KARPW. Atwood
Internet-DraftConcordia University/CSE
Intended status: InformationalG. Lebovitz
Expires: September 1, 2010Juniper
 February 28, 2010

Framework for Cryptographic Authentication of Routing Protocol Packets on the Wire


In the March of 2006 the IAB held a workshop on the topic of "Unwanted Internet Traffic". The report from that workshop is documented in RFC 4948 (Andersson, L., Davies, E., and L. Zhang, “Report from the IAB workshop on Unwanted Traffic March 9-10, 2006,” August 2007.) [RFC4948]. Section 8.2 of RFC 4948 calls for "[t]ightening the security of the core routing infrastructure." Four main steps were identified for improving the security of the routing infrastructure. One of those steps was "securing the routing protocols' packets on the wire." One mechanism for securing routing protocol packets on the wire is the use of per-packet cryptographic message authentication, providing both peer authentication and message integrity. Many different routing protocols exist and they employ a range of different transport subsystems. Therefore there must necessarily be various methods defined for applying cryptographic authentication to these varying protocols. Many routing protocols already have some method for accomplishing cryptographic message authentication. However, in many cases the existing methods are dated, vulnerable to attack, and/or employ cryptographic algorithms that have been deprecated. This document is one of a series concerned with defining a roadmap of protocol specification work for the use of modern cryptogrpahic 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 integrity. The overall roadmap reflects the input of both the security area and routing area in order to form a jointly agreed upon and prioritized work list for the effort.

Status of this Memo

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Table of Contents

1.  Introduction
    1.1.  Terminology
    1.2.  Requirements Language
    1.3.  Scope
    1.4.  Goals
    1.5.  Non-Goals
    1.6.  Audience
2.  Common Framework
    2.1.  Framework Elements
3.  Framework Components
    3.1.  Key Management Protocol
    3.2.  KeyStore
    3.3.  Routing Protocol Mechanisms
4.  Framework APIs
    4.1.  KMP-to_Keystore API
    4.2.  KMP-to-Routing Protocol API
    4.3.  Keystore-to-Routing Protocl API
5.  Security Considerations
6.  IANA Considerations
7.  Acknowledgements
8.  Change History (RFC Editor: Delete Before Publishing)
9.  Needs Work in Next Draft (RFC Editor: Delete Before Publishing)
10.  References
    10.1.  Normative References
    10.2.  Informative References
§  Authors' Addresses


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 (Andersson, L., Davies, E., and L. Zhang, “Report from the IAB workshop on Unwanted Traffic March 9-10, 2006,” August 2007.) [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:

This document addresses the last bullet, securing the packets on the wire of the routing protocol exchanges. The document addresses Keying and Authentication for Routing Protocols, aka "KARP".


1.1.  Terminology

Within the scope of this document, the following words, when beginning with a capital letter, or spelled in all capitals, hold the meanings described to the right of each term. If the same word is used uncapitalized, then it is intended to have its common english definition.

Pre-Shared Key. A key used by both peers in a secure configuration. Usually exchanged out-of-band prior to a first connection.
Routing Protocol
When used with capital "R" and "P" in this document the term refers the Routing Protocol for which work is being done to provide or enhance its peer authentication mechanisms.
Pseudorandom number function, or sometimes called pseudorandom number generator (PRNG). An algorithm for generating a sequence of numbers that approximates the properties of random numbers. The sequence is not truly random, in that it is completely determined by a relatively small set of initial values that are passed into the function. An example is SHA-256.
Key derivation function. A particular specified use of a PRF that takes a PSK, combines it with other inputs to the PRF, and produces a result that is suitable for use as a Traffic Key.
The type and value used by one peer of an authenticated message exchange to signify to the other peer who they are. The Identifier is used by the receiver as a lookup index into a table containing further information about the peer that is required to continue processing the message, for example a Security Association (SA) or keys.
Identity Proof
A cryptographic proof for an asserted identity, that the peer really is who they assert themselves to be. Proof of identity can be arranged between the peers in a few ways, for example PSK, raw assymetric keys, or a more user-friendly representation of assymetric keys, such as a certificate.
Security Association or SA
The parameters and keys that together form the required information for processing secure sessions between peers. Examples of items that may exist in an SA include: Identifier, PSK, Traffic Key, cryptographic algorithms, key lifetimes.
Key Management Protocol. A protocol used between peers to exchange SA parameters and Traffic Keys. Examples of KMPs include IKE, TLS, and SSH.
KMP Function
Any actual KMP used in the general KARP solution framework
Peer Key
Keys that are used between peers as the identity proof. These keys may or may not be connection specific, depending on how they were established, and what form of identity and identity proof is being used in the system.
Traffic Key
The actual key used on each packet of a message.

