What actually happens to Bitcoin the day a quantum computer arrives? In the third episode of The Quantum Bitcoin Podcast, Bitcoin historian Pete Rizzo and co-host Nathan Jeffay put that question to Jameson Lopp, the Bitcoin security researcher who has spent the past year writing the attack scenarios out in full and who authored BIP-361, the first Bitcoin Improvement Proposal of his 14 years in Bitcoin.
Episode three maps what the attack actually looks like: why a quantum attacker works in silence rather than in public, how roughly six blocks of block space could sweep 95% of the most valuable exposed addresses before anyone knows it is happening, what Lopp heard when he asked quantum computing companies directly whether they would take vulnerable coins, why address reuse has already exposed around 30% of all Bitcoin, and why he expects roughly 2.6 million coins to never migrate at all. It closes with the uncomfortable part: what deprecating elliptic curve cryptography would mean for people who cannot move their coins, why Lopp thinks the real constraint is not the computer but the decade Bitcoin needs to agree on anything, and what he actually wants to see happen on Q-Day.
The Quantum Bitcoin Podcast is a series examining the quantum threat to Bitcoin, designed to be watched in sequence. Each episode opens with a discussion between the hosts, presents extended interviews with expert guests on a single key question, and closes with a recap of how the evidence has changed their thinking.
Presented in partnership with Starkware.
CHAPTERS
00:00 Cold open
01:24 What this episode covers
02:08 Rizzo and Nathan set up the question
06:40 Meet the expert: Jameson Lopp
07:38 Why quantum is half a dozen problems at once
10:35 Q-Day and the real target: Bitcoin's signatures
14:16 What a quantum attacker does first
15:58 Six blocks: how the sweep plays out
17:44 Why nobody announces a working quantum computer
20:19 The board meeting: asking the quantum companies directly
22:47 Enigma, salvage law, and the softer target
25:04 Why Lopp refuses to predict a date
27:50 Safe until you spend: the mempool attack
29:44 Address reuse and the 30% already exposed
31:38 The migration math: 17.5 million move, 2.6 million don't
33:41 Why the upgrade takes a decade
36:19 Why Lopp rejects the collective action framing
38:24 A systemic threat, not an individual one
43:49 Deprecating elliptic curve cryptography
46:38 Rescue paths and why nobody gets rug pulled
49:06 Setting the record straight on Satoshi's coins
53:12 Every other chain has this problem
56:40 What Lopp wants to happen on Q-Day
57:30 Recap: what we learned about the attack scenarios
GUESTS
Jameson Lopp is a Bitcoin security researcher and co-founder of Casa, with 14 years in Bitcoin and a decade working in Bitcoin security, previously at BitGo. He is the author of BIP-361, which proposes deprecating elliptic curve cryptography on a fixed timeline to force migration before a quantum attacker arrives, and he publishes his research at lopp.net.
FOLLOW
The Quantum Bitcoin Podcast: https://www.youtube.com/@QuantumBitcoinPodcast
Pete Rizzo: https://x.com/pete_rizzo_
Starkware: https://starkware.co/
Jameson Lopp: https://x.com/lopp
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