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Network Working Group                                         R. Pietrak
Internet-Draft                                          February 4, 2021
Intended status: Standards Track
Expires: August 8, 2021

  Cookie Extention Limitting Its Availability to User Agent Components


   This memo addresses cookies security by introduction of an additional
   constraints, web application designer may impose on cookie
   availability for localhost applications components.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on August 8, 2021.

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   than English.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  CookieRadius attribute  . . . . . . . . . . . . . . . . . . .   4
   4.  Security  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   As of current standard, HTTP state management mechanism RFC 6265
   [refs.RFC6265], provide tools (in the form of cookie attributes) to
   limit the dissemination of any particular cookie.  Those constraints

   o  Cookie domain

   o  Cookie expiration time

   o  HttpOnly attribute

   o  SecureOnly attribute

   But, current standard doesn't provide means to control the scope
   cookies are available to localhost components, like user agent
   software.  These days search engines provide host of evidence that
   programmers continuesly look for such means.  Usually, the question
   is: "How do I limit my session cookie to just a single tab?".

   The questions comes from evident need to move away out off user
   session-ID (acquired after login/pass veryfication) visible in plain
   sight as part of URL referring to the access limitted pages.  Usually
   such modyfications are evaluated under strict requirement, that
   current functionality remains unaltered.  Here the required
   functionality usually boils down to having such session-ID not shared

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   among interface components which waren't involved in credencials
   veryfication.  Meaning, that only the tab that provided credencials
   (login/pass) will be authorised to access those particular resources.
   In other words: since currently every window and every tab may have a
   diffrent URL retrieved, it should also be possible for it to have
   different (from other tabs) session login credencials.

   This is considered a desired (even required) feature.

   As of now, storing such login session credencials within a Cookie
   (which is also whidely used to hold session credencials) alters this
   functionality, and so is not acceptable for those migrations.  The
   functionality is lost, because a cookie set in one tab of web browser
   will be immediately available to all other tabs.

   On the other hand, current functionality of sharing all cookies
   between all application components is desired by other web
   application programmers.  This memo introduces cookie attribute,
   which will maintain current cookie behavior, while allowing for
   currently missing cookie scope limitations to be defined by web
   application programmer.

2.  Terminology

   The following terms will be used in this memo:

   user:  Within a computer system the term "user" means any set of
      components holding the same security credencials.  These
      credencials may originate (or be derived) from a physical person
      giving them out to a login application, or they may originate from
      kernel mainteined vault of credencials designated for system
      components when system (unattended) application actions are due.
      System services like ntp service, or MTA (mail transport agent)
      are examples of the later case.

   application:  Any programatic component of a computer system.

   window:  Any input/output channel, that an application may have an
      access to independently from other such channels.  An example of
      such channel is GUI window, which gets data (like graphics) from
      an application, while all other windows of that same application
      does not get disturbed by that data stream.  Every HTTP
      datastream, from open to close is considered a separate window,
      with the exeption below, where "tabs" are defined.

   window-tab:  Any part of a window, that holds and presents (or
      processes) one HTML document, including all objects that may be
      retrieved separately (separate HTTP connections), but are a part

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      (functional or aestetical) of the main document.  It's valid to
      say, that a tab is whatever is necesary to present (or processe)
      whatever server returns in response for a single user click,
      including all the subcomponents, that HTML defines to be retrieved
      as a result of that click.

   tab:  synonim to window-tab

   viewport:  A single window-tab currently selected (activated/focused/
      visible) to/by the user.

3.  CookieRadius attribute

   CookieRadius attribute can have only one of the following four
   values, and system behavior for each of them is the following:

   World:  Cookie will be available to all user applications.  Every web
      browsers launched by a particular user will see that cookie.

   Windows:  Cookie will be available to all the windows of an
      application that received that cookie.

   Tabs:  Cookie will be available to all the tabs of the same window.
      A window, a tab that received that cookie, belongs to.

   Viewport:  Cookie will not be available to any other system
      component, but the tab, that received it.

   When CookieRadius is not defined by a cookie, it MUST be assumed to
   have a value of "Windows".  When CookieRadius is defined, but it's
   value is unrecognized, applications MUST assume it's value is

   HttpOnly cookie attribute is completely independent and
   implementations WILL NOT correlate values of HttpOnly attribute with
   any value of CookieRadius attribute.

   Cookie "domain" interferes with CookieRadius only when its value is
   "Viewport".  In that case (either explicitly set or assumed as
   default), "domain" is set to domain of URL retrieved irrespectively
   of setting within the cookie.  Consequently availability of such
   cookie is not only limitted to a single viewport, but also to a
   "domain" the tab content originated from.  In other words, "Viewport"
   cookies never traverse domains.

   One notable consequence of the above "domain" restriction is the
   fact, that no other component (like an embeded picture from a
   different "domain") will ever get any information of user getting

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   logged-in to any particular "main-tab-domain".  This is a security

   User agent MAY let users further tighten the scope of a cookie below
   the radius declared in CookieRadius attribute, but it MUST NOT allow
   user to expand the radius.  That is particularly important for
   "HttpOnly=false" cookies.

4.  Security

   The actual impact of the proposed cookie attribute can only be
   truelly evaluated after its wide implementation and use in other then
   here presented scenarios.  The potencial to limit the leackage of
   security data (login credencials) between application components may
   help improve internet security.

5.  References

              Barth, A., "HTTP State Management Mechanism", RFC 6265,
              April 2011.

Author's Address

   Rafal Pietrak

   Email: cookie.rp@ztk-rp.eu

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