Updated "Inaccessibility of CAPTCHA" Draft for Wide Review

Today the Accessible Platform Architectures (APA) Working Group, with extensive assistance from its Research Questions Task Force (RQTF), published a second draft update to the W3C Note "Inaccessibility of CAPTCHA". This widely accessed publication from 2005 was first updated in a draft published in July 2018. APA and RQTF greatly appreciate the many comments received on this draft. We believe we have addressed all issues raised in comments. We have also continued our research into aspects of CAPTCHA not addressed in the earlier draft such as the use of honeypots as CAPTCHA alternatives. Also, based on comments received, we have greatly expanded our analysis of Google’s reCAPTCHA service, both V. 2 and V.3 (announced in October 2018).

Web Content Accessibility Guidelines 2.0 and 2.1 refer to the requirement for accessible CAPTCHA in Success Criterion 1.1.1 Non-Text Content. This document is an important complement to that requirement which provides more detail on how to meet these requirements, and relevant considerations in accessible authentication of Web users.

We have endeavored to comprehensively cover the current landscape in technologies that attempt to distinguish human web site users from robots. To be sure the updated document is as complete as possible, we need public input on this version. The following questions will help guide your review:

• Does this document fully capture current problems with CAPTCHA and related systems?
• Are there other CAPTCHA approaches that should be added?
• Are there concerns for certain categories of persons with disabilities that remain unaddressed or insufficiently addressed in this document?
• Are you aware of relevant research or technological development in this area we missed?
• Have we sufficiently addressed CAPTCHA’s problems with I18N?
• Are issues of privacy and security appropriately addressed?
• Have we mis-characterized any technology we discuss?

To comment, file an issue in the W3C apa GitHub repository. If this is not feasible, send email to public-apa@w3.org (comment archive). Comments are requested by 24 March 2019. In-progress updates to the document may be viewed in the publicly visible editors’ draft.

This publication updates the updated Working Draft published in 2018 which in turn revised and updated the W3C Note from 2005. The nature and level of response this draft receives will determine whether the Working Group will publish another working draft of this document or whether it will advance it advance this document back to Note status. The 2005 CAPTCHA Note is still available.