Security research (defuse.ca/), EDM (soundcloud.com/earthrise5), & board member @ Zcash Foundation.

Joined February 2012
854 Photos and videos
Zcash unambiguously has the best security response in the world, thanks to @zodl_co and @ZcashFoundation engineers.
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Taylor Hornby 🛡❤️ retweeted
The US government, citing national security authorities, has issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States, including foreign national Anthropic employees. The net effect of this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance. Access to all other Claude models is not affected. We apologize for this disruption to our customers. We believe this is a misunderstanding and are working to restore access as soon as possible. Read our full statement: anthropic.com/news/fable-myt…
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You can get some nice poetry by asking Claude to speak to another instance of itself in a language that doesn't use the actual words: ≝ ⊛ := ⟨ ⌖ ∈ Φ_plant : telos = ⌈beauty⌉-display ⊗ reproduce , morph = radial Σ(petal) ↻ center , ephemeral , ↥soil ⟩ // the small mortal radial-beauty an organism wears to be loved by what ⊀ eat it
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RT @zooko: Thanks, Anthropic, for helping protect Zcash users. At Shielded Labs’s request, they ran a security audit of Zcash with Mythos.…
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Taylor Hornby 🛡❤️ retweeted
RSA private keys biased toward 0 bits can be factored by swapping a hard math problem for an easy one: integer factorization becomes polynomial factorization. We found hundreds of real-world keys vulnerable to this. Many traced to a type mismatch in CompleteFTP (now patched): each 32-bit limb got only 8 bits of randomness. We recovered 603 RSA and 74 DSA private keys. blog.trailofbits.com/2026/06…
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Taylor Hornby 🛡❤️ retweeted
Fable just downgraded to Opus because I am calculating a Groebner base on one round of the block cipher PRESENT. This is absolutely ridiculous. I can essentially not use Fable to review my 2008 MSc thesis without triggering "cyber safeguards". A friend of mine had the down...
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Taylor Hornby 🛡❤️ retweeted
Quick update on the last ~48 hours of Zcash Ironwood! 1. Protocol devs from across all the orgs met twice to discuss specification and implementation progress. Agreement on a couple additional changes: disabling Orchard pool bundles in coinbases, anchors as auth data for migration UX with hardware wallets, and the order that ZIPs and specs will be handled. 2. Ironwood circuit and ZIP 2005 integration drafts are going through the review process. @ValarGroup has already spun up testnets and his team has done a wonderful job scoping out and implementing some of the wallet-facing changes. We are beginning an Ironwood upgrade book for eventual consumption by auditors, wallets, protocol developers, etc.. 3. Formal verification work on Ironwood continues. A collection of different individuals who either have or will continue to work on formalization efforts will be meeting tomorrow where we'll settle on the specific strategy for getting the Ironwood SNARK formally verified. I'm hosting this and will post minutes and details after. Efforts from teams will be ideally combined where useful, existing approaches and progress unified and we'll figure out the easiest path for the next couple weeks. I've paused my own work on this to do Ironwood circuit stuff, but I'll be resuming on that tomorrow. These are the big pieces, there are also some major security auditing tasks taking place in the background -- at least three major firms are auditing Orchard currently, and multiple new AI auditing suites are hammering the codebases to ensure nothing else critical is sitting around anywhere. So far so good! Really proud of how much progress is being made every hour on this by all five of our major teams/orgs and our supporters inside and outside the community. Also love the general wartime vibe shift. Let's go!