Definitions of items specific to the general KARP framework are described in more detail in the Framework section Section 2 (Common Framework).


1.2.  Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].

When used in lower case, these words convey their typical use in common language, and are not to be interpreted as described in RFC2119 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].


1.3.  Scope

Four basic tactics may be employed in order to secure any piece of data as it is transmitted over the wire: privacy (or encryption), authentication, message integrity, and non-repudiation. The focus for this effort, and the scope for this framework document, will be message authentication and packet integrity only. This work explicitly excludes, at this point in time, the other two tactics: privacy and non-repudiation. Since the objective of most routing protocols is to broadly advertise the routing topology, routing messages are commonly sent in the clear; confidentiality is not normally required for routing protocols. However, ensuring that routing peers truly are the trusted peers expected, and that no rogue peers or messages can compromise the stability of the routing environment is critical, and thus our focus. The other two explicitly excluded tactics, privacy and non-repudiation, may be addressed in future work.

It is possible for routing protocol packets to be transmitted employing all four security tactics mentioned above using existing standards. For example, one could run unicast, layer 3 or above routing protocol packets through IPsec ESP (Kent, S., “IP Encapsulating Security Payload (ESP),” December 2005.) [RFC4303]. This would provide the added benefit of privacy, and non-repudiation. However, router platforms and systems have been fine tuned over the years for the specific processing necessary for routing protocols' non-encapsulated formats. Operators are, therefore, quite reluctant to explore new packet encapsulations for these tried and true protocols.

In addition, at least in the case of BGP and LDP, these protocols already have existing mechanisms for cryptographically authenticating and integrity checking the packets on the wire. Products with these mechanisms have already been produced, code has already been written and both have been optimized for the existing mechanisms. Rather than turn away from these mechanisms, we want to enhance them, updating them to modern and secure levels.

There are two main work phases for the roadmap, and for any Routing Protocol work undertaken as part of the roadmap. The first is to enhance the Routing Protocol's current authentication mechanism, ensuring it employs modern cryptographic algorithms and methods for its basic operational model, fulfilling the requirements defined in the Requirements section of the Design Guidelines document [**need reference**], and protecting against as many of the threats as possible as defined in the Threats section of the same dcoument. Many of the Routing Protocols' current mechanisms use manual keys, so the first phase updates will focus on shoring up the manual key mechanisms that exist.

The second work phase is to define the use of a key management protocol (KMP) for creating and managing session keys used in the Routing Protocols' message authentication and data integrity functions. It is intended that a general KMP framework -- or a small number of frameworks -- can be defined and leveraged for many Routing Protocols.

Therefore, the scope of this roadmap of work includes:

Making use of existing routing protocol security protocols, where they exist, and enhancing or updating them as necessary for modern cryptographic best practices,
Developing a framework for using automatic key management in order to ease deployment, lower cost of operation, and allow for rapid responses to security breaches, and
Specifying the automated key management protocol that may be combined with the bits-on-the-wire mechanisms.

The work also serves as an agreement between the Routing Area and the Security Area about the priorities and work plan for incrementally delivering the above work. This point is important. There will be times when the best-security-possible will give way to vastly-improved-over-current-security-but-admittedly-not-yet-best-security-possible, in order that incremental progress toward a more secure Internet may be achieved. As such, this document will call out places where agreement has been reached on such trade offs.

This document does not contain protocol specifications. Instead, it defines the areas where protocol specification work is needed and sets a direction, a set of requirements, and a relative priority for addressing that specification work.

There are a set of threats to routing protocols that are considered in-scope for this document/roadmap, and a set considered out-of-scope. These are described in detail in the Threats section of [**somewhere**].

NOTE: Cross-references now indicated by [** some text *]] were valid in the original draft by Greg. They will be properly indicated in the next version, once all three companion documents are published and available in the repository.


