Grin & Mimblewimble: Voldemort's Invisibility Cloak and the Privacy Frontier

1. A Spell Thrown Into the Research Channel

Grin's history dates the drop to August 1, 2016: a user named majorplayer logged into the #bitcoin-wizards IRC channel, posted a Tor-hosted text file, and disappeared. Andrew Poelstra's follow-up separately places an anonymous person using the name Tom Elvis Jedusor on a Bitcoin research IRC channel at about 04:30 UTC on August 2. The document itself was titled Mimblewimble, signed Tom Elvis Jedusor, and dated 19 July 2016. Its complaint was concrete: nearly 150 million Bitcoin transactions had to be replayed to confirm 4 million unspent outputs, while the transaction graph fed companies whose business was monitoring users.^[3][2][1]

hi, i have an idea for improving privacy in bitcoin. my friend who knows technology says this channel would have interest^[3]

— majorplayer

Grin's documentation notes that Tom Elvis Jedusor is the French name for Tom Riddle — Lord Voldemort — and Mimblewimble is Harry Potter's tongue-tying curse. The author explained the name in one line:^[3]

I call my creation Mimblewimble because it is used to prevent the blockchain from talking about all user's information^[1]

— Tom Elvis Jedusor

In October 2016, Andrew Poelstra published a follow-up paper, dated 6 October, that tightened the design. It estimated 15 gigabytes for Bitcoin-scale transaction history and claimed compact-chain data could fall below one megabyte, excluding the UTXO set, which it estimated above 100 gigabytes with rangeproofs. Within two weeks, the idea had a second pseudonym.^[2][3]

2. The Magic: No Amounts, No Addresses

The trick begins with a deletion: "The first thing we need to do is remove Bitcoin Script." General scripts cannot be merged, and merging is the point. Instead, every amount becomes a Pedersen commitment, C = rG + vH — the value blinded by a secret key — and a transaction is valid when its outputs minus its inputs, plus the fee, sum to zero. Verification proves no money was created, without anyone seeing an amount.^[1]

Ownership changes shape with it: because the blinding factors act as secret keys, there are no addresses. Grin's documentation lists three privacy properties — no addresses, no amounts, and merging a transaction into the one that spends it — so a block becomes one giant transaction in which spent-through data is cut away and only a roughly 100-byte kernel survives per transaction. The documentation also claims growth at about one quarter Bitcoin's rate — a project claim.^[1][4]

However, to achieve these goals, Mimblewimble cannot support a general-purpose scripting system such as that in Bitcoin.^[2]

— Andrew Poelstra

That was the price: Poelstra's paper warned that dropping script precludes zero-knowledge contingent payments, cross-chain atomic swaps, and micropayment channels in their Bitcoin form. Grin's developers later documented elliptic-curve routes back to multi-signatures, atomic swaps, timelocks, and Lightning-style channels.^[2][4]

3. Interactive Money and the Edges of the Cloak

Spending is a handshake. The original paper prescribes a sender–recipient "ritual" for jointly building each transaction, and Grin's FAQ confirms wallets must exchange data directly — though not simultaneously online, since the exchange can run over email or Signal.^[1][4]

The cloak has edges. Grin's documentation says a relay listener can identify which outputs a pending transaction spends before cut-through; it presents Dandelion as protection for originating IP addresses. Ivan Bogatyy reported tracing roughly 96 percent of Grin transactions using three sniffer nodes over several days in May 2019, reconstructing who paid whom while amounts remained protected. His write-up says Grin's developers knew such an attack was theoretically possible.^[4][11]

Contemporaneous reporting noted that Beam lets users switch off anonymity and make transactions auditable. Grin's documentation says a relay observer can link a pending transaction to spent outputs; Bogatyy reported reconstructing links while amounts remained protected. These are sourced boundaries, not universal positions.^[7][4][11]

4. Beam First, Grin Twelve Days Later

Beam moved first: the company-built chain launched mainnet on January 3rd, 2019, with zero coins in circulation and — per Beam's tokenomics — no pre-mine or ICO. Twelve days later, on January 15th, Grin's genesis block was mined.^[6][3][7]

Beam's funding model was written into emission. Its official documentation scheduled 20 Treasury coins per block in year one and 10 through year five, intended to repay investors, incentivize the core team, and fund the Beam Foundation. It said the monthly distribution would be roughly 35 percent investors, 45 percent core team and advisors, and 20 percent Foundation, from a supply capped at 262,800,000 coins with Bitcoin-style halvings.^[6]

Grin ran the other way, as contemporaneous coverage framed it: "the philosophically pure cryptocurrency – community driven and funded, not premined and with no taxation on mining," set against Beam's company-controlled 20 percent. At the time of that January 7 report, Beam's hashrate had reached 1.68 MSol per second on Equihash. Both framings are journalism's, not adjudications.^[7]

Grin's manifesto was its emission: a new grin every second, forever — 60 grin per block on a 60-second block goal, with no maximum supply. Its stated rationale was a constant subsidy protecting mining over decades, with relative dilution below 10 percent after ten years. Those are project intentions, not audited outcomes. Months after launch, Ignotus Peverell — named for the wizard who received the Cloak of Invisibility — disappeared; contributors continued the work, some funded by donations.^[5][4][3]

5. Delistings, Extension Blocks, and a Cloak That Fit Other Shoulders

The cited 2019 records describe exchange actions, not a regulatory ruling on Mimblewimble. Upbit delisted six privacy coins on September 30 citing FATF guidance; OKEx Korea separately ended support for five on October 10. Grin and Beam appeared on neither list. For June 2022, Cointelegraph reported, citing 8BTC, that five major South Korean exchanges announced Litecoin delistings after exchanges flagged MWEB. Its report directly documents Upbit's AML-law analysis. These were exchange decisions, not court judgments or protocol-wide bans.^[9][12]

Litecoin activated MWEB as a soft fork in May 2022 after 75 percent miner signaling on May 2, at block 2,257,920. The opt-in feature hides amounts only for extension-block users; the Litecoin Foundation says it does not provide 100 percent privacy. Cointelegraph later reported, citing 8BTC, that five major South Korean exchanges announced Litecoin delistings after exchanges flagged MWEB; the article directly documents Upbit's AML-law analysis.^[8][12]

In terms of fungibility and privacy, I believe MWEB gets you 90% there. For most people that's good enough. It's the difference between living in a glass house vs living in a house with windows. For people who need 100% privacy, they can live in a house with no windows.^[8]

— Charlie Lee

People carried the migration: MWEB's lead developer was David Burkett of Grin++, paid through community funding. Grin's repository still states the chain is live with mainnet, and Beam's documentation remains active. The core idea outlived its first two launches — an editorial interpretation, not a ledger fact.^[8][10][6]