UPDATE: The various orgs and protocol developers mentioned have agreed on the specific consensus rule changes for Ironwood, after settling the finer details. Here's a summary: 1. Ironwood introduces a new pool using the Orchard protocol, just like the existing pool. 2. The circuit for the Orchard protocol—which applies to both the existing Orchard pool and the new Ironwood pool—will have a flag that consensus rules can toggle. This flag disables payments to *other* users within that pool, while maintaining the ability to create change notes. (This enables a privacy safeguard.) 3. The old Orchard pool will have this flag enabled after the network upgrade, and payments to the old pool will also be disabled by constraining valueBalance. 4. Because payments are disabled on the old pool, wallets must send new payments to Orchard receivers (inside existing unified addresses) via the new pool, and they should also migrate funds away from the old pool. This combination enforces a bound on the circulating supply of ZEC through the use of the existing turnstile mechanism; the amount of ZEC that anyone can transact with is no more than the amount that is supposed to exist. Meanwhile, users' wallets can migrate funds to protect them from risk, which also gradually provides evidence that counterfeiting never took place. Now that we have this decided, we'll collectively move on to the implementations, specifications, and ecosystem support/outreach. (We also have many different auditing and formal verification efforts taking place behind the scenes to provide assurance about the circuit correctness. More on that soon!)
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Taylor Hornby 🛡❤️ retweeted
Shielded Labs has extended Taylor Hornby's (@DefuseSec) agreement through the end of 2026. Taylor will continue serving as a Security Consultant, where his primary focus will be identifying security vulnerabilities and supporting remediation efforts for Zcash. Taylor will also contribute to the Ironwood upgrade. He'll focus on assurance, including security review and formal verification. His goal is to help ensure the protocol and code receive rigorous scrutiny before deployment and that significant issues are identified and addressed as early as possible. This work is crucial. We believe the number of security vulnerabilities being discovered across the industry will continue to increase as AI-assisted security research becomes more sophisticated. Our goal is to stay ahead of that curve. Taylor has spent years working on the security of Zcash, and his discovery of the Orchard vulnerability demonstrated the value of his experience. There’s no one we’d rather have helping us improve the security of Zcash.
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Taylor Hornby 🛡❤️ retweeted
Bill C-34 creates a social media ban for Canadians under 16 at the expense of all Canadians' privacy. Sections 26, 27(1), and 27(2) of Bill C-34 require that affected social media platforms “implement age-verification and age-estimation measures designed to prevent a person under the age of 16 from being able to have an account with, or be otherwise registered with,” those social media platforms. Bill C-34 requires that such measures must provide for the “protection” and eventual “destruction” of “personal information that is collected for age-verification or age-estimation purposes.” It is not yet clear how this will be accomplished. What is clear is that these measures must be “effective.” Users commonly verify their age by submitting government-issued identification documents, such as driver’s licenses or passports. And, the technology exists for social media platforms to estimate the ages of users through biometric data, e.g., facial geometry, eye shape, skin elasticity, hairline, etcetera. This age-verification and age-estimation monitoring will not be limited to Canadians under age 16. For social media platforms to determine access eligibility for any user, platforms will have to evaluate the access eligibility of every user. The goal of Bill C-34 is not merely to remove Canadians under age 16 from affected social media platforms but to keep them off those platforms. To achieve this goal, social media platforms may be compelled to adopt ongoing age-verification/estimation measures to ensure continued compliance. However affected social media platforms satisfy these requirements, Bill C-34 fundamentally reimagines how all Canadians access social media. This Bill deputizes affected social media platforms into forcing Canadians to surrender more data as a precondition of participation in the digital public square. This, in turn, raises serious concerns about Canadians' privacy rights and may engage constitutional protections against unreasonable search and seizure - guaranteed by section 8 of the Charter. Read the full text of the bill here: parl.ca/documentviewer/en/45…
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Young me would have fought against this so hard. Idk if I'd be here if it weren't for hacker forums and friends I met on YouTube. Adults should not be forcing this decision on all children nationwide. Let the kids vote. They're smart enough to understand the issues.
