work on a manually-keyed version of
      a routing protocol's authentication mechanism, consideration
      must be made for the eventual use of a KMP. In particular,
      design teams must consider what parameters would need to be
      handed to the routing protocols by a KMP.
      Examples of parameters that might need to be passed are:  a
      security association identifier (e.g. IPsec SPI, or TCP-AO's
      KeyID), a key lifetime (which may be represented either in
      bytes or seconds), the cryptographic algorithms being used, the
      keys themselves, and the directionality of the keys (i.e.,
      receive versus the sending keys)
   3.1. Consider Asymmetric Keys
      The use of asymmetric keys can be a very powerful way to
      authenticate machine peers as used in routing protocol peer
      exchanges. If generated on the machine, and never moved off the
      machine, these keys will not need to be changed if an
      administrator leaves the organization. Since the keys are
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      random, and long, they are far less susceptible to off-line
      dictionary and guessing attacks.
      An easy and simple way to use asymmetric keys is to start by
      having the router generate a public/private key pair. At the
      time of this writing, the recommended key size for algorithms
      based on integer factorization cryptography like RSA is 1024
      bits and 2048 for extremely valuable keys like the root key
      pair used by a certification authority. It is believed that a
      1024-bit RSA key is equivalent in strength to 80-bit symmetric
      keys and 2048-bit RSA keys to 112-bit symmetric keys. Elliptic
      Curve Cryptography [RFC4492] (ECC) appears to be secure with
      shorter keys than those needed by other asymmetric key
      algorithms. NIST guidelines [NIST-800-57] state that ECC keys
      should be twice the length of equivalent strength symmetric key
      algorithms. Thus, a 224-bit ECC key would roughly have the same
      strength as a 112-bit symmetric key.
      Many routers have the ability to be remotely managed using SSH
      [RFC4252] and [RFC4253]. As such, routers will also have the
      ability to generate and store an asymmetric key pair, because
      this is the common authentication method employed to by SSH
      when a user connects to a router for management sessions.
      Once an asymmetric key pair is generated, the KMP generating
      security association parameters and keys for routing protocol
      may use the machine's asymmetric keys for the identity proof.
      The form of the identity proof could be raw keys, the more
      easily administrable self-signed certificate format, or a PKI-
      issued [RFC5280] certificate credential.
      Regardless which form we eventually standardize, the proof of
      this identity presentation can be as simple as a strong hash,
      which could be represented in a human readable and transferable
      form of some pairs of ASCII characters. More complex, but also
      more secure, the identity proof could be verified through the
      use of a PKI system's revocation checking mechanism, (e.g.
      Certificate Revocation List (CRL) or OCSP responder). If the
      SHA-1 fingerprint is used, the solution could be as simple as
      loading a set of neighbor routers' peer ID strings into a table
      and listing the associated fingerprint string for each ID
      string. In most organizations or peering points, this list will
      not be longer than a thousand or so routers, and often the list
      will be much shorter. In other words, the entire list for a
      given organization's router ID & hash could easily be held in a
      router's configuration file, uploaded, downloaded and move
      about at will. And it doesn't matter who sees or gains access
      to these fingerprints, because they can be distributed publicly
      as it needn't be kept secret.
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   3.2. Cryptographic Keys Life Cycle
      Cryptographic keys should have a limited lifetime and may need
      to be changed when an operator who had access to them leaves.
      Using a key chain also does not help as one still has to change
      all the keys in the key chain when an operator having access to
      all those keys leaves the company. Additionally, key chains
      will not help if the routing transport subsystem does not
      support rolling over to the new keys without bouncing the
      routing sessions and adjacencies. So the first step is to fix
      the routing stack so that routing protocols can change keys
      without breaking or bouncing the adjacencies.
      An often cited reason for limiting the lifetime of a key is to
      minimize the damage from a compromised key. It could be argued
      that it is likely a user will not discover an attacker has
      compromised the key if the attacker remains "passive" and thus
      relatively frequent key changes will limit any potential damage
      from compromised keys.
      Another threat against the long-lived key is that one of the
      systems storing the key, or one of the users entrusted with the
      key, will be subverted. So, while there may not be
      cryptographic motivations of changing the keys, there could be
      a system security motivations for doing the same.
      Although manual key distribution methods are subject to human
      error and frailty, more frequent manual key changes might
      actually increase the risk of exposure as it is during the time
      that the keys are being changed that they are likely to get
      disclosed. In these cases, especially when very strong
      cryptography is employed, it may be more prudent to have fewer,
      well controlled manual key distributions rather than more
      frequent, poorly controlled manual key distributions. In
      general, where strong cryptography is employed, physical,
      procedural, and logical access protection considerations often
      have more impact on the key life than do algorithm and key size
      For incremental deployments we could start by associating life
      times with the send and the receive keys in the key chain for
      the long-lived keys. This is an incremental approach that we
      could use until the cryptographic keying material for
      individual sessions is derived from the keying material stored
      in a database of long-lived cryptographic keys as described in
      [I-D.ietf-saag-crypto-key-table]. A key derivation function
      (KDF) and its inputs are also specified in the database of
      long-lived cryptographic keys; session-specific values based on
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      the routing protocol are input to the KDF. Protocol-specific
      key identifiers may be assigned to the cryptographic keying
      material for individual sessions if needed.
      The long-lived cryptographic keys used by the routing protocols
      can be either inserted manually in a database or can make use
      of an automated key management protocol to do this.
   4. RoadMap
   4.1. Work Phases on any Particular Protocol
      It is believed that improving security for any routing protocol
      will be a two step process or could be said to involve two
      phases. The first would be to fix the manual key management
      procedures that currently exist within the routing protocols
      today using modern cryptography algorithms and key agility. The
      second phase would be to design and move to an automated key
      management mechanism. This is like a crawl, walk and run
      process. In order to deliver that to the operators in a way
      that we could complete these action items a little bit a time
      and make some incremental advance over what is currently
      deployed in the wild, we believe that it is therefore useful to
      cleanly separate the key management protocol from the routing
      transport subsystem mechanism. This would mean that the routing
      transport subsystem is oblivious to how the keys are derived,
      exchanged and downloaded as long as there is something that it
      can use. It is like having a routing protocol configuration
      switch that requests the security module for the "KARP security
      parameters" so that it can refer to some module written by
      people good in security and who will be maintaining it over the
      time and insert those parameters in the routing exchange.
      The desired end state for the KARP work contains several items.
      First, the people desiring to deploy securely authenticated and
      integrity validated packets between routing peers have the
      tools specified, implemented and shipping in order to deploy.
      These tools should be fairly simple to implement, and not more
      complex than the security mechanisms to which the operators are
      already accustomed. (Examples of security mechanisms to which
      router operators are accustomed include: the use of asymmetric
      keys for authentication in SSH for router configuration, the
      use of pre-shared keys (PSKs) in TCP MD5 for BGP protection,
      the use of self-signed certificates for HTTPS access to device
      Web-based user interfaces, the use of strongly constructed
      passwords and/or identity tokens for user identification when
      logging into routers and management systems.)  While the tools
      that we intend to specify may not be able to stop a deployment
      from using "foobar" as an input key for every device across
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      their entire routing domain, we intend to make a solid, modern
      security system that is not too much more difficult than that.
      In other words, simplicity and deployability are keys to
      success.  The Routing Protocols will specify modern
      cryptographic algorithms and security mechanisms.  Routing
      peers will be able to employ unique, pair-wise keys per peering
      instance, with reasonable key lifetimes, and updating those
      keys on a regular basis will be operationally easy, causing no
      service interruption.
      Achieving the above described end-state using manual keys may
      be pragmatic only in very small deployments.  In larger
      deployments, this end state will be much more operationally
      difficult to reach with only manual keys.  Thus, there will be
      a need for key life cycle management, in the form of a key
      management protocol, or KMP.  We expect that the two forms,
      manual key usage and KMP usage, will co-exist in the real
      In accordance with the desired end state just described, we
      define two main work phases for each Routing Protocol:
      1. Enhance the Routing Protocol's current authentication
         mechanism(s). This work involves enhancing a Routing
         Protocol's current security mechanisms in order to achieve a
         consistent, modern level of security functionality within its
         existing key management framework.  It is understood and
         accepted that the existing key management frameworks are
         largely based on manual keys.  Since many operators have
         already built operational support systems (OSS) around these
         manual key implementations, there is some automation
         available for an operator to leverage in that way, if the
         underlying mechanisms are themselves secure.  In this phase,
         we explicitly exclude embedding or creating a KMP.  Refer to
         [I-D.ietf-karp-threats-reqs] for the list of the requirements
         for Phase 1 work.
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      2. Develop an automated key management framework.  The second
         phase will focus on the development of an automated keying
         framework to facilitate unique pair-wise (group-wise, where
         applicable) keys per peering instance.  This involves the use
         of a KMP.  The use of automatic key management mechanisms
         offers a number of benefits over manual keying. Most
         importantly it provides fresh traffic keying material for
         each session, thus helping to prevent inter-connection replay
         attacks. A KMP is also helpful because it negotiates unique,
         pair wise, random keys without administrator involvement.  It
         negotiates several SA parameters like algorithms, modes, and
         parameters required for the secure connection, thus providing
         interoperability between endpoints with disparate
         capabilities and configurations. In addition it could also
         include negotiating the key life times. The KMP can thus keep
         track of those lifetimes using counters, and can negotiate
         new keys and parameters before they expire, again, without
         administrator interaction. Additionally, in the event of a
         breach, changing the KMP key will immediately cause a rekey
         to occur for the Traffic Key, and those new Traffic Keys will
         be installed and used in the current connection.  In summary,
         a KMP provides a protected channel between the peers through
         which they can negotiate and pass important data required to
         exchange proof of identities, derive Traffic Keys, determine
         re-keying, synchronize their keying state, signal various
         keying events, notify with error messages, etc.
   4.2. Work Items Per Routing Protocol
      Each Routing Protocol will have a team (the [Routing_Protocol]-
      KARP team) working on incrementally improving the security of a
      Routing Protocol. These teams will have the following main work
   PHASE 1:
      Characterize the RP
         Assess the Routing Protocol to see what authentication and
         integrity mechanisms it has today.  Does it needs
         significant improvement to its existing mechanisms or not?
         This will include determining if modern, strong security
         algorithms and parameters are present and if the protocol
         supports key agility without bouncing adjacencies.
      Define Optimal State
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         List the requirements for the Routing Protocol's session key
         usage and format to contain modern, strong security
         algorithms and mechanisms, per the Requirements document
         [I-D.ietf-karp-threats-reqs].  The goal here is to determine
         what is needed for the Routing Protocol to be used securely
         with at least manual key management.
      Gap Analysis
         Enumerate the requirements for this protocol to move from
         its current security state, the first bullet, to its optimal
         state, as listed just above.
       Transition and Deployment Considerations
         Document the operational transition plan for moving from the
         old to the new security mechanism.  Will adjacencies need to
         bounce?  What new elements/servers/services in the
         infrastructure will be required?  What is an example work
         flow that an operator will take?  The best possible case is
         if the adjacency does not break, but this may not always be
       Define, Assign, Design
         Create a deliverables list of the design and specification
         work, with milestones. Define owners. Release one or more
   PHASE 2:
      KMP Analysis
         Review requirements for KMPs.  Identify any nuances for this
         particular routing protocol's needs and its use cases for a
         KMP.  List the requirements that this Routing Protocol has
         for being able to be used in conjunction with a KMP.  Define
         the optimal state and check how easily it can be decoupled
         from the KMP.
      Gap Analysis
         Enumerate the requirements for this protocol to move from
         its current security state to its optimal state, with
         respect to the key management.
      Define, Assign, Design
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         Create a deliverables list of the design and specification
         work, with milestones.  Define owners.  Generate the design
         and document work for a KMP to be able to generate the
         Routing Protocol's session keys for the packets on the wire.
         These will be the arguments passed in the API to the KMP in
         order to bootstrap the session keys for the Routing
         There will also be a team formed to work on the base
         framework mechanisms for each of the main categories.
   5. Routing Protocols in Categories
      This section groups the Routing Protocols into categories,
      according to attributes set forth in Categories Section
      (Section 2). Each group will have a design team tasked with
      improving the security of the Routing Protocol mechanisms and
      defining the KMP requirements for their group, then rolling
      both into a roadmap document upon which they will execute.
      BGP, LDP, PCEP and MSDP
         These Routing Protocols fall into the category of the one-
         to-one peering messages, and will use peer keying protocols.
         BGP [RFC4271], PCEP [RFC5440] and MSDP [RFC3618] messages
         are transmitted over TCP, while LDP [RFC5036] uses both UDP
         and TCP.  A team will work on one mechanism to cover these
         TCP unicast protocols. Much of the work on the Routing
         Protocol update for its existing authentication mechanism
         has already occurred in the TCPM Working Group, on the TCP-
         AO [RFC5925] document, as well as its cryptography-helper
         document, TCP-AO-CRYPTO [RFC5926].  However, TCP-AO cannot
         be used for discovery exchanges carried in LDP as those are
         carried over UDP. A separate team might want to look at LDP.
         Another exception is the mode where LDP is used directly on
         the LAN.  The work for this may go into the Group keying
         category (along with OSPF) as mentioned below.
      OSPF, ISIS, and RIP
         The Routing Protocols that fall into the category Group
         Keying *with one-to-many peering) includes OSPF [RFC2328],
         ISIS [RFC1195] and RIP [RFC2453].  Not surprisingly, all
         these routing protocols have two other things in common.
         First, they are run on a combination of the OSI datalink
         layer 2, and the OSI network layer 3.  By this we mean that
         they have a component of how the routing protocol works
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         which is specified in Layer 2 as well as in Layer 3.
         Second, they are all internal gateway protocols(IGPs).  The
         keying mechanisms will be much more complicated to define
         for these than for a one-to-one messaging protocol.
         Because it is less of a routing protocol, per se, and more
         of a peer liveness detection mechanism, Bidirectional
         Forwarding Detection (BFD) [RFC5880] will have its own team.
         BFD is also different from the other protocols covered here
         as it works on millisecond timers and would need separate
         considerations to mitigate the potential for DoS attacks. It
         also raises interesting issues [RFC6039] with respect to the
         sequence number scheme that is generally deployed to protect
         against replay attacks as this space can rollover quite
         frequently because of the rate at which BFD packets are
      RSVP and RSVP-TE
         The Resource reSerVation Protocol [RFC2205] allows hop-by-
         hop authentication of RSVP neighbors, as specified in
         [RFC2747]. In this mode, an integrity object is attached to
         each RSVP message to transmit a keyed message digest.  This
         message digest allows the recipient to verify the identity
         of the RSVP node that sent the message, and to validate the
         integrity of the message. Through the inclusion of a
         sequence number in the scope of the digest, the digest also
         offers replay protection.
         [RFC2747] does not dictate how the key for the integrity
         operation is derived.  Currently, most implementations of
         RSVP use a statically configured key, on a per interface or
         per neighbor basis.
         RSVP relies on a per peer authentication mechanism, where
         each hop authenticates its neighbor using a shared key or a
         Trust in this model is transitive.  Each RSVP node trusts
         explicitly only its RSVP next hop peers, through the message
         digest contained in the INTEGRITY object [RFC2747. The next
         hop RSVP speaker in turn trusts its own peers and so on.
         See also the document "RSVP security properties" [RFC4230]
         for more background.
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         The keys used for protecting the RSVP messages can be group
         keys (for example distributed via GDOI [RFC3547], as
         discussed in [I-D.weis-gdoi-mac-tek]).
         The trust an RSVP node has to another RSVP node has an
         explicit and an implicit component.  Explicitly the node
         trusts the other node to maintain the integrity (and,
         optionally confidentiality) of RSVP messages depending on
         whether authentication or encryption (or both) are used.
         This means that the message has not been altered or its
         contents seen by another, non-trusted node.  Implicitly each
         node trusts the other node to maintain the level of
         protection specified within that security domain  Note that
         in any group key management scheme, like GDOI, each node
         trusts all the other members of the group with regard to
         data origin authentication.
