Hitoshi Kokumai

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Cryptography and Expanded Password System

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Prof. Hideki Imai, who pushed my back to move ahead confidently in 2001 when he was the chair of Japan’s CRYPTREC, used to emphasize repeatedly how critical it is to get the credential data hashed whether online or offline. It is from him that I learnt about Deffie-Hellman Key Exchange, Elliptic Curve Cryptography, etc.

We jointly tried the methodology of using the high-entropy credential data generated by

Expanded Password System  (EPS) as the seed of RSA key pair; the user's private key does not physically exist anywhere in the universe, but it can be re-generated in-the-fly out of the images that the user picks up for authentication for each login. It proved to work on the internet.

Thereafter, we took up the experiment of incorporating EPS into PAKE. We were able to demonstrate that it worked with no friction in the lab environment.

These projects, sponsored by government agencies, were completed in 2003 – 2004. In retrospect, we seem to have started these forward-looking projects a bit too early.

Cryptography helps EPS, and EPS helps Cryptography.

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Easy 10 manage reletons between accounts and corresponding passwords.<br />
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Torturous login is hstory. Login is now comfortable, relaxing and heaing<br />
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Seemingly Fatal Drawbacks of Pictorial Password – Shoulder Surfing & Low Entropy

We have been advocating Expanded Password System that accepts images as well as texts from 2001. We have since kept hearing our proposition blamed for two major ‘drawbacks’ of using images – Shoulder Surfing and Low Entropy. So many people are still misguided to take it for granted as if it were the case.

 The fact is that threats of shoulder surfing can be mitigated with ease by some simple techniques - images to get shrunk prior to tapping, texts allocated to images for quiet typing and so on at the end of developers, with the simplest solution being just looking around you before tapping the images at the end of users. How can it be a fatal drawback?

 Another seemingly serious problem of low entropy can be eliminated at the end of developers without giving any extra burden on users.

 With Expanded Password System, each image or character is presented by the image identifier data which can be of any length. Assume that your password is “CBA123” and that the image ‘C’ is identified as X4s& eI0w, and so on.

 When you input CBA123, the authentication data that the server receives is not the easy-to-break“CBA123”, but something like “X4s&eI0wdoex7RVb%9Ub3mJvk…………..” which could be automatically altered periodically or at each access where desired, all without involving users.

 Passwords of sufficient entropy, if properly hashed, can stand fierce brute force attacks. How can it be a fatal drawback?


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Hitoshi Kokumai

Hitoshi Kokumai

11ヶ月前 #4

Thanks Debesh. I hope that people's perception will be very different when they come to know that our products are used by the Japan's Army where the number of users has increased 10-fold over the 7-year period since 2013.

Hitoshi Kokumai

Hitoshi Kokumai

11ヶ月前 #3

#1
Thanks Zacharias. I am sorry to be very late in coming back to you. I had missed your comment. I would like to believe that cybersecurity people will come to comprehend the meaning of our proposition when they have come out of the pitfall of wrongly perceived security effects of password-less authentication and password-killer biometrics. As for the subject of cryptographic keys, you might be interested in my recent article "Account Recovery by Expanded Password System".https://www.bebee.com/producer/@hitoshi-kokumai/account-recovery-with-expanded-password-system

Debesh Choudhury

Debesh Choudhury

11ヶ月前 #2

The possibilities of graphical passwords are yet to be fully explored. Once your application is tested and adopted by some common people, maybe then the experts will break their heads into it.

Zacharias 🐝 Voulgaris

Let's think outside the box a little. I believe the EPS you propose has benefits that the conventional CS people fail to fathom due to their innate attachment to a framework that's starting to become obsolete, even if they haven't realized it yet. There are serious issues in that framework that EPS can solve or at least contribute to their solution. For example, the need to use new keys all the time and the lack of reliable solutions regarding the storage of larger keys which can be leveraged for symmetric encryption solutions (e.g. for in-house CS applications). Also, most CS professionals are completely ignorant of the business aspects of their systems something that's a liability in and of itself. I propose a novel CS solution that tackles these issues head-on and leverages the advantages of EPS. Feel free to message me to discuss this further (preferably through email). Cheers!

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