1.4.  Goals

The goals and general guidance for this work roadmap follow:

Provide authentication and integrity protection for packets on the wire of existing routing protocols
Deliver a path to incrementally improve security of the routing infrastructure. The principle of crawl, walk, run will be in place. Routing protocol authentication mechanisms may not go immediately from their current state to a state containing the best possible, most modern security practices. Incremental steps will need to be taken for a few very practical reasons. First, there are a considerable number of deployed routing devices in operating networks that will not be able to run the most modern cryptographic mechanisms without significant and unacceptable performance penalties. The roadmap for any one routing protocol MUST allow for incremental improvements on existing operational devices. Second, current routing protocol performance on deployed devices has been achieved over the last 20 years through extensive tuning of software and hardware elements, and is a constant focus for improvement by vendors and operators alike. The introduction of new security mechanisms affects this performance balance. The performance impact of any incremental step of security improvement will need to be weighed by the community, and introduced in such a way that allows the vendor and operator community a path to adoption that upholds reasonable performance metrics. Therefore, certain specification elements may be introduced carrying the "SHOULD" guidance, with the intention that the same mechanism will carry a "MUST" in the next release of the specification. This gives the vendors and implementors the guidance they need to tune their software and hardware appropriately over time. Last, some security mechanisms require the build out of other operational support systems, and this will take time. An example where these three reasons are at play in an incremental improvement roadmap is seen in the improvement of BGP's (Rekhter, Y., Li, T., and S. Hares, “A Border Gateway Protocol 4 (BGP-4),” January 2006.) [RFC4271] security via the update of the TCP Authentication Option (TCP-AO) (Touch, J., Mankin, A., and R. Bonica, “The TCP Authentication Option,” March 2010.) [I‑D.ietf‑tcpm‑tcp‑auth‑opt] effort. It would be ideal, and reflect best common security practice, to have a fully specified key management protocol for negotiating TCP-AO's authentication material, using certificates for peer authentication in the keying. However, in the spirit of incremental deployment, we will first address issues such as cryptographic algorithm agility, replay attacks, TCP session resetting in the base TCP-AO protocol before we layer key management on top of it.
The deploy-ability of the improved security solutions on currently running routing infrastructure equipment. This begs the consideration of the current state of processing power available on routers in the network today.
Operational deploy-ability - The acceptability of a solution will also be measured by how deployable the solution is by common operator teams using common deployment processes and infrastructures, i.e., we will try to make these solutions fit as well as possible into current operational practices or router deployment. This will be heavily influenced by operator input, to ensure that what we specify can -- and, more importantly, will -- be deployed once specified and implemented by vendors. Deployment of incrementally more secure routing infrastructure in the Internet is the final measure of success. Measurably, we would like to see an increase in the number of surveyed respondents who report deploying the updated authentication mechanisms anywhere across their network, as well as a sharp rise in usage for the total percentage of their network's routers.
Interviews with operators show several points about routing security. First, over 70% of operators have deployed transport connection protection via TCP-MD5 on their EBGP [ISR2008] (McPherson, D. and C. Labovitz, “Worldwide Infrastructure Security Report,” October 2008.) . Over 55% also deploy MD5 on their IBGP connections, and 50% deploy MD5 on some other IGP. The survey states that "a considerable increase was observed over previous editions of the survey for use of TCP MD5 with external peers (eBGP), internal peers (iBGP) and MD5 extensions for IGPs." Though the data are not captured in the report, the authors believe anecdotally that of those who have deployed MD5 somewhere in their network, only about 25-30% of the routers in their network are deployed with the authentication enabled. None report using IPsec to protect the routing protocol, and this was a decline from the few that reported doing so in the previous year's report.
From my personal conversations with operators, of those using MD5, almost all report deploying with one single manual key throughout the entire network. These same operators report that the one single key has not been changed since it was originally installed, sometimes five or more years ago. When asked why, particularly for the case of BGP using TCP MD5, the following reasons are often given:
Changing the keys triggers a TCP reset, and thus bounces the links/adjacencies, undermining Service Level Agreements (SLAs).
For external peers, difficulty of coordination with the other organization is an issue. Once they find the correct contact at the other organization (not always so easy), the coordination function is serialized and on a per peer/AS basis. The coordination is very cumbersome and tedious to execute in practice.
Keys must be changed at precisely the same time, or at least within 60 seconds (as supported by two major vendors) in order to limit connectivity outage duration. This is incredibly difficult to do, operationally, especially between different organizations.
Relatively low priority compared to other operatoinal issues.
Lack of staff to implement the changes device by device.
There are three use cases for operational peering at play here: peers and interconnection with other operators, Internal BGP and other routing sessions within a single operator, and operator-to-customer-CPE devices. All three have very different properties, and all are reported as cumbersome. One operator reported that the same key is used for all customer premise equipment. The same operator reported that if the customer mandated, a unique key could be created, although the last time this occurred it created such an operational headache that the administrators now usually tell customers that the option doesn't even exist, to avoid the difficulties. These customer-uniqe keys are never changed, unless the customer demands so.
The main threat at play here is that a terminated employee from such an operator who had access to the one (or few) keys used for authentication in these environments could easily wage an attack -- or offer the keys to others who would wage the attack -- and bring down many of the adjacencies, causing destabilization to the routing system.
Whatever mechanisms we specify need to be easier than the current methods to deploy, and should provide obvious operational efficiency gains along with significantly better security and threat protection. This combination of value may be enough to drive much broader adoption.
Address the threats enumerated above in the "Threats" section [**somewhere**] for each routing protocol, along a roadmap. Not all threats may be able to be addressed in the first specification update for any one protocol. Roadmaps will be defined so that both the security area and the routing area agree on how the threats will be addressed completely over time.
Create a re-usable architecture, framework, and guidelines for various IETF working teams who will address these security improvements for various Routing Protocols. The crux of the KARP work is to re-use that framework as much as possible across relevant Routing Protocols. For example, designers should aim to re-use the key management protocol that will be defined for BGP's TCP-AO key establishment for as many other routing protocols as possible. This is but one example.
Bridge any gaps between IETF's Routing and Security Areas by recording agreements on work items, roadmaps, and guidance from the Area leads and Internet Architecture Board (IAB,