         RSVP TE [RFC3209] [RFC3473] [RFC4726] [RFC5151] is an
         extension of the RSVP protocol for traffic engineering. It
         supports the reservation of resources across an IP network
         and is used for establishing MPLS label switch paths (LSPs),
         taking into consideration network constraint parameters such
         as available bandwidth and explicit hops. RSVP-TE signaling
         is used to establish both intra and inter-domain TE LSPs.
         When signaling an inter-domain RSVP-TE LSP, operators may
         make use of the security features already defined for RSVP-
         TE [RFC3209].  This may require some coordination between
         domains to share keys ([RFC2747],[RFC3097]), and care is
         required to ensure that the keys are changed sufficiently
         frequently.  Note that this may involve additional
         synchronization, should the domain border nodes be protected
         with Fast Reroute, since the merge point (MP) and point of
         local repair (PLR) should also share the key.
         For inter-domain signaling for MPLS-TE, the administrators
         of neighboring domains must satisfy themselves as to the
         existence of a suitable trust relationship between the
         domains. In the absence of such a relationship, the
         administrators should decide not to deploy inter-domain
         signaling, and should disable RSVP-TE on any inter-domain
         KARP will currently be working only on RSVP-TE as the native
         RSVP lies outside the scope of the WG charter.
      PIM-SM and PIM-DM
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          Finally, the multicast protocols PIM-SM [RFC4601] and PIM-DM
         [RFC3973] will be grouped together. PIM-SM multicasts
         routing information (Hello, Join/Prune, Assert) on a link-
         local basis, using a defined multicast address.  In
         addition, it specifies unicast communication for exchange of
         information (Register, Register-Stop) between the router
         closest to a group sender and the "rendezvous point" (RP).
         The RP is typically not "on-link" for a particular router.
         While much work has been done on multicast security for
         application-layer groups, little has been done to address
         the problem of managing hundreds or thousands of small one-
         to-many groups with link-local scope.  Such an
         authentication mechanism should be considered along with the
         router-to-Rendezvous Point authentication mechanism.  The
         most important issue is ensuring that only the "authorized
         neighbors" get the keys for (S,G), so that rogue routers
         cannot participate in the exchanges.  Another issue is that
         some of the communication may occur intra-domain, e.g. the
         link-local messages in an enterprise, while others for the
         same (*,G) may occur inter-domain, e.g. the router-to-
         Rendezvous Point messages may be from one enterprise's
         router to another.
         One possible solution proposes a region-wide "master" key
         server (possibly replicated), and one "local" key server per
         speaking router. There is no issue with propagating the
         messages outside the link, because link-local messages, by
         definition, are not forwarded. This solution is offered only
         as an example of how work may progress; further discussion
         should occur in this work team. Specification of a link-
         local protection mechanism for PIM-SM is defined in
         [RFC4601], and this mechanism has been updated in PIM-SM-
         LINKLOCAL [RFC5796].  However, the KMP part is completely
         unspecified, and will require work outside the expertise of
         the PIM working group to accomplish, another example of why
         this roadmap is being created.
   6. Gap Analysis
      The [I-D.ietf-karp-threats-reqs] document lists the generic
      requirements for the security mechanisms that must exist for
      the various routing protocols that come under the purview of
      KARP. There will be different design teams working for each of
      the categories of routing protocols defined.
      To start, design teams must review the "Threats and
      Requirements for Authentication of Routing Protocols" document
      [I-D.ietf-karp-threats-reqs]. This document contains detailed
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      descriptions of the threat analysis for routing protocol
      authentication and integrity in general. Note that it will not
      contain all the authentication-related threats for any one
      routing protocol, or category of routing protocols. The design
      team must conduct a protocol-specific threat analysis to
      determine if threats beyond those in the [I-D.ietf-karp-
      threats-reqs] document arise in the context of the protocol
      (group), and to describe those threats.
      The [I-D.ietf-karp-threats-reqs] document also contains many
      security requirements. Each routing protocol design team must
      walk through each section of the requirements and determine one
      by one how its protocol either does or does not relate to each
      requirement. Examples include modern, strong cryptographic
      algorithms, with at least one such algorithm listed as a MUST;
      algorithm agility; secure use of simple PSKs; intra-connection
      replay protection; inter-connection replay protection, etc.
      When doing the gap analysis we must first identify the elements
      of each routing protocol that we wish to protect. In case of
      protocols riding on top of IP, we might want to protect the IP
      header and the protocol headers, while for those that work on
      top of TCP, it will be the TCP header and the protocol payload.
      There is patently value in protecting the IP header and the TCP
      header if the routing protocols rely on these headers for some
      information (for example, identifying the neighbor which
      originated the packet).
      Then there will be a set of Cryptography requirements that we
      might want to look at. For example, there MUST be at least on
      set of cryptography algorithms or constructions whose use is
      supported by all implementations and can be safely assumed to
      be supported by any implementation of the authentication
      option. The design teams should look for this for the protocol
      that they are working on. If such algorithms or constructions
      are not available then some should be defined to support
      interoperability by having a single default.
      Design teams MUST ensure that the default cryptographic
      algorithms and constructions supported by the routing protocols
      are accepted by the community. This means that the protocols
      MUST NOT rely on non-standard or ad-hoc hash functions, keyed-
      hash constructions, signature schemes, or other functions, and
      MUST use published and standard schemes.
      Care should also be taken to ensure that the routing protocol
      authentication scheme is capable of supporting algorithms other
      than its defaults, in order to adapt to future discoveries.
