Skip to main content

OmniBroker Protocol
draft-hallambaker-omnibroker-00

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft whose latest revision state is "Expired".
Author Phillip Hallam-Baker
Last updated 2012-06-27
RFC stream (None)
Formats
Additional resources
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-hallambaker-omnibroker-00
Internet Engineering Task Force                          P. Hallam-Baker
Internet-Draft                                         Comodo Group Inc.
Intended status: Standards Track                           June 27, 2012
Expires: December 29, 2012

                          OmniBroker Protocol
                    draft-hallambaker-omnibroker-00

Abstract

   An Omnibroker is an agent chosen and trusted by an Internet user to
   provide information such as name and certificate status information
   that are in general trusted even if they are not trustworthy.  Rather
   than acting as a mere conduit for information provided by existing
   services, an Omnibroker is responsible for curating those sources to
   protect the user.

   The Omnibroker Protocol (OBP) provides an aggregated interface to
   trusted Internet services including DNS, OCSP and various forms of
   authentication service.  Multiple transport bindings are supported to
   permit efficient access in virtually every common deployment scenario
   and ensure access in any deployment scenario in which access is not
   being purposely denied.

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 December 29, 2012.

Copyright Notice

   Copyright (c) 2012 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

Hallam-Baker            Expires December 29, 2012               [Page 1]
Internet-Draft             OmniBroker Protocol                 June 2012

   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.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  4
   2.  Purpose  . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  A Curated Service  . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Connection Broker  . . . . . . . . . . . . . . . . . . . .  6
       2.2.1.  Service Connection Broker  . . . . . . . . . . . . . .  6
       2.2.2.  Peer Connection Broker . . . . . . . . . . . . . . . .  7
       2.2.3.  Connection Broker API  . . . . . . . . . . . . . . . .  7
     2.3.  Service Advertisement  . . . . . . . . . . . . . . . . . .  8
       2.3.1.  Connection Advertisement API . . . . . . . . . . . . .  8
     2.4.  Credential Validation Broker . . . . . . . . . . . . . . .  8
     2.5.  Authentication Gateway . . . . . . . . . . . . . . . . . .  8
     2.6.  Credential Announcement  . . . . . . . . . . . . . . . . .  8
   3.  Omnibroker Connection Maintenance Service  . . . . . . . . . .  9
     3.1.  Authentication . . . . . . . . . . . . . . . . . . . . . .  9
       3.1.1.  Broker Authentication  . . . . . . . . . . . . . . . .  9
       3.1.2.  Device Authentication  . . . . . . . . . . . . . . . .  9
     3.2.  OBPConnection  . . . . . . . . . . . . . . . . . . . . . .  9
       3.2.1.  Top  . . . . . . . . . . . . . . . . . . . . . . . . .  9
       3.2.2.  Message: Request . . . . . . . . . . . . . . . . . . . 10
       3.2.3.  Message: Response  . . . . . . . . . . . . . . . . . . 10
       3.2.4.  Structure: Cryptographic . . . . . . . . . . . . . . . 10
       3.2.5.  Structure: ImageLink . . . . . . . . . . . . . . . . . 11
       3.2.6.  Structure: Connection  . . . . . . . . . . . . . . . . 11
       3.2.7.  Bind . . . . . . . . . . . . . . . . . . . . . . . . . 12
       3.2.8.  Message: BindRequest . . . . . . . . . . . . . . . . . 12
       3.2.9.  Message: BindResponse  . . . . . . . . . . . . . . . . 12
       3.2.10. Message: OpenRequest . . . . . . . . . . . . . . . . . 12
       3.2.11. Message: OpenResponse  . . . . . . . . . . . . . . . . 13
       3.2.12. Message: TicketRequest . . . . . . . . . . . . . . . . 14
       3.2.13. Message: TicketResponse  . . . . . . . . . . . . . . . 14
       3.2.14. Unbind . . . . . . . . . . . . . . . . . . . . . . . . 14
       3.2.15. Message: UnbindRequest . . . . . . . . . . . . . . . . 14
       3.2.16. Message: UnbindResponse  . . . . . . . . . . . . . . . 14
   4.  Omnibroker Connection Query Service  . . . . . . . . . . . . . 15
     4.1.  OBPQuery . . . . . . . . . . . . . . . . . . . . . . . . . 15

Hallam-Baker            Expires December 29, 2012               [Page 2]
Internet-Draft             OmniBroker Protocol                 June 2012

