[realaravinth]

Author of mCaptcha here o/

mCaptcha uses PoW and that is energy inefficient, but it not as bad as the PoWs used in blockchains. The PoW difficulty factor in mCaptcha is significantly lower than blockchains, where several miners will have to pool their resources to solve a single challenge. In mCaptcha, it takes anywhere between 200ms to 5s to solve a challenge. Which is probably comparable to the energy used to train AI models used in reCAPTCHA.

The protection mechanisms used to guard access to the internet must be privacy-respecting and idempotent. mCaptcha isn't perfect, and I'm constantly on the lookout for finding better and cleaner ways to solve this problem.

[Tmpod]

> Which is probably comparable to the energy used to train AI models used in reCAPTCHA.

I had not considered that. Naturally, we're just speculating here, but yeah that does sound plausible.

I was also no aware of the "hard" 5s bound (which you seem to have tested on a normal smartphone setup); sounds neat.

[bluish29]

> Which is probably comparable to the energy used to train AI models used in reCAPTCHA

Are you comparing the energy it takes to train a model which is bounded and defined with unbounded inference which can (in principle) go multiple order of magnitude depending on the usage? Or maybe I misunderstood what you are trying to say? then I apologize in advance.

[realaravinth]

I am, but what I said was more of a hypothesis than a fact :)

From what I understand of reCAPTCHA, the model isn't static and is continuously learning from every interaction[0]:

> reCAPTCHA’s risk-based bot algorithms apply continuous machine learning that factors in every customer and bot interaction to overcome the binary heuristic logic of traditional challenge-based bot detection technologies.

I don't know the energy demands of such a system.

mCaptcha, under attack situations, will at most take 5s of CPU time on a busy (regular multitasking with multiple background process) smartphone.

[0]: https://www.google.com/recaptcha/about/