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      Ideally, authentication MUST be performed on routing protocols
      packets oblivious to the order in which they have arrived, so
      that it does not get influenced by packets loss and reordering.
      Design teams should ensure that their protocols authentication
      mechanism is able to accommodate rekeying. This is essential
      since its well known that keys must periodically be changed.
      Also what the designers must ensure is that this rekeying event
      MUST NOT affect the functioning of the routing protocol. For
      example, OSPF rekeying requires coordination among the adjacent
      routers, while ISIS requires coordination among routers in the
      entire domain.
      If new authentication and security mechanisms are needed then
      the design teams must design in such a manner that the routing
      protocol authentication mechanism remains oblivious of how the
      keying material is derived. This decouples the authentication
      mechanism from the key management system that is employed.
      Design teams should also note that many routing protocols
      require prioritized treatment of certain protocol packets and
      authentication mechanisms should honor this.
      Not all routing protocol authentication mechanisms provide
      support for replay attacks, and the design teams should
      identify such authentication mechanisms and work on them so
      that this can get fixed. The design teams must look at the
      protocols that they are working on and see if packets captured
      from the previous/stale sessions can be replayed.
      What might also influence the design is the rate at which the
      protocol packets are originated. In case of protocols like BFD,
      where packets are originated at millisecond intervals, there
      are some special considerations that must be kept in mind when
      defining the new authentication and security mechanisms.
      It is imperative that the new authentication and security
      mechanisms defined support incremental deployment, as it is not
      feasible to deploy a new routing protocol authentication
      mechanism throughout the network instantaneously. It may also
      not be possible to deploy such a mechanism to all routers in a
      large AS at one time. This means that the designers must work
      on this aspect of authentication mechanism for the routing
      protocol that they are working on. The mechanisms must provide
      backward compatibility in the message formatting, transmission,
      and processing of routing information carried through a mixed
      security environment.
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      The designers should also consider whether the current
      authentication mechanisms impose considerable processing
      overhead on a router that's doing authentication. Most
      currently deployed routers do not have hardware accelerators
      for cryptographic processing and these operations can impose a
      significant processing burden under some circumstances. The
      proposed solutions should be evaluated carefully with regard to
      the processing burden that they will impose, since deployment
      may be impeded if network operators perceive that a solution
      will impose a processing burden which either entails
      substantial capital expenses or threatens to destabilize the
   7. Security Considerations
      As mentioned in the Introduction, RFC4948 [RFC4948] identifies
      additional steps needed to achieve the overall goal of
      improving the security of the core routing infrastructure.
      Those include validation of route origin announcements, path
      validation, cleaning up the IRR databases for accuracy, and
      operational security practices that prevent routers from
      becoming compromised devices. The KARP work is but one step in
      a necessary system of security improvements.
      The security of cryptographic-based systems depends on both the
      strength of the cryptographic algorithms chosen and the
      strength of the keys used with those algorithms. The security
      also depends on the engineering of the protocol used by the
      system to ensure that there are no non-cryptographic ways to
      bypass the security of the overall system.
   7.1. Use Strong Keys
      Care should be taken to ensure that the selected key is
      unpredictable, avoiding any keys known to be weak for the
      algorithm in use. [RFC4086] contains helpful information on
      both key generation techniques and cryptographic randomness.
      In addition to using a key of appropriate length and
      randomness, deployers of KARP protocols SHOULD use different
      keys between different routing peers whenever operationally
      possible. This is especially true when the Routing Protocol
      takes a static Traffic Key as opposed to a Traffic Key derived
      on a per-connection basis using a KDF. The burden for doing so
      is understandably much higher than for using the same static
      Traffic Key across all peering routers. Depending upon the
      specific KMP it can be argued that generally using a KMP
      network-wide increases peer-wise security. This is because if
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      attackers sitting between two routers learn or guess the
      Traffic Key for that connection, it still does not gain them
      access to the Traffic key being used in other connections.
      However, whenever using manual keys, it is best to design a
      system where a given pre-shared key (PSK) will be used in a
      KDF, mixed with connection-specific material, in order to
      generate session unique -- and therefore peer-wise -- Traffic
      Keys. Doing so has the following advantages: the Traffic Keys
      used in the per-message MAC operation are peer-wise unique, it
      provides inter-connection replay protection, and, if the per-
      message MAC covers some connection counter, intra-connection
      replay protection.
      Note that certain key derivation functions (e.g.
      KDF_AES_128_CMAC, as used in TCP-AO [RFC5926], the pseudorandom
      function (PRF) used in the KDF may require a key of a certain
      fixed size as an input. For example, AES_128_CMAC requires a
      128 bit (16 byte) key as the seed. However, for convenience to
      the administrators, a specification may not want to require the
      entry of a PSK of exactly 16 bytes. Instead, a specification
      may call for a key prep routine that could handle a variable
      length PSK, one that might be less or more than 16 bytes (see
      [RFC4615], section 3, as an example). That key prep routine
      would derive a key of exactly the required length and thus
      suitable as a seed to the PRF. This does NOT mean that
      administrators are safe to use weak keys. Administrators are
      encouraged to follow [RFC4086. We simply attempted to "put a
      fence around stupidity", in as much as possible.
      A better option, from a security perspective, is to use some
      representation of a device-specific asymmetric key pair as the
      identity proof, as described in section "Unique versus Shared
      Keys" section.
