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Versions: (draft-ymbk-bgpsec-rtr-rekeying) 00 01 02 03 04 05 06 07 08 09 10 11 12 13

Network Working Group                                            R. Bush
Internet-Draft                             IIJ Lab / Dragon Research Lab
Intended status: Standards Track                               S. Turner
Expires: October 7, 2017                                           sn3rd
                                                                K. Patel
                                                            Arrcus, Inc.
                                                           April 5, 2017


                        Router Keying for BGPsec
                     draft-ietf-sidr-rtr-keying-13

Abstract

   BGPsec-speaking routers are provisioned with private keys in order to
   sign BGPsec announcements.  The corresponding public keys are
   published in the global Resource Public Key Infrastructure, enabling
   verification of BGPsec messages.  This document describes two methods
   of generating the public-private key-pairs: router-driven and
   operator-driven.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
   be interpreted as described in RFC 2119 [RFC2119] only when they
   appear in all upper case.  They may also appear in lower or mixed
   case as English words, without normative meaning.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 16, 2017.






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Copyright Notice

   Copyright (c) 2017 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
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Management / Router Communication  . . . . . . . . . . . . . .  3
   3.  Exchanging Certificates  . . . . . . . . . . . . . . . . . . .  4
   4.  Set-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   5.  PKCS#10 Generation . . . . . . . . . . . . . . . . . . . . . .  4
     5.1.  Router-Generated Keys  . . . . . . . . . . . . . . . . . .  4
     5.2.  Operator-Generated Keys  . . . . . . . . . . . . . . . . .  5
   6.  Installing Certified Keys  . . . . . . . . . . . . . . . . . .  5
   7.  Advanced Deployment Scenarios  . . . . . . . . . . . . . . . .  6
   8.  Key Management . . . . . . . . . . . . . . . . . . . . . . . .  7
     8.1.  Key Validity . . . . . . . . . . . . . . . . . . . . . . .  8
     8.2.  Key Roll-Over  . . . . . . . . . . . . . . . . . . . . . .  8
     7.3.  Key Revocation . . . . . . . . . . . . . . . . . . . . . .  9
     8.4.  Router Replacement . . . . . . . . . . . . . . . . . . . .  9
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   10.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
   11.  References  . . . . . . . . . . . . . . . . . . . . . . . . . 11
     11.1.  Normative References  . . . . . . . . . . . . . . . . . . 11
     11.1.  Informative References  . . . . . . . . . . . . . . . . . 12
   Appendix A.  Management/Router Channel Security  . . . . . . . . . 14
   Appendix B.  The n00b Guide to BGPsec Key Management . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17


1.  Introduction

   BGPsec-speaking routers are provisioned with private keys, which
   allow them to digitally sign BGPsec announcements.  To verify the
   signature, the public key, in the form of a certificate [I-D.ietf-
   sidr-bgpsec-pki-profiles], is published in the Resource Public Key
   Infrastructure (RPKI).  This document describes provisioning of



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   BGPsec-speaking routers with the appropriate public-private key-
   pairs.  There are two sub-methods, router-driven and operator-driven.

   These two sub-methods differ in where the keys are generated: on the
   router in the router-driven method, and elsewhere in the operator-
   driven method.  Routers are required to support at least one of the
   methods in order to work in various deployment environments.  Some
   routers may not allow the private key to be off-loaded while others
   may.  While off-loading private keys would ease swapping of routing
   engines, exposure of private keys is a well known security risk.

   In the operator-driven method, the operator generates the private/
   public key-pair and sends it to the router, perhaps in a PKCS#8
   package [RFC5958].

   In the router-driven method, the router generates its own public/
   private key-pair, uses the private key to sign a PKCS#10
   certification request [I-D.ietf-sidr-bgpsec-pki-profiles], which
   includes the public key), and returns the certification request to
   the operator to be forwarded to the RPKI Certification Authority
   (CA).  The CA returns a PKCS#7, which includes the certified public
   key in the form of a certificate, to the operator for loading into
   the router; and the CA also publishes the certificate in the RPKI.

   The router-driven model mirrors the model used by traditional PKI
   subscribers; the private key never leaves trusted storage (e.g.,
   Hardware Security Module).  This is by design and supports classic
   PKI Certification Policies for (often human) subscribers which
   require the private key only ever be controlled by the subscriber to
   ensure that no one can impersonate the subscriber.  For non-humans,
   this model does not always work.  For example, when an operator wants
   to support hot-swappable routers the same private key needs to be
   installed in the soon-to-be online router that was used by the the
   soon-to-be offline router.  This motivated the operator-driven model.

   The remainder of this document describes how operators can use the
   two methods to provision new and existing routers.  The methods
   described involve the operator configuring the two end points and
   acting as the intermediary.  Section 7 describes a method that
   requires more capable routers.

   Useful References: [I-D.ietf-sidr-bgpsec-protocol] describes gritty
   details, [I-D.ietf-sidr-bgpsec-pki-profiles] specifies the format for
   the PKCS #10 request, and [I-D.ietf-sidr-bgpsec-algs] specifies the
   algorithms used to generate the signature.

2.  Management / Router Communication




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   Operators are free to use either the router-driven or operator-driven
   method as supported by the platform.  Regardless of the method
   chosen, operators first establish a secure communication channel
   between the management system and the router.  How this channel is
   established is router-specific and is beyond scope of this document.
   Though other configuration mechanisms might be used, e.g.  NetConf
   (see [RFC6470]); for simplicity, in this document, the communication
   channel between the management platform and the router is assumed to
   be an SSH-protected CLI.  See Appendix A for security considerations
   for this channel.

3.  Exchanging Certificates

   The operator management station can exchange certificate requests and
   certificates with routers and with the RPKI CA infrastructure using
   the application/pkcs10 media type [RFC5967] and application/
   pkcs7-mime [RFC5751], respectively, and may use FTP or HTTP per
   [RFC2585], or the Enrollment over Secure Transport (EST) [RFC7030].

4.  Set-Up

   To start, the operator uses the communication channel to install the
   appropriate RPKI Trust Anchor' Certificate (TA Cert) in the router.
   This will later enable the router to validate the router certificate
   returned in the PKCS#7.

   The operator also configures the Autonomous System (AS) number to be
   used in the generated router certificate.  This may be the sole AS
   configured on the router, or an operator choice if the router is
   configured with multiple ASs.

   The operator configures or extracts from the router the BGP RouterID
   to be used in the generated certificate.  In the case where the
   operator has chosen not to use unique per-router certificates, a
   RouterID of 0 may be used.

5.  PKCS#10 Generation

   The private key, and hence the PKCS#10 request, which is sometimes
   referred to as a Certificate Signing Request (CSR), may be generated
   by the router or by the operator.

5.1.  Router-Generated Keys

   In the router-generated method, once the protected session is
   established and the initial Set-Up (Section 4) performed, the
   operator issues a command or commands for the router to generate the
   public/private key pair, to generate the PKCS#10 request, and to sign



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   the PKCS#10 with the private key.  Once generated, the PKCS#10 is
   returned to the operator over the protected channel.

   If a router was to communicate directly with a CA to have the CA
   certify the PKCS#10, there would be no way for the CA to authenticate
   the router.  As the operator knows the authenticity of the router,
   the operator mediates the communication with the CA.

   The operator adds the chosen AS number and the RouterID to send to
   the RPKI CA for the CA to certify.

5.2.  Operator-Generated Keys

   In the operator-generated method, the operator generates the
   public/private key pair on a management station and installs the
   private key into the router over the protected channel.  Beware that
   experience has shown that copy and paste from a management station to
   a router can be unreliable for long texts.

   Alternatively, the private key may be encapsulated in a PKCS #8
   [RFC5958], the PKCS#8 is further encapsulated in Cryptographic
   Message Syntax (CMS) SignedData [RFC5652], and signed by the AS's End
   Entity (EE) certificate.

   The router SHOULD verify the signature of the encapsulated PKCS#8 to
   ensure the returned private key did in fact come from the operator,
   but this requires that the operator also provision via the CLI or
   include in the SignedData the RPKI CA certificate and relevant AS's
   EE certificate(s).  The router should inform the operator whether or
   not the signature validates to a trust anchor; this notification
   mechanism is out of scope.

   The operator then creates and signs the PKCS#10 with the private key,
   and adds the chosen AS number and RouterID to be sent to the RPKI CA
   for the CA to certify.

6.  Installing Certified Keys

   The operator uses RPKI management tools to communicate with the
   global RPKI system to have the appropriate CA validate the PKCS#10
   request, sign the key in the PKCS#10 (i.e., certify it) and generated
   PKCS#7 response, as well as publishing the certificate in the Global
   RPKI.  External network connectivity may be needed if the certificate
   is to be published in the Global RPKI.

   After the CA certifies the key, it does two things:

   1.  Publishes the certificate in the Global RPKI.  The CA must have



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       connectivity to the relevant publication point, which in turn
       must have external network connectivity as it is part of the
       Global RPKI.

   2.  Returns the certificate to the operator's management station,
       packaged in a PKCS#7, using the corresponding method by which it
       received the certificate request.  It SHOULD include the
       certificate chain below the TA Certificate so that the router can
       validate the router certificate.

   In the operator-generated method, the operator SHOULD extract the
   certificate from the PKCS#7, and verify that the private key it holds
   corresponds to the returned public key.

   In the operator-generated method, the operator has already installed
   the private key in the router (see Section 5.2).

   The operator provisions the PKCS#7 into the router over the secure
   channel.

   The router SHOULD extract the certificate from the PKCS#7 and verify
   that the private key corresponds to the returned public key.  The
   router SHOULD inform the operator whether it successfully received
   the certificate and whether or not the keys correspond; the mechanism
   is out of scope.

   The router SHOULD also verify that the returned certificate validates
   back to the installed TA Certificate, i.e., the entire chain from the
   installed TA Certificate through subordinate CAs to the BGPsec
   certificate validate.  To perform this verification the CA
   certificate chain needs to be returned along with the router's
   certificate in the PKCS#7.  The router SHOULD inform the operator
   whether or not the signature validates to a trust anchor; this
   notification mechanism is out of scope.

   Note: The signature on the PKCS#8 and Certificate need not be made by
   the same entity.  Signing the PKCS#8, permits more advanced
   configurations where the entity that generates the keys is not the
   direct CA.

   Even if the operator cannot extract the private key from the router,
   this signature still provides a linkage between a private key and a
   router.  That is the server can verify the proof of possession (POP),
   as required by [RFC6484].

7.  Advanced Deployment Scenarios

   More PKI-capable routers can take advantage of this increased



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   functionality and lighten the operator's burden.  Typically, these
   routers include either pre-installed manufacturer-generated
   certificates (e.g., IEEE 802.1 AR [802.1AR]) or pre-installed
   manufacturer-generated Pre-Shared Keys (PSK) as well as PKI-
   enrollment functionality and transport protocol, e.g., CMC's "Secure
   Transport" [RFC7030] or the original CMC transport protocol's
   [RFC5273].  When the operator first establishes a secure
   communication channel between the management system and the router,
   this pre-installed key material is used to authenticate the router.

   The operator burden shifts here to include:

   1.  Securely communicating the router's authentication material to
       the CA prior to operator initiating the server's CSR.  CAs use
       authentication material to determine whether the router is
       eligible to receive a certificate. Authentication material at a
       minimum includes the router's AS number and RouterID as well as
       the router's key material, but can also include additional
       information. Authentication material can can be communicated to
       the CA (i.e., CSRs signed by this key material are issued
       certificates with this AS and RouterID) or to the router (i.e.,
       the operator uses the vendor-supplied management interface to
       include the AS number and routerID in the router-generated CSR).

   2.  Enabling the router to communicate with the CA.  While the
       router-to-CA communications are operator-initiated, the
       operator's management interface need not be involved in the
       communications path.  Enabling the router-to-CA connectivity MAY
       require connections to external networks (i.e., through
       firewalls, NATs, etc.).

   Once configured, the operator can begin the process of enrolling the
   router.  Because the router is communicating directly with the CA,
   there is no need for the operator to retrieve the PKCS#10 from the
   router or return the PKCS#7 to the router as in Section 6.  Note that
   the checks performed by the router, namely extracting the certificate
   from the PKCS#7, verifying the private key corresponds to the
   returned public key, and that the returned certificate validated back
   to an installed trust anchor, SHOULD be performed.  Likewise, the
   router SHOULD notify the operator if any of these fail, but this
   notification mechanism is out of scope.

   When a router is so configured the communication with the CA SHOULD
   be automatically re-established by the router at future times to
   renew or rekey the certificate automatically when necessary (See
   Section 8). This further reduces the tasks required of the operator.

8.  Key Management



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   An operator's responsibilities do not end after key generation, key
   provisioning, certificate issuance, and certificate distribution.
   They persist for as long as the operator wishes to operate the
   BGPsec-speaking router.

8.1.  Key Validity

   It is critical that a BGPsec speaking router ensures that it is
   signing with a valid private key at all times.  To this end, the
   operator needs to ensure the router always has a non-expired
   certificate.  I.e. the key used to sign BGPsec announcements always
   has an associated certificate whose expiry time is after the current
   time.

   Ensuring this is not terribly difficult but requires that either:

   1.  The router has a mechanism to notify the operator that the
       certificate has an impending expiration, and/or

   2.  The operator notes the expiry time of the certificate and uses a
       calendaring program to remind them of the expiry time, and/or

   3.  The RPKI CA warns the operator of pending expiration, and/or

   4.  Use some other kind of automated process to search for and track
       the expiry times of router certificates.

   It is advisable that expiration warnings happen well in advance of
   the actual expiry time.

   Regardless of the technique used to track router certificate expiry
   times, it is advisable to notify additional operators in the same
   organization as the expiry time approaches thereby ensuring that the
   forgetfulness of one operator does not affect the entire
   organization.

   Depending on inter-operator relationship, it may be helpful to notify
   a peer operator that one or more of their certificates are about to
   expire.

8.2.  Key Roll-Over

   Routers that support multiple private keys also greatly increase the
   chance that routers can continuously speak BGPsec because the new
   private key and certificate can be obtained and distributed prior to
   expiration of the operational key.  Obviously, the router needs to
   know when to start using the new key.  Once the new key is being
   used, having the already distributed certificate ensures continuous



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   operation.

   Whether the certificate is re-keyed (i.e., different key in the
   certificate with a new expiry time) or renewed (i.e., the same key in
   the certificate with a new expiry time) depends on the key's lifetime
   and operational use.  Arguably, re-keying the router's BGPsec
   certificate every time the certificate expires is more secure than
   renewal because it limits the private key's exposure.  However, if
   the key is not compromised the certificate could be renewed as many
   times as allowed by the operator's security policy.  Routers that
   support only one key can use renewal to ensure continuous operation,
   assuming the certificate is renewed and distributed well in advance
   of the operational certificate's expiry time.

7.3.  Key Revocation

   Certain unfortunate circumstances may occur causing a need to revoke
   a router's BGPsec certificate.  When this occurs, the operator needs
   to use the RPKI CA system to revoke the certificate by placing the
   router's BGPsec certificate on the Certificate Revocation List (CRL)
   as well as re-keying the router's certificate.

   When an active router key is to be revoked, the process of requesting
   the CA to revoke, the process of the CA actually revoking the
   router's certificate, and then the process of re-keying/renewing the
   router's certificate, (possibly distributing a new key and
   certificate to the router), and distributing the status takes time
   during which the operator must decide how they wish to maintain
   continuity of operations, with or without the compromised private
   key, or whether they wish to bring the router offline to address the
   compromise.

   Keeping the router operational and BGPsec-speaking is the ideal goal,
   but if operational practices do not allow this then reconfiguring the
   router to disabling BGPsec is likely preferred to bringing the router
   offline.

   Routers which support more than one private key, where one is
   operational and other(s) are soon-to-be-operational, facilitate
   revocation events because the operator can configure the router to
   make a soon-to-be-operational key operational, request revocation of
   the compromised key, and then make a next generation soon-to-be-
   operational key, all hopefully without needing to take offline or
   reboot the router.  For routers which support only one operational
   key, the operators should create or install the new private key, and
   then request revocation of the compromised private key.

8.4.  Router Replacement



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   Currently routers often generate private keys for uses such as SSH,
   and the private keys may not be seen or off-loaded from the router.
   While this is good security, it creates difficulties when a routing
   engine or whole router must be replaced in the field and all software
   which accesses the router must be updated with the new keys.  Also,
   any network based initial contact with a new routing engine requires
   trust in the public key presented on first contact.

   To allow operators to quickly replace routers without requiring
   update and distribution of the corresponding public keys in the RPKI,
   routers SHOULD allow the private BGPsec key to inserted via a
   protected session, e.g., SSH, NetConf (see [RFC6470]), SNMP.  This
   lets the operator escrow the old private key via the mechanism used
   for operator-generated keys, see Section 5.2, such that it can be re-
   inserted into a replacement router. The router MAY allow the private
   key to be to be off-loaded via the protected session, but this SHOULD
   be paired with functionality that sets the key into a permanent non-
   exportable state to ensure that it is not off-loaded at a future time
   by unauthorized operations.

9.  Security Considerations

   The router's manual will describe whether the router supports one,
   the other, or both of the key generation options discussed in the
   earlier sections of this draft as well as other important security-
   related information (e.g., how to SSH to the router).  After
   familiarizing one's self with the capabilities of the router,
   operators are encouraged to ensure that the router is patched with
   the latest software updates available from the manufacturer.

   This document defines no protocols so in some sense introduces no new
   security considerations.  However, it relies on many others and the
   security considerations in the referenced documents should be
   consulted; notably, those document listed in Section 1 should be
   consulted first.  PKI-relying protocols, of which BGPsec is one, have
   many issues to consider so many in fact entire books have been
   written to address them; so listing all PKI-related security
   considerations is neither useful nor helpful; regardless, some boot-
   strapping-related issues are listed here that are worth repeating:

   Public-Private key pair generation:  Mistakes here are for all
      practical purposes catastrophic because PKIs rely on the pairing
      of a difficult to generate public-private key pair with a signer;
      all key pairs MUST be generated from a good source of non-
      deterministic random input [RFC4086].

   Private key protection at rest:  Mistakes here are for all practical
      purposes catastrophic because disclosure of the private key allows



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      another entity to masquerade as (i.e., impersonate) the signer;
      all private keys MUST be protected when at rest in a secure
      fashion.  Obviously, how each router protects private keys is
      implementation specific.  Likewise, the local storage format for
      the private key is just that, a local matter.

   Private key protection in transit:  Mistakes here are for all
      practical purposes catastrophic because disclosure of the private
      key allows another entity to masquerade as (i.e., impersonate) the
      signer; transport security is therefore strongly RECOMMENDED.  The
      level of security provided by the transport layer's security
      mechanism SHOULD be commensurate with the strength of the BGPsec
      key; there's no point in spending time and energy to generate an
      excellent public-private key pair and then transmit the private
      key in the clear or with a known-to-be-broken algorithm, as it
      just undermines trust that the private key has been kept private.
      Additionally, operators SHOULD ensure the transport security
      mechanism is up to date, in order to addresses all known
      implementation bugs.

   SSH key management is known, in some cases, to be lax
   [I-D.ylonen-sshkeybcp]; employees that no longer need access to
   routers SHOULD be removed the router to ensure only those authorized
   have access to a router.

   Though the CA's certificate is installed on the router and used to
   verify that the returned certificate is in fact signed by the CA, the
   revocation status of the CA's certificate is rarely checked as the
   router may not have global connectivity or CRL-aware software.  The
   operator MUST ensure that installed CA certificate is valid.

10.  IANA Considerations

   This document has no IANA Considerations.

11.  References

11.1.  Normative References

   [I-D.ietf-sidr-bgpsec-algs]
              Turner, S., "BGP Algorithms, Key Formats, & Signature
              Formats", draft-ietf-sidr-bgpsec-algs (work in
              progress), March 2013.

   [I-D.ietf-sidr-bgpsec-pki-profiles]
              Reynolds, M., Turner, S., and S. Kent, "A Profile for
              BGPSEC Router Certificates, Certificate Revocation Lists,
              and Certification Requests", draft-ietf-sidr-bgpsec-pki-



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              profiles (work in progress), October 2012.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, DOI
              10.17487/RFC2119, March 1997, <http://www.rfc-
              editor.org/info/rfc2119>.

   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,
              "Randomness Requirements for Security", BCP 106, RFC 4086,
              DOI 10.17487/RFC4086, June 2005, <http://www.rfc-
              editor.org/info/rfc4086>.

   [RFC4253]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
              January 2006, <http://www.rfc-editor.org/info/rfc4253>.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, DOI 10.17487/RFC5652, September 2009,
              <http://www.rfc-editor.org/info/rfc5652>.

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958, DOI
              10.17487/RFC5958, August 2010, <http://www.rfc-
              editor.org/info/rfc5958>.


   [802.1AR]  IEEE SA-Standards Board, "IEEE Standard for Local and
              metropolitan area networks - Secure Device Identity",
              December 2009,
              <http://standards.ieee.org/findstds/standard/802.1AR-
              2009.html>.

11.1.  Informative References

   [I-D.ietf-sidr-bgpsec-protocol]
              Lepinski, M., "BGPSEC Protocol Specification", draft-ietf-
              sidr-bgpsec-protocol (work in progress), February 2013.

   [I-D.ylonen-sshkeybcp]
              Ylonen, T. and G. Kent, "Managing SSH Keys for Automated
              Access - Current Recommended Practice", draft-ylonen-
              sshkeybcp (work in progress), April 2013.

   [RFC2585]  Housley, R. and P. Hoffman, "Internet X.509 Public Key
              Infrastructure Operational Protocols: FTP and HTTP",
              RFC 2585, DOI 10.17487/RFC2585, May 1999, <http://www.rfc-
              editor.org/info/rfc2585>.

   [RFC3766]  Orman, H. and P. Hoffman, "Determining Strengths For



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              Public Keys Used For Exchanging Symmetric Keys", BCP 86,
              RFC 3766, DOI 10.17487/RFC3766, April 2004,
              <http://www.rfc-editor.org/info/rfc3766>.

   [RFC5273]  Schaad, J. and M. Myers, "Certificate Management over CMS
              (CMC): Transport Protocols", RFC 5273, DOI
              10.17487/RFC5273, June 2008, <http://www.rfc-
              editor.org/info/rfc5273>.

   [RFC5480]  Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
              "Elliptic Curve Cryptography Subject Public Key
              Information", RFC 5480, DOI 10.17487/RFC5480, March 2009,
              <http://www.rfc-editor.org/info/rfc5480>.

   [RFC5647]  Igoe, K. and J. Solinas, "AES Galois Counter Mode for the
              Secure Shell Transport Layer Protocol", RFC 5647, DOI
              10.17487/RFC5647, August 2009, <http://www.rfc-
              editor.org/info/rfc5647>.

   [RFC5656]  Stebila, D. and J. Green, "Elliptic Curve Algorithm
              Integration in the Secure Shell Transport Layer",
              RFC 5656, DOI 10.17487/RFC5656, December 2009,
              <http://www.rfc-editor.org/info/rfc5656>.

   [RFC5751]  Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
              Mail Extensions (S/MIME) Version 3.2 Message
              Specification", RFC 5751, DOI 10.17487/RFC5751, January
              2010, <http://www.rfc-editor.org/info/rfc5751>.

   [RFC5967]  Turner, S., "The application/pkcs10 Media Type", RFC 5967,
              DOI 10.17487/RFC5967, August 2010, <http://www.rfc-
              editor.org/info/rfc5967>.

   [RFC6187]  Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure
              Shell Authentication", RFC 6187, DOI 10.17487/RFC6187,
              March 2011, <http://www.rfc-editor.org/info/rfc6187>.

   [RFC6470]  Bierman, A., "Network Configuration Protocol (NETCONF)
              Base Notifications", RFC 6470, DOI 10.17487/RFC6470,
              February 2012, <http://www.rfc-editor.org/info/rfc6470>.

   [RFC6484]  Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate
              Policy (CP) for the Resource Public Key Infrastructure
              (RPKI)", BCP 173, RFC 6484, DOI 10.17487/RFC6484, February
              2012, <http://www.rfc-editor.org/info/rfc6484>.

   [RFC6668]  Bider, D. and M. Baushke, "SHA-2 Data Integrity
              Verification for the Secure Shell (SSH) Transport Layer



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              Protocol", RFC 6668, DOI 10.17487/RFC6668, July 2012,
              <http://www.rfc-editor.org/info/rfc6668>.

   [RFC7030]  Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
              "Enrollment over Secure Transport", RFC 7030, DOI
              10.17487/RFC7030, October 2013, <http://www.rfc-
              editor.org/info/rfc7030>.


   [SP800-57] National Institute of Standards and Technology (NIST),
              Special Publication 800-57: Recommendation for Key
              Management - Part 1 (Revised), March 2007.

Appendix A.  Management/Router Channel Security

   Encryption, integrity, authentication, and key exchange algorithms
   used by the secure communication channel SHOULD be of equal or
   greater strength than the BGPsec keys they protect, which for the
   algorithm specified in [I-D.ietf-sidr-bgpsec-algs] is 128-bit; see
   [RFC5480] and by reference [SP800-57] for information about this
   strength claim as well as [RFC3766] for "how to determine the length
   of an asymmetric key as a function of a symmetric key strength
   requirement."  In other words, for the encryption algorithm, do not
   use export grade crypto (40-56 bits of security), do not use Triple
   DES (112 bits of security).  Suggested minimum algorithms would be
   AES-128: aes128-cbc [RFC4253] and AEAD_AES_128_GCM [RFC5647] for
   encryption, hmac-sha2-256 [RFC6668] or AESAD_AES_128_GCM [RFC5647]
   for integrity, ecdsa-sha2-nistp256 [RFC5656] for authentication, and
   ecdh-sha2-nistp256 [RFC5656] for key exchange.

   Some routers support the use of public key certificates and SSH.  The
   certificates used for the SSH session are different than the
   certificates used for BGPsec.  The certificates used with SSH should
   also enable a level of security commensurate with BGPsec keys;
   x509v3-ecdsa-sha2-nistp256 [RFC6187] could be used for
   authentication.

Appendix B.  The n00b Guide to BGPsec Key Management

   This appendix is informative.  It attempts to explain all of the PKI
   technobabble in plainer language.

   BGPsec speakers send signed BGPsec updates that are verified by other
   BGPsec speakers.  In PKI parlance, the senders are referred to as
   signers and the receivers are referred to as relying parties.  The
   signers with which we are concerned here are routers signing BGPsec
   updates.  Signers use private keys to sign and relying parties use
   the corresponding public keys, in the form of X.509 public key



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   certificates, to verify signatures.  The third party involved is the
   entity that issues the X.509 public key certificate, the
   Certification Authority (CA).  Key management is all about making
   these key pairs and the certificates, as well as ensuring that the
   relying parties trust that the certified public keys in fact
   correspond to the signers' private keys.

   The specifics of key management greatly depend on the routers as well
   as management interfaces provided by the routers' vendor.  Because of
   these differences, it is hard to write a definitive "how to," but
   this guide is intended to arm operators with enough information to
   ask the right questions.  The other aspect that makes this guide
   informative is that the steps for the do-it-yourself (DIY) approach
   involve arcane commands while the GUI-based vendor-assisted
   management console approach will likely hide all of those commands
   behind some button clicks.  Regardless, the operator will end up with
   a BGPsec-enabled router.  Initially, we focus on the DIY approach and
   then follow up with some information about the GUI-based approach.

   The first step in the DIY approach is to generate a private key; but
   in fact what you do is create a key pair; one part, the private key,
   is kept very private and the other part, the public key, is given out
   to verify whatever is signed.  The two models for how to create the
   key pair are the subject of this document, but it boils down to
   either doing it on-router (router-driven) or off-router (operator-
   driven).

