The Gringotts Guide to Grimm


“MimbleWimble”, we cast this spell so mote it be. GRIMM was born.

Grimm Manifesto

The Gringotts Guide to Grimm

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Uncle Vernon, who had gone very pale, whispered something that sounded like “Mimblewimble.” 

Excerpt From: J. K. Rowling. “Harry Potter 1 — Harry Potter and the Sorcerer’s Stone.”


MimbleWimble is a relatively new privacy protocol whose story begins in 2016. Unlike other privacy protocols like Crytponote and ZeroCoin/ZeroCash, MimbleWimble has a focus on scaling. To date, its most famous implementations are Grin and Beam. But there are others too…

We [Grimm] are the first and only mimblewimble project which implemented assetchain technology

Andrew Cop, Grimm developer

The origins of MimbleWimble are as mysterious as those of Bitcoin, and it also starts with a paper being dropped in a mailing list, in this case the Bitcoin Wizards IRC channel.

It was published[1] on July 19, 2016 under the pseudonym “Tom Elvis Jedusor” which is the French name of Voldemort from Harry Potter.[2]


In the paper Tom Elvis Jedusor credits Maxwell, von Saberhagen, Noether and others for the advances in blockchain privacy but notes that they all make the scaling issues worse.

These solutions are very good and would make Bitcoin very safe to use. Bu tthe problem of too much data is made even worse. Confidential transactions require multi-kilobyte proofs on every output, and van Saberhagen signatures require every output to be stored for ever, since it is not possible to tell when they are truly spent.

Tom Elvis Jedusor

A high-level overview introduces an in-depth explanation of the workings of the protocol by Tari Labs University.

  • No addresses. The concept of Mimblewimble addresses does not exist.
  • Completely private. Every transaction is confidential.
  • Compact blockchain. Mimblewimble uses a different set of security guarantees to Bitcoin, which leads to a far more compact blockchain.

The lighter weight of the Mimblewinble protocol derives from how it validates signatures in UTXO transactions. Rather than validating each input’s signature as with Bitcoin, all inputs are summed up to create a new key which is validated. This technique also obfuscates where the inputs originated, hence the privacy.

The Mimblewimble protocol uses blinding factors of balancing inputs and outputs in a commitment scheme as private keys. Sender and receiver must interact to construct a joint signature to authorize a transfer of funds. Blocks in Mimblewimble have all their constituent transactions aggregated into one giant transaction, erasing the original transaction boundaries. The initial block download further benefits from cut-through, in which all spent outputs cancel against corresponding inputs, erasing most of the blockchain history.[3]

Wikipedia, MimbleWimble

Plain English descriptions of the protocol rapidly become complex. Andrew Poelstra of Blockstream admits as much in this entertaining presentation on the subject.

Elliptic Curve cryptography plays a major role in making it all work and Nothing-up-my-sleeve numbers, or magic numbers, are used to generate randomness in cryptographic tasks and are hardcoded into the protocol. These are numbers which are demonstrably straightforward or simple, and cannot be held in suspicion of having a hidden agenda or backdoor. Numbers like the square root of 2 (as used in SHA-1) or the the first 10 numbers in pi.

Magic numbers are beautifully explained in this Computerphile video.

The name of the protocol, MimbleWimble, attests to this magic and to its privacy by referencing the wizarding world of Harry Potter in which MimbleWimble, also known as the Tongue-Tying Curse, is used to silence its target. Not from the Harry Potter books mind you, but rather an Electronic Arts game which conflated the curse with Uncle Vernon’s muggle mutterings.

For all its magic the protocol lacks the power of Script which permits multisig and time-lock, and an array of powerful features. Various solutions are being worked on, and the interview in this article with Grimm developer Andrew Cop is concerned in part with just that.


Komodo Platform, with its unique multi-chain architecture, allows for the creation of an unlimited number of independent blockchains. Traditionally, the Komodo team has called independent blockchains launched with Komodo “Assetchains.”

Komodo Platform blog

Komodo offers powerful scripting and the ability to create independent blockchains secured by Komodo. Smart chains using script and smart contracts can interoperate, creating a horizontally scalable ecosystem as is presented in this slick video.

These ideas helped inspire a MimbleWimble coin which addresses the shortcomings of the original protocol.


