CAPTCHA like mechanisms : Impact on confidentiality of Info Humans have  sensory and cognitive skills for solving simple problems that prove to be extremely hard for computer software. Such skills include, but are not limited to processing of sensory information.

One example of the above is randomised distortion of a text image so that it is easily recognisable by humans through their advantage in identification of objects and letters within a noisy graphical environment. This poses a sort of one way function ; where solution by a human is almost instantaneous but that by a computer takes a  lot of effort.

The preceding of course describes a CAPTCHA.

The questions are:


What kind of 'confidentiality' are we looking with such mechanisms? Simply put we have a text which is confidential to a machine. There is no key exchange involved. 
Are their any tangible gains in using such a method and then enciphering the text through a deterministic crypto function (RSA, DES, etc.)
Any references in this regards?
What kind of 'confidentiality' are we looking with such mechanisms? Simply put we have a text which is confidential to a machine. There is no key exchange involved. 


I'd put this down as a kind of obfuscation for machines. That is, unless you take all the knowledge of the world as key.


  Are their any tangible gains in using such a method and then enciphering the text through a deterministic crypto function (RSA, DES, etc.)


No, because you first would have to establish trust for a public key or share an (authenticated) secret. Besides that, it is unclear what this would defend against.

Using TLS could be beneficial, although not strictly necessary. The attack vectors probably do not include man in the middle or even eavesdropping. Basically it's just a challenge response protocol. I could see how eavesdropping lots of challenges/responses could make it possible to build up a table though.


  Any references in this regards?


Nope, sorry.