Legendre Symbol Breakthrough in ECC

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#21Dec 9, 2019, 04:27 AM
Your 256-step tree for secp256k1 is gonna have so many branches and magic numbers. Good luck with that.
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#22Dec 9, 2019, 07:00 AM
In the toy example, the tree had only about 10-15 nodes, not 67 leaves. The depth was logarithmic, and the branching was binary. The magic numbers are based on the curve properties, not random.
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#23Dec 9, 2019, 11:30 AM
I counted 21 branches, not the 6-7 you claimed. Where’s this logarithmic depth you talk about?
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#24Dec 9, 2019, 03:52 PM
It’s logarithmic when you use a 256-bit lookup. ECDLP can be solved in 256 logical steps. But secp256k1 is generic, and the Legendre symbol won't leak scalar data.
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#25Dec 9, 2019, 08:57 PM
Thanks for the critique! You're right, there are more branches in the toy example than I’d like. But in a group of 67, a decision tree with depth ~5-6 is typically enough.
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Legendre Symbol Breakthrough in ECC | Cryptotalks · Page 2