@rainjlin

Software Engineer

Taiwan
Joined June 2021
Yu-Chieh Lin retweeted
gm ☕ here's your weekly reminder to trust yourself
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Yu-Chieh Lin retweeted
Replying to @iancr
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Yu-Chieh Lin retweeted
🛡️
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Yu-Chieh Lin retweeted
⚛️ Bitcoin does not have a quantum computer problem today. It has a migration problem, and migrations could take years to get right. SHRINCS is the first Bitcoin-specific post-quantum proposal I have seen that makes a serious end-to-end trade-off, and it deserves to be read carefully rather than cheered or dismissed. Their work is the proposal. I wrote an analysis of the challenges that come with it, the ones that only become visible when you look past the signature scheme and into the wallets that have to run it. The migration really has three questions: - which scheme Bitcoin should support - what that scheme does to the protocol and the wallet ecosystem - what happens to coins that have never been moved by their owner. Almost all of the public discussion is still on the first one, which is probably the easiest of the three. SHRINCS is conservative where it matters. It is hash-based, so it leans on the SHA-256 that Bitcoin already depends on instead of stacking a lattice assumption on top. A single 48-byte public key commits to both a compact stateful path (Flexible XMSS and WOTS+C) and a stateless SLH-DSA fallback. Verification is the pleasant surprise. It is mostly SHA-256, and the draft reports a worst-case cost per signature byte below BIP340 Schnorr. The stateful path uses one-time keys, and each one must sign exactly once. The counter must never move backwards, it must be committed to persistent storage before the signature leaves the device, and it must never be restored from a backup. Sign two different messages from the same slot and an observer can steal your fund. SHRINCS handles this better than a purely stateful scheme. If the state is lost or merely uncertain, the seed still derives the stateless key, so you lose efficiency rather than funds. The cost is that wallet state stops being application data and becomes cryptographic state whose rollback can take user funds: hundreds of counters for hundreds of UTXOs, across several devices and several software wallets, on hardware where hash-based keygen already takes minutes. There are also capabilities we do not get back. Non-hardened BIP32 derivation, and with it watch-only wallets as we build them today. Compact Schnorr-style threshold signing. None of this makes SHRINCS a bad proposal, and the spec is honest about its own status: non-standard SLH-DSA parameters, constructions outside the NIST standard, security proof pending. It does mean the cost of this migration cannot be only measured in signature bytes. The stateful aspect of SHRINCS would be very challenging in terms of security and UX. The uncomfortable part is that picking the signature scheme may be the easiest question here. ledger.com/blog-shrincs-bitc…
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Yu-Chieh Lin retweeted
Welcome to 2026 :)
Been using LLMs the entire year, but yesterday was the first time I sent them out bug-hunting proper in my codebase. Well... we're fucked. They traced a way to brick an Ark, going from the mobile app, through the cloud, laptop it's plugged into, firmware, USB stack, kernel.
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Yu-Chieh Lin retweeted
C-level access isn't something students usually get. Our CTO @P3b7_ sat down with Blockchain at Berkeley for an hour on post-quantum and AI agents. @CalBlockchain nitter.cf/CalBlockchain/status/2…
How secure is your crypto in cold storage? 🔐 We sat down with Charles Guillemet (@P3b7_), CTO of @Ledger, to discuss hardware wallet security, post-quantum cryptography, and exploit-resilient agentic payments. Full podcast out now. 🎙️
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Yu-Chieh Lin retweeted
GM. keys offline. peace of mind. let's go.
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its a gm because the coffee is hot and the assets are secure 🤝
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Yu-Chieh Lin retweeted
AI-accelerated attacks are already here. Meet the AI force for good that's been built to stop them by @DonjonLedger 👇
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Yu-Chieh Lin retweeted
Security used to depend on flaws being expensive to find. AI made them cheap. High-severity flaws flagged in 2026 are already 6x the four-year average. Our CTO @P3b7_ sits down with @Mo_RELS, Head of Brand Development, to discuss what that does to the threat model, why secure hardware holds where connected software folds, and the ethics of finding bugs at machine speed. Full episode here 👇
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Yu-Chieh Lin retweeted
Nothing can shut down open source. GitHub Status this morning would like a word.
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Yu-Chieh Lin retweeted
Everyone's worried about their AI agents going rogue. But the real question isn't "will AI agents act without your permission?" It's "when they try, what stops them?" Ledger signer, your hardware root of trust.
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Yu-Chieh Lin retweeted
Musk, Altman and Dario are predicting the end of the world again and asking everyone to slow the frontier. In a couple of months they will ship a stronger model. These PR rituals are now part of the PDLC! We now have dozens of open-weight models with weak or removable guardrails, sitting very close to the closed frontier. On a lot of verticals, specialized models already beat the general ones. You could control nuclear spread because the moat was deep knowledge, materials and plant. Here the moat is mostly capital. The economic prize is huge. I don't see how humans globally agree to leave that value on the table so a rival doesn't take it. We've run that competition for millennia. Pacing three US labs does not pace open weights, China, or the next team that trains on leaked outputs. The models are already out of the room they want to pace.
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Yu-Chieh Lin retweeted
Finding a security flaw used to take an expert months. It now just takes a prompt. High-severity vulnerabilities flagged in 2026 are already 6x the four-year average. And we're just getting started. But there is hope. Our CTO @P3b7_ sits down with @Mo_RELS on what changed, why secure hardware holds where software folds, and what you can do about it. Subscribe wherever you get your podcasts. Full episode next week.
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Yu-Chieh Lin retweeted
it's as if we knew 😅
Introducing the world's first foldable signer. Meet Ledger Bend™. When the market's not looking so great, simply fold your signer away. Out of sight, out of mind. Unfold when green candles return. Your keys stay offline either way 🔐
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Keystone wholeheartedly supports this 🤝 We've always believed security is stronger with multiple experts on it, not just one team. That's part of why we open-sourced our code, so researchers worldwide can scrutinize it, find gaps, and help us improve. It's also how we've built partnerships with @SlowMist_Team, @BlockSecTeam, @Offside_Labs, @zknoxhq & @OneKey_Anzen to harden our codebase, and in every one of those, responsible disclosure made the difference. It gave us time to ship fixes and get our users updated before anything went public. Now, AI is lowering the barrier to security research, and more people are finding bugs than ever. That's great for the community, but how that information gets handled matters a lot more when people's funds and years of builders' work are on the line. That's exactly why responsible disclosure is a must. We're glad to join our industry peers in making this the standard, and we'll hold up our end. Respect to @P3b7_ for stepping up and leading this 🤝
📌 AI made finding bugs cheap, but it didn’t make responsible disclosure optional. Finding and exploiting vulnerabilities has never been easier. A few hours of prompting now does what used to take a skilled researcher weeks. Unfortunately, defenders no longer enjoy the asymmetry they relied on. Security is still a cat-and-mouse game, but with many more cats, the user suffers. Which is exactly why the process around disclosure matters more than ever. How it works, and it is not complicated: ➤ A researcher finds a bug and contacts the vendor privately. ➤ The vendor reproduces, acknowledges, and both sides agree on a timeline. 90 days is the common default, more or less depending on severity, capacity to fix... ➤ During that window both sides keep it secret while the vendor fixes and ships. ➤ Once users are protected, both sides publish. The ecosystem learns. The researcher usually gets paid. The issue now is the barrier is so low that anyone can surface a finding with no security background, and some skip straight to the audience: ❗Presenting a reproduction of an already-fixed bug as a live compromise. ❗Full disclosure of a bug that is not fixed yet. ❗"Critical vulnerability found" teasers, dripping details for engagement. Call it what it is: attention farming with someone else's risk. When the bug sits between a user and their funds, this is reckless. Especially in crypto, where there is no chargeback. But the damage doesn't require live funds to be at stake. Manufactured panic causes harm of its own, because it drives people away from self-custody, and that damages the whole ecosystem. So I have three asks: 1️⃣ For users: software and hardware have bugs, always. The single most effective thing you can do is stay updated and follow basic security hygiene. That has never mattered more than today. The time between releases and malicious actors exploiting the vulnerabilities have shrunk dramatically due to LLMs and that one can't afford to be passive and postpone security updates any more 2️⃣ For new researchers with a fresh model and a real, validated finding: welcome, we need you. Use the vendor's disclosure process. That is not bureaucracy. It is the difference between making the ecosystem safer and putting users in the crosshairs for a few likes. Remember that security communication must be accurate and proportionate. State the severity, affected versions, and fix status in the first sentence, not the tenth. 3️⃣ And to everyone building in this industry, vendors and researchers alike: let's make coordinated disclosure the norm we defend out loud, not the fine print. Reward the researchers who do it right. Refuse to amplify the ones who trade user safety for reach. This is how we win, together. Some of the actors already support the initiative. @Ledger @Trezor @FoundationHQ @AnchorWatch @_SEAL_Org and others Spread the message.
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