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Versions: (draft-ymbk-bgpsec-rtr-rekeying) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 draft-ietf-sidrops-rtr-keying

SIDR Working Group                                             S. Turner
Internet-Draft                                                IECA, Inc.
Intended status: BCP                                            K. Patel
Expires: August 27, 2013                                   Cisco Systems
                                                                 R. Bush
                                         Internet Initiative Japan, Inc.
                                                       February 23, 2013


                        Router Keying for BGPsec
                     draft-ietf-sidr-rtr-keying-01

Abstract

   BGPsec-speaking routers must be provisioned with private keys and the
   corresponding public key must be published in the global RPKI
   (Resource Public Key Infrastructure).  This document describes two
   ways of provisioning public/private keys, router-driven and operator-
   driven.

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 August 27, 2013.

Copyright Notice

   Copyright (c) 2013 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



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   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.

1.  Introduction

   BGPsec-speaking routers must be provisioned with private keys and the
   corresponding public key must be published in the global RPKI
   (Resource Public Key Infrastructure).  The public key is published in
   the RPKI in the form of a certificate [I-D.ietf-sidr-bgpsec-pki-
   profiles].  This document describes two methods for generating the
   necessary public/private key-pair: router-driven and operator-driven.

   The difference between the two models is where the keys are
   generated.  Keys are generated on the router in the router-drive
   method but elsewhere by the operator in the operator-drive model.
   The router-driven model is most familiar to PKI subscribers because
   its design supports CPs (Certification Policies), often times for
   human subscribers, that 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 in
   particular 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 installed in the soon-to-be offline router.

   The remainder of this document describes how operators can use the
   two methods to provision new and existing routers.

   Note that in both models, the key pair is for algorithms defined in
   [I-D.ietf-sidr-bgpsec-algs].  The first version specifies ECDSA on
   the P-256 curve.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [RFC2119].

   It is assumed that the reader understands BGPsec [I-D.ietf-sidr-
   bgpsec-overview] [I-D.ietf-sidr-bgpsec-protocol], the RPKI [RFC6480],
   and [I-D.ietf-sidr-bgpsec-pki-profiles].

3.  Provisioning a New Router

   When commissioning a new router, operators may use either the router-
   driven or operator-drive methods.  Regardless of the method chosen,
   the operator first needs to establish a secure communication channel



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   with the router.  Today, this is done via a proprietary management
   box directly connected to the router on the serial/craft port {spt:
   is serial/craft port the correct terminology?}.  After the management
   box has been physically connected to the router, the operator
   authenticates to the management box, via a proprietary mechanism
   {spt: is this really proprietary or it is leap-of-faith?}, and uses
   the CLI (command line interface) to generate the router's SSH (Secure
   Shell) key [RFC4253], retrieve the router's SSH public key, install
   the operator's SSH key(s), configures the Ethernet port [IEEE-802.3],
   BGPSEC-router number {spt: assume this is where the BGPSEC-router #
   will get "installed" for the router-driven case to know what to put
   in the PKCS#10}, etc. {spt: did I miss anything?}.

   {spt: i added CA certificate in the above for the router to verify
   that the CA actually signed the certificate.  overkill?}

   {spt: this could go here or in the security considerations.  i am
   ambivalent about where it ends up, but i think we should have this
   data in here somewhere.  i'd like to think if we're provisioning
   these routers with ECDSA keys that we're going to be using algorithms
   at least as good!?  the one that gives me heartburn is hmac-sha2-256
   seems like there ought to be a 128-bit truncated version to match
   with the others.}

   The SSH encryption, integrity, authentication, and key exchange
   mechanisms used by the router and operator SHOULD be of comparable
   strength to BGPSEC key, which is 128-bit strength, e.g., for
   encryption: aes128-cbc [RFC4253] and AEAD_AES_128_GCM [RFC5647], for
   integrity: hmac-sha2-256 [RFC6668] and AESAD_AES_128_GCM [RFC5647],
   for authentication: ecdsa-sha2-nistp256 [RFC5656], and for key
   exchange: ecdh-sha2-nistp256 [RFC5656].

   {spt: i'm unsure whether the following is being done, but it could be
   done so i think it's worth mentioning it.}

   Note that if the router supports public key certificates at this
   point, which would have had to have been provided by the operator at
   this point, x509v3-ecdsa-sha2-nistp256 [RFC6187] could be used
   instead for authentication.  The SSH certificate, profiled in
   [RFC6187], would be different than the BGPSEC certificate.

   {spt: do the commands to generate/deposit a key need to come over the
   ethernet port or if they can come over the management port?}

   Once generated, the operator establishes an SSH connection with the
   router and the management box is no longer needed.  At this point,
   the choice of router-driven or operator-driven is vendor specific.




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3.1.  Router-Generated Keys

   In the router-driven method, once an SSH connection is established
   between the operator and the router the operator issues a command, or
   commands, to generate the public/private key pair on the router, to
   generate the PKCS#10 that includes the router number and public key,
   and sign the PKCS#10 with the private key.  [I-D.ietf-sidr-bgpsec-
   pki-profiles] specifies the format for the PKCS #10 and the algorithm
   used to generate the signature is specified in [I-D.ietf-sidr-bgpsec-
   algs].

   {spt: Not sure if the distinction I made here between direct and
   indirect makes any sense.}

   The PKCS#10 request can be directly transferred to the RPKI CA over
   the Ethernet port if the router supports protocols such as FTP and
   HTTP [RFC2585] using the application/pkcs10 media type [RFC5967] or
   EST (Enrollment over Secure Transport) [I-D.ietf-pkix-est].  The CA
   returns a successful request as a PKCS#7 [I-D.ietf-sidr-bgpsec-pki-
   profiles], which includes the certificate, and uploads the
   certificate to the global RPKI.  The response can be returned using
   the application/pkcs7-mime media type [RFC5751] if the router
   supports protocols such as FTP and HTTP.

   The PKCS#10 request can also be indirectly transferred to the RPKI CA
   through the operator.  The operator off-loads the PKCS#10 and uploads
   the request to their RPKI software management tools.  The tools
   create and publish the certificate for the public key, and return the
   PKCS#7 to the router.

   {spt: the bit about checking the returned certificate is new, but i
   think a good idea.  but, does the CA's certificate get returned in
   the PKCS#7 - I couldn't find that in the cert profile?}

   The router SHOULD extract the certificate from the PCKCS#7 and verify
   that the private key corresponds to the returned public key.  The
   router SHOULD inform the operator that it has successfully received
   its certificate; this mechanism is out of scope.  When the keys do
   not correspond, the router SHOULD inform the operator; this mechanism
   is out of scope.   The router SHOULD also verify the returned
   certificate back to a trust anchor,  but to perform this verification
   either the CA's certificate needs to be installed on the router via
   the CLI or the CA's certificate needs to be returned along with the
   router's certificate in the PKCS#7.  The router SHOULD inform the
   operator if the signature does not validate to a trust anchor; this
   notification mechanism is out of scope.  After performing these
   checks, the router need not retain the certificate.




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   Note that even if the operator can not get the private key off the
   router this still provides a linkage between a private key and a
   router.

3.2.  Operator-Generated Keys

   In the operator-driven method, the operator generates the private key
   and it is installed over the SSH connection established between the
   operator and the router.  The operator uses their RPKI management
   tools to generate the keys, the PKCS#10 certification request, the
   certificate, and the PKCS#7 certification response as well as publish
   the certificate for the public key in the global RPKI.  The private
   key MUST support the algorithm specified in [I-D.ietf-sidr-bgpsec-
   algs], which for ECDSA is specified in [RFC5915].  The PKCS#10 and
   PKCS#7 are as specified in [I-D.ietf-sidr-bgpsec-pki-profiles].

   {spt: i figured maybe we could sign the PKCS#8, but that would have
   to be done with a key other than the CA's key.  It would have to be
   the operator's EE key.}

   Along with the PKCS#7, the operator returns the private key.  The
   private key is encapsulated in a PKCS #8 [RFC5958], the PKCS#8 is
   further encapsulated in a CMS (Cryptographic Message Syntax)
   SignedData [RFC5652], and signed by the operator's EE certificate.

   The router SHOULD verify the signature on the encapsulated PKCS#8 to
   ensure the returned private key in fact came from the operator, but
   this requires that the operator also provision via the CLI or include
   in the SignedData the RPKI CA certificates and operator's EE
   certificates.  The router SHOULD inform the operator if the signature
   does not validate to a trust anchor; this notification mechanism is
   out of scope.

   The router SHOULD extract the certificate for the PKCS#7 and verify
   that the private key corresponds to the returned public key.  The
   router SHOULD inform the operator that it has successfully received
   its certificate; this mechanism is out of scope.  When the keys do
   not correspond, the router SHOULD inform the operator; this mechanism
   is out of scope.  The router SHOULD also verify the returned
   certificate back to a trust anchor,  but to perform this verification
   either the CA's certificate needs to be installed on the router via
   the CLI or the CA's certificate needs to be returned along with the
   router's certificate in the PKCS#7.  The router SHOULD inform the
   operator if the signature does not validate to a trust anchor; this
   notification mechanism is out of scope.  After performing these
   checks, the router need not retain the certificate.

5.  Other Use Cases



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   Current router code generates private keys for uses such as SSH, but
   the private keys may not be seen or off-loaded via CLI or any other
   means.  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, the 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 be off-loaded via the
   CLI, NetConf (see [RFC6470]), SNMP, etc.  This lets the operator
   upload the old private key via the mechanism used for operator-
   generated keys, see Section 3.2.