“Grimm is a fork of Beam. Komodo gave us the idea for assetchains, but our implementation and code is different,” explained Andrew Cop in an interview we had over Telegram. He is the co-founder and lead developer of Grimm, a project he started with fellow Russian Den Novak late last year.

Grimm (XGM), had a fair launch with no ICO. The project is currently funded by the developers themselves, and through community donations.

Andrew Cop and Den Novak have implemented their take on assetchains into the MimbleWimble protocol. These they call Confidential Parallel-chains.

Grimm is a first modular platform with a new Confidential Parallel-chains architecture that provides the ability to create your own independent mimblewimble blockchain for any project or product. New blockchains created on the Grimm platform are called Confidential Assetchains.

Grimm Website

Grimm is unusual in other ways too. 

Grin uses Cuckoo Cycle mining algorithms for ASIC and GPU mining respectively. However, Grimm avoids these and uses a variant of Zcash’s Equihash mining algorithm dubbed GrimmPOW. I asked Andrew about this in the interview.

Grimm first came to my attention when it appeared as a new listing on the TradeOgre exchange. Turns out it’s also listed on Citex, Graviex and Vitex — and Coinmarketcap! For such a new coin with limited resources this came as a surprise, and in my curiosity I quizzed Andrew about this too. I did not anticipate his answer.

These exchanges added us for free.

Andrew Cop

A well-written manifesto greets visors to the Grimm website , and hearkens back to the ideals of the cypherpunk movement from whose great well sprang Bitcoin.

What we see.

We see existing conditions and systems of control, not governed by logic or reason but by greed, corporatism, subversion, bureaucracy, censorship, and inefficiency. We have a strong distrust for inherently flawed and corrupt systems. Our value transparency, free speech, privacy, and real decentralization. 

Grimm Manifesto

The Interview

Grimm (XGM) founders and core devs Andrew Cop (left) and Den Novak (right)

Could you please give us a summary of the Grimm manifesto, and tell us who wrote it?

We called our whitepaper “Manifesto”, because in addition to the technical part of the project, it contains an appeal to everyone who cares about their personal data. In recent years, the world has adopted more and more laws designed to control the Internet. The ideas of the confidentiality in the internet were first described by a group of cypherpunks organized by Eric Hughes, Timothy C. May, and John Gilmore, and published in the famous Cypherpunk Manifesto by Eric Hughes in 1993 (by the way, the bitcoin whitepaper was first sent out through cypherpunk’s mailing list). 

Cryptocurrencies and signatures, cryptography, and open source code helps people to achieve privacy today. But the public ledger (used in Bitcoin cryptocurrency and forks) means that it’s actually possible for anyone to view the transactions (amounts and addresses) that are taking place, even if the blockchain doesn’t tell you who each of its digital wallets belongs to. 

Knowledge of amounts and addresses means tracking and following the transactions until they end up at a centralized exchange. It is also possible to track the users IP addresses if an entity runs a large amount of relay nodes on the network. Public ledger must hide real transaction amounts and addresses. In Grimm project we focus on the protection of personal and transaction data, on network scalability and easy-to-use services for users.

Why did you start Grimm?

There are many add-in methods of increasing the privacy of transactions on the blockchain used at privacy coins (like Zcash, Monero, etc), but we sees more promise in scalable cryptocurrencies built from the ground with default built-in privacy. We are fans of the magic Mimblewimble protocol, we have many ideas and opportunities to develop it and we are C++ programmers. So, we launched Grimm project to implement our ideas and make the best privacy technologies accessible, and user-friendly to everyone.

What do other privacy coins lack?

No privacy by default, difficulty to use, low scalability, rapid growth in the size of the blockchain data, unclear use cases. No mass adoption.

Why did you call it Grimm?

It was important for us to make the project image animated and personable. GRIMM — an abbreviation for GRIM and Mimblewimble. The project logo is a ‘grimly smile’, grinning at inherently flawed and corrupt systems.

How private are Grimm transactions?

Grimm (XGM) is fundamentally private and powered by the Mimblewimble protocol. Blockchain does not store transactions and addresses. Grimm operates on confidential transactions (CT) and uses a blinding factor that encrypts all inputs and outputs along with their public and private keys. Only two sides are dedicated to the details of the transaction. 

