Privacy Crypto Grin's First Hard Fork Planned for July

This summer will see the first network upgrade for Grin, a privacy-oriented cryptocurrency that uses the technology Mimblewimble.

AccessTimeIconJun 5, 2019 at 7:34 p.m. UTC
Updated Sep 13, 2021 at 9:16 a.m. UTC
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Grin developers have reached a rough agreement on a block number and expected date of activation for the crypto network's first ever system-wide upgrade or hard fork.

Proposed by Quentin Le Sceller, a Grin core developer and software engineer at blockchain startup BlockCypher, during a developer call on Tuesday, the proposed activation block number is 262,080. The network is expected to hit this block height on July 17.

On Wednesday, developers re-discussed Le Sceller's hard fork timeline, which also calls for launching a private test network for the upgrade in the beginning of June and activation of the upgrade on the public Grin test network – called Floonet – on June 19.

Taking a step back, Grin is a privacy-focussed cryptocurrency that leverages a technology called MimbleWimble to obfuscate transaction activity. Launched back in January, Grin raised roughly $65,000 from crowd-sourced donations in the months preceding its launch. After receiving a mysterious bitcoin donation in early May worth roughly $300,000, the project presently holds roughly holds about $420,000 in funds.

During today's impromptu meeting, Grin core developer Michael Cordner who goes by the pseudonym "Yeastplume" emphasized that while the proposed timeline could change, efforts should be taken to stick by the schedule.

"If the date slips, we'll communicate it closer to the time," wrote Cordner in the developer chatroom. "But we should really try to keep to it, which is another reason [why] we should keep all non-[hard fork] related [pull requests] out until post [Grin version] 2.0.0."


The scheduled hard fork in July is actually one of four anticipated system-wide upgrades in Grin's two-year roadmap of the Grin blockchain, designed to keep specialized mining hardware from proliferating on the network.

Most notably, Grin employs two different proof-of-work mining algorithms that dictate the efficacy of using ASICs versus more general computing devices called GPUs. One called Cuckatoo31+ is explicitly ASIC-friendly while the other, called Cuckaroo29, is designed to optimize for GPU-specific capabilities.

Overtime the vision is to gradually phase out Cuckaroo29 in favor of Cuckatoo31+ given a philosophy that no mining algorithm can remain ASIC-resistant forever. But in order to ensure that the secondary mining algorithm – Cuckaroo29 – stays truly ASIC-resistant for the initial period of two years, Grin developers agreed to execute minor changes to the later upgrade every six or so months.

Grin's first upcoming hard fork will execute a change to the Cuckaroo29 mining algorithm designed to ensure its ASIC-resistant qualities on the network. However, Le Sceller emphasized to CoinDesk that in a matter of two years, this mining algorithm "will disappear."

In addition, Grin developers are expected to discuss sometime this month potential delays or holds to the schedule of the Cuckatoo31+ mining algorithm taking effect in 2021 and beyond.

Other changes

Outside of the mining algorithm tweak, Grin's first hard fork activation will also feature notable upgrades to the cryptocurrency's wallet software aimed at increasing wallet flexibility and usability.

One of the proposals going into the hard fork titled "improved bulletproof rewind scheme," Le Sceller tells CoinDesk will basically enable new kinds of wallet including multi-signature wallets and "watch-only" wallets alongside regular ones.

"A watch-only wallet is just a way to see the output of a wallet (i.e. the balance and the incoming funds) but you won't be able to spend them," detailed Le Sceller. "This is useful for a lot of stuff. [For example,] auditing or simply if you do not want to use your private key just to see your wallet balance."

Additionally, Grin's wallet API will also get a boost to enable new functions such as transaction invoicing.

Le Sceller highlighted:

"Regarding the new API version, [Grin developer] Yeastplume has been working on it for some time now and it's an enhanced version using JSON-RPC (compared to the previous one which was using REST)...A website using Grin [tokens] can create an invoice and the client only 'need to sign it' which reduces the number of back and forth."

Le Sceller added that mining pools, exchanges, and other users interacting with the Grin protocol will need to upgrade both their node and wallet software in order to accept new blocks and build transactions past the anticipated hard fork point.

He also emphasized that while developers reached a consensus today around the hard fork timeline, "all the dates in the document that I shared are tentative and not definitive," indicating potential for change after further discussion in months to come.

Fork image via Shutterstock 


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