Bitcoin Core Roadmap Unveils Signature Optimization Plan

Bitcoin developers outlined a plan today to replace the network's signature scheme with an alternative.

AccessTimeIconMar 23, 2017 at 8:35 p.m. UTC
Updated Sep 29, 2023 at 11:58 a.m. UTC

Bitcoin Core developers released a new technology roadmap today that charts the project's planned transition from its current digital signature algorithm to a more advanced alternative.

If implemented, the proposal would find 'Schnorr signatures' replacing the ECDSA signatures bitcoin uses today to sign transactions. By making the switch, developers argue they can decrease the total data in bitcoin's blockchain by up to 25%.

For users, this means nodes that store the network's transaction history would see better bandwidth while using less storage to secure the entire blockchain.

The post describes:

"Assuming every historical signature would be reduced to 1 byte, except for one per transaction, analysis suggest[s] the method would result in at least a 25% reduction in terms of storage and bandwidth."

For the project's open-source development team, the introduction of the signature change into the roadmap follows its prominent featuring at Scaling Bitcoin Milan last October.

There, Bitcoin Core developer Pieter Wuille made an impassioned pitch for the change, while appealing to the broader community to help handle identified roadblocks.

To implement Schnorr signatures, bitcoin would require a modification of its OP_CHECKSIG and OP_CHECKMULTISIG functions so that they can stack public keys.

Today, bitcoin's current blockchain size is around 110 GB.

Ifs and buts

Still, the idea is not without potential difficulties.

According to Wuille, Schnorr signatures face a "cancellation" problem, an issue that potentially opens the door for an adversarial participant to subtract a key from the multisig transaction and eliminate one of the parties in the wallet.

Further, according to Bitcoin Core developer Greg Maxwell, integrating Schnorr does not require SegWit activation, though he said the controversial code makes the process easier.

For this reason, the Schnorr feature is unlikely to be implemented until a decision on Segwit activation has been formalized.

"I doubt this would be done without SegWit, though it could be," Maxwell said.

The comments come at a time when progress on bitcoin's scaling issues has effectively stalled, with developers pulling out of a meeting this May that would have sought to unite industry participants.

Calligraphy image via Shutterstock


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