1.5.  Non-Goals

The following two goals are considered out-of-scope for this effort:

Privacy of the packets on the wire, at this point in time. Once this roadmap is realized, we may revisit work on privacy.
Message content security. This work is being addressed in other IETF efforts, such as SIDR.


1.6.  Audience

The audience for this roadmap includes:

o Routing Area working group chairs and participants -
These people are charged with updates to the Routing Protocol specifications. Any and all cryptographic authentication work on these specifications will occur in Routing Area working groups, with close partnership with the Security Area. Co-advisors from Security Area may often be named for these partnership efforts.
o Security Area reviewers of routing area documents -
These people are delegated by the Security Area Directors to perform reviews on routing protocol specifications as they pass through working group last call or IESG review. They will pay particular attention to the use of cryptographic authentication and corresponding security mechanisms for the routing protocols. They will ensure that incremental security improvements are being made, in line with this roadmap.
o Security Area engineers -
These people partner with routing area authors/designers on the security mechanisms in routing protocol specifications. Some of these security area engineers will be assigned by the Security Area Directors, while others will be interested parties in the relevant working groups.
o Operators -
The operators are a key audience for this work, as the work is considered to have succeeded if the operators deploy the technology, presumably due to a perception of significantly improved security value coupled with relative similarity to deployment complexity and cost. Conversely, the work will be considered a failure if the operators do not care to deploy it, either due to lack of value or perceived (or real) over-complexity of operations. And as such, the GROW and OPSEC WGs should be kept squarely in the loop as well.


2.  Common Framework

Each of the categories of routing protocols above will require unique designs for authenticating and integrity checking their protocols. However, a single underlying framework for delivering automatic keying to those solutions will be pursued. Providing such a single framework will significantly reduce the complexity of each step of the overall roadmap. For example, if each Routing Protocol needed to define its own key management protocol this would balloon the total number of different sockets that need to be opened and processes that need to be simultaneously running on an implementation. It would also significantly increase the run-time complexity and memory requirements of such systems running multiple Routing Protocols, causing perhaps slower performance of such systems. However, if we can land on a very small set (perhaps one or two) of automatic key management protocols, KMPs, that the various Routing Protocols can use, then we can reduce this implementation and run-time complexity. We can also decrease the total amount of time implementers need to deliver the KMPs for the Routing Protocols that will provide better threat protection.

The components for the framework are listed here, and described in the next section:

The framework is modularized for how keys and security association (SA) parameters generally get passed from a KMP to a transport protocol. It contains three main blocks and APIs.

   +------------+   +--------------------+           +-----------+
   |            |   |                    | Check     |           |
   | Identifier +-->|                    +---------->|  Identity |
   |            |   |    KMP Function    |           |   Proof   |
   +----------- +   |                    |<----------+           |
                    |                    |  Approve  +-----------+
+---------------+   +-------+--------+---+
|               |          /|\      /|\
| Manual        |           |        |
| Configuration |           |        |
|               |           |        |
+-------------+-+           |        |
             /|\   KMP-to-  |        |
              |    Keystore |        |
              |    API      |        |
             \|/           \|/       |
            +-+-------------+-+      |
            |                 |      | KMP-to-
            |                 |      | RoutingProtocol
            |      KeyStore   |      | API
            |                 |      |
            +---------+-------+      |
                     /|\             |
                      |              |
        KeyStore-to-  |              |
 RoutingProtocol API  |              |
                      |             \|/
          |           |                            |
          |           |           Common Routing   |
          |          \|/          Protocol         |
          |   +-------+-------+   Security         |
          |   |               |   Mechanisms       |
          +---|  Traffic      |----+---+---+---+---+
          |   |   Key(s)      |    |   |   |   |   |
          |   |               |    |   |   |   |   |  A, B, C, D ->
          |   +---------------+    | A | B | C | D |  Specific
          |                        |   |   |   |   |  Routing Protocol
          |                        |   |   |   |   |  Security
          |                        |   |   |   |   |  Mechanisms