       4.1.1.  Top  . . . . . . . . . . . . . . . . . . . . . . . . . 15
       4.1.2.  Structure: Identifier  . . . . . . . . . . . . . . . . 15
       4.1.3.  Structure: Connection  . . . . . . . . . . . . . . . . 15
       4.1.4.  Structure: Advice  . . . . . . . . . . . . . . . . . . 16
       4.1.5.  Structure: Service . . . . . . . . . . . . . . . . . . 16
       4.1.6.  Message: Request . . . . . . . . . . . . . . . . . . . 17
       4.1.7.  Message: Response  . . . . . . . . . . . . . . . . . . 17
       4.1.8.  QueryConnect . . . . . . . . . . . . . . . . . . . . . 17
       4.1.9.  Message: QueryConnectRequest . . . . . . . . . . . . . 18
       4.1.10. Message: QueryConnectResponse  . . . . . . . . . . . . 18
       4.1.11. Advertise  . . . . . . . . . . . . . . . . . . . . . . 18
       4.1.12. Message: AdvertiseRequest  . . . . . . . . . . . . . . 18
       4.1.13. Message: AdvertiseResponse . . . . . . . . . . . . . . 19
       4.1.14. Validate . . . . . . . . . . . . . . . . . . . . . . . 19
       4.1.15. Message: ValidateRequest . . . . . . . . . . . . . . . 19
       4.1.16. Message: ValidateResponse  . . . . . . . . . . . . . . 19
       4.1.17. QueryCredentialPassword  . . . . . . . . . . . . . . . 19
       4.1.18. Message: CredentialPasswordRequest . . . . . . . . . . 20
       4.1.19. Message: CredentialPasswordResponse  . . . . . . . . . 20
   5.  Transport Bindings . . . . . . . . . . . . . . . . . . . . . . 20
     5.1.  HTTP over TLS  . . . . . . . . . . . . . . . . . . . . . . 20
       5.1.1.  Message Encapsulation  . . . . . . . . . . . . . . . . 20
       5.1.2.  Request  . . . . . . . . . . . . . . . . . . . . . . . 21
       5.1.3.  Response . . . . . . . . . . . . . . . . . . . . . . . 21
       5.1.4.  Example  . . . . . . . . . . . . . . . . . . . . . . . 21
     5.2.  DNS Tunnel . . . . . . . . . . . . . . . . . . . . . . . . 21
       5.2.1.  Request  . . . . . . . . . . . . . . . . . . . . . . . 21
       5.2.2.  Response . . . . . . . . . . . . . . . . . . . . . . . 22
       5.2.3.  Example  . . . . . . . . . . . . . . . . . . . . . . . 22
     5.3.  UDP  . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
       5.3.1.  Request  . . . . . . . . . . . . . . . . . . . . . . . 22
       5.3.2.  Response . . . . . . . . . . . . . . . . . . . . . . . 22
       5.3.3.  Example  . . . . . . . . . . . . . . . . . . . . . . . 22
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 23
     7.1.  Denial of Service  . . . . . . . . . . . . . . . . . . . . 23
     7.2.  Breach of Trust  . . . . . . . . . . . . . . . . . . . . . 23
     7.3.  Coercion . . . . . . . . . . . . . . . . . . . . . . . . . 23
   8.  To do  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
   9.  For discussion.  . . . . . . . . . . . . . . . . . . . . . . . 23
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 23
   11. Normative References . . . . . . . . . . . . . . . . . . . . . 23
   Appendix A.  Example Data. . . . . . . . . . . . . . . . . . . . . 24
     A.1.  Ticket A . . . . . . . . . . . . . . . . . . . . . . . . . 24
     A.2.  Ticket B . . . . . . . . . . . . . . . . . . . . . . . . . 24
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 24

Hallam-Baker            Expires December 29, 2012               [Page 3]
Internet-Draft             OmniBroker Protocol                 June 2012

1.  Definitions

1.1.  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 RFC 2119 [RFC2119].

2.  Purpose

   An Omnibroker is an agent chosen and trusted by an Internet user to
   provide information such as name and certificate status information
   that are in general trusted even if they are not trustworthy.  Rather
   than acting as a mere conduit for information provided by existing
   services, an Omnibroker is responsible for curating those sources and
   providing autheticated, curated results to the endpoint client.

   Unlike the traditional trusted information services that are expected
   to deliver the same response to a query regardless of who asks the
   question, OBP permits an Omnibroker to return a response that is
   tailored to the specific party asking the question.  This permits the
   use of an authentication approach that has negligible impact on
   performance and permits an Omnibroker to answer questions that a
   traditional public Internet information service could not.  In
   particular, an Omnibroker can broker peer to peer connections

2.1.  A Curated Service

   In the traditional configuration, an Internet host accepts DNS
   service from the IP address specified by the local network provider,
   frequently the DNS server advertised by the local DHCP service.  This
   approach creates an obvious security risk as DNS is clearly a trusted
   service and a random DNS service advertised by the local DNS is
   clearly not trustworthy.

