Security Services for the Registration Data Access Protocol
draft-ietf-weirds-rdap-sec-05

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Internet Engineering Task Force                            S. Hollenbeck
Internet-Draft                                             Verisign Labs
Intended status: Standards Track                                 N. Kong
Expires: February 20, 2014                                         CNNIC
                                                         August 19, 2013

      Security Services for the Registration Data Access Protocol
                     draft-ietf-weirds-rdap-sec-05

Abstract

   The Registration Data Access Protocol (RDAP) provides "RESTful" web
   services to retrieve registration metadata from domain name and
   regional internet registries.  This document describes information
   security services including authentication, authorization,
   availability, data confidentiality, and data integrity for RDAP.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 20, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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
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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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
     2.1.  Acronyms and Abbreviations  . . . . . . . . . . . . . . .   3
   3.  Information Security Services and RDAP  . . . . . . . . . . .   3
     3.1.  Authentication  . . . . . . . . . . . . . . . . . . . . .   3
       3.1.1.  Federated Authentication  . . . . . . . . . . . . . .   4
     3.2.  Authorization . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Availability  . . . . . . . . . . . . . . . . . . . . . .   6
     3.4.  Data Confidentiality  . . . . . . . . . . . . . . . . . .   6
     3.5.  Data Integrity  . . . . . . . . . . . . . . . . . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The Registration Data Access Protocol (RDAP) is specified in multiple
   documents, including "Registration Data Access Protocol Lookup
   Format" [I-D.ietf-weirds-rdap-query], "JSON Responses for the
   Registration Data Access Protocol (RDAP)"
   [I-D.ietf-weirds-json-response], and "HTTP usage in the Registration
   Data Access Protocol (RDAP)" [I-D.ietf-weirds-using-http].

   One goal of RDAP is to provide security services that do not exist in
   the WHOIS [RFC3912] protocol, including authentication,
   authorization, availability, data confidentiality, and data
   integrity.  This document describes how each of these services is
   achieved by RDAP.  Where applicable, informational references to
   requirements for a WHOIS replacement service [RFC3707] are noted.

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2.  Conventions Used in This Document

   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 RFC 2119 [RFC2119].

2.1.  Acronyms and Abbreviations

      DNR: Domain Name Registry

      HTTP: Hypertext Transfer Protocol

      JSON: JavaScript Object Notation

      RDAP: Registration Data Access Protocol

      RIR: Regional Internet Registry

      TLS: Transport Layer Security

3.  Information Security Services and RDAP

   RDAP itself does not include native security services.  Instead, RDAP
   relies on features that are available in other protocol layers to
   provide needed security services including authentication,
   authorization, availability, data confidentiality, and data
   integrity.  A description of each of these security services can be
   found in "Internet Security Glossary, Version 2" [RFC4949].  No
   requirements have been identified for other security services.

3.1.  Authentication

   WHOIS does not provide features to identify and authenticate clients.
   As noted in section 3.1.4.2 of "Cross Registry Internet Service
   Protocol (CRISP) Requirements" [RFC3707], there is utility in
   allowing server operators to offer "varying degrees of access
   depending on policy and need".  Clients have to be identified and
   authenticated to provide that utility.

   RDAP's authentication framework needs to accommodate anonymous access
   as well as verification of identities using a range of authentication
   methods and credential services.  To that end, RDAP clients and
   servers MUST implement the authentication framework specified in
   "HTTP Authentication: Basic and Digest Access Authentication"
   [RFC2617].  The "basic" scheme can be used to send a client's user
   name and password to a server in plaintext, based64-encoded form.
   The "digest" scheme can be used to authenticate a client without
   exposing the client's plaintext password.  If the "basic" scheme is

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   used, HTTP Over TLS [RFC2818] MUST be used to protect the client's
   credentials from disclosure while in transit (see Section 3.4).

   Servers MUST support either Basic or Digest authentication; they are
   not required to support both.  Clients MUST support both to
   interoperate with servers that support one or the other.

   The Transport Layer Security Protocol [RFC5246] includes an optional
   feature to identify and authenticate clients who possess and present
   a valid X.509 digital certificate [RFC5280].  Support for this
   feature is OPTIONAL.

   RDAP does not impose any unique server authentication requirements.
   The server authentication provided by TLS fully addresses the needs
   of RDAP.  In general, transports for RDAP must either provide a TLS-
   protected transport (e.g., HTTPS) or a mechanism that provides an
   equivalent level of server authentication.

   Work on HTTP authentication methods continues.  RDAP ought to be
   agile enough to support additional methods as they are defined.

3.1.1.  Federated Authentication

   The traditional client-server authentication model requires clients
   to maintain distinct credentials for every RDAP server.  This
   situation can become unwieldy as the number of RDAP servers
   increases.  Federated authentication mechanisms allow clients to use
   one credential to access multiple RDAP servers and reduce client
   credential management complexity.  RDAP MAY include a federated
   authentication mechanism that permits a client to access multiple
   RDAP servers in the same federation with one credential.

   Federated authentication mechanisms used by RDAP are OPTIONAL.  If
   used, they MUST be fully supported by HTTP.  OAuth, OpenID, and CA-
   based mechanisms are three possible approaches to provide federated
   authentication.

   The OAuth authorization framework [RFC6749] describes a method for
   users to access protected web resources without having to hand out
   their credentials.  Instead, clients are issued access tokens by
   authorization servers with the permission of the resource owners.
   Using OAuth, multiple RDAP servers can form a federation and the
   clients can access any server in the same federation by providing one
   credential registered in any server in that federation.  The OAuth
   authorization framework is designed for use with HTTP and thus can be
   used with RDAP.

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   OpenID [OpenID] is a decentralized single sign-on authentication
   system that allows users to log in at multiple web sites with one ID
   instead of having to create multiple unique accounts.  An end user
   can freely choose which OpenID provider to use, and can preserve
   their Identifier if they switch OpenID providers.

   Note that OAuth and OpenID do not consistently require data
   confidentiality services to protect interactions between providers
   and consumers.  HTTP Over TLS [RFC2818] can be used as needed to
   provide protection against man-in-the-middle attacks.

   The Transport Layer Security Protocol [RFC5246], Section 7.4.6,
   describes the specification of a client certificate.  Clients who
   possess and present a valid X.509 digital certificate, issued by an
   entity called a "Certification Authority" (CA), could be identified
   and authenticated by a server who trusts the corresponding CA.  A
   certificate authentication method can be used to achieve federated
   authentication in which multiple RDAP servers all trust the same CAs
   and then any client with a certificate issued by a trusted CA can
   access any RDAP server in the federation.  This certificate-based
   mechanism is supported by HTTPS and can be used with RDAP.

3.2.  Authorization

   WHOIS does not provide services to grant different levels of access
   to clients based on a client's authenticated identity.  As noted in
   section 3.1.4.2 of "Cross Registry Internet Service Protocol (CRISP)
   Requirements" [RFC3707], there is utility in allowing server
   operators to offer "varying degrees of access depending on policy and
   need".  Access control decisions can be made once a client's identity
   has been established and authenticated (see Section 3.1).

   Server operators SHOULD offer varying degrees of access depending on
   policy and need in conjunction with the authentication methods
   described in Section 3.1.  If such varying degrees of access are
   supported, an RDAP server MUST provide granular access controls (that
   is, on a per registration data object basis) in order to implement
   authorization policies.  Some examples:

   -  Clients will be allowed access only to data for which they have a
      relationship.

   -  Unauthenticated or anonymous access status may not yield any
      contact information.

   -  Full access may be granted to a special group of authenticated
      clients.

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   The type of access allowed by a server will most likely vary from one
   operator to the next.

3.3.  Availability

   An RDAP service has to be available to be useful.  There are no RDAP-
   unique requirements to provide availability, but as a general
   security consideration a service operator needs to be aware of the
   issues associated with denial of service.  A thorough reading of
   "Internet Denial-of-Service Considerations" [RFC4732] is advised.

   An RDAP service MAY use a throttling mechanism to limit the number of
   queries that a single client can send in a given period of time.  If
   used, the server SHOULD return a 429 response code as described in
   "Additional HTTP Status Codes" [RFC6585].  A client that receives a
   429 response SHOULD decrease its query rate, and honor the Retry-
   After header field if one is present.  Note that this is not a
   defense against denial-of-service attacks, since a malicious client
   could ignore the code and continue to send queries at a high rate.  A
   server might use another response code if it did not wish to reveal
   to a client that rate limiting is the reason for the denial of a
   reply.

