I Watched 4,364 Blocks of Ethereum Classic Get Rewritten in August 2020. My Three-Confirmation Rule Died That Week.

Four thousand three hundred sixty-four. That is how many blocks somebody quietly rebuilt on Ethereum Classic while I sat up past one in the morning on August 6, 2020, at my dining room table, refreshing an exchange status page on a laptop I had already closed and reopened twice cuz the page kept refusing to say anything useful.

Sitting on that exchange was 212 ETC I had moved off my own Ledger two days earlier, worth about $2,100 that week, headed for a sale meant to cover a $612 car insurance renewal due the following Friday. The deposit showed pending. A deposit is not yours til the exchange credits it. That sentence had never meant anything concrete to me before that night. It meant everything at 1 AM with the insurance portal open in one tab and the word pending glowing in another.

Nobody stole my coins. The attacker went after exchanges, and the published estimates put the haul near $168,000 across the attacks, most of it aimed at a single venue. What died that week was my definition of the word confirmed. The rule I replaced it with starts with a detail I spotted at 2 AM: one exchange had quietly raised its ETC deposit requirement past 10,000 confirmations, which is its own kinda confession.

the deposit I made on Tuesday

The transfer itself was boring, the way transfers are until they are not. Tuesday afternoon I sent 212 ETC from my Ledger to the exchange, watched it land at three confirmations in under a minute cuz ETC blocks come every 13 seconds, and went back to work. Three confirmations. Done, I figured. My whole rule fit in those two words, and I had carried it around since 2017 without ever asking where the number three came from.

what a reorg looks like from a couch

Watching a reorg feels like nothin', at first. The block explorer keeps ticking. The classic-chain version of Etherscan kept showing blocks landing right on schedule, 13 seconds apart, honest-looking as anything. Underneath, the same block heights were being proposed, orphaned, rebuilt, and orphaned again by an attacker who had rented enough hashpower to out-mine the entire honest chain for days at a stretch. The chain did not crash. The chain lied, politely, block by block, and every dashboard I owned told me it was fine.

Coinbase pauses, the page says nothing

Coinbase paused ETC deposits and withdrawals while the reorgs piled up, and the status page went thru phases like weather. My 212 coins sat pending the whole time, neither credited nor returned, while I refreshed and refreshed and absorbed that a support queue moves at the speed of continents. At least one other venue raised its deposit requirement past 10,000 confirmations, which means somebody's risk desk did the math on how deep a rewrite could go and picked a number bigger than the attack. Waiting became the strategy. I did not sleep much that week, and the sale I had planned for Friday simply did not happen.

the 10,000-confirmation confession

That 10,000 number deserves its own paragraph, cuz it is the most honest document of the whole episode. Confirmations are just blocks, and blocks on a cheap chain are just minutes of rented hashpower, so a venue that says 10,000 is telling you it prices a rewrite in days, not seconds. Nobody advertised it. It sat in a deposit-requirements table next to the same ETC ticker that had always claimed 3-foot confirmation times. Reading a risk desk's fears thru a settings table is now a skill I did not know I was learning.

three confirmations, thirty minutes, done

My old rule deserved the autopsy it got that week. Three confirmations on ETC took about 40 seconds, and I treated that like a stamp of permanence cuz Bitcoin lore says six blocks and you are safe. The lore was written for a chain with so much hashpower that rewriting six blocks would cost more than any theft could possibly pay. ETC is not that chain. ETC never was that chain. On cheap-hash chains, three confirmations just means three minutes of work for whoever wants to spend it, and in August 2020 somebody spent it again and again across two weeks.

the rule I wrote that week

The new rule went into my phone notes on August 9, 2020, and it fits in two lines. Bitcoin keeps the three-confirmation shortcut, because rewriting Bitcoin would cost a billionaire more than any theft pays. Small-hash chains are different animals: confirmations stop counting blocks and start counting minutes, I wait a full hour before I call a deposit real, and I read the network status page before I go to sleep. Depth over count. Cheap blocks buy cheap rewrites, so the only honest unit is time.

what it actually protects

What the hour protects is boring and total. It protects the deposit from un-happening, which is the only thing a reorg can do to it. It protects me from forwarding a package, paying an invoice, or calling a sale closed against money that can silently walk backward outta existence an hour later. It does nothin' against losing my keys, nothin' against a bad contract, nothing against an exchange blowing up, and I keep separate rules for each of those. One risk, one rule. That discipline is the whole reason this one has survived six years.

the test in January

In January I moved 38 ETC between wallets, the first time in over a year I touched that chain at all, and I caught myself waiting the full hour outta pure habit before logging the transfer as done. The status page said all clear in nine minutes. I waited fifty-one more anyways. The dining room table is the same one from 2020, and the laptop stays closed during transfers now, cuz one long night taught me that watching blocks land proves the chain is alive, not that it is honest. That is it. That is the whole rule.