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Network Working Group                                     A. Hope-Bailie
Internet-Draft                                                    Ripple
Intended status: Standards Track                        October 31, 2017
Expires: May 4, 2018


                             HTTP-Payments
                   draft-hope-bailie-http-payments-00

Abstract

   HTTP-Payments describes a mechanism for passing a standardized
   payment request in the headers of an HTTP 402 response and the
   expected behaviour of HTTP clients that receive such a response.

Feedback

   This specification is an early experiment in bringing the work of the
   W3C Web Payments working group to the HTTP protocol.  It is
   maintained at https://github.com/adrianhopebailie/http-payments [1].

   The work is inspired by work in the Interledger community on
   [HTTP-ILP]

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 https://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 May 4, 2018.

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



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   (https://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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Payment Methods . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  HTTP Status Code 402  . . . . . . . . . . . . . . . . . . . .   3
     4.1.  The "Pay" Header  . . . . . . . . . . . . . . . . . . . .   3
     4.2.  The "Pay-Token" Header  . . . . . . . . . . . . . . . . .   4
     4.3.  The "Pay-Balance" Header  . . . . . . . . . . . . . . . .   4
     4.4.  Flow  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.5.  Example . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   6
     5.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Appendix A.  Security Considerations  . . . . . . . . . . . . . .   6
   Appendix B.  IANA Considerations  . . . . . . . . . . . . . . . .   6
     B.1.  Payment Method Identifier Short-string Registry . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The W3C Web Payments working group has defined a Web Platform API
   that is being widely deployed to browsers for requesting a payment.
   The PaymentRequest API [W3C.CR-payment-request-20170921], defines an
   interface for a website to pass a payment request to the user agent
   via this API.

   The user agent will then, through interaction with the user, complete
   or reject the requested payment.

   HTTP-Payments describes a manner in which an HTTP server can request
   payment from a client in the same manner as a website would from a
   user agent using the W3C APIs.

   The critical portion of the payment request is the set of, one or
   more, supported payment methods and associated payment-method-
   specific data.  HTTP-Payments defines a mechaism by which these are
   expressed in the response headers of an HTTP request for which the
   server requires a payment.



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   In the website and user-agent scenario, when handling the payment
   request, the user-agent will prompt the user to pick one of the
   supported payment methods and will then handle the payment in a
   manner that is appropriate for that payment method.  In an HTTP-
   Payment, the HTTP client will perform this function, likely with no
   user interaction.

2.  Terminology

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

3.  Payment Methods

   A payment method is a way that the payee can be paid.  Examples
   include, via credit card, bank wire transfer, or Bitcoin.

   A payment method is identified by a payment method identifier as
   specified in the Payment Method Identifiers specification [2].  This
   is either a standardized short-string, identified in a registry
   maintained by the W3C Web Payments WG, or a URL.

   The most common case will be for the URL form to be used.  In cases
   where there is no authority responsible for the payment method that
   can host the payment method URL, the WG will consider adding a new
   identifier for the payment method to the registry.

   Payment methods define the data that the payer and payee need to
   exchange, to complete a payment, and the process by which this
   occurs.

4.  HTTP Status Code 402

   The HTTP Status Code, 402 (Payment Required) is currently defined in
   [RFC7231] as "reserved for future use".  Using HTTP-Payment a service
   MAY respond to any request with the 402 response code and use the
   "Pay" header to specify the payment request details.

4.1.  The "Pay" Header

   The body of the "Pay" header is defined as follows:

Pay: <payment-method-identifier> <amount> <address> <payment-method-data>

   Multiple "Pay" headers MAY be present in an HTTP 402 response.

   The fields in the header are:



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   o  payment-method: The payment method identifier for the accepted
      payment method.  Either a standardized short-string or a URL.

   o  amount: The amount that must be paid, expressed as an integer.
      The currency, scale and precision of the destination account are
      expected to be expressed in the account address.

   o  address: A payment-method specific payee address.  For example, if
      the payment method is Bitcoin this would be a Bitcoin address.

   o  payment-method-data: Payment method specific data.  This is either
      a URI identifying the data or, if it is small enough, is the data
      itself, BASE64URL encoded as described in [RFC4648], Section 5.

