James Lovejoy on detecting and mitigating double-spends (EP.111)
On The Brink with Castle Island
Release Date: 08/10/2020
Isha Varshney (Celo) on Stablecoin Adoption Across Markets (EP.631)
On The Brink with Castle Island
Wyatt sits down with from the to talk stablecoins. Covered in this episode: Payments in Kenya and Sub-Saharan Africa Stablecoin usage and USDT The future of non-stable tokens
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Weekly Roundup 05/30/25 (Bitcoin Access Vehicles, GME buys BTC, Pangea Fund) (EP.630)
On The Brink with Castle Island
Matt and Nic are back with another week of news and deals. In this episode: Warning signs for the Bitcoin access vehicles? Has Bitcoin lost the MoE battle? Is OCP 2.0 over? The Dept of Labor rescinds their anti-crypto 401k guidance Cantor Fitzgerald is launching a bitcoin/gold fund Is it mathematically possible to give Bitcoin upside and gold downside? Content mentioned:
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Anthony Yim (Artemis) on Stablecoin Payments from the Ground Up (EP.629)
On The Brink with Castle Island
We sit down with Anthony Yim, cofounder, to talk about the from Artemis, CIV, and Dragonfly, providing brand new estimates of stablecoin payments volume. In this episode: Why we decided to work on the new report How we obtained the estimates Why we decided to put together a bottom-up estimate Stablecoin b2b volumes compared to traditional b2b How do you measure stablecoin transactions? Download the report at
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Markus Franke and Denney Kwok (Mento Labs) on Stablecoins for FX (EP.628)
On The Brink with Castle Island
and from join the show. In this episode: Non-USD stablecoins On-chain FX Microlending and financing for emerging markets
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Weekly Roundup 05/23/25 (Genius Cloture, Sui hack, $Trump dinner) (EP.627)
On The Brink with Castle Island
Matt and Nic are back for another week of news and deals. In this episode: Trump’s crypto dinner reviewed Bitcoin access vehicles NYT stablecoin coverage Sui is hacked and censors the blockchain Kraken is launching tokenized stocks Circle in acquisition talks The GENIUS Act passes Cloture in the Senate Hong Kong passes stablecoin legislation
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Andrew MacKenzie (Agant) on British Pound Stablecoins (EP.626)
On The Brink with Castle Island
Wyatt sits down with , founder of the issuer of GBPA, a pound sterling stablecoin. In this episode: The potential emergence of non-USD stablecoins The prospect of a GBP-backed stablecoin The British crypto regulatory environment How global financial institutions are positioning around stablecoins
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Weekly Roundup 05/16/25 (GENIUS is back, Coinbase data breach, Big Tech stables) (EP.625)
On The Brink with Castle Island
Matt and Nic are back with another week of news and deals. In this episode: Why is Boston such a good sports city? Price inflation in dinosaur skeletons Cryptopunks IP is sold Machinsky is sentenced Nakamoto Holdings launches Meta wants to add stablecoins to its platforms Exchanges are honeypots for KYC data Coinbase suffers a data breach The GENIUS act is going to a vote next week GENIUS act new provisions More Movement shenanigans Thailand is launching a $150m crypto token Content mentioned in this episode: Tuongvy Le and Austin Campbell published a paper, "", which...
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Alex Cutler (Aerodrome) on DeFi’s Next Steps (EP.624)
On The Brink with Castle Island
Wyatt sits down with Alex Cutler, founder of for another episode in our stablefi series. In this episode: DEX trading advantages Building on-chain FX DeFi as a backbone
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TN (Pendle) on Stable Yield (EP.623)
On The Brink with Castle Island
Wyatt sits down with TN, cofounder of . Covered in this episode: How Pendle works The evolution from alt yield to stable yield DeFi's future core assets
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Weekly Roundup 05/09/25 (GENIUS stalls, Coinbase buys Deribit, Bessent on stables) (EP.622)
On The Brink with Castle Island
Matt and Nic are back with another week of news and deals. In this episode: We have a new Pope The etymology of ampersand The GENIUS act collapses spectacularly Coinbase consummates its acquisition of Deribit Did World Liberty Financial’s USD1 torpedo the GENIUS act? Did “pro crypto” democrats snake on the industry Scott Bessent thinks stablecoins could reach $2T The OCC says banks can provide crypto custody and execution Stripe is launching stablecoin financial accounts The SEC explores a sandbox for tokenized securities Tariff the L2s
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]