Grin FAQ: Everything You Wanted To Know About Grin


Since launching last week, the crypto community has been buzzing about Grin. So what is it, and why are people excited? Saddle up, here's your Grin FAQ.

What is Grin?

Grin is a much-buzzed-about cryptocurrency that implements the MimbleWimble protocol, bringing with it interesting features for privacy and scalability, as well as a different approach to monetary policy than other cryptocurrencies featuring perpetual linear inflation. Grin’s mainnet went live on January 15th, offering what was billed as a “fair launch” - no pre-mine, no founder’s reward, and no other privileged incentive for insiders.

What is MimbleWimble and where did it come from?

MimbleWimble is a blockchain protocol optimized for privacy and scalability. It was first proposed in a paper released in July 2016 by a developer using the pseudonym Tom Elvis Judesor - the French styling of Harry Potter arch-villain Lord Voldemort’s birth name.

Over the next few months, the paper was kicked around by many in the Bitcoin developer community, including Blockstream’s Andrew Poelstra, who wrote an updated “precise” version of the MW white paper in October 2016. While initially, MW was envisioned as either an upgrade or side chain to Bitcoin, challenges around backwards-compatibility led to a shift in attention to native implementations.

What makes MimbleWimble’s approach to privacy different?  

While privacy isn’t the only aspect of MimbleWimble that has people excited, it’s perhaps the most notable technical change as compared to other protocols. So, what’s the story?

Money systems have two major requirements: 1) they have to be able to verify that, in a transaction, the money received = money sent; 2) transactions can only be initiated by the holders of the money.

Bitcoin achieves these requirements by broadcasting the 1. Sender’s address; 2. Amount of coins sent; 3. Receivers address. Great for creating a money system that works; not so good for concerns around privacy and confidential transactions.

MimbleWimble takes advantage of the fact that it is easy to multiple by hard to factorize. MW uses blinding factors (in other words, a number you multiply the transaction amount by) to obscure exact transaction amounts while still allowing onlookers to validate that outputs match inputs, while also allowing the sender to validate that they have those coins to send in the first place. What this means in practice is that there are no addresses and no amounts, but the key requirements of the money system remain.

To learn more about MimbleWimble and privacy, start by reading Conor O’Higgins “Mimblewimble explained like you’re 12,” and then when you’ve got your head around that, graduate up to Arjun Balaji’s “MimbleWimble: History, Technology, and the Mining Industry.”

How did Grin start?

Not long after the Poelstra update to the MW paper, another pseudonymous developer - this time going by Ignotus Peverell - Harry Potter’s distant ancestor and first owner of his famed cloak of invisibility - created a GitHub project that included a partial implementation of MW and a vision for a project ethos. This was followed in March 2017 by a technical introduction to Grin. Since then, a group of developers - some of whom are public, others who have claimed pseudonyms - have led the protocol through 4 testnets, ultimately leading to mainnet launch on January 15th, 2019.

Why are people so interested in Grin?

There is a lot going into the interest around Grin.

Privacy: As mentioned above, interest in privacy is one of the biggest drivers for Grin (and MimbleWimble in general). Contrary to some narratives, this isn’t about criminal activity but about the idea that as the capacity for surveillance grows, we need not only a right to policy but technology to protect it.

Technical approaches: In addition to the technical work going into Grin’s approach to privacy, MimbleWimble also has an interesting approach to scalability that involves aggregating and eliminating old transactions that were already validated in past blocks to reduce the overall size of the blockchain.

Monetary policy: Grin is taking an avowedly different approach to monetary policy and coin emissions than other projects. Rather than a variable inflation schedule and a capped total supply, Grin will be emitted at 1 grin per second indefinitely. This creates significant inflation at the beginning (designed to incentivize early miners to secure the network), evolving to extremely low but still persistent monetary supply inflation in the long run. The project has been explicit about its desire to be predominantly used as a form of digital cash.

Approach to ASICs: Grin is taking what might be called a pragmatic approach to ASICs. Recognizing that 1) ASICs do create security benefits for the network; and that 2) they tend to be inevitable, Grin is employing a dual proof of work structure. Cuckaroo will be ASIC-resistant (in large part via planned 6 month algorithm changes a la Monero) and start receiving 90% of the block reward, moving to 0% over the course of the first two years). Cuckatoo31+ will start at 10%, eventually moving to 100% after two years, and is designed to simplify ASIC design in order to encourage robust ASIC competition.

Fair Launch & Contrast To ICOs: Coming off a year of ICOs with steep investor discounts, Grin’s “Fair Launch” - featuring no discounts, no pre-mine, no founder’s reward, not even a foundation to raise money - feels fundamentally different. While some have questioned how “fair” it is when an estimated $100m+ of VC money is flowing into special purpose mining vehicles, the reality is that those are simply market forces, and the fact that those well-financed powers don’t have any special advantages relative to their size is, in itself, something different.

Narrative Intrigue: Between MimbleWimble being named after a tongue-tying curse in Harry Potter and proposed by a pseudonymous developer and Grin furthering that with its own obscure creator, the project has both homage to Bitcoin’s roots but also its own mythology that is growing. This isn’t everyone’s cup of tea, but for many weaves mystique around the project.

When did mining begin & who is participating?

Mainnet went live on January 15, 2019. Investor & editor Eric Meltzer estimated that, conservatively, $100m had been invested into professional mining operations. Estimates of the number of GPUs mining Grin meanwhile, jumped to over 88,000 within just a few days. 

Is anyone else working on Mimble Wimble?  

Indeed! Another company called Beam is also live. They are taking a more traditional approach, with venture backing and a founder’s reward, and have a slightly different approach to the privacy technology.

Learn more: