TL;DR: Late into the evening on 18 May 2019, independent developer Mark B. Lundeberg, Chris Pacia of alternative Bitcoin Cash (BCH) full node, bchd, and an independent miner known as checksum0 collaborated to create the first ever successful Schnorr multisignature (multisig) transaction on the BCH network, donating to Free Ross, a group dedicated to achieving justice for Ross Ulbricht.

First Bitcoin Cash Schnorr Multisig Transaction

The decoded OP_RETURN read, “BCH is about giving people the freedom to make their own choices, to pursue their own happiness, however they individually see fit.” Indeed, multisig is pretty much as it implies: multiple signatures (keys) are needed to move funds. It’s an especially important way for cryptocurrency exchanges, for example, to have yet another layer of security (the Electron Cash wallet, at the user level, also has it as a feature). Perhaps the easiest example of multisig involves a common husband and wife savings account. Under one iteration of the idea, no money can be moved from their account unless both agree (and variations on that theme).

Schnorr Signatures, however, came to BCH after its 15 May 2019 network upgrade, where Lundeberg was a lead in advancing their inclusion, another first for the Bitcoin community. He was careful to describe the improvement as “basic” and at their very beginning stages, but nevertheless Schnorr garnered headlines as evidence Bitcoin Cash development is proceeding at a nice pace.

Upon completing the transaction, the three asked CoinSpice publish their private keys as proof:

3c33570f986612912464cc61259ceeeba18c2c494e9de505a78c4222277d1b56

a145c109b44521329421227a7d29b4bcbb4e75a37743435d2978c02cbb45842f

8426999585720f236608b8a7112759f93269acf1124b0f82edbfa862cc8a6d0d

checksum0 announced on Twitter mere minutes after, “@MarkLundeberg @ChrisPacia and I made the first Schnorr multisignature in history. The transaction is a donation to @Free_Ross. Proof will be published shortly.” Lundeberg would later tease how “you can’t prove that, maybe my first Schnorr tx was me and 100 other people,” underlining the point of greater transaction privacy through what all three participants describe as a “very very very beta multisig tool” Lundeberg released on GitHub.

Efficiency, Privacy Improvement

Lundeberg and checksum0 also published transcripts of the historic transaction on GitHub Gist, here and here, respectively. They stressed theirs was an experiment, warning what they’ve accomplished is a demonstration and isn’t necessarily secure just yet. “Beware, funds can be easily lost!” Lundeberg cautioned.

checksum0 explained to CoinSpice, “Schnorr signatures are an efficiency improvement to BCH, but they’re also a privacy improvement. Outside observers cannot know what this transaction is, for example. It could have been a regular transaction, a multisignature involving 100 persons, or a variety of other use cases yet to be developed. The outside observer would have no idea,” he pointed out, echoing Lundeberg. Schnorr “also allows things that were previously impossible on Bitcoin, like the aforementioned 100 person multisignature — all of that produces a very very small transaction (smaller than a regular p2pkh transaction, disregarding the OP_RETURN, that is),” checksum0 noted.

The donated amount ($35.97 USD) is not only historic but also symbolic, as protecting relative anonymity and cash-like properties of peer-to-peer transactions often brings to mind the plight of Ross Ulbricht. He was accused and later convicted of being mastermind behind Silk Road, a site that demonstrated early evidence bitcoin could be used as digital cash in the real world. Ulbricht would become an example of governments’ hostility to the notion of both privacy and using crypto. He’s now serving two life sentences plus 40 years without the possibility of parole for what many legal experts consider a rather tame, low-level crime: bringing together buyers and sellers of goods and services governments frown upon … through a website. For more information, visit FreeRoss.org.

DISCLOSURE: The author holds cryptocurrency as part of his financial portfolio, including BCH.

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