   A policy of only using a chosen DNS service provides a reduction in
   risk but only a modest one since the standard DNS service does not
   provide authenticated results.  Many local area networks intercept
   all DNS traffic and process it through the local DNS server
   regardless of the intended destination IP address.  This practice is
   highly desirable if it would prevent a client from accessing an
   untrustworthy DNS service in place of a trustworthy local DNS service
   and extreemly undesirable in the contrary case.

   In addition to ensuring the authenticity of DNS resolution responses,
   such services frequently provide filtering of Internet addresses the
   network provider considers undesirable.  Many workplaces block access

Hallam-Baker            Expires December 29, 2012               [Page 4]
Internet-Draft             OmniBroker Protocol                 June 2012

   to Web sites that are considered detrimental to productivity.  Many
   parent subscribe to services that filter content they consider
   undesirable.  While the value of such services is debatable they are
   services that those customers have chosen to deploy on their networks
   to meet their perceived security requirements.  New security
   proposals that do not support such capabilities or seek to actually
   circumvent them will not be acceptable to those constituencies.

   While DNS filtering is a form of censorship, not all forms of DNS
   filering are intrinsically undesirable censorship.  Spam filtering is
   also a form of censorship albeit one that is not normally regarded as
   such because it most Internet users now consider it to be an
   essential security control.  Anti-Virus tools are also a form of
   censorship.  DNS filtering tools that block access to sites that
   distribute malware are also a form of censorship and are rapidly
   gaining popularity for the same reason.

   While all forms of censorship raise civil liberties concerns,
   censorship should not automatically raise civil liberties objections.
   It is not the fact that filtering is taking place but the party that
   is in control of the filtering that should raise civil liberties
   concerns.  In an Internet of 2 billion users, all users are obliged
   to perform some filtering.  OBP is designed to make the party that is
   in control of the filtering process apparent and provide the end user
   with the ability to select the Omnibroker of their choice.

   DNSSEC provides a means of determining that a DNS record is the
   authentic record published by the source but this capability alone
   does not meet the security requirements for DNS resolution services
   as they have come to be understood since the protocol was first
   proposed.

   Internet users want to be safe from all forms of attack, not just the
   DNS resolver mani-in-the-middle attack that 'end-to-end' deployment
   of DNSSEC is designed to address.  An Internet user is far more
   likely to be directed to a site with a DNS name controlled by a
   criminal gang than be subject to a man-in-the-middle attack.

   Most users would prefer to have an Internet connection that is
   'curated' to remove at least some of the locations they consider to
   be undesirable.  The fact that an organised criminal gang has put a
   host on the Internet does not mean that any other Internet user
   should be obliged to allow it to connect to any of the machines that
   they own.

   The same argument for curating the raw results applies to other forms
   of trusted information service.  The fact that a Certificate
   Authority has issued a digital certificate and considers it to be

Hallam-Baker            Expires December 29, 2012               [Page 5]
Internet-Draft             OmniBroker Protocol                 June 2012

   valid should not mean that the end party is automatically considered
   trustworthy by anyone and for any purpose.

   The deployment of security policy capabilities presents another case
   in which direct reliance on raw data is undesirable.  While security
   policies such as 'host always offers TLS' or 'mail server always
   signs outgoing mail with DKIM' can provide considerable security
   advantages, only some of the security policy information that is
   published is accurate and kept up to date.  Curating such data
   sources typically proves essential if an unacceptable rate of false
   positives is to be avoided.

   Although a client is permitted to curate its own data sources it
   rarely has a sufficient amount of data to make decisions as
   accurately as a network service that can draw on a wide variety of
   additional data including tracking of communication patterns,
   historical data series and third party reputation services.

   Curation in the network offers better asgility than the client
   approach.  Agility is an important consideration when an attacker
   changes their strategy rapidly and repeatedly to counter new
   defensive controls.

   While curating trusted data sources is an established and proven
   practice, current practice has been to curate each source
   individually.  This approach avoids the need to write a new protocol
   but limits the information a curator can leverage to detect potential
   danger.  Leveraging multiple data sources simultaneously allows
   better accuracy than applying each individually.

2.2.  Connection Broker

   The OBP service connection broker answers the query 'what connection
   parameters should be used to establish the best connection to
   interract with party X according to protocol Y. Where 'best' is
   determined by the Omnibroker which MAY take into account parameters
   specified by the relying party.

2.2.1.  Service Connection Broker

   The OBP service connection broker supports and extends the
   traditional DNS resolution service that resolves a DNS name (e.g.
   www.example.com) to return an IP address (e.g. 10.1.2.3).

