AI Is Rereading Crypto’s Old Code, and Finding What Humans Missed

Key Takeaways

• Zcash had a 4-year-old flaw hiding in its code until Claude Opus 4.8 helped a researcher finally uncover it.
• Coldcard’s 2021 firmware flaw preceded more than $100 million in estimated bitcoin thefts across thousands of addresses.
• Chainalysis says malicious onchain dead-drop activity jumped 440%, showing how quickly AI-assisted threats are picking up steam.

Things are certainly changing fast. An encrypted German Army transmission from July 1941 survived 85 years before an AI-assisted effort finally cracked it this month. The message was almost comically ordinary, essentially someone in Rosenow asking which way to march, but AI agents helped search archives, write code, simulate Enigma, and test possibilities until the old problem gave way. Crypto has spent 2026 discovering what happens when that ability to look again gets pointed at software containing actual money.

AI Goes Hunting Through Old Code

Zcash provided one of the cleanest examples in May. Researcher Taylor Hornby, working for Shielded Labs, used Claude Opus 4.8 in a custom audit agent and uncovered a flaw in the Orchard shielded-pool circuit dating to 2022. In testing, the vulnerability could create unlimited counterfeit ZEC without detection. No theft was established, and developers patched it within days, but a potentially catastrophic bug had survived roughly four years before AI-assisted review found it. Later, the Zcash team claimed to leverage Mythos to parse and audit the code and found no new bugs.