James Lovejoy on detecting and mitigating double-spends (EP.111)
On The Brink with Castle Island
Release Date: 08/10/2020
Weekly Roundup 07/18/25 (GENIUS is Law, Clarity passes, narrow banking and GENIUS) (EP.647)
On The Brink with Castle Island
Matt and Nic are back for another week of news and deals. In this episode: The Coldplay concert incident It’s Crypto Week in Washington Talos acquires Coin Metrics Do you need an MTL to run a fantasy football league? GENIUS Act is law pending Trump’s signature Clarity Act passes the House ICO Fairshake raises $141m Grayscale is preparing for an IPO Adam Back’s Bitcoin access vehicle Polymarket beats the allegations Is GENIUS creating a narrow bank system? Governor Waller's comments on stablecoins and banks
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Nikhil Raghuveera (Predicate) on Policy Engines for Blockchains (EP.646)
On The Brink with Castle Island
Wyatt sits down with of to talk policy for blockchain applications. In this episode: How Predicate’s “rules for blockchain transactions” are making on-chain finance more scalable and secure Creating more compliant stablecoin transfer systems suitable to mass financial use cases The future of secure money movement How leading software and financial firms can integrate transaction policies in their workflows
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Weekly Roundup 07/11/25 (New BTC ATH, Crypto Week, Zelensky suit scandal) (EP.645)
On The Brink with Castle Island
Matt and Nic are back for another week of news and deals. In this episode: Bitcoin hits a new ATH and no one is talking about it Grok goes haywire The White House posts chudjak Core Weave looks to buy Core Scientific Stablecoins are going to pay yield anyway Did Zelenskyy wear a suit? How should prediction markets be settled? ICO is coming up Hester Peirce issues a warning on tokenized securities Crypto Week in Congress is coming up Jonathan Gould has been confirmed as Comptroller of the Currency There are new public access vehicles Andreessen wants you to leave Delaware A fundamental...
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Zac Townsend (Meanwhile) on Bitcoin Life Insurance (EP.644)
On The Brink with Castle Island
, the founder and CEO of , joins the show. In this episode we discuss: Zac’s background and the path that led him to start Meanwhile. The mechanics of Bitcoin denominated life insurance. How Meanwhile generates Bitcoin yield. Zac’s views on the evolution of Bitcoin treasury companies. To learn more about Meanwhile visit
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Charles Hamel (Opera MiniPay) on Globalizing Dollar Access (EP.643)
On The Brink with Castle Island
Charles Hamel, Product Director at joins the show. In this episode: Stablecoin habits in emerging markets Prospects for local stablecoins What’s next on the stablecoin horizon
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Weekly Roundup 07/04/25 (Tokenized stocks, Crypto Week, BBB passes) (EP.642)
On The Brink with Castle Island
Matt and Nic are back for another week of news and deals. In this episode: EthCC troubles Robinhood has been shipping Figma owns BTC The House GOP has declared "crypto week" in July Circle and Ripple are applying for bank charters AI companies are buying Bitcoin miners Sharia finance The BBB passes America teeters towards default The Sohan Parekh fiasco How do tokenized stocks work? Another architect of OCP2.0 bites the dust Is AI going to usher in a socialist revolution? Ric Edelman wants you to buy crypto Franklin Templeton is worried about...
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Chris Maurice (Yellow Card) on Stablecoin Adoption in Africa (EP.641)
On The Brink with Castle Island
Chris Maurice, founder of , a pan-Africa stablecoin business and exchange, rejoins the show. In this episode: How Chris feels about the crypto space in 2025 as compared to when he started a decade ago How Yellow Card evolved from being a retail BTC exchange to being an enterprise payment platform for stablecoins How Chris realized that stablecoins were all about b2b transfers How businesses in EM use stablecoins, and what the alternatives are Regional differences within Africa in terms of stablecoin adoption Shifting regulatory attitudes in Africa Does Chris worry about crypto-dollarization...
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Bernardo Bilotta (Stables Money) on Stablecoin Fintech in APAC (EP.640)
On The Brink with Castle Island
Wyatt sits down with , founder of In this episode: Stablecoin usage in APAC, for saving, spending, and beyond Retail adoption that bleeds into institutional adoption The forward-looking path for stablecoin finance
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Weekly Roundup 06/27/25 (Bitcoin for mortages, Fiserv adopts stables, Fed drops reputation risk) (EP.639)
On The Brink with Castle Island
Matt and Nic are back for another week of news and deals. In this episode: Golden age of prediction markets NYC mayor’s election What’s happening with Canton? The FHFA says crypto can be a qualifying asset for mortages Our thoughts on the market structure bill The significance of the Fiserv stablecoin pilot $500m public access vehicle for BNB The Fed drops reputational risk in bank supervision EO for debanking is rumored Kraken HQ is moving to Wyoming Texas buys Bitcoin Will banking hours be obsolete?
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Josh Frank (The Tie) on Crypto Market Intelligence (EP.638)
On The Brink with Castle Island
, the founder and CEO of joins the show. In this episode we discuss: The origin story behind The Tie and how Josh approached founding the business. The digital asset data market. How sentiment data has evolved in the digital asset industry. The buy-side landscape for digital assets and how Josh sees that evolving in the coming years. The Canton Network and how The Tie is working with this new protocol. To learn more about The Tie visit their .
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]