Today, a patent involving the acceleration of cryptographic operations on elliptic curves has expired. Invented by Gallant, Lambert, and Vanstone, this technique is commonly referred to as GLV Endomorphism and can now be activated in Bitcoin Core in order to improve the speed and efficiency of Bitcoin’s signature verification.

Hal Finney, GLV Endomorphism, and Patents

The use of GLV Endomorphism was first explored by Hal Finney, one of Bitcoin’s earliest contributors and the first person to receive a Bitcoin transaction from Satoshi Nakamoto.

In his post on February 8th, 2011, Finney shared that he had been inspired to experiment with this technique after reading the Guide to Elliptic Curve Cryptography, by Hankerson, Menezes and Vanstone - the same Vanstone who submitted the patent. His initial tests were promising, revealing an estimated 25% increase in the optimization of signature verification.

Since then, the feature has been implemented in Bitcoin Core but has yet to be enabled due to the existing patent around the cryptography that was filed on December 23rd, 1999. 

“Implementing it was one of the original motivations in developing the libsecp256k1 library, which has since replaced all cryptographic use of OpenSSL in Bitcoin Core,” shared Andrew Poelstra of Blockstream with the BTC Times. “(But) it was disabled by default to avoid patent concerns and has never been enabled in Bitcoin Core.”

With the patent expiring, Bitcoin developers will now move quickly to enable GLV Endomorphism: the feature had actually been rigorously tested throughout the development of the libsecp256k1 library, making the optimization just as well-tested and mature as any other part of the library.

Once activated, nodes should expect to see a significant drop in ongoing resource usage as Bitcoin Core will now utilize the new signature verification method for freshly received transactions and blocks.

“Once you've caught up to the tip, nodes need to verify every new transaction and block that comes in. All of that will see a direct reduction in CPU usage,” Pieter Wuille of Chaincode Labs told the BTC Times. 

Dr. Adam Back of Blockstream commented, “this performance improvement was first drawn attention to for use in Bitcoin by Hal Finney. Even though he’s no longer with us, his contributions can still be felt.”

The use of GLV Endomorphism is expected to be activated in Bitcoin Core with the next Core release.

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