   When using an Omnibroker as a service connection broker, a client
   specifies both the DNS name (e.g. www.example.com) and the Internet
   protocol to be used (e.g. _http._tcp).  The returned connection
   parameters MAY include:

Hallam-Baker            Expires December 29, 2012               [Page 6]
Internet-Draft             OmniBroker Protocol                 June 2012

      The IP protocol version, address and port number to establish a
      connection to.

      If appropriate, a security transport such as TLS or IPSEC.

      If appropriate, a description of a service credential such as a
      TLS certificate or a constraint on the type of certificates that
      the client should consider acceptable.

      If appropriate, application protocol details such as version and
      protocol options.

   If an attempt to connect with the parameters specified fails, a
   client MAY report the failure and request a new set of parameters.

2.2.2.  Peer Connection Broker

   Each OBP request identifies both the account under which the request
   is made and the device from which it is made.  An OBP broker is thus
   capable of acting as a peer connection broker service or providing a
   gateway to such a service.

   When using Omnibroker as a peer connection broker, a client specifies
   the account name and DNS name of the party with which a connection is
   to be established (e.g. alice@example.com) and the connection
   protocol to be used (e.g. _xmpp-client._tcp)

   The returned connection parameters are similar to those returned in
   response to a service broker query.

2.2.3.  Connection Broker API

   In the traditional BSD sockets API a network client performs a series
   of calls to resolve a network name to a list of IP addresses, selects
   one and establishes an IP connection to a port specified by the
   chosen application protocol.

   OBP anticipates a higher level abstract API that encapsulates this
   complexity, hiding it from the application code.

   In the case that one (or more) OBP services are configured, the
   library supporting the SHOULD obtain connection parameters from the
   OBP service.  Otherwise, it SHOULD establish a connection using the
   traditional calling sequence of resolving a host name to obtain an IP
   address, etc.

Hallam-Baker            Expires December 29, 2012               [Page 7]
Internet-Draft             OmniBroker Protocol                 June 2012

2.3.  Service Advertisement

   Service advertisement is the converse of service resolution.  An
   Internet application wishing to accept inbound connections specifies
   one or more sets of connection parameters for the Omnibroker to
   register with whatever naming, discovery or other services may be
   appropriate.

2.3.1.  Connection Advertisement API

   OBP anticipates the use of a high level API for connection
   advertisement that is the converse of the Connection broker API.
   Instead of establishing a connection, the API is used to advertise
   that a connection is offered either as a service or a peer.

   An application MAY offer multiple types of connection with different
   connection properties (e.g.  IPv4/IPv6, with and without SSL, etc.).
   This MAY be supported by marking certain properties as being optional
   and/or by permitting the API to be called multiple times with
   different properties specified.

2.4.  Credential Validation Broker

   A credential validation broker reports on the validity and
   trustworthiness of credentials presented to a client by Internet
   services and/or peers.

   The service provided by OBP is similar to that provided by OCSP and
   SCVP.  Like SCVP, OBP is an agent selected by the relying party to
   validate certificates and/or construct trust paths on its behalf.

2.5.  Authentication Gateway

   Every OBP request is strongly authenticated by means of a shared
   secret that is unique to the account and the device.  This may be
   leveraged to permit use as an authentication gateway, providing
   access to other credentials that the client has established the right
   to use.

   An Authentication Gateway MAY provide access to account names and
   passwords that the account holder has chosen to store in the cloud
   for access to sites that do not support a stronger, cryptographically
   based form of authentication such as OAuth.

2.6.  Credential Announcement

   An Authentication Gateway can only provide access to credentials that
   it has notice of.  A client uses the Credential Announcement

Hallam-Baker            Expires December 29, 2012               [Page 8]
Internet-Draft             OmniBroker Protocol                 June 2012

   transaction to advise the service of a new credential.

3.  Omnibroker Connection Maintenance Service

3.1.  Authentication

   The principle function of the OBP Connection Maintenance Protocol is
   to establish and maintain the cryptographic parameters used to
   authenticate and encrypt

   The user needs to authenticate the broker service regardless of any
   authentication requirements of the broker.

3.1.1.  Broker Authentication

   The OBP connection maintenance protocol transport MUST provide a
   trustworthy means of verifying the identity of the broker (e.g. an
   Extended Validation SSL certificate).

   If the device supports a display capability, authentication of the
   device and user MAY be achieved by means of an authentication image.
   Such an authentication image is generated by the broker and passed to
   the client in the OpenResponse message.  The user then verifies that
   the image presented on the device display is the same as that
   presented on the account maintenance console.

3.1.2.  Device Authentication

   If device authentication is required, the mechanism to be used
   depends on the capabilities of the device, the requirements of the
   broker and the existing relationship between the user and the broker.

   If the device supports some means of data entry, authentication MAY
   be achieved by entering a passcode into the device that was
   previously delivered to the user out of band.

   The passcode authentication mechanism allows the device to establish
   a proof that it knows the passcode without disclosing the passcode.
   This property provides protection against Man-In-The-Middle type
   disclosure attacks.

3.2.  OBPConnection

3.2.1.  Top

   OBP Connection Management Query requests and responses contain the
   following common elements:

Hallam-Baker            Expires December 29, 2012               [Page 9]
Internet-Draft             OmniBroker Protocol                 June 2012

3.2.2.  Message: Request

   The following parameters MAY be specified in any request:

   Ticket : Binary [0..1]

   Opaque ticket issued by the server that identifies the cryptographic
   parameters for encryption and authentication of the message payload.

   MAC : Binary [1..1]

   Message Authentication Code formed over the canonical form of the
   message payload.

3.2.3.  Message: Response

   The following parameters MAY be specified in any response:

   MAC : Binary [1..1]

   Message Authentication Code formed over the canonical form of the
   message payload.

3.2.4.  Structure: Cryptographic

   Parameters describing a cryptographic context.

   Protocol : Label [0..1]

   OBP tickets MAY be restricted to use with either the management
   protocol (Management) or the query protocol (Query).  If so a service
   would typically specify a ticket with a long expiry time or no expiry
   for use with the management protocol and a separate ticket for use
   with the query protocol.

   Secret : Binary [1..1]

   Shared secret

   Encryption : Label [1..1]

   Encryption Algorithm selected

   Authentication : Label [1..1]

   Authentication Algorithm selected

   Ticket : Binary [1..1]

Hallam-Baker            Expires December 29, 2012              [Page 10]
Internet-Draft             OmniBroker Protocol                 June 2012

   Opaque ticket issued by the server that identifies the cryptographic
   parameters for encryption and authentication of the message payload.

   Expires : DateTime [0..1]

   Date and time at which the context will expire

3.2.5.  Structure: ImageLink

   Algorithm : Label [0..1]

   Image encoding algorithm (e.g.  JPG, PNG)

   Image : Binary [0..1]

   Image data as specified by algorithm

3.2.6.  Structure: Connection

   Contains information describing a network connection.

   Name : Name [0..1]

   DNS Name.  Since one of the functions of an OBP service is name
   resolution, a DNS name is only used to establish a connection if
   connection by means of the IP address fails.

   Port : Integer [0..1]

   TCP or UDP port number.

   Address : Binary [0..1]

   IPv4 (32 bit) or IPv6 (128 bit) service address

   Priority : Integer [0..1]

   Service priority.  Services with lower priority numbers SHOULD be
   attempted before those with higher numbers.

   Weight : Integer [0..1]

   Weight to be used to select between services of equal priority.

   Transport : Label [0..1]

   OBP Transport binding to be used valid values are HTTP, DNS and UDP.

Hallam-Baker            Expires December 29, 2012              [Page 11]
Internet-Draft             OmniBroker Protocol                 June 2012

   Expires : DateTime [0..1]

   Date and time at which the specified connection context will expire.

3.2.7.  Bind

   Binding a device is a two step protocol that begins with the Start
   Query followed by a sequence of Ticket queries.

3.2.8.  Message: BindRequest

   The following parameters MAY occur in either a StartRequest or
   TicketRequest:

   Encryption : Label [0..Many]

   Encryption Algorithm that the client accepts.  A Client MAY offer
   multiple algorithms.  If no algorithms are specified then support for
   the mandatory to implement algorithm is assumed.  Otherwise mandatory
   to implement algorithms MUST be specified explicitly.

   Authentication : Label [0..Many]

   Authentication Algorithm that the client accepts.  If no algorithms
   are specified then support for the mandatory to implement algorithm
   is assumed.  Otherwise mandatory to implement algorithms MUST be
   specified explicitly.

3.2.9.  Message: BindResponse

   The following parameters MAY occur in either a StartResponse or
   TicketResponse:

   Cryptographic : Cryptographic [0..Many]

   Cryptographic Parameters.

   Service : Connection [0..Many]

   A Connection describing an OBP service point

3.2.10.  Message: OpenRequest

   The OpenRequest Message is used to begin a device binding
   transaction.  Depending on the authentication requirements of the
   service the transaction may be completed in a single query or require
   a further Ticket Query to complete.

Hallam-Baker            Expires December 29, 2012              [Page 12]
Internet-Draft             OmniBroker Protocol                 June 2012

   If authentication is required, the mechanism to be used depends on
   the capabilities of the device, the requirements of the broker and
   the existing relationship between the user and the broker.

   If the device supports some means of data entry, authentication MAY
   be achieved by entering a passcode previously delivered out of band
   into the device.

