Hi Alok

Just to bring to your attention, there is a security challenge in this approach.
CAPTCHA is essentially used to fight against Bots and to prevent them from 
guess the CAPTCHA.
As I see, you have the words placed in Alt text. It is not a big deal to read 
the alt dext fromDocument object and convert the numbers in words back to 

Check it out.


From: Ai [mailto:ai-boun...@accessindia.inclusivehabitat.in] On Behalf Of Alok 
Kaushik via Ai
Sent: Tuesday, August 8, 2017 8:49 AM
To: ai@accessindia.inclusivehabitat.in
Cc: Alok Kaushik <alok.li...@gmail.com>
Subject: [Ai] For software developers - creating custom accessible CAPTCHA

In one of my recent software development works I created a CAPTCHA that is 
accessible for screen readers using the following approach.

1.       Generate a random 5 digit number.

2.       Generate an image containing the embedded 5 digit number. Image is 
programmatically generated and is  not an image that could be downloaded. 5 
digit number is communicated to the captcha generating code using encryption.

3.       Convert the complete 5 digit number in English words, including the 
words thousand and hundred.

4.       Assign the converted number in words as the alternate text of the 
image dynamically. This would allow the screen readers to read out the number 
in words, while  other users will see regular image.

5.       Track the random number as a session variable for later comparison.

I am writing this for following two reasons.

1.       This approach seems to be working for me. Want to know if anyone sees 
any issue in this either in usability or security.

2.       If anyone doing software development is interested in implementing 
this, I can share the code off the list.



Caution: The Reserve Bank of India never sends mails, SMSs or makes calls 
asking for personal information such as your bank account details, passwords, 
etc. It never keeps or offers funds to anyone. Please do not respond in any 
manner to such offers, however official or attractive they may look.

Notice: This email and any files transmitted with it are confidential and 
intended solely for the use of the individual or entity to whom they are 
addressed. If you are not the intended recipient, any dissemination, use, 
review, distribution, printing or copying of the information contained in this 
e-mail message and/or attachments to it are strictly prohibited. If you have 
received this email by error, please notify us by return e-mail or telephone 
and immediately and permanently delete the message and any attachments. The 
recipient should check this email and any attachments for the presence of 
viruses. The Reserve Bank of India accepts no liability for any damage caused 
by any virus transmitted by this email.
1. Contents of the mails, factual, or otherwise, reflect the thinking of the 
person sending the mail and AI in no way relates itself to its veracity;

2. AI cannot be held liable for any commission/omission based on the mails sent 
through this mailing list..

To check if the post reached the list or to search for old posting, reach:

Ai mailing list

Reply via email to