6.  Security Considerations

   Operator-generated keys could be intercepted in transport and the
   recipient router would have no way of knowing a substitution had been
   made or that the key had been disclosed by a monkey in the middle.
   Hence transport security is strongly RECOMMENDED.  As noted in
   Section 3, the level of security provided by the transport security
   SHOULD be commensurate with the BGPsec key.  Additionally, operators
   SHOULD ensure the transport security implementation is up to date and
   addresses all known implementation bugs.

   All generated key pairs MUST be generated from a good source of non-
   deterministic random input [RFC4086] and the private key MUST be
   protected in a secure fashion.  Disclosure of the private key leads
   to masquerade [RFC4949].  The local storage format for the private
   key is a local matter.

   Though the CA's certificate is installed on the router and used to
   verify the returned certificate is in fact signed by the CA, the
   revocation status of the CA's certificate is not checked.  The
   operator MUST ensure that installed CA certificate is valid.

   Operators need to manage their SSH keys to ensure only those
   authorized to access the router can.  As employees no longer need
   access to the router, their keys SHOULD be removed from the router.

7.  IANA Considerations

   This document has no IANA Considerations.

8.  References

8.1.  Normative References



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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,
              "Randomness Requirements for Security", BCP 106, RFC 4086,
              June 2005.

   [RFC4253]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, January 2006.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, September 2009.

   [RFC5915]  Turner, S. and D. Brown, "Elliptic Curve Private Key
              Structure", RFC 5915, June 2010.

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958, August
              2010.

   [I-D.ietf-sidr-bgpsec-algs]
              Turner, S., "BGP Algorithms, Key Formats, & Signature
              Formats", draft-ietf-sidr-bgpsec-algs (work in progress),
              September 2012.

   [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-profiles (work in progress),
              October 2012.

8.2.  Informative References

   [I-D.ietf-sidr-bgpsec-overview]
              Lepinski, M. and S. Turner, "An Overview of BGPSEC",
              draft-ietf-sidr-bgpsec-overview (work in progress),
              December 2012.

   [I-D.ietf-sidr-bgpsec-protocol]
              Lepinski, M., "BGPSEC Protocol Specification",
              draft-ietf-sidr-bgpsec-protocol (work in progress),
              October 2012.

   [I-D.ietf-pkix-est]
              Pritikin, M, Yee, P., and D. Harkins "Enrollment over
              Secure Transport", draft-ietf-pkix-est (work in progress),
              February 2013.




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   [IEEE-802.3]
              ISO/IEC 8802-3 Information technology -
              Telecommunications and information exchange between
              systems - Local and metropolitan area networks -
              Common specifications - Part 3:  Carrier Sense
              Multiple Access with Collision Detection (CSMA/CD)
              Access Method and Physical Layer Specifications, 2008.

   [RFC2585]  Housley, R. and P. Hoffman, "Internet X.509 Public Key
              Infrastructure Operational Protocols: FTP and HTTP",
              RFC 2585, May 1999.

   [RFC4253]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, January 2006.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2", FYI
              36, RFC 4949, August 2007.

   [RFC5647]  Igoe, K. and J. Solinas, "AES Galois Counter Mode for the
              Secure Shell Transport Layer Protocol", RFC 5647, August
              2009.

   [RFC5656]  Stebila, D. and J. Green, "Elliptic Curve Algorithm
              Integration in the Secure Shell Transport Layer",
              RFC 5656, December 2009.

   [RFC5751]  Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
              Mail Extensions (S/MIME) Version 3.2 Message
              Specification", RFC 5751, January 2010.

   [RFC5967]  Turner, S., "The application/pkcs10 Media Type", RFC 5967,
              August 2010.

   [RFC6187]  Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure
              Shell Authentication", RFC 6187, March 2011.

   [RFC6470]  Bierman, A., "Network Configuration Protocol (NETCONF)
              Base Notifications", RFC 6470, February 2012.

   [RFC6480]  Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", RFC 6480, February 2012.

   [RFC6668]  Bider, D. and M. Baushke, "SHA-2 Data Integrity
              Verification for the Secure Shell (SSH) Transport Layer
              Protocol", RFC 6668, July 2012.






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Authors' Addresses

   Sean Turner
   IECA, Inc.
   3057 Nutley Street, Suite 106
   Fairfax, Virginia  22031
   US

   Email: turners@ieca.com


   Keyur Patel
   Cisco Systems
   170 West Tasman Drive
   San Jose, CA  95134
   US

   Email: keyupate@cisco.com


   Randy Bush
   Internet Initiative Japan, Inc.
   5147 Crystal Springs
   Bainbridge Island, Washington  98110
   US

   Phone: +1 206 780 0431 x1
   Email: randy@psg.com























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