3.4.  Data Confidentiality

   WHOIS does not provide the ability to protect data from inadvertent
   disclosure while in transit.  Web services such as RDAP commonly use
   HTTP Over TLS [RFC2818] to provide that protection by encrypting all
   traffic sent on the connection between client and server.  It is also
   possible to encrypt discrete objects (such as command path segments
   and JSON-encoded response objects) at one endpoint, send them to the
   other endpoint via an unprotected transport protocol, and decrypt the
   object on receipt.  Encryption algorithms as described in "Internet
   Security Glossary, Version 2" [RFC4949] are commonly used to provide
   data confidentiality at the object level.

   There are no current requirements for object-level data
   confidentiality using encryption.  Support for this feature could be
   added to RDAP in the future.

   As noted in Section 3.1, the HTTP "basic" authentication scheme can
   be used to authenticate a client.  When this scheme is used, HTTP
   Over TLS MUST be used to protect the client's credentials from
   disclosure while in transit.  If the policy of the server operator
   requires encryption to protect client-server data exchanges (such as
   to protect non-public data that can not be accessed without client
   identification and authentication), HTTP Over TLS MUST be used to
   protect those exchanges.

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3.5.  Data Integrity

   WHOIS does not provide the ability to protect data from modification
   while in transit.  Web services such as RDAP commonly use HTTP Over
   TLS [RFC2818] to provide that protection by using a keyed Message
   Authentication Code (MAC) to detect modifications.  It is also
   possible to sign discrete objects (such as command path segments and
   JSON-encoded response objects) at one endpoint, send them to the
   other endpoint via a transport protocol, and validate the signature
   of the object on receipt.  Digital signature algorithms as described
   in "Internet Security Glossary, Version 2" [RFC4949] are commonly
   used to provide data integrity at the object level.

   There are no current requirements for object-level data integrity
   using digital signatures.  Support for this feature could be added to
   RDAP in the future.

   The most specific need for this service is to provide assurance that
   HTTP 30x redirection hints [RFC2616] and response elements returned
   from the server are not modified while in transit.  If the policy of
   the server operator requires message integrity for client-server data
   exchanges, HTTP Over TLS MUST be used to protect those exchanges.

4.  IANA Considerations

   This document does not specify any IANA actions.  This section can be
   removed if this document is published as an RFC.

5.  Security Considerations

   One of the goals of RDAP is to provide security services that do not
   exist in the WHOIS protocol.  This document describes the security
   services provided by RDAP and associated protocol layers, including
   authentication, authorization, availability, data confidentiality,
   and data integrity.  Non-repudiation services were also considered
   and ultimately rejected due to a lack of requirements.  There are,
   however, currently-deployed WHOIS servers that can return signed
   responses that provide non-repudiation with proof of origin.  RDAP
   might need to be extended to provide this service in the future.

   As an HTTP-based protocol RDAP is susceptible to code injection
   attacks.  Code injection refers to adding code into a computer system
   or program to alter the course of execution.  There are many types of
   code injection, including SQL injection, dynamic variable or function
   injection, include file injection, shell injection, and HTML-script
   injection among others.  Data confidentiality and integrity services
   provide a measure of defense against man-in-the-middle injection
   attacks, but vulnerabilities in both client-side and server-side

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   software make it possible for injection attacks to succeed.
   Consistently checking and validating server credentials can help
   detect man-in-the-middle attacks.

   As noted in Section 3.1.1, digital certificates can be used to
   implement federated authentication.  There is a risk of too-
   promiscuous, or even rogue, CAs being included in the list of
   acceptable CAs that the TLS server sends the client as part of the
   TLS client-authentication handshake and lending the appearance of
   trust to certificates signed by those CAs.  Periodic monitoring of
   the list of CAs that RDAP servers trust for client authentication can
   help reduce this risk.

   The Transport Layer Security Protocol [RFC5246] includes a null
   cipher suite that does not encrypt data and thus does not provide
   data confidentiality.  This option must not be used when data
   confidentiality services are needed.

   Data integrity services are sometimes mistakenly associated with
   directory service operational policy requirements focused on data
   accuracy.  "Accuracy" refers to the truthful association of data
   elements (such as names, addresses, and telephone numbers) in the
   context of a particular directory object (such as a domain name).
   Accuracy requirements are out of scope for this protocol.

   Additional security considerations are described in the
   specifications for HTTP [RFC2616], HTTP basic and digest access
   authentication [RFC2617], HTTP Over TLS [RFC2818], and additional
   HTTP status codes [RFC6585].  Security considerations for federated
   authentication systems can be found in the OAuth [RFC6749] and OpenID
   [OpenID] specifications.

6.  Acknowledgements

   The authors would like to acknowledge the following individuals for
   their contributions to this document: Richard Barnes, Marc Blanchet,
   Ernie Dainow, Spencer Dawkins, Jean-Philippe Dionne, Byron Ellacott,
   Stephen Farrell, Tony Hansen, Peter Koch, Murray Kucherawy, Barry
   Leiba, Andrew Newton, and Linlin Zhou.

7.  References

7.1.  Normative References

   [I-D.ietf-weirds-json-response]
              Newton, A. and S. Hollenbeck, "JSON Responses for the
              Registration Data Access Protocol (RDAP)", draft-ietf-
              weirds-json-response-05 (work in progress), August 2013.

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   [I-D.ietf-weirds-rdap-query]
              Newton, A. and S. Hollenbeck, "Registration Data Access
              Protocol Query Format", draft-ietf-weirds-rdap-query-06
              (work in progress), August 2013.

   [I-D.ietf-weirds-using-http]
              Newton, A., Ellacott, B., and N. Kong, "HTTP usage in the
              Registration Data Access Protocol (RDAP)", draft-ietf-
              weirds-using-http-07 (work in progress), July 2013.

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

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A., and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [RFC6585]  Nottingham, M. and R. Fielding, "Additional HTTP Status
              Codes", RFC 6585, April 2012.

7.2.  Informative References

   [OpenID]   OpenID Foundation, "OpenID Authentication 2.0 - Final ",
              December 2007, <http://specs.openid.net/auth/2.0>.

   [RFC3707]  Newton, A., "Cross Registry Internet Service Protocol
              (CRISP) Requirements", RFC 3707, February 2004.

   [RFC3912]  Daigle, L., "WHOIS Protocol Specification", RFC 3912,
              September 2004.

   [RFC4732]  Handley, M., Rescorla, E., IAB, "Internet Denial-of-
              Service Considerations", RFC 4732, December 2006.

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

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

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   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC6749]  Hardt, D., "The OAuth 2.0 Authorization Framework", RFC
              6749, October 2012.

Appendix A.  Change Log

   Initial -00:  Adopted as working group document.
   -01:  Extensive text additions and revisions based on in-room
      discussion at IETF-85.  Sections for data integrity and non-
      repudiation have been removed due to a lack of requirements, but
      both topics are now addressed in the Security Considerations
      section.
   -02:  Fixed document names in the Introduction.  Modified text in
      Section 3.1.1 to clarify requirement.  Added text to Section 3.3
      to describe rate limiting.  Added new data integrity section.
      Updated security considerations to describe injection attacks.
   -03:  Extensive updates to address WG last call comments: rewrote
      introduction, removed references to draft documents, changed
      "HTML" to "HTTP" in Section 5, eliminated upper case words that
      could be misunderstood to be normative guidance, rewrote
      Section 3.4 and Section 3.5.
   -04:  Address AD evaluation comments: In Section 3.1 change "RDAP
      MUST include an authentication framework that can accommodate" to
      "RDAP's authentication framework needs to accommodate"; in
      Section 3.2 change "RDAP MUST include an authorization framework
      that is capable of providing granular (per registration data
      object) access controls according to the policies of the operator"
      to "An RDAP server MUST provide granular access controls (that is,
      on a per registration data object basis) in order to implement
      authorization policies"; move RFCs 4732, 5280, and 6749 from
      normative to informative subsection.
   -05:  Address IETF last call comments: Added text to Section 3.1.1 to
      recommend the use of HTTP over TLS.  Modified Section 3.2 to
      clarify granular access control text.  Added additional Security
      Considerations.  Made references to RFC 5246 and OpenID
      informative.  Minor typo fixes.

Authors' Addresses

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   Scott Hollenbeck
   Verisign Labs
   12061 Bluemont Way
   Reston, VA  20190
   US

   Email: shollenbeck@verisign.com
   URI:   http://www.verisignlabs.com/

   Ning Kong
   China Internet Network Information Center
   4 South 4th Street, Zhongguancun, Haidian District
   Beijing  100190
   China

   Phone: +86 10 5881 3147
   Email: nkong@cnnic.cn

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