The secp256k1 elliptic curve, Pedersen’s commitment and Bulletproof, Schnorr’s signature, blinding factors and decoy outputs, Dandelion ++ and CoinJoin — all these methods, cryptographic primitives and signatures work in a single bundle to ensure the highest level of Grimm (XGM) confidentiality.

GrimmPOW is an Equihash 150_5 algorithm variant. Why doesn’t Grimm use Cuckaroo or Cuckatoo?

ASIC resistance is a core value of XGM. Cuckoo Cycle is no longer considered ASIC resistant. For the future we are considering the possibility of moving to the RandomX mining algorithm for additional protection from FPGA.

Grimm uses Komodo technology and somehow merges it with Mimblewimble to create Confidential Parallel Chains. Can you tell us more about how this all works?

Most people don’t actually know what difference between Parallel Chains(we call it Assetchains) and “Assets”, and often confuse these concepts. Assetchain is a new cryptocurrency with its own Blockchain (and here lies the main difference) that hold all the characteristics of the parent chain and privacy by default (with the ability to change all parameters), but are also completely independent of the parent chain. Assets (aka tokens) are not cryptocurrencies, they haven’t own blockchain and recorded in the parent blockchain (the fees for the transactions for the assets (tokens) are paid in parent blockchain cryptocurrency).

So, Assetchain is a Grimm runtime fork. Users can use all Grimm binaries (GUI/cli wallet, node, explorer node, etc) to run different blockchains from one place (including Grimm mainnet) just by setting the parameters: Coin name, pre-mine amount in the first block, founders tax, set difficulty algorithm parameters, choose mining algorithm, merged mining possibility, tokens creation possibility and other parameters and rules. Each assetchain has a unique network signature. All Parallel chains can automatically receive updates from Grimm platform.

What stage of development are Confidential Parallel Chains at? Are they working on mainnet today?

We published a pre-release on Nov 12, 2019 with working Parallel chains on mainnet. You can find video instruction on our YouTube channel and creation guides on github. There only CLI interface for assetchains and basics parameters for creation own blockchains released. The full release with assetchains “GOTHIC” will be published on April 12, 2020. 

Main features:

  • Grimm mainnet hardfork (new difficulty algorithm, min fee)
  • 51% attack protection (mainnet and Assetchains)
  • User-friendly interface for creating Assetchains
  • One GUI Wallet for Grimm and Assetchains 
  • New list POW algorithms for Assetchains
  • Full set of parameters to configure Assetchain

What are the use-cases for Confidential Parallel Chains?

Grimm platform users can create DeFi applications that are designed to help people become part of the financial world using blockchain technology. On Grimm platform user scan run not only DeFi applications but games, dapps, cryptocurrency exchanges, and any other project or application that needs a blockchain. Assetchains can use in corporation system management. And the most important thing is the privacy by default in all use-cases.

What are Grimm’s other features?

Grimm platform features:

  • Customizable. Allowing creators to change parameters in their own blockchain from algorithm to consensus rules. Possibility to choosing whether or not to receive upgrades from Grimm platform.
  • Confidential Assets. Possibility to allowing Assetchain users to create own assets on mimblewimble protocol like colored tokens.
  • Easy Blockchain creation Kit. Allows to create own blockchain without in-depth technical knowledge. User friendly.
  • Fast. Possibility to allowing one Assetchain to verify transactions for any other assetchain for significant increase TPS.
  • Scalable. Transactional data stored on the blockchain does not increase with the number of users, as nodes store only unused outputs and block headers. As a result, the weight of blockchain is reduced by several times.
  • Private but optionally Transparent. Assetchains operates on confidential transactions and uses a blinding factor. Only two sides are dedicated to the details of the transaction. But if necessary, the sender of the payment can generate and provide proof of payment to a third party. However, Assetchain creator can set non-confidential signatures by default.
  • Same API for all Assetchains. Allows to create cross platform applications.

Komodo created Delegated Proof-of-Work for security. As a small POW coin using some KMD tech do you ever plan to use dPOW?

dPOW is a great decentralized mechanism to protect blockchains with small levels of hashing security from 51% Attacks using the bitcoin network. But for using this mechanism we need to pay for dPoW notarization costs (BTC transaction fees to keep dPoW security up and running). So we are not looking at this yet.

