James Lovejoy on detecting and mitigating double-spends (EP.111)
On The Brink with Castle Island
Release Date: 08/10/2020
Weekly Roundup 11/27/25 (Who we are thankful for, S&P downgrades Tether) (EP.687)
On The Brink with Castle Island
Matt and Nic record a special Thanksgiving episode of OTB. In this episode: What’s the deal with deep fried turkeys? Polymarket gets CTFC approval Klarna is launching a stablecoin on Tempo Upbit is hacked Berachain drama Tether gets a downgrade from S&P Robinhood is spinning up their own prediction market with Susquehanna Are Visa and Mastercard moving fast enough? Who are we thankful for?
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Weekly Roundup 11/21/25 (Quantum FUD, DAT hangover, stablecoin duration risk) (EP.686)
On The Brink with Castle Island
Matt and Nic are back for another week of news and deals. In this episode: Is Quantum FUD causing Bitcoin to sell off? Ray Dalio is worry about Quantum Scott Aaronson is worried about quantum computing Vitalik is worried about quantum Quantum upgrade scenarios Are we still suffering from the flash crash? The DATs are selling DAT spot arbitrage Will the US government end up with the Satoshi coins Should the government bail out AI? Will NFTs come back? IBIT is Harvard’s largest 13F position David Frum on stablecoins Will stablecoins require a bailout?
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Weekly Roundup 11/14/25 (Miran speech, Cash App adds Stables, DAT Hangover)(EP.685)
On The Brink with Castle Island
Matt and Nic are back for another week of news and deals. In this episode: The Senate Ag Cmte publishes a Market Structure draft Paul Atkins’ token taxonomy speech Fed Governor Stephen Miran gives a major stablecoin speech Grayscale files their S-1 Coinbase announces a tokensale platform Coinbase is leaving Delaware The Coinbase BVNK deal falls through Visa Direct adds stablecoin support The Czech republic buys Bitcoin DATs are struggling CBDC holdouts Jack Dorsey bends the knee on stablecoins Content mentioned: Stephen Miran,
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Weekly Roundup 11/07/25 (Balancer hack, DATs are suffering, Zcash rally) (EP.684)
On The Brink with Castle Island
Matt and Nic are back with another week of news and deals. In this episode: Tom Brady’s clone dog We reminisce on the Nic Carter v Mike Green debate Is the government shutdown draining market liquidity? The trouble with Opendimes Balancer hacked Stream finance’s xUSD collapses DATs are selling coins Why is Zcash rallying? Are stablecoins the lightbulb of crypto Content mentioned: JW Verret,
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Keone Hon (Monad Foundation) on Blockchains Built to Scale (EP.683)
On The Brink with Castle Island
, founder of the Foundation joins the show. In this episode: From the point of view of Keone's trading background, what is the promise of blockchains? Reimagining financial systems with blockchains in 2025 Why build Monad, and for anyone using a chain, why use Monad? How the importance of decentralization and chain efficiency becomes underscored during fragile market periods Auto-Deleveraging (ADL): What it is and why it is important. Where is there economic efficiency to be created? How has Keone gone about building a team to tackle this challenge? What would make Monad "successful" in 2-3...
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Giovanni Vignone (Octane Security) on Protecting Onchain Assets (EP.682)
On The Brink with Castle Island
Wyatt sits down with , the founder of , a crypto security platform focused on vetting application code pre-deployment. In this episode we discuss: What poses the greatest threat to crypto right now? How are hackers evolving? What are the important categories of crypto-facing cybersecurity? How much should startup teams be spending on security? How should teams think about counterparty risk? What do you wish early stage teams knew? Where is there room for improved security practices across the industry?
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Weekly Roundup 10/31/25 (DATs selling coins, prediction market problems, Bessent’s pesos) (EP.681)
On The Brink with Castle Island
Matt and Nic are back for more news and deals. In this episode: Mastercard buys Zerohash for around $2b Fiserv has a catastrophic day Bitwise launches a Solana staking ETF Is there another regional banking crisis? EthZilla sold some ETH to buy back shares Will there be activists with the DATs? Are prediction markets structurally doomed? Sen Tillis introduces the Ensuring Fair Access to Banking act Could you go back and time and trade effectively? Bessent’s great peso trade What’s going to happen with Venezuela? We review the Iran-Contra scandal Content mentioned in this episode: ...
