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As part of a learning more about deep learning, I have been experimenting with writing ResNets with Dense layers to do different types of regression.

I was interested in trying a harder problem and have been working on a network that, given a private key, could perform point multiplication along ECC curve to obtain a public key.

I have tried training on a dataset of generated keypairs, but am seeing the test loss values bounce around like crazy with train loss values eventually decreasing after many epochs due to what I assume is overfitting.

Is this public key generation problem even solvable with a deep learning architecture? If so, am I doing something wrong with my current approach?

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  • $\begingroup$ Can you explain further what you mean by ResNets with Dense layers? What are the hidden sizes, # of layers, activation function, etc? $\endgroup$ Dec 21 '20 at 21:36
  • $\begingroup$ Also, to clarify, the network was able to predict the training instances correctly right? Only the test instances have poor accuracy? What is the training accuracy? $\endgroup$ Dec 21 '20 at 22:03
  • $\begingroup$ @user3667125 28 blocks of layers. Layers are 32 wide, and there is a skip connection every 2 layers. ReLU activation function. I am dealing with 256 byte input and 264 byte output, so I just pass these in as byte arrays. $\endgroup$
    – superuser
    Dec 24 '20 at 0:43
  • $\begingroup$ @user3667125 The problem is that currently the model just gives a value near 128 for every byte, since loss function is MSE. $\endgroup$
    – superuser
    Dec 24 '20 at 0:44
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    $\begingroup$ @user3667125 Ok, thanks for the ideas. I actually was thinking the same things haha. I 've been working on a simpler point addition network and was also playing around with modulus operations and actually just writing a simple network to compute x raised to a constant and mod some other constant. Will keep you updated! If you want to post an answer I'll give you the bounty. $\endgroup$
    – superuser
    Dec 25 '20 at 19:20
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I don't know of any neural network that can do cryptography well, so you would have to do a little experimenting yourself. The main thing that sticks out to me is that doing operations in the elliptical curve requires the modulus operator since it works in finite field, and I think neural networks have a hard time learning the modulus operator in general. So I would focus on that first. Some things to help the network learn the modulus operator:

  • I would try to increase the hidden layers to a number 4x-10x bigger than the input dimension, which maps it to a higher dimension to hopefully learn more complex behavior.
  • I would use less layers, maybe only 2-4 hidden layers, to speed up the development time.
  • Most importantly, I would train with a LOT of data points (25% of the total possible finite field possibilities). I don't think the neural network can learn unless the number of data is this high.
  • For reference, someone got a network to learn the modulus operator using these points.

For rapid iterating, I would test with a much smaller finite field. E.g. use a 8 bit security and see if the neural network can do well with that first before moving on to the full 256-bit security key (or whatever your end goal is).

Taking this a step further, I would first test to see if the neural network can even perform a point addition in the elliptical curve well, because if it doesn't then it definitely can't do point multiplication which is needed to compute the public key.

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