4.2.  The "Pay-Token" Header

   An HTTP client that makes a paid-HTTP request, after paying for the
   request to be processed, MAY attach a "Pay-Token" header with a token
   referencing the payment.

   This mechanism can be employed by services wishing to accept payments
   without binding these to an HTTP session.

4.3.  The "Pay-Balance" Header

   Ann HTTP Service that accepts payments may respond to any request
   with a "Pay-Balance" header.  This contains an integer indicating the
   current balance of paid credit the client has with the HTTP service.

4.4.  Flow

   Upon receipt of a 402 response, an HTTP client MUST look for any
   "Pay" headers and parse these.  The client can discard all headers
   for which it is not equipped to make a payment (i.e. filter on
   payment-method-identifier)

   The client MUST then select the header that is preferred for
   processing based upon external interactions (such as with a human
   user) or pre-configured rules.  The client MUST attempt to make a
   payment using the payment method identified in the header, for the
   amount specified, and to the destination address specified.

   The payment-method specific data SHOULD be sufficient for the system
   processing the payment to reconcile the payment with the original
   HTTP request.






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   The client SHOULD receive a token in return for completeing the
   payment.  If the payment method used does return a token to the
   payer, it MUST pass this token in subsequent HTTP requests.

   The token MUST be passed in the "Pay-Token" header, BASE64URL encoded
   as described in [RFC4648], Section 5.

   The HTTP service MUST process the "Pay-Token" header and use this to
   reconcile this HTTP request with the payment received prior.

4.5.  Example

   Client requests access to a paid resource:

   POST /upload HTTP/1.1
   Host: myservice.example

   Server responds with payment request (and optionally indicates that
   the client has a zero balance):

HTTP/1.1 402 Payment Required
Pay: http://interledger.org 10 us.nexus.ankita.~recv.filepay SkTcFTZCBKgP6A6QOUVcwWCCgYIP4rJPHlIzreavHdU
Pay-Balance: 0

   Client makes the payment through an appropriate payment side-channel
   and then attempts the request again:

   POST /upload HTTP/1.1
   Host: myservice.example
   Pay-Token: 7y0SfeN7lCuq0GFF5UsMYZofIjJ7LrvPvsePVWSv450

   Server responds:

   HTTP/1.1 200 Success
   Pay-Balance: 0

5.  References

5.1.  Normative References

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <https://www.rfc-editor.org/info/rfc4648>.

   [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
              DOI 10.17487/RFC7231, June 2014,
              <https://www.rfc-editor.org/info/rfc7231>.



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   [W3C.CR-payment-method-id-20170914]
              Bateman, A., Koch, Z., McElmurry, R., and M. Caceres,
              "Payment Method Identifiers", World Wide Web Consortium
              CR CR-payment-method-id-20170914, September 2017,
              <https://www.w3.org/TR/2017/
              CR-payment-method-id-20170914>.

   [W3C.CR-payment-request-20170921]
              Bateman, A., Koch, Z., McElmurry, R., Denicola, D., and M.
              Caceres, "Payment Request API", World Wide Web Consortium
              CR CR-payment-request-20170921, September 2017,
              <https://www.w3.org/TR/2017/CR-payment-request-20170921>.

5.2.  Informative References

   [HTTP-ILP]
              Interledger Community Group, "HTTP-ILP", October 2017,
              <https://github.com/interledger/rfcs/
              blob/58d8dcb015b160a381313126fa3065c64406db05/0014-http-
              ilp/0014-http-ilp.md>.

5.3.  URIs

   [1] https://github.com/adrianhopebailie/http-payments

   [2] W3C.CR-payment-method-id-20170914

Appendix A.  Security Considerations

   TBD

Appendix B.  IANA Considerations

B.1.  Payment Method Identifier Short-string Registry

   The W3C maintains a registry of standardized short-string payment
   method identifiers as part of the [Payment Method Identifier]
   specification.  If standardized short-string identifiers are to be
   used for HTTP-Payments this may be better served as an IANA registry.

Author's Address










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   Adrian Hope-Bailie
   Ripple
   315 Montgomery Street
   San Francisco, CA  94104
   US

   Phone: -----------------
   Email: adrian@ripple.com
   URI:   https://www.ripple.com










































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