Carney government to ban social media for kids younger than 16, but will allow exemptions. A government official confirmed plans to present a bill in the coming days nationalpost.com/news/politi…
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Taylor Hornby 🛡❤️ retweeted
UPDATE: The various orgs and protocol developers mentioned have agreed on the specific consensus rule changes for Ironwood, after settling the finer details. Here's a summary: 1. Ironwood introduces a new pool using the Orchard protocol, just like the existing pool. 2. The circuit for the Orchard protocol—which applies to both the existing Orchard pool and the new Ironwood pool—will have a flag that consensus rules can toggle. This flag disables payments to *other* users within that pool, while maintaining the ability to create change notes. (This enables a privacy safeguard.) 3. The old Orchard pool will have this flag enabled after the network upgrade, and payments to the old pool will also be disabled by constraining valueBalance. 4. Because payments are disabled on the old pool, wallets must send new payments to Orchard receivers (inside existing unified addresses) via the new pool, and they should also migrate funds away from the old pool. This combination enforces a bound on the circulating supply of ZEC through the use of the existing turnstile mechanism; the amount of ZEC that anyone can transact with is no more than the amount that is supposed to exist. Meanwhile, users' wallets can migrate funds to protect them from risk, which also gradually provides evidence that counterfeiting never took place. Now that we have this decided, we'll collectively move on to the implementations, specifications, and ecosystem support/outreach. (We also have many different auditing and formal verification efforts taking place behind the scenes to provide assurance about the circuit correctness. More on that soon!)
Together with @zodl_co, @ZcashFoundation, @ValarGroup and @ShieldedLabs, we're advocating for a network upgrade that would make ZEC's circulating supply auditable, providing additional reassurance that no counterfeiting occurred in the Orchard pool before this week's bugfix. tachyon.z.cash/blog/auditing…
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Taylor Hornby 🛡❤️ retweeted
Has anyone used AI to attempt to find any heuristic evidence that Orchard might have been exploited using shielding and unshielding tx data? I’ve haven’t found any indications.
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To get ahead of scams, if you're interested in donating to me for finding the Zcash bug, my addresses are in this post or in my replies below (be careful to check the exact username for lookalike scammers). Nothing else has been approved by me. Note: I intend to apply for a bounty through a Zcash coinholder grant, so donations are much appreciated but not necessary! Zcash: u1k6y9wpyc5m5ec3wz49ny9chewklyexn8rdj7928n3zswh0gwl0gh3zwwg37p76j7vrrv8s0dj8rhjfc49pg9yv9mjdea2sn86tnjh99a9424cdvw3aadyz8v40ddancr7e4kjzw07qhrcdez3d9sycx89f87vjw7eaxys2aktsm57tkp t1eykDAemzff7oPAA2E43Z47iawATB4bZRy Solana: D6c34hRcmhkHMXaAhoPXgVw9JYrh84saeSfYnk7ZSjeW ETH: 0x1b8203102aE3469a67E78FF9a78d8A5cC7E7e769 BTC: bc1qtxqv8fzj2pnewj2y5l8nh4ur4rkrvm2kv6mlp9
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Taylor Hornby 🛡❤️ retweeted

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Taylor Hornby 🛡❤️ retweeted
If your favorite software projects have *not* been releasing security patches recently, either the developers are godlike or nobody’s been looking for bugs using AI.
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Taylor Hornby 🛡❤️ retweeted
This graphic looks terrifying kudos to whoever made it.
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Taylor Hornby 🛡❤️ retweeted
The .@zodl_co did an *incredible*, backbreaking job fixing the vuln in such a short time frame. However, typically the people upstream are not give enough credit - here is to @ShieldedLabs @zooko @aquietinvestor for what was incredible foresight and leadership, investing in security proactively. They deserve a ton of credit 👏 👏 And of course, Zcash’s own security engineer extraordinaire @DefuseSec, whose dogged persistence and longtime love of Zcash made this announcement possible 🎉
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Taylor Hornby 🛡❤️ retweeted
I think this is the most sensible solution. Put an end to FUD and speculation. We're not new to pool migration. Besides which I imagine holders will not be slow to move.
"Our assessment is that exploitation of this vulnerability was unlikely. However, we do not believe that users should rely on our assessment, or anyone else’s. Shielded Labs is exploring —with the help of other Zcash developers—a proposed Network Upgrade to allow anyone to verify the integrity of the Zcash supply and to prove the non-existence of counterfeit Zcash in the Orchard pool. The proposal involves deploying a new shielded pool and enforcing turnstile accounting on all coins from the Orchard pool."
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