 Figure 1: Automatic Key Management Framework 


2.1.  Framework Elements

Each element of the framework is described here:

o Common Routing Protocol security mechanisms -
In each case, the Routing Protocol will contain one or more mechanism(s) for using session keys in their security option. The common mechanisms part will allow a routing protocol to receive updates from the KeyStore and to poll for updates from the KeyStore, including the passing of all possible required attributes relevant to that Routing Protocol.
o Specific Routing Protocol security mechanisms -
These parts will be specific to a particular Routing Protocol. When the Routing Protocol uses a transport substrate, e.g., the way BGP, LDP and MSDP use TCP, then this applies to the security mechanism the includes that substrate.
NOTE: the point of this two-layer approach is that there will be one generic abstraction layer that can sit on top of any/all Routing Protocols. The hope is that the Routing Protocol Demon development teams can write this part once, and use it for any routing Protocol. There may be evolution over time of the abstraction layer so as to contain capabilities and attribute definitions as needed by routing Protocols yet-to-be-addressed in this architecture. However, the new Routing Protocol would still leverage all that had gone into the abstraction layer before.
o KeyStore -
Each implementation will also contain a protocol independent mechanism for storing keys, called the KeyStore. The KeyStore will have multiple different logical containers, one container for each Session Association or Multicast Session Association that any given Routing Protocol will need. The container will store the parameters needed for the SA or the MSA, for example, detalis of the authentication/encryption algorithms employed, the valid lifetime of the keys, the direction in which the key needs to be applied (inward/outward/both), the group SPI, a KeyID, etc. A key stored here may be a Peer Key or a Traffic Key. Further details may be found in [I‑D.polk‑saag‑rtg‑auth‑keytable] (Polk, T. and R. Housley, “Routing Authentication Using A Database of Long-Lived Cryptographic Keys,” December 2009.) and [I‑D.housley‑saag‑crypto‑key‑table] (Housley, R. and T. Polk, “Database of Long-Lived Symmetric Cryptographic Keys,” November 2009.). Note that a specific Routing Protocol may utilize both communication between two peers and communication among groups of peers. As an example, PIM-SM sends distant messages (Register and Register-Stop) using unicast, and "link-local" messages (Hello, Assert, Join/Prune) using multicast [I‑D.ietf‑pim‑sm‑linklocal] (Atwood, W., Islam, S., and M. Siami, “Authentication and Confidentiality in PIM-SM Link-local Messages,” December 2009.).
o Peer Key -
A key used between peers from which a traffic key is derived. An example is a Pre-Shared Key.
o Traffic Key -
The actual key used on each packet of a message. This key may be derived from the key existing in the KeyStore. This will depend on whether the key in KeyStore was a manual PSK for the peers, or whether a connection-aware KMP created the key. Further, it will be connection specific, so as to provide inter- and intra-connection replay protection.
o KMP -
There will be an automated key management protocol, KMP. This KMP will run between the peers. The KMP serves as a protected channel between the peers, through which they can negotiate and pass important data required to exchange proof of key identifiers, derive session keys, determine re-keying, synchronize their keying state, signal various keying events, notify with error messages, etc. As an analogy, in the IPsec protocol (RFC4301 (Kent, S. and K. Seo, “Security Architecture for the Internet Protocol,” December 2005.) [RFC4301], RFC4303 (Kent, S., “IP Encapsulating Security Payload (ESP),” December 2005.) [RFC4303] and RFC4306 (Kaufman, C., “Internet Key Exchange (IKEv2) Protocol,” December 2005.) [RFC4306]) IKEv2 is the KMP that runs between the two peers, while AH and ESP are two different base protocols that take session keys from IKEv2 and use them in their transmissions. In the analogy, the Routing Protocol, say BGP and LDP, are analogous to ESP and AH, while the KMP is analogous to IKEv2 itself.
o Identifiers -
A KMP is fed by identities. The identities are text strings used by the peers to indicate to each other that each are known to the other, and authorized to establish connections. Those identities must be represented in some standard string format, e.g. an IP address -- either v4 or v6, an FQDN, an RFC 822 email address, a Common Name [RFC PKI], etc. Note that even though routers do not normally have email addresses, one could use an RFC 822 email address string as a formatted identifier for a router. They would do so simply by putting the router's reference number or name-code as the "NAME" part of the address, left of the "@" symbol. They would then place some locational context in the "DOMAIN" part of the string, to the right of the "@" symbol. An example would be "". This document does not suggest this string value at all. Instead, the concept is used only to clarify that the type of string employed does not matter. It also does not matter what specific text you chose to place in that string type. It only matters that the type of string -- and its format -- must be agreed upon by the two endpoints. Further, the string can be used as an identifier in this context, even if the string is not actually provisioned in its source domain. For example, the email address "" may not actually exist as an email address in that domain, but that string of characters may still be used as an identifier type(s) in the routing protocol security context. What is important is that the community decide on a small but flexible set of Identifiers they will all support, and that they decide on the exact format of those string. The formats that will be used must be standardized and must be sensible for the routing infrastructure.
o Identity Proof -
Once the form of identity is decided, then there must be a cryptographic proof of that identity, that the peer really is who they assert themselves to be. Proof of identity can be arranged between the peers in a few ways, for example pre-shared keys, raw assymetric keys, or a more user-friendly representation of assymetric keys, such as a certificate. Certificates can be used in a way requiring no additional supporting systems -- e.g. public keys for each peer can be maintained locally for verification upon contact. Certificate management can be made more simple and scalable with the use of minor additional supporting systems, as is the case with self-signed certificates and a flat file list of "approved thumbprints". Self-signed certificates will have somewhat lower security properties than Certificate Authority signed certificates [RFC Certs]. The use of these different identity proofs vary in ease of deployment, ease of ongoing management, startup effort, ongoing effort and management, security strength, and consequences from loss of secrets from one part of the system to the rest of the system. For example, they differ in resistance to a security breach, and the effort required to remediate the whole system in the event of such a breach. The point here is that there are options, many of which are quite simple to employ and deploy.
o Profiles -
Once the KMP, Identifiers and Proofs mechanisms are converged upon, they must be clearly profiled for each Routing Protocol, so that implementors and deployers alike understand the different pieces of the solution, and can have similar configurations and interoperability across multiple vendors' devices, so as to reduce management difficulty. The profiles SHOULD also provide guidance on when to use which various combinations of options. This will, again, simplify use and interoperability.