   7.2. Internal vs. External Operation
      Design teams must consider whether the protocol is an internal
      routing protocol or an external one, i.e. does it primarily run
      between peers within a single domain of control or between two
      different domains of control?  Some protocols may be used in
      both cases, internally and externally, and as such various
      modes of authentication operation may be required for the same
      protocol. While it is preferred that all routing exchanges run
      with the best security mechanisms enabled in all deployment
      contexts, this exhortation is greater for those protocols
      running on inter-domain point-to-point links, and greatest for
      those on shared access link layers with several different
      domains interchanging together, because the volume of attackers
      are greater from the outside.  Note however that the
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      consequences of internal attacks maybe no less severe -- in
      fact they may be quite a bit more severe -- than an external
      attack.  An example of this internal versus external
      consideration is BGP which has both EBGP and IBGP modes.
      Another example is a multicast protocol where the neighbors are
      sometimes within a domain of control and sometimes at an inter-
      domain exchange point.  In the case of PIM-SM running on an
      internal multi-access link, it would be acceptable to give up
      some security to get some convenience by using a group key
      among the peers on the link.  On the other hand, in the case of
      PIM-SM running over a multi-access link at a public exchange
      point, operators may favor security over convenience by using
      unique pair-wise keys for every peer.  Designers must consider
      both modes of operation and ensure the authentication
      mechanisms fit both.
      Operators are encouraged to run cryptographic authentication on
      all their adjacencies, but to work from the outside in, i.e.
      EBGP links are a higher priority than the IBGP links because
      they are externally facing, and, as a result, more likely to be
      targeted in an attack.
   7.3. Unique versus Shared Keys
      This section discusses security considerations regarding when
      it is appropriate to use the same authentication key inputs for
      multiple peers and when it is not. This is largely a debate of
      convenience versus security. It is often the case that the best
      secured mechanism is also the least convenient mechanism. For
      example, an air gap between a host and the network absolutely
      prevents remote attacks on the host, but having to copy and
      carry files using the "sneaker net" is quite inconvenient and
      does not scale.
      Operators have erred on the side of convenience when it comes
      to securing routing protocols with cryptographic
      authentication. Many do not use it at all. Some use it only on
      external links, but not on internal links. Those that do use it
      often use the same key for all peers in a network. It is common
      to see the same key in use for years, e.g., the key was entered
      when authentication mechanisms were originally configured, or
      the routing gear was deployed.
      The goal for designers is to create authentication and
      integrity mechanisms that are easy for operators to deploy and
      manage, and still use unique keys between peers (or small
      groups on multi-access links), and for different sessions among
      the same peers. Operators have the impression that they NEED
      one key shared across the network, when in fact they do not.
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      What they need is the relative convenience they experience from
      deploying cryptographic authentication with one key (or a few
      keys), compared to the inconvenience they would experience if
      they deployed the same authentication mechanism using unique
      pairwise keys. An example is BGP Route Reflectors. Here
      operators often use the same authentication key between each
      client and the route reflector. The roadmaps defined from this
      guidance document should allow for unique keys to be used
      between each client and the peer, without sacrificing much
      convenience. Designers should strive to deliver peer-wise
      unique keying mechanisms with similar ease-of-deployment
      properties as today's one-key method.
      Operators must understand the consequences of using the same
      key across many peers. Unique keys are more secure than shared
      keys because they reduce both the attack target size and the
      attack consequence size. In this context, the attack target
      size represents the number of unique routing exchanges across a
      network that an attacker may be able to observe in order to
      gain security association credentials, i.e. crack the keys. If
      a shared key is used across the entire internal domain of
      control, then the attack target size is very large. The larger
      the attack target, the easier it is for the attacker to gain
      access to analysis data, and greater the volume of analysis
      data he can access in a given time frame, both of which make
      the job easier. Using the same key across the network makes the
      attack vulnerability surface more penetrable than unique keys.
      The above attack can be mitigated to a certain extent by using
      strong keys. Another argument against using the same key is
      that if the same key that is used in multiple devices then a
      compromise of any one of the devices will expose the key. Also
      since the same key is supported on many devices this is known
      by many people which affects its distribution to all of the
      Consider also the attack consequence size, the amount of
      routing adjacencies that can be negatively affected once a
      breach has occurred, i.e., once the keys have been acquired by
      the attacker.
      Again, if a shared key is used across the internal domain, then
      the consequence size is the whole network. Ideally, unique key
      pairs would be used for each adjacency.
      In some cases use of shared keys is needed because of the
      problem space. For example, a multicast packet is sent once but
      then consumed by several routing neighbors. If unique keys were
      used per neighbor, the benefit of multicast would be erased
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      because sender would have to create a different announcement
      packet for each receiver. Though this may be desired and
      acceptable in some small number of use cases, it is not the
      norm. Shared (i.e., group) keys are an acceptable solution
      here, and much work has been done already in this area (see
      MSEC working group).
   7.4. Out-of-Band External Configuration vs. Peer-to-Peer Key
      This section discusses the security and use case considerations
      for keys placed on devices through out-of-band configuration
      versus through peer-to-peer key management protocol exchanges.
      Note, when we say here "Peer-to-Peer KMP" we do not mean in-
      band to the Routing Protocol. Instead, we mean that the
      exchange occurs in-line, over IP, between the two routing
      peers. In peer-to-peer KMP the peers handle the key and
      security association negotiation between themselves, whereas in
      an out-of-band configuration system the keys are placed in the
      device through some other configuration or management method or
      interface, via a third party.