   The OpenRequest specifies the properties of the service (Account,
   Domain) and Device (ID, URI, Name) that will remain constant
   throughout the period that the device binding is active and
   parameters to be used for the mutual authentication protocol.

   Account : String [0..1]

   Account name of the user at the OBP service

   Domain : Name [0..1]

   Domain name of the OBP broker service

   HavePasscode : Boolean [0..1] Default =False

   If 'true', the user has entered a passcode value for use with
   passcode authentication.

   HaveDisplay : Boolean [0..1] Default =False

   Specifies if the device is capable of displaying information to the
   user or not.

   Challenge : Binary [0..1]

   Client challenge value to be used in authentication challenge

   DeviceID : URI [0..1]

   DeviceURI : URI [0..1]

   DeviceName : String [0..1]

3.2.11.  Message: OpenResponse

   An Open request MAY be accepted immediately or be held pending
   completion of an inband or out-of-band authentication process.

   The OpenResponse returns a ticket and a set of cryptographic
   connection parameters in either case.  If the

Hallam-Baker            Expires December 29, 2012              [Page 13]
Internet-Draft             OmniBroker Protocol                 June 2012

   Challenge : Binary [0..1]

   Challenge value to be used by the client to respond to the server
   authentication challenge.

   ChallengeResponse : Binary [0..1]

   Server response to authentication challenge by the client

   VerificationImage : ImageLink [0..Many]

   Link to an image to be used in an image verification mechanism.

3.2.12.  Message: TicketRequest

   The TicketRequest message is used to (1) complete a binding request
   begun with an OpenRequest and (2) to refresh ticket or connection
   parameters as necessary.

   ChallengeResponse : Binary [0..1]

   The response to a server authentication challenge.

3.2.13.  Message: TicketResponse

   The TicketResponse message returns cryptographic and/or connection
   context information to a client.

3.2.14.  Unbind

   Requests that a previous device association be deleted.

3.2.15.  Message: UnbindRequest

   Since the ticket identifies the binding to be deleted, the only thing
   that the unbind message need specify is that the device wishes to
   cancel the binding.

3.2.16.  Message: UnbindResponse

   Reports on the success of the unbinding operation.

   If the server reports success, the client SHOULD delete the ticket
   and all information relating to the binding.

   A service MAY continue to accept a ticket after an unbind request has
   been granted but MUST NOT accept such a ticket for a bind request.

Hallam-Baker            Expires December 29, 2012              [Page 14]
Internet-Draft             OmniBroker Protocol                 June 2012

4.  Omnibroker Connection Query Service

4.1.  OBPQuery

4.1.1.  Top

4.1.2.  Structure: Identifier

   Specifies an Internet service by means of a DNS address and either a
   DNS service prefix, an IP port number or both.  An Internet peer
   connection MAY be specified by additionally specifying an account.

   Name : Name [1..1]

   The DNS name of the service to connect to.

   Internationalized DNS names MUST be encoded in punycode encoding.

   Account : Label [0..1]

   Identifies the account to connect to in the case that a peer
   connection is to be established.

   Service : Name [0..1]

   The DNS service prefix defined for use with DNS records that take a
   service prefix including SRV.

   Port : Integer [0..1]

   IP Port number.

   A service identifier MUST specify either a service or a port or both.

4.1.3.  Structure: Connection

   IPVersion : Integer [0..1]

   Contains the IP version field.  If absent, IPv4 is assumed.

   IPProtocol : Integer [0..1]

   Contains the IP protocol field.  If absent, TCP is assumed.

   IPAddress : Binary [0..1]

   IP address in network byte order.  This will normally be an IPv4 (32
   bit) or IPv6 (128 bit) address.

Hallam-Baker            Expires December 29, 2012              [Page 15]
Internet-Draft             OmniBroker Protocol                 June 2012

   IPPort : Integer [0..1]

   IP port. 1-65535

   TransportPolicy : String [0..1]

   Transport security policy as specified in [TBS]

   ProtocolPolicy : String [0..1]

   Application security policy specification as specified by the
   application protocol.

   Advice : Advice [0..1]

   Additional information that a service MAY return to support a service
   connection identification.

4.1.4.  Structure: Advice

   Additional information that a service MAY return to support a service
   connection identification.  For example, DNSSEC signatures chains,
   SAML assertions, DANE records, Certificate Transparency proof chains,
   etc.

   Type : Label [0..1]

   The IANA MIME type of the content type

   Data : Binary [0..1]

   The advice data.

4.1.5.  Structure: Service

   Describes a service connection

   Identifier : Identifier [0..Many]

   Internet addresses to which the service is to be bound.

   Connection : Connection [0..1]

   Service connection parameters.