[after writing this all up, I'm not sure we really need the key_store in the middle. As long as we standardize fully all the calls needed from any Routing Protocol to any KMP, then there can be a generic hand-down function from the KMP to the Routing Protocol when the key and parameters are ready. Let's sleep on it.]

[will need state machines and function calls for these APIs, as one of the work items. In essence, there is a need for a core team to develop the APIs out completely in order for the Routing Protocol teams to use them. Need to get this team going asap.]

o KMP-to-RoutingProtocol API -
There will be an API for the Routing Protocol to request a session key of the KMP, and be notified when the keys are available for it. The API will also contain a mechanism for the KMP to notify the Routing Protocol that there are new keys that it must now use, even if it didn't request those keys. The API will also include a mechanism for the KMP to receive requests for session keys and other parameters from the routing protocol. The KMP will also be aware of the various Routing Protocols and each of their unique parameters that need to be negotiated and returned.
o KeyStore-to-RoutingProtocol API -
There will be an API for Routing Protocol to retrieve (or receive; it could be a push or a pull) the keys from the KeyStore. This will enable implementers to reuse the same API calls for all their Routing Protocols. The API will necessarily include facility to retrieve other SA parameters required for the construction of the Routing Protocol's packets, such as key IDs or key lifetimes, etc.
o KMP-to-KeyStore API -
There will be an API for the KMP to place keys and parameters into the KeyStore after their negotiation and derivation with the other peer. This will enable the implementers to reuse the same calls for multiple KMPs that may be needed to address the various categories of Routing Protocols as described in the section defining categories in the Design Guidelines document [**need reference**].

In addition to other business, administrative, and operational terms they must already exchange prior to forming first adjacencies, it is assumed that two parties deploying message authentication on their routing protocol will also need to decide upon acceptable security parameters for the connection. This will include the form and content of the identity each use to represent the other. It will also include the type of keys to be used, e.g. PSK, raw assymetric keys, certificate. Also, it will include the acceptable cryptographic algorithms, or algorithm suite. This agreement is necessary in order for each to properly configure the connection on their respective devices. The manner in which they agree upon and exchange this policy information is normally via phone call or written exchange, and is outside the scope of the KARP effort, but assumed to have occured. We take as a given that each party knows the identity types and values, key types and values, and acceptable cryptographic algorithms for both their own device and the peer that form the security policy for configuration on their device.

