Brink, the new profit founded by John Newbery and Mike Schmidt to train and support Bitcoin developers, today announced Gloria Zhao as its first fellow. After graduating from Berkeley with a degree in computer science this month, Zhao will familiarize himself with contributing to Bitcoin Core and related open source projects under the mentorship of Newbery. Her year-long fellowship is funded by donations from Square Crypto and the Human Rights Institute.
“I want to be a serious and long-term Bitcoin Core developer, which I don’t imagine is a very unusual interest or anything, but there are a ton of technical and psychological barriers to overcome,” said Zhao Bitcoin Magazine. “Having a supportive community has been hugely important in my personal journey and, overall, John showed a strong interest and ability to nurture new contributors into long term contributors. My main reason for joining the Brink fellowship instead of grants is the mentorship it offers. “
Zhao will focus specifically on a package exchange, a planned upgrade to Bitcoin’s handling of unconfirmed transactions that could improve Bitcoin’s user experience, optimize fee market dynamics, and – perhaps most importantly – make Tier 2 protocols such as the Lightning Network more robust.
Mempool Bitcoin node (memory pool) is the collection of transactions it has received but not yet confirmed in a block. Nodes send transactions from their mempool to peers on the network, and miners select transactions from their mempool to include in a new block.
Swimming pools have a size limit. This limit can be configured for each node (the default for Bitcoin Core nodes is 300 megabytes) but when full, some transactions must be dropped from the mempool before new transactions can be added. Currently, this option is fee-based: transactions with the lowest fees are dropped from fempools in favor of higher-fee transactions.
This may seem like the obvious answer, because miners usually apply the same policy when choosing which transactions they cover in blocks: the transactions that pay them the most fees. And yet, there is a subtle – but important – difference. To maximize their income, miners do not only choose on the basis of fees included in individual transactions, they also choose based on interdependent combined transaction fees.
If, in technical terms, the “parent” transaction sends coins from address A to address B, and the “child” transaction sends the coins from address B to address C, the child can only confirm if is the parent also confirm. Thus, a miner might choose to include a parent in a block even if it involves a very low fee, as long as the child includes a high enough fee to compensate.
Sometimes it becomes useful that miners base their choice on clusters of transactions rather than just individual transactions. If a low-fee transaction that takes a long time to confirm, the recipient can choose to spend the unconfirmed coins for himself in a new transaction with a high fee to confirm both. This trick is called Child Pays For Parent (CPFP).
CPFP can be especially important in scenarios where a transaction needs confirmation before a time lapse expires. The most obvious example is a “transaction of justice” (also known as a “penalty transaction”), which is key to the security of the Lightning Network. These transactions need timely confirmation to prevent a malicious Lightning channel partner from claiming more money than he is entitled to.
Although CPFP can be used to prevent such scenarios, it does not always work.
“The danger comes when the child, in a CPFP scenario, is fine, but the parent does not meet the minimum mempool policy,” Zhao explained. “Say the mempool therefore fully that the parent’s fee is lower than the lowest fee transaction in the mempool. Then, your hands are tied. Currently, the validation logic does not consider CPFP for such a transaction. “
That is, if nodes drop the parent transaction from the mempool because it doesn’t have enough fees, they won’t accept the child transaction either: it spends coins that the nodes are unaware of. In the context of Lightning, this means the justice transaction would not confirm in time, and the malicious channel partner escapes theft.
A package relay would solve this problem by introducing a change to mempool exchange policies and a node transaction that allows it to apply CPFP type logic. Although implementation details have not yet been worked out, it would essentially allow for bundling of dependent transactions. Bitcoin nodes would receive and transmit transaction packs, protecting transactions that do not individually meet mempool policy.
“An Exchange Package will strengthen Bitcoin’s tier security guarantees, enabling the Bitcoin ecosystem to safely expand in functionality and usability through protocols such as the Lightning Network.”
Brink’s one-year fellowship program, unique in the Bitcoin industry, will help more developers contribute to Bitcoin projects. Fellowships will be funded by donations, with Zhao’s program funded by donations from Square Crypto ($ 100,000) and the Human Rights Foundation’s Bitcoin Development Fund ($ 50,000).
Square Crypto is the Bitcoin development arm of Square, the payments company founded and run by Jack Dorsey (also co-founder and CEO of Twitter). Apart from employing a small team of Bitcoin developers, whose main focus is the Lightning Development Kit, Square Crypto has so far announced 19 grants to various Bitcoin projects and developers. The Zhao Brink Fellowship will be the 20th.
“Brink is creating the first bitcoin mentorship program of its kind, and we want to support it,” said Crypto Square leader Steve Lee Bitcoin Magazine. “We are delighted that Gloria was selected as the recipient of the first fellowship, and are happy that our funding will go to it. The package relay project is very valuable for bitcoin, essential for security and aligns well with the goals of Square Crypto. “
The Human Rights Institute (HFR) is a not-for-profit based in New York that promotes and protects human rights globally. Earlier this year, the foundation launched its Bitcoin Development Fund, a donation-based fund to support Bitcoin developers that makes Bitcoin’s network more private, decentralized and resilient. The Zhao fellowship represents the fourth grant awarded by the Human Rights Institute.
“HRF is delighted to support Gloria through our Bitcoin Development Fund,” said HFR Chief Strategy Officer Alex Gladstein. “Her work focuses on a critical infrastructure that paves the way for Bitcoin to become more private in scale, and which is very much in line with our mission.”
He added: “This gift will be amplified by the fact that she is helping to support the Gloria fellowship at Brink, where she will receive world-class mentorship and guidance, making her work as effective and efficient as possible.”
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