   If you are generating keys on the router (router-driven), then you
   will need to access the router.  Again, how you access the router is
   router-specific, but generally the DIY approach uses the CLI and
   accessing the router either directly via the router's craft port or
   over the network on an administrative interface.  If accessing the
   router over the network be sure to do it securely (i.e., use SSHv2).
   Once logged into the router, issue a command or a series of commands
   that will generate the key pair for the algorithms noted in the main
   body of this document; consult your router's documentation for the
   specific commands.  The key generation process will yield multiple
   files: the private key and the public key; the file format varies
   depending on the arcane command you issued, but generally the files
   are DER or PEM-encoded.

   The second step is to generate the certification request, which is
   often referred to as a certificate signing request (CSR) or PKCS#10,
   and to send it to the CA to be signed.  To generate the CSR, you
   issue some more arcane commands while logged into the router; using
   the private key just generated to sign the certification request with
   the algorithms specified in the main body of this document; the CSR
   is signed to prove to the CA that the router has possession of the



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   private key (i.e., the signature is the proof-of-possession).  The
   output of the command is the CSR file; the file format varies
   depending on the arcane command you issued, but generally the files
   are DER or PEM-encoded.

   The third step is to retrieve the signed CSR from the router and send
   it to the CA.  But before sending it, you need to also send the CA
   the subject name and serial number for the router.  The CA needs this
   information to issue the certificate.  How you get the CSR to the CA,
   is beyond the scope of this document.  While you are still connected
   to the router, install the Trust Anchor (TA) for the root of the PKI.
    At this point, you no longer need access to the router for BGPsec-
   related initiation purposes.

   The fourth step is for the CA to issue the certificate based on the
   CSR you sent; the certificate will include the subject name, serial
   number, public key, and other fields as well as being signed by the
   CA.  After the CA issues the certificate, the CA returns the
   certificate, and posts the certificate to the RPKI repository.  Check
   that the certificate corresponds to the private key by verifying the
   signature on the CSR sent to the CA; this is just a check to make
   sure that the CA issued a certificate corresponding to the private
   key on the router.

   If generating the keys off-router (operator-driven), then the same
   steps are used as the on-router key generation, (possibly with the
   same arcane commands as those used in the on-router approach), but no
   access to the router is needed the first three steps are done on an
   administrative workstation: o Step 1: Generate key pair; o Step 2:
   Create CSR and sign CSR with private key, and; o Step 3: Send CSR
   file with the subject name and serial number to CA.

   After the CA has returned the certificate and you have checked the
   certificate, you need to put the private key and TA in the router.
   Assuming the DIY approach, you will be using the CLI and accessing
   the router either directly via the router's craft port or over the
   network on an admin interface; if accessing the router over the
   network make doubly sure it is done securely (i.e., use SSHv2)
   because the private key is being moved over the network.  At this
   point, access to the router is no longer needed for BGPsec-related
   initiation purposes.

   NOTE: Regardless of the approach taken, the first three steps could
   trivially be collapsed by a vendor-provided script to yield the
   private key and the signed CSR.

   Given a GUI-based vendor-assisted management console, then all of
   these steps will likely be hidden behind pointing and clicking the



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   way through GPsec-enabling the router.

   The scenarios described above require the operator to access each
   router, which does not scale well to large networks.  An alternative
   would be to create an image, perform the necessary steps to get the
   private key and trust anchor on the image, and then install the image
   via a management protocol.

   One final word of advice; certificates include a notAfter field that
   unsurprisingly indicates when relying parties should no longer trust
   the certificate.  To avoid having routers with expired certificates
   follow the recommendations in the Certification Policy (CP) [RFC6484]
   and make sure to renew the certificate at least one week prior to the
   notAfter date.  Set a calendar reminder in order not to forget!

Authors' Addresses

   Randy Bush
   IIJ / Dragon Research Labs
   5147 Crystal Springs
   Bainbridge Island, Washington  98110
   US

   Email: randy@psg.com


   Sean Turner
   sn3rd

   Email: sean@sn3rd.com


   Keyur Patel
   Arrcus, Inc.

   Email: keyur@arrcus.com















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