I implemented an optimized ECDSA verify for the secp256k1 curve used by Bitcoin, based on pages 125-129 of the Guide to Elliptic Curve Cryptography, by Hankerson, Menezes and Vanstone. I own the book but I also found a PDF on a Russian site which is more convenient.
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I am celebrating this post because today the patent covering this idea has finally expired, and this is going to be activated in the next bitcoin core release.
Thank you to all the great minds who contributed to this.
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