      An example of an out-of-band external mechanism could be an
      administrator who makes a remote management connection (e.g.
      using SSH) to a router and manually enters the keying
      information, e.g., the algorithm, the key(s), the key
      lifetimes, etc. Another example could be an OSS system that
      inputs the same information using a script over an SSH
      connection, or by pushing configuration through some other
      management connection, standard (Netconf-based) or proprietary.
      The drawbacks of an out-of-band mechanism include: lack of
      scaleability, complexity, and speed of changing if a security
      breach is suspected. For example, if an employee who had access
      to keys was terminated, or if a machine holding those keys was
      believed to be compromised, then the system would be considered
      insecure and vulnerable until new keys were generated and
      distributed. Those keys then need to be placed into the OSS
      system, and the OSS system then needs to push the new keys --
      often during a very limited change window -- into the relevant
      devices. If there are multiple organizations involved in these
      connections, because the protected connections are inter-
      domain, this process is very complicated.
      The principle benefit of out-of-band configuration mechanism is
      that once the new keys/parameters are set in OSS system, they
      can be pushed automatically to all devices within the OSS's
      domain. Operators have mechanisms in place for this already for
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      managing other router configuration data. In small environments
      with few routers, a manual system is not difficult to employ.
      We further define a peer-to-peer key exchange as using
      cryptographically protected identity verification, session key
      negotiation, and security association parameter negotiation
      between the two routing peers. The KMP among peers may also
      include the negotiation of parameters, like cryptographic
      algorithms, cryptographic inputs (e.g. initialization vectors),
      key life-times, etc.
      There are several benefits of a peer-to-peer KMP versus
      centrally managed and distributing keys. It results in key(s)
      that are privately generated, and need not be recorded
      permanently anywhere. Since the traffic keys used in a
      particular connection are not a fixed part of a device
      configuration no security sensitive data exists anywhere else
      in the operator's systems which can be stolen, e.g. in the case
      of a terminated or turned employee. If a server or other data
      store is stolen or compromised, the thieves gain limited or no
      access to current traffic keys. They may gain access to key
      derivation material, like a PSK, but may not be able to access
      the current traffic keys in use. In this example, these PSKs
      can be updated in the device configurations (either manually or
      through an OSS) without bouncing or impacting the existing
      session at all. In the case of using raw asymmetric keys or
      certificates, instead of PSKs, the data theft (from the data
      store) would likely not result in any compromise, as the key
      pairs would have been generated on the routers, and never leave
      those routers. In such a case no changes are needed on the
      routers; the connections will continue to be secure,
      uncompromised. Additionally, with a KMP regular rekey
      operations occur without any operator involvement or oversight.
      This keeps keys fresh.
      There are a few drawbacks to using a KMP. First, a KMP requires
      more cryptographic processing for the router at the beginning
      of a connection. This will add some minor start-up time to
      connection establishment versus a purely manual key management
      approach. Once a connection with traffic keys has been
      established via a KMP, the performance is the same in the KMP
      and the out-of-band case. KMPs also add another layer of
      protocol and configuration complexity which can fail or be
      misconfigured. This was more of an issue when these KMPs were
      first deployed, but less so as these implementations and
      operational experience with them has matured.
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      The desired end goal for KARP WG is to develop a strong peer-
      to-peer KMP; an Out-of-and external Key Management protocol is
      out of scope.
      Within this constraint there are two approaches for a KMP:
      The first, is to use an Out-of-band Key Management protocol
      that runs independent of the routing and the signaling
      protocols. It would run on its own port and use its own
      transport (to avoid interfering with the routing protocol that
      it is serving). When a routing protocols needs a key, it would
      contact the local instance of this key management protocol and
      request a key. The KMP generates a key that is delivered to the
      routing protocol for it to use for authenticating and integrity
      verification of the routing protocol packets. This KMP could
      either be an existing key management protocol like ISAKMP/IKE,
      GKMP, etc., extended for the routing protocols, or it could be
      a new KMP, designed for the routing protocol context.
      The second approach is to define an In-band KMP extension for
      existing routing protocols putting the key management
      mechanisms inside the protocol itself. In this case, the key
      management messages would be carried within the routing
      protocol packets, resulting in very tight coupling between the
      routing protocols and the key management protocol.
   8. Acknowledgments
      Much of the text for this document came originally from draft-
      lebovitz-karp-roadmap, authored by Gregory M. Lebovitz.
      We would like to thank Sam Hartman, Eric Rescorla, Russ White,
      Stephen Kent, Stephen Farrell, Adrian Farrel, Michael Barnes
      and Vishwas Manral for their comments on the draft.
   9. IANA Considerations
      This document places no requests to IANA.
   10. References
   10.1. Normative References
      [RFC2119] Bradner, S.,"Key words for use in RFCs to Indicate
                Requirement Levels", BCP 14, RFC 2119, March 1997.
      [RFC4948] Andersson, L., et. al, "Report from the IAB workshop
                on Unwanted Traffic March 9-10, 2006", RFC 4948,
                August 2007.
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   10.2. Informative References
      [RFC1195] Callon, R. , "Use of OSI IS-IS for Routing in TCP/IP
                and Dual Environments", RFC 1195, December 1990.
      [RFC2205] Braden, R., et. al, "Resource ReSerVation Protocol
                (RSVP) Version 1 Functional Specification", RFC 2205,
                September 1197.
      [RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April 1998.
      [RFC2453] Malkin, G., "RIP Version 2", RFC 2453, November 1998.
