Cryptologist and cybersecurity researcher ZK · Post-Quantum Cryptography · Secure Systems Building @encryptorium Author of Cleartext · https://teapawt.org/t.co/7h9NoaHgfO
Joined May 2025
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Andreas Renz retweeted
so happy with the @Cloudflare job, ngl before joining I thought the motto “help build a better internet” was just another mission statement, but ppl genuinely care about it and about transparency, asking themselves “does this help build a better internet?” when designing new features/products, and holding themselves to high ethical standards, loving it 🧡
and PS: really cool announcements coming up next week 🎂
Andreas Renz retweeted
Can a sufficiently powerful quantum computer forge the signatures used to authorize Bitcoin and Ethereum transactions? What would it take to upgrade both networks before that happens?
In this new lecture, Stanford cryptographer @danboneh explores why blockchains may turn to signatures built from hash functions. He also presents new research on threshold signing.
The talk ends with the questions Bitcoin still has to answer, including whether post-quantum signatures will require larger blocks, what happens to abandoned coins, and how someone such as Satoshi could prove ownership after Bitcoin’s current signatures have been retired.
00:00 Why blockchains need to prepare for quantum computers
03:05 Why Bitcoin may bet on hash-based signatures
06:25 The “big footgun” in stateful signatures
08:58 A quantum-safe signature that takes one billion hashes
14:13 Inside SLH-DSA’s virtual tree
20:30 How Bitcoin and Ethereum could make the switch
23:48 What happens when a wallet loses its state?
32:47 Can threshold signing survive the quantum transition?
36:39 How to hide lattice cryptography from the blockchain
38:49 Why threshold one-time signatures seem impossible
45:36 How context prevents forged signatures
49:37 The forgotten idea behind Winternitz signatures
54:50 Turning one-time signatures into threshold signatures
1:04:27 Will quantum-safe signatures require bigger Bitcoin blocks?
1:06:26 Abandoned bitcoin and Satoshi’s recovery problem
Andreas Renz retweeted
Most PQC migration plans assume the hard part is choosing algorithms. For a lot of deployed zero-knowledge, the hard part is that the thing needing replacement is the verifier, and you probably don't control its schedule.
March made the distinction concrete. OtterSec broke six zkVMs on a Fiat-Shamir transcript binding bug. Jolt, Nexus, Cairo-M, Ceno, Expander, Binius64. Six organizations, one mistake, fixed in a line or two each. Weeks later Trail of Bits forged an attestation against Google's zero-knowledge proof of quantum cryptanalysis, not with a quantum computer but with memory safety defects in the Rust guest program. SP1 worked. Groth16 worked. The proof system faithfully proved a program that would accept invalid resource accounting.
Both failures were local. Both got patched.
Shor is not local, and there is no defective code to fix. Andreas Renz's (@0xLoopTheory) layered analysis is the map I've been using here, because it separates the question people ask, which algorithm, from the one that decides the outcome, which is whether the commitment layer can be swapped at all. Groth16, Halo 2, Bulletproofs and common Nova instantiations fail that test. They need a successor proof system and a new verifier, sometimes behind a fork.
Zcash paid the cheap version of that bill in July. Two months, a hard fork, a pool closed to deposits, and it never changed proof systems at all.
Nobody outside a protocol can schedule the expensive version. That is the part I think this industry has not priced.
postquantum.com/post-quantum…
#zeroknowledge #PQC #infosec
Andreas Renz retweeted
Okay, so I am going to document my current ongoing(feb-now) journey to learn cryptography and ZK .
I actually came to know about zk in dec 2025.
I was so fascinated that i thought lets do it, only to realise few weeks later what have i taken a dip into.
And from mar 2026 , Moonmath Manual study group started. Initially , since no one was coming forward to lead the discussion, i put myself out to lead the sessions. Few days later Nicolas Huber(PhD scholar) also joined to lead.
Why this ?
1. accountability
2. better articulation of thoughts - I(we) mostly think, we know something until the time comes to actually explain it to someone. And I(we) freeze.
3. inspire other ppl.
The format is gonna be very popular 1001 from @0xLoopTheory
Although i have started my journey in feb 2026, but i am starting this documenting stuff , after almost 5 months.
We are still going through @LeastAuthority moonmath manual, so if you are interested, you can join us by joining
Grateful for the community :
@__zkhack__ for the platform, whiteboard session, etc...
Nicholas Huber - for leading the sessions with me.
@AnnaRRose - for her consistent contribution in zk community, manages podcast, zkmesh, zkhack, etc
@LauriPelto - giving insights
@LeastAuthority for the moonmath manual
@Jeyffre he is the reason i came to know about zk
@RareSkills_io - for the zk book
We are currently going through @LeastAuthority moonmath manual chapter 6.
We have went through arithmetic, abstract algebra, and elliptic curve. And it was a pure ride.
If you wanna join, join the zkhack discord.
The discussions are lead mostly by Nicolas Huber and me
I know i(we) have a long way to go. But why not enjoy the process.
Cheers...
Andreas Renz retweeted
Google Trust Services shifts some Google services to ECDSA leaf certificates by default in Q2 2026. Classical cleanup, not PQC: how TLS migrates in layers.