Common Mechanisms - In as much as they exist, the framework will capture mechanisms that can be used commonly not only within a particular category of Routing Protocol and Routing Protocol to KMP, but also between Routing Protocol categories. Again, the goal here is simplifying the implementations and runtime code and resource requirements. There is also a goal here of favoring well vetted, reviewed, operationally proven security mechanisms over newly brewed mechanisms that are less well tried in the wild.


3.  Framework Components

This section will contain additional information/commentary on the operation of the components.


3.1.  Key Management Protocol

[[The following text needs a home.]]

[[Manav]] Should there be some text on key rollover or keys expiring? Who takes care of these events, the KMP or the Routing Protocol? I believe that it should be the former.

[[Greg]] If there is a kmp, then the kmp can put the new SA parameters (including keys) into the KeyStore. However, based on our experience with TCP-AO, there are several things that the base RoutingProtocol needs to do to handle key rollover so that no routing messages are dropped. Allowing for overlapping or multiple, simulatneously valid KeyIDs is one requirements. polling for updates, or receiving updates from, KeyStore is another requirement. For now, however, it would be better to capture these in the threats-requirements document, and then let each routing protocol category design team figure out the details as apporpriate for their protocol(s).


3.2.  KeyStore

[[The following text needs a home.]]

[[Greg]] If one continues down this thought exercise, one could imagine an IANA registry filled with attributes as would be required for any SA parameters that any KARP-following protocol would want / need to use, such that both the KMP-to-KeyStore API and the KeyStore-to-RtgProto API would reference that registry, and it would grow over time as new categories of RoutingProtocols find need for this or that attribute to make their specific SA's complete.


3.3.  Routing Protocol Mechanisms

[[Issue to be resolved]]

[[Manav]] I am not sure I completely understand what would get into Common RtgProto auth mechanisms?

[[Manav]] Is it some infrastructure that protocols like OSPF and ISIS can use, or all RPs (PIM, OSPFv3, etc) using IPSec may want to use?

[[Greg]] Probably only those protocols taking keys from IKE directly (assuming IKEv2 would be the KMP, whic is still up for discussion), and not relevant to keys created from IKE for IPsec (IKE already knows how to pass keys SA parameters to IPsec).

[[Manav]] If so, then some protocols (BGP?) may want KMP to directly speak to them, in which case KMP-to-RoutingProtocol API should also have a direct connection to Specific routing protocol auth security mechanism.

[[Greg]] We discussed this on the planning call for the first draft. We decided that there are times when, as the routing protocol kicks-off, it sees that the protocol config calls for authentication. In this case, the routing protocol needs to tell the KMP that it needs keys and SA parameters. Also, though this isn't the exchange I agree with, we might decide that it is the RoutingProtocol's responsibility to tell the KMP when active keys are approaching expiry, and ask for new keys. (On this point, I favor the KMP keeping track of this, and negotiating new Keys for the RoutingProtocol when needed.) But we aren't done with that discussion yet. As we get into the detailed work on RoutingProtocol(s) categories, we may find other uses for the direct KMP-to-RoutingProtocol-Auth-Mechanism abstraction layer, so we decided to keep it.

[[Manav]] On second thoughts, wouldnt KMP only interact with the KeyStore and RPs with Keystore - why would we want the RPs to speak to KMP?

[[Greg]] See explanation directly above.

[[Manav, later]] Would be extremely helpful if we can have a section with the pros and cons of having IKEv2 as the KMP as against defining a new KMP for RPs.

[[Bill]] Unicast relationships may well use something such as IKEv2; multicast relationships will need to use a group key management protocol, such as GDOI some variant of GDOI.


4.  Framework APIs

This will be new work.


4.1.  KMP-to_Keystore API

To be written.


4.2.  KMP-to-Routing Protocol API

To be written.


4.3.  Keystore-to-Routing Protocl API

To be written.


5.  Security Considerations


6.  IANA Considerations

This document has no actions for IANA.


7.  Acknowledgements

Almost all the text for draft-00 of this document was pasted in from draft-lebovitz-karp-roadmap, which was written by Gregory Lebovitz. Bill Atwood took the role as editor for the first version of this framework document.


8.  Change History (RFC Editor: Delete Before Publishing)

[NOTE TO RFC EDITOR: this section for use during I-D stage only. Please remove before publishing as RFC.]

kmart-framework-00- (original submission, based on draft-lebovitz-karp-roadmap-00)


9.  Needs Work in Next Draft (RFC Editor: Delete Before Publishing)

[NOTE TO RFC EDITOR: this section for use during I-D stage only. Please remove before publishing as RFC.]

List of stuff that still needs work


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 (TXT, HTML, XML).
[RFC4593] Barbir, A., Murphy, S., and Y. Yang, “Generic Threats to Routing Protocols,” RFC 4593, October 2006 (TXT).
[RFC4948] Andersson, L., Davies, E., and L. Zhang, “Report from the IAB workshop on Unwanted Traffic March 9-10, 2006,” RFC 4948, August 2007 (TXT).


10.2. Informative References

[] Lebovitz, G., “Cryptographic Algorithms, Use and Implementation Requirements for TCP Authentication Option,” March 2009.
[I-D.housley-saag-crypto-key-table] Housley, R. and T. Polk, “Database of Long-Lived Symmetric Cryptographic Keys,” draft-housley-saag-crypto-key-table-01 (work in progress), November 2009 (TXT).
[I-D.ietf-pim-sm-linklocal] Atwood, W., Islam, S., and M. Siami, “Authentication and Confidentiality in PIM-SM Link-local Messages,” draft-ietf-pim-sm-linklocal-10 (work in progress), December 2009 (TXT).
[I-D.ietf-tcpm-tcp-ao-crypto] Lebovitz, G. and E. Rescorla, “Cryptographic Algorithms for TCP's Authentication Option, TCP-AO,” draft-ietf-tcpm-tcp-ao-crypto-03 (work in progress), March 2010 (TXT).
[I-D.ietf-tcpm-tcp-auth-opt] Touch, J., Mankin, A., and R. Bonica, “The TCP Authentication Option,” draft-ietf-tcpm-tcp-auth-opt-11 (work in progress), March 2010 (TXT).
[I-D.polk-saag-rtg-auth-keytable] Polk, T. and R. Housley, “Routing Authentication Using A Database of Long-Lived Cryptographic Keys,” draft-polk-saag-rtg-auth-keytable-02 (work in progress), December 2009 (TXT).
[ISR2008] McPherson, D. and C. Labovitz, “Worldwide Infrastructure Security Report,” October 2008.
[RFC1195] Callon, R., “Use of OSI IS-IS for routing in TCP/IP and dual environments,” RFC 1195, December 1990 (TXT, PS).
[RFC2328] Moy, J., “OSPF Version 2,” STD 54, RFC 2328, April 1998 (TXT, HTML, XML).
[RFC2453] Malkin, G., “RIP Version 2,” STD 56, RFC 2453, November 1998 (TXT, HTML, XML).
[RFC3562] Leech, M., “Key Management Considerations for the TCP MD5 Signature Option,” RFC 3562, July 2003 (TXT).
[RFC3618] Fenner, B. and D. Meyer, “Multicast Source Discovery Protocol (MSDP),” RFC 3618, October 2003 (TXT).
[RFC3973] Adams, A., Nicholas, J., and W. Siadak, “Protocol Independent Multicast - Dense Mode (PIM-DM): Protocol Specification (Revised),” RFC 3973, January 2005 (TXT).
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, “Randomness Requirements for Security,” BCP 106, RFC 4086, June 2005 (TXT).
[RFC4107] Bellovin, S. and R. Housley, “Guidelines for Cryptographic Key Management,” BCP 107, RFC 4107, June 2005 (TXT).
[RFC4271] Rekhter, Y., Li, T., and S. Hares, “A Border Gateway Protocol 4 (BGP-4),” RFC 4271, January 2006 (TXT).
[RFC4301] Kent, S. and K. Seo, “Security Architecture for the Internet Protocol,” RFC 4301, December 2005 (TXT).
[RFC4303] Kent, S., “IP Encapsulating Security Payload (ESP),” RFC 4303, December 2005 (TXT).
[RFC4306] Kaufman, C., “Internet Key Exchange (IKEv2) Protocol,” RFC 4306, December 2005 (TXT).
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, “Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised),” RFC 4601, August 2006 (TXT, PDF).
[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 (TXT).
[RFC4949] Shirey, R., “Internet Security Glossary, Version 2,” RFC 4949, August 2007 (TXT).
[RFC5036] Andersson, L., Minei, I., and B. Thomas, “LDP Specification,” RFC 5036, October 2007 (TXT).
[RFC5226] Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” BCP 26, RFC 5226, May 2008 (TXT).


Authors' Addresses

  J. William Atwood
  Concordia University/CSE
  1455 de Maisonneuve Blvd, West
  Montreal, QC H3G 1M8
Phone:  +1(514)848-2424 ext3046
  Gregory Lebovitz
  Juniper Networks, Inc.
  1194 North Mathilda Ave.
  Sunnyvale, CA 94089-1206