      [RFC2747] Baker, F., Lindell, B., and M. Talwar, "RSVP
                Cryptographic Authentication", RFC 2747, January
      [RFC3097] Braden, R, and Zhang, L., "RSVP Cryptographic
                Authentication -- Updated Message Type Value", RFC
                3097, April 2001
      [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
                V., and G. Swallow, "RSVP-TE: Extensions to RSVP for
                LSP Tunnels", RFC 3209, December 2001.
      [RFC3473] Berger, L., "Generalized Multi-Protocol Label
                Switching (GMPLS) Signaling Resource ReserVation
                Protocol-Traffic Engineering (RSVP-TE) Extensions",
                RFC 3473, January 2003.
      [RFC3547] Baugher, M., Weis, B., Hardjono, T., and H. Harney,
                "The Group Domain of Interpretation", RFC 3547, July
      [RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery
                Protocol (MSDP)", RFC 3618, October 2003.
      [RFC3973] Adams, A., Nicholas, J., and W. Siadak, "Protocol
                Independent Multicast - Dense Mode (PIM-DM): Protocol
                Specification (Revised)", RFC 3973, January 2005.
      [RFC4086] Eastlake, D., Schiller, J., and S. Crocker,
                Randomness      Requirements for Security", BCP 106,
                RFC 4086, June 2005.
      [RFC4107] Bellovin, S. and R. Housley, "Guidelines for
                Cryptographic Key Management", BCP 107, RFC 4107,
                June 2005.
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      [RFC4230] Tschofenig, H. and R. Graveman, "RSVP Security
                Properties", RFC 4230, December 2005.
      [RFC4252] Ylonen, T., et. al, "The Secure Shell (SSH)
                Authentication Protocol", RFC 4252, January 2006.
      [RFC4253] Ylonen, T., et. al, "The Secure Shell (SSH) Transport
                Layer Protocol", RFC 4253, January 2006
      [RFC4271] Rekhter, Y., Li, T. and Hares, S.,"A Border Gateway
                Protocol 4 (BGP-4)", RFC 4271, January 2006.
      [RFC4492] Blake-Wilson, S., "Elliptical Curve Cryptography
                (ECC) Cipher Suites for Transport Layer Security
                (TLS)", RFC 4492, May 2006
      [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I.
                Kouvelas,"Protocol Independent Multicast - Sparse
                Mode (PIM-SM): Protocol Specification (Revised)", RFC
                4601, August 2006.
      [RFC4615] Song, J., Poovendran, R., Lee, J., and T. Iwata, "The
                Advanced Encryption Standard-Cipher-based Message
                Authentication Code-Pseudo-Random Function-128 (AES-
                CMAC-PRF-128) Algorithm for the Internet Key Exchange
                Protocol (IKE)", RFC 4615, August 2006.
      [RFC4726] Farrel, A., et. al.,"A Framework for Inter-Domain
                Multiprotocol Label Switching Traffic Engineering",
                RFC 4726, November 2006.
      [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
                Specification", RFC 5036, October 2007.
      [RFC5151] Farrel, A., et. al.,"Inter-Domain MPLS and GMPLS
                Traffic Engineering -- Resource Reservation Protocol-
                Traffic Engineering (RSVP-TE) Extensions", RFC 5151,
                February 2008.
      [RFC5280] Cooper, D., et. al.,"Internet X.509 Public Key
                Infrastructure Certificate and Certificate Revocation
                List (CRL) Profile", RFC 5280, May 2008
      [RFC5440] Vasseur, J.P. and Le Roux, J.L., "Path Computation
                Element (PCE) Communication Protocol (PCEP)", RFC
                5440, March 2009
                            Expires January 2012             [Page 27]

   Internet-Draft          KARP Design Guidelines        September 2011
      [RFC5796] Atwood, W., Islam, S., and M. Siami, "Authentication
                and Confidentiality in PIM-SM Link-local Messages",
                RFC 5796, March 2010.
      [RFC5880] Katz, D. and Ward, D., "Bidirectional Forwarding
                Detection", RFC 5880, June 2010.
      [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
                Authentication Option", RFC 5925, June 2010.
      [RFC5926] Lebovitz, G., "Cryptographic Algorithms, Use and
                Implementation Requirements for TCP Authentication
                Option", RFC 5926, June 2010.
      [RFC6039] Manral, V., Bhatia, M., Jaeggli, J. and White,
                R.,"Issues with Existing Cryptographic Protection
                Methods for Routing Protocols", RFC 6039, October
      [I-D.ietf-karp-threats-reqs] Lebovitz, G., "KARP Threats and
                Requirements", Work in Progress, October 2010.
       [I-D.ietf-saag-crypto-key-table] Housley, R. and Polk, T.,
                "Database of Long-Lived Cryptographic Keys" , Work in
                Progress, September 2009
      [I-D.weis-gdoi-mac-tek] Weis, B. and S. Rowles, "GDOI Generic
                Message Authentication Code Policy", Work in
                Progress, June 2010.
      [IRR] Merit Network Inc , "Internet Routing Registry Routing
                Assets Database", 2006, http://www.irr.net/.
      [NIST-800-57] US National Institute of Standards & Technology,
                "Recommendation for Key Management Part 1: General
                (Revised)", March 2007
                            Expires January 2012             [Page 28]

   Internet-Draft          KARP Design Guidelines        September 2011
      Author's Addresses
      Gregory M. Lebovitz
      USA 95003
      Email: gregory.ietf@gmail.com
      Manav Bhatia
      Email: manav.bhatia@alcatel-lucent.com
                            Expires January 2012             [Page 29]

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