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Geetha Panchapakesan (Tesser) on Enabling FIs to Utilize Stablecoins (EP.680)
On The Brink with Castle Island
, the founder and CEO of , joins the show. In this episode: Geetha's background in payments and how she arrived in stablecoins Major shifts across payments over Geetha’s career Building a one-stop shop solution for financial institutions, PSPs and MSBs Where FIs are today as it relates to engaging to stablecoins Regulatory tailwinds post-GENIUS See more at
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Weekly Roundup 10/24/25 (Quantum, Crypto Pardons, Fed Payment Accounts) (EP.679)
On The Brink with Castle Island
Matt and Nic are back with another week of news and deals. In this episode: Old fashioned crime is back Quantum risk to Bitcoin More outcry in Washington over the Democratic edits to market structure CZ gets a presidential pardon Federal Reserve announces a payments charter
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Weekly Roundup 10/17/25 (Flash crash, pig butchering scam busted, Erebor charter granted) (EP.678)
On The Brink with Castle Island
Matt and Nic are back with another week of news and deals. In this episode: We dissect the market structure behind the flash crash last week What happened with Binance and Ethena? Palmer Luckey’s de novo bank Erebor gets an OCC charter Paxos’ fat finger The US government has seized $15b in funds tied to pig butchering scams
info_outlineJames Lovejoy, recent MEng MIT grad and former graduate researcher at the MIT Digital Currency Initiative, joins the show to talk about his masters thesis and associated project focusing on detecting double-spends in proof of work cryptocurrencies. Previously, little data was collected in a systematic way to detect double-spends and reorganizations across many cryptocurrencies. James' project sheds light on previously unknown security properties of PoW. In this episode:
- How James came to work on Vertcoin
- Why James thinks ASIC resistance is valuable
- James' blockchain monitoring project and why it matters
- Why reorgs are challenging to detect
- Why investigating the economic damage of reorgs is difficult
- How James noticed a 51% attack in progress on Vertcoin and intervened to save Bittrex money – and how this can be replicated
- Why understanding Nicehash is critical to detecting and dealing with 51% attacks
- James' critiques of dominant theoretical models of PoW security
- How James found reorgs and counterattacks happening on BTG in real time
- Why exchange processes like KYC might actually help protect blockchains from reorgs
- How permissionless trading and leverage makes certain blockchains more vulnerable to attacks
- Rules of thumb for confirmation requirements for exchanges
- The issue with calling coins "Nicehash-able" – and why it's likely a lowball
- How exchanges can proactively mitigate the risk of 51% attacks and what they should be targeting
- How BTG developers finally defeated deep reorgs
- Whether James is confident in the long-term prospects of PoW
- Whether James still believes in GPU mining
Content referenced in this episode
- James Lovejoy, An Empirical Analysis of Chain Reorganizations and Double-Spend Attacks on Proof-of-Work Cryptocurrencies
- Raphael Auer, Beyond the doomsday economics of “proof-of work” in cryptocurrencies
- Eric Budish, The Economic Limits of Bitcoin and the Blockchain
- Hasu, Prestwich, and Curtis, A model for Bitcoin's security and the declining block subsidy
- Carlsten, Kalodner, Narayanan, Weinberg, On the Instability of Bitcoin Without the Block Reward
- Moroz, Aronoff, Narula, Parkes, Double-Spend Counterattacks: Threat of Retaliation in Proof-of-Work Systems
- Judmayer et al, Pay-To-Win: Cheap, Crowdfundable, Cross-chain Incentive Manipulation Attacks on Cryptocurrencies
- Liao and Katz, Incentivizing Blockchain Forks via Whale Transactions
- James Lovejoy and David Vorick, ASICs and cryptocurrencies: benefits and drawbacks [debate]
- Nic Carter, It's the settlement assurances, stupid [blog]
- Elaine Ou, Cryptocurrency Deals can Always be Erased, for a Price [article]