Hallam-Baker            Expires December 29, 2012              [Page 16]
Internet-Draft             OmniBroker Protocol                 June 2012

4.1.6.  Message: Request

   Every query request contains the following common elements:

   Index : Integer [0..1]

   Index used to request a specific response when multiple responses are
   available.

   Ticket : Binary [0..1]

   OBP ticket previously returned by the broker protocol that identifies
   the cryptographic parameters used to authenticate and encrypt the
   request and response data.

   MAC : Binary [0..1]

   Authentication value formed over the canonical form of the OBP
   request (JSON syntax).

4.1.7.  Message: Response

   Every Query Response contains the following common elements:

   Status : Integer [1..1]

   Status return code value

   Index : Integer [0..1]

   Index of the current response.

   Count : Integer [0..1]

   Number of responses available.

   MAC : Binary [0..1]

   Authentication value formed over the canonical form of the OBP
   request (JSON syntax).

4.1.8.  QueryConnect

   Requests a connection context to connect to a specified Internet
   service or peer.

Hallam-Baker            Expires December 29, 2012              [Page 17]
Internet-Draft             OmniBroker Protocol                 June 2012

4.1.9.  Message: QueryConnectRequest

   Specifies the Internet service or peer that a connection is to be
   established to and the acceptable security policies.

   Identifier : Identifier [0..1]

   Identifies the service or peer to which a connection is requested.

   Policy : Label [0..Many]

   Acceptable credential validation policy.

   ProveIt : Boolean [0..1]

   If set the broker SHOULD send advice to permit the client to validate
   the proposed connection context.

4.1.10.  Message: QueryConnectResponse

   Returns one or more connection contexts in response to a
   QueryConnectRequest Message.

   Connection : Connection [0..Many]

   An ordered list of connection contexts with the preferred connection
   context listed first.

   Advice : Advice [0..1]

   Proof information to support the proposed connection context.

   Policy : Label [0..Many]

   Policy under which the credentials have been verified.

4.1.11.  Advertise

   Advises a broker that one or more Internet services are being offered
   with particular attributes.

4.1.12.  Message: AdvertiseRequest

   Specifies the connection(s) to be established.

   The attributes required depend on the infrastructure(s) that the
   broker is capable of registering the service with.

Hallam-Baker            Expires December 29, 2012              [Page 18]
Internet-Draft             OmniBroker Protocol                 June 2012

   Service : Service [0..Many]

   Describes a connection to be established.

4.1.13.  Message: AdvertiseResponse

   Specifies the connection(s)

   Service : Service [0..Many]

   Describes a connection that was established.

4.1.14.  Validate

   The Validate query requests validation of credentials presented to
   establish a connection.  For example credentials presented by a
   server in the process of setting up a TLS session.

4.1.15.  Message: ValidateRequest

   Specifies the credentials to be validated and the purpose for which
   they are to be used.

   Service : Service [0..1]

   Describes the service for which the credentials are presented for
   access.

   Credential : Credential [0..1]

   List of credentials for which validation is requested.

   Policy : Label [0..Many]

   Policy under which the credentials have been verified.

4.1.16.  Message: ValidateResponse

   Reports the status of the credential presented.

   Policy : Label [0..Many]

   Policy under which the credentials have been verified.

4.1.17.  QueryCredentialPassword

   The QueryCredentialPassword query is used to request a password
   credential that the user has previously chosen to store at the

Hallam-Baker            Expires December 29, 2012              [Page 19]
Internet-Draft             OmniBroker Protocol                 June 2012

   broker.

4.1.18.  Message: CredentialPasswordRequest

   Requests a password for the specified account.

   Account : String [0..1]

   The account for which a password is requested.

4.1.19.  Message: CredentialPasswordResponse

   Returns a password for the specified account.

   Password : String [0..1]

   The requested password.

5.  Transport Bindings

   To achieve an optimal balance of efficiency and availability, OBP
   supports three transport bindings:

      Supports all forms of OBP transaction in all network environments.

      Provides efficient support for a subset of OBP query transactions
      that is accessible in most network environments.

      Provides efficient support for all OBP query transactions and is
      accessible in most network environments.

   Support for the HTTP over TLS binding is REQUIRED.

   An OBP broker SHOULD offer multiple connections

5.1.  HTTP over TLS

   OBP requests and responses are mapped to HTTP POST requests and
   responses respectively.  Java Script Object Notation (JSON) encoding
   is used to encode requests and responses.

5.1.1.  Message Encapsulation

   Requests and responses are mapped to HTTP POST transactions.  'The
   Content-Type MUST be specified as application/json.  The Character
   set MUST be specified as UTF-8.

Hallam-Baker            Expires December 29, 2012              [Page 20]
Internet-Draft             OmniBroker Protocol                 June 2012

   Request and response messages are encoded using JSON notation [TBS]
   to produce a payload.  The payload is in turn encoded using JSON
   Signature and Encryption encoding [TBS]:

   [The Security Object being defined contains three slots: headers,
   payload and signatures.  Since this is not specified in the JSON
   signatures spec it will be added as a separate section here in the
   next itteration.]

5.1.2.  Request

   Requests are mapped to HTTP POST Requests.  The URL value is ignored.

   Note that even though the specification permits the OpenRequest
   message to be presented without authentication, the message MUST be
   presented as a security object payload even if both the headers and
   Signatures elements are empty.  An OpenRequest message MUST NOT be
   presented directly without an enclosing security object.

5.1.3.  Response

   Requests are mapped to HTTP Responses.  The Content-Type MUST be
   specified as application/json.  The Character set MUST be specified
   as UTF-8.

   Since the response content is not cacheable, the response SHOULD
   specify Pragma: no-cache.

5.1.4.  Example

   [To be generated from spec]

5.2.  DNS Tunnel

   The DNS Tunnel mode of operation makes use of DNS TXT resource record
   requests and responses to tunnel OBP requests.  Due to the
   constraints of this particular mode of operation, use of this
   transport is in practice limited to supporting transactions that can
   be expressed within 500 bytes.  These include the QueryConnect and
   ValidateRequest interactions.

5.2.1.  Request

   Requests are mapped to DNS TXT queries.  The request is mapped onto
   the DNS name portion of the query by concatenating the following data
   items:

Hallam-Baker            Expires December 29, 2012              [Page 21]
Internet-Draft             OmniBroker Protocol                 June 2012

      A single DNS label containing the BASE32 encoding of the Message
      Authentication Code of the Payload data

      One or more DNS labels containing the JSON request message in
      BASE32 encoding.  If more than one label is specified, the labels
      are concatenated before base32 decoding takes place.
      Concatentation observes the normal DNS convention that the least
      significant data is presented first but without added periods

      A single DNS label containing the BASE32 encoding of the ticket.

      The DNS name of the service to which the request is directed.

5.2.2.  Response

   Requests are mapped to DNS TXT records.  The TXT record contains a
   JSON encoded response as defined in the HTTP transport binding.

5.2.3.  Example

   [To be generated from spec]

5.3.  UDP

   The UDP transport MAY be used for transactions where the request fits
   into a single UDP packet and the response can be accomadated in 16
   UDP packets.  As with the Web Service Binding, Java Script Object
   Notation (JSON) encoding is used to encode requests and responses.

5.3.1.  Request

   TBS

5.3.2.  Response

   TBS

5.3.3.  Example

   [To be generated from spec]

6.  Acknowledgements

   [List of contributors]

Hallam-Baker            Expires December 29, 2012              [Page 22]
Internet-Draft             OmniBroker Protocol                 June 2012

7.  Security Considerations

7.1.  Denial of Service

7.2.  Breach of Trust

7.3.  Coercion

8.  To do

      The specification should define and use a JSON security object.

      Formatting of the abstract data items needs to be improved

      Need to specify the UDP transport binding

      Should specify how each data item is represented in JSON format
      somewhere.  This is obvious for some of the data types but needs
      to be fully specified for things like DateTime.

      Run the code to produce proper examples.

      Write a tool to transclude the example and other xml data into the
      document source.

      Fully document the API section.

9.  For discussion.

      Should the specification use the form urlencoded convention like
      OAUTH does?

      How should responses be cryptographically linked to requests?

10.  IANA Considerations

   [TBS list out all the code points that require an IANA registration]

11.  Normative References

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.

Hallam-Baker            Expires December 29, 2012              [Page 23]
Internet-Draft             OmniBroker Protocol                 June 2012

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

   [RFC4366]  Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
              and T. Wright, "Transport Layer Security (TLS)
              Extensions", RFC 4366, April 2006.

   [X.509]    International Telecommunication Union, "ITU-T
              Recommendation X.509 (11/2008): Information technology -
              Open systems interconnection - The Directory: Public-key
              and attribute certificate frameworks", ITU-T
              Recommendation X.509, November 2008.

   [X.680]    International Telecommunication Union, "ITU-T
              Recommendation X.680 (11/2008): Information technology -
              Abstract Syntax Notation One (ASN.1): Specification of
              basic notation", ITU-T Recommendation X.680,
              November 2008.

Appendix A.  Example Data.

A.1.  Ticket A

A.2.  Ticket B

Author's Address

   Phillip Hallam-Baker
   Comodo Group Inc.

   Email: philliph@comodo.com

Hallam-Baker            Expires December 29, 2012              [Page 24]