In October 2019, Idena blockchain announced it would pay $25,000 for the first person or team who would be able to solve their AI-hard captchas with an AI.

These AI-hard captchas that are also referred as FLIPS or “Filter for Live Intelligent People” are the centerpiece of their blockchain that has now almost 500 users and a marketcap of over 2 million USD.

Issuing such a price was of course a good way for them to prove the safety of their blockchain.

Example of a “FLIP” Idena participants have to choice which one of both image stories is the most relevant, left or right.

As of today Feb 19, 2020 the challenge rules read as following:

Contestants need to achieve at least 80% accuracy of flip solving in three consecutive validation rounds using publicly available flips created by Idena participants for the validations. Protocol:

— The hash of the AI source code must be published on any public blockchain and emailed at info@idena.io at least three days before the first planned test round.

— The contestant runs three tests on full sets of flips created by Idena participants for the three consecutive validations. The results should be emailed at info@idena.io after each test round.

— After the third successful test round, the contestant provides the Idena team the source code, builds and the sample data required to reproduce the results.

Since I was one of the first persons to express my intention to prove that an AI is capable of solving Idena Flips I contributed in the definition of the protocol and I consider it to be very fair.

For a long time I also disclosed information on how well my AI was performing for every validation session, and this was perhaps a mistake of mine.

As I started to get closer and closer to the 80% mark, the the Idena team decided to take a measure that is pretty much the cancelation of the $25,000 price by making the current challenge protocol obsolete.

Indeed, with version 4.0 of the Idena client that will be released any time soon flips will be encrypted and not publicly available, this means that the challenge protocol becomes obsolete.

The official reason behind it is to prevent an AI from attacking the network:

AI can learn to solve flips by having a huge dataset of flips produced by a big network: 1 million network of people will generate millions of flips per epoch which is enough for machine learning.

The threat is mitigated by flips encryption. Each flip is available only for those participants who solve it during the validation session. There are around 10–15 persons who see it. Honest participants delete keys after the validation preventing flips collection.

Currently only about 10,000 flips were created on the network, that is much less than the millions of flips per epoch Idena claims is required for an AI to solve flips. My belief is that because of my publications they know that much less training datasets are actually required and don’t want to admit it. Neither do they want to pay the $25,000 price of course!

W hat does this mean for the AI resistance claim?

The new approach Idena has taken to prevent AI attacks by using Flip obfuscation is commonly called security through obsucurity and has been dismissed many times.

By Encrypting the Flips they make it harder for an attacker to collect large collections of Flips to feed an AI, but they cannot prevent it from happening.

Generating a significant amount flips is quite doable for an attacker by either using micro worker services such as Amazon Mechanical Turk or some kind of social engineering, by creating a game where people have to create funny flips for example.

Also there is no incentive anymore for an attacker to reveal his AI and get the challenge price, worse, flip encryption will make detecting such an AI in the wild much harder.