Are you worried about 51% Attacks?

Yes, every pow coin must be worried about it. That’s why we announced implementing 51% attack protection from next release “Gothic”. It based on deep reorg protection and will protect Grimm and Assetchains from potential 51% attack.

The team seems to be just you and Den Novak. What are your backgrounds and experience in blockchain, and out of blockchain?

Yes, the core team is Andrew Cop and Den Novak. We are from Russia, Moscow. I have Bachelor’s Degree in Cyber Security. Den has a BA in Economics and Management, and has interest in coding and webdesign. We involved with blockchain technology from 2015. Started from mining, created mining pools to orders, advised some ICO and crypto projects (custom-designed mvp), etc. Grimm is our first public project.

Are there other team members, and are you looking to grow the team?

We have a promo group from Grimm community activists, who help us promote Grimm in social networks. We want to grow the team, but at this stage we can’t pay for work.

You’ve had some trouble with another Mimblewimble coin called Beam. Can you tell us what happened?

🙂 Yes indeed, we had a dispute with lead dev of Beam, that started in telegram groups. We are the first and only mimblewimble project which implemented assetchain technology and developing it, not even mentioned in any Beam document or source code. Confidential Assetchains were developed by Grimm from scratch. Also, we pre-released assets (tokens) based on Beam’s codebase (opensource project), which can be created on the assetchain if the option is enabled. So, Beam’s lead dev, not understanding the difference between Assetchain and Asset, began to claim that Assetchain is their development which they have been doing for more than a year and that Assetchains have vulnerabilities. We tried to explain that Assetchains are not Assets, but they insulted us and blocked us in mimblewimble telegram groups. In general, Beam works very hard, but its goals are outdated, the project is boring. New trends and protocols appear very quickly. A written roadmap for a couple of years ahead may become irrelevant in six months.
In any case, we are glad that Beam lead dev created a medium account and Twitter account just for a dispute with Grimm project.

In a short time you’ve successfully listed on several exchanges including TradeOgre. Congratulations. How were the listing fees paid for?

Thanks. Grimm was fair launched, without fundraising, ico, pre-mine or founders tax. So, we do not have any funds at this moment to pay fees for exchange listings. These exchanges added us for free. Grimm is opensource project and integration guide was published on our website for exchanges/pools. Also we are always online and ready to help. We will be glad to all exchanges and mining pools, who want to add us.

How does Grimm fund development, and is it sustainable?

Grimm is developing with our own funds and through community donations (we haven’t received any donations at this time).
So we cant say that it’s sustainable.

Why do you think Grimm isn’t better known?

Grimm focused on the fair launch with donations scheme funding. For example, we offered our community to collect donations to Grimm for listing on the Hotbit exchange. Reports were published on github. And what do you think? During the month, we collected only 5% of the required amount. We brought back donations. Grimm could be a more popular project than it is now, if the community realized that they can become a real force for promoting the project.

What’s planned for Grimm in the future?

Working confidential tokens, cross-chain (and cross-assetchain) atomic swaps, Defi apps based on assetchains, Lightning second layer scaling solution, Dex, — these are just a few Grimm opportunities that we are working on and will continue to develop in future. Schnorr multi-signature functionality combined with simple smart contracts off-chain using scriptless scripts open up a new privacy world for businesses and commercial solutions.


Andrew Cop and Den Novak have got Grimm (XGM) off to a flying start. With multiple exchange listings already under their wing, they are now preparing for the “Gothic” network upgrade.

There is huge room for growth, which will likely follow if the project can garner more support and grow the community as it matures. As MimbleWimble is being explored by many crypto developers, Grimm pushes the limits of this fledgling privacy protocol to see what else it can offer beyond scaling and privacy.

Useful Links

Manifesto (whitepaper)
Andrew Cop
Andrew Cop (GitHub)
Den Novak
TradeOgre (XGM)
MimbleWimble whitepaper


Thanks to Andrew Cop and Den Novak for their time and detailed replies.

D. G. Altman
Fascinated by blockchain technology. Privacy advocate since forever with concerns over transparent ledgers in a cashless society. Coding in English (US) and Java at breakfast. Altcoin Maximalist

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