MimbleWimble and GRIN Coin: A Return to the Original Vision of Bitcoin?

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What is MimbleWimble?

MimbleWimble began as a gleam in the eye of anonymous developers in July 2016, who published a text file titled “MimbleWimble” that contained plans for a new blockchain protocol that promised to bring Bitcoin back to its cypherpunk roots. The idea was based around scalability and anonymity and it caught the attention of others in the cryptocurrency space. Within a few months, the coding for the MimbleWimble protocol had begun.

Now, 2.5 years later, two networks designed to test MimbleWimble have finally launched their mainnets. This article focusses mainly on one of them: Grin, which has generated a lot of attention within the crypto community.

What is Grin?

Grin is an implementation of MimbleWimble launched in January 2019. It is written in Rust and uses two versions of Cuckoo Cycle as its PoW algorithm (an ASIC-resistant one and an ASIC-friendly one). Unlike Bitcoin, there is no public ledger. The network uses no addresses and encrypts all amounts. However, Grin relies on Bitcoin’s CoinJoin method to achieve scalability and privacy.

In the words of its anonymous developers, Grin is designed to be simple, fast (one block per minute), and hold a fixed block reward of 60 Grins over time with a decreasing dilution. It is not trying to compete with Bitcoin or Ethereum. It is trying to offer an alternative. Here are a Grin explorer and a repository of GUI/mobile wallets that are currently available.

Genesis of Grin

MimbleWimble was born in August 2016 when a user with the pseudonym “majorplayer” linked to a file in the IRC channel #bitcoin-wizards that described MimbleWimble as a private and scalable upgrade for Bitcoin. Cryptography researchers took notice, including Blockstream’s Andrew Poelstra, who wrote a more technical whitepaper for MimbleWimble later that year.

Originally, the project was intended to be a sidechain for Bitcoin. However, Bitcoin’s scripting system presented limitations, and in mid-2017 the developers decided to launch a new cryptocurrency: Grin.

Grin’s developers seek to remain true to cypherpunk principals. The project was funded entirely by the community. There was no ICO, no airdrops, and no pre-mining. “No funny business,” according to Igno Peverell, Grin’s pseudonymous lead developer.

Grin coin went live on January 15th, 2019, almost two weeks after the launch of its competing implementation, Beam.

Grin vs Beam

Grin and Beam are the two different implementations of the MimbleWimble network. While coding for Grin began October 2016 coding for Beam did not begin until March 2018. Nonetheless, the Beam mainnet launched almost two weeks before the Grin mainnet.

There is a stark difference between the two projects. Grin represents community-driven decentralization and the original spirit of crypto, while Beam is more corporate-based. For example, Grin uses open source governance, there are no founders’ rewards, and the developers are volunteers working part-time. Meanwhile, Beam is backed by venture capital with a paid, full-time team of developers. Beam also uses part of its 20% block reward to fund development (Grin relies on donations).

Other differences between Grin and Beam:

  • The main Grin implementation is in Rust while the main Beam implementation is in C++.
  • Beam uses Equihash, Grin uses Cuckoo Cycle (both ASIC resistant PoW algorithms). The Grin team has stated ASICs are centralizing and unreliable, but also admitted they are unavoidable. Thus, Grin uses two separate proof-of-work algorithms: Cuckatoo31+, which is ASIC-friendly, and Cuckaroo29, which is ASIC-resistant. The proof-of-work balances mining rewards between the two every 24 hours. Technical details are explained in this post. The Cuckoo readme is here.
  • There is a constant, infinite supply of Grin to discourage hoarding. Grin’s block reward is 60 Grins per block, and one block is created per minute — so one Grin is created each second. The team states this monetary policy was designed to discourage hoarding and improve distribution. In contrast, Beam has a fixed supply of approximately 263m coins.
  • Finally, Grin coin is intended to be a usable currency; whereas Beam places emphasis on being a store of value.

Grin and Beam have been described as in friendly competition. Indeed, Beam’s FAQ describes Grin’s team as not “100% focused on the project” and its technical decisions as “less practical.” However, the FAQ adds “That said, we have immense respect for Grin team and wish them success.” It seems to be true. Beam recently donated BTC to Grin’s security audit fund.

Photo by emhmark3

A Return to GPU Mining

Grin has also been touted as the coin to bring back GPU mining. The Grin team recommends a GPU with over “3.7 GB of very fast DRAM”. Check the Grin forum for updated discussion on this matter. You can check the implementation for a standalone Grin miner, and official mining stats.

The Grin mining pool GrinMint was released by BlockCypher. Soon after launch, Grinmint announced a 2.5% fee for their mining pool, 0.5% of which is for the Grin development fund.

Criticism of Grin

A major limitation of Grin as a cryptocurrency is transactions require both participants to be online at the same time. Some people have suggested they might run their wallets on servers that are continuously on. However, this solution could eventually lead to centralization, which Grin is trying to avoid with its ASIC resistant PoW algorithm.

In addition, MimbleWimble does not support scripts. Some users consider this a defect since scripts make a blockchain programmable. However, programmability is not one of Grin’s main goals. As Poelstra explains, “the design philosophy of Grin is to be as simple as possible.” Nevertheless, Grin’s FAQ page links to messages from 2017 claiming scripting could be possible.

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Grin’s Target Audience

Some say that Grin will be a coin for Bitcoin maximalists more than investors. In other words, people will be drawn to the tech underpinning Grin, instead of the possibility of getting rich.

MimbleWimble and Grin’s coding appeal to a tech-savvy community that is already well-aware of cryptocurrencies and their potential. Grin’s landing page has a look reminiscent of cypherpunk. The Harry Potter references in the pseudonyms of the developers and the name “MimbleWimble” itself suggest Grin is for a niche audience. On the other hand, Beam uses branding in a way that is more similar to EOS or TRON and is clearly catering to a more mainstream crypto crowd.


Grin’s open-source code and grassroots community have caught the interest of those who identify with the original spirit of cypherpunk. Some may see Grin as a throwback to a time when profit was less central to the cryptocurrency space. This is why in crypto forums and in the media Grin is described as everything from cute but ineffective, to the coin that will save Satoshi’s original dream. A mere five months from its release is too soon to tell what its future will be. But without a doubt, many people will be keeping an eye on Grin’s performance.

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Mina Down

Mina Down

Writer interested in blockchain projects that will add to the social good