#postquantumcryptography #webpki...Show more
Andreas Renz retweeted
Yesterday I wrote that it had finally sunk in. Today the first copy arrived in the mail.
A real book. Real weight. My name on the spine.
I've looked at this cover on a screen a hundred times. Holding it is something else entirely. Thank you all. 💙
Andreas Renz retweeted
I’ve moved my active posting to @0xLoopTheory .
That’s where I write about cryptography, PQC, ZK, secure systems, and the projects I’m building now.
This old account will stay parked, but I won’t really use it anymore.
Andreas Renz retweeted
We’ve received notice that the Department of Commerce has lifted export controls on Claude Fable 5 and Mythos 5.
We'll begin restoring access tomorrow, and will share an update soon.
We’re grateful to our users for their patience, and to everyone who worked with us on redeploying the models.
Andreas Renz retweeted
Yesterday we wrapped up our 14th edition of the zkSummit. Hosted in Rome, it was honestly one of our best yet.
Thanks to everyone who came out, to the speakers, sponsors and team! 💜🇮🇹
All videos are coming throughout the coming week! #zk14
Andreas Renz retweeted
Already received some great feedback. Would love to have more eyes on it to refine the book.
If you are interested or know someone who is, please let me know.
And please share to reach the right people :)
Thank you!
Andreas Renz retweeted
🎙 For ep 400, @AnnaRRose brings back @danboneh — Stanford professor & one of the sharpest minds in crypto. They cover Google's quantum algorithm announcement, why rushing PQ transitions might be riskier than quantum itself, algebraic vs hash-based signatures, hybrid sig schemes, new ZK advances, and the Ethereum Foundation's $ 1M Proximity Prize. A milestone episode.
zeroknowledge.fm/podcast/400…
Andreas Renz retweeted
If you are in this situation, use @RareCodeAI
You CANNOT learn Rust from reading a book or watching a video.
You must get your hands dirty and put in the reps.
However, "getting your hands dirty" with Rust is very dizzying because the compiler is so strict.
How RareCode does it
1) Carefully design the problems to steer the student clear of unexpected issues
2) Slowly introduce new syntax through direct practice while reviewing prior syntax
Most Rust courses are designed as "here is a list of things you need to learn."
RareCode is designed as "what realistic programming problems can the student solve given their level of knowledge, and what new problems can we introduce that motivate new syntax while reviewing previous lessons?"
Only after you've done the reps will everything you read in books stick. Without the reps, you will be in a doom loop of watching and rewatching tutorials.
Andreas Renz retweeted
A week ago I wrote about PQC fear-selling. This week @solana published "Quantum Readiness." Same anti-pattern from opposite ends.
Vendors substitute urgency for discovery. L1 announcements substitute reassurance for discovery. Both skip the same step: the actual threat model.
The engineering signal in the Solana post is real. @anza_xyz and @jump_firedancer chose Falcon independently, and that is the kind of convergence you want to see when an L1 commits to a primitive.
The framing around it is where it gets soft. Six specific places: the "ahead in preparation" claim against Ethereum, public-key exposure for dormant accounts, "quick" migration that skips the mechanism, Winternitz Vault scope, Falcon implementation hazards, and performance reassurance without migration-level numbers.
Full piece, now live on @hackernoon: hackernoon.com/solanas-quant…
Andreas Renz retweeted
I need to get this off my chest: the way some people talk about post-quantum migration genuinely grinds my gears.
Not because they are worried about quantum computers. They should be. Not because they ask about hybrid algorithms. That is a valid question.
What grinds my gears is the confidence.
People jump straight to "which algorithm should we roll out?" before they can answer the much more boring question: "where are we even using cryptography?"
I keep seeing the same pattern. Hybrid this, PQC-ready that, apply it across the board, put it on the roadmap, add it to the slide deck. It all sounds serious until you ask where the crypto actually lives. Then suddenly the answer is somewhere between a config file, an old diagram, a vendor promise, and "someone probably knows."
That is the bit that has been stuck in my head for weeks.
"We can have a look at the config file."
That is not a migration strategy. That is archaeology.
And when you mention a cryptographic bill of materials, people treat it like paperwork. "We do not need that. We have the config." No. You have fragments. You have assumptions. You have whatever survived the last reorg, migration, outsourcing wave, and urgent production fix.
The code you wrote is only part of the story. The uncomfortable part is the crypto buried in vendor libraries, firmware, appliances, SaaS dependencies, backup systems, old archives, and code-signing chains nobody has touched in years.
And somehow, this is all supposed to be solved by "just slapping on PQC."
That phrase drives me insane.
Slap it on where? On the thing nobody has inventoried? In the system nobody owns end-to-end? Across dependencies nobody can fully explain?
Post-quantum migration is not a paint job. It is not algorithm shopping. It is not a checkbox that says "PQC ready" because those words appeared in a vendor PDF.
I am not anti-PQC. I am very much pro-PQC. Harvest now, decrypt later is real. The migration needs to happen. The timelines are not generous.
But I am anti-pretending.
If you cannot answer "where do we use what," you are not migrating.
You are guessing in a more expensive font.
Andreas Renz retweeted
The next months are going to be difficult for many teams. Funding may tighten, while security risks will increase
The good news: one internal security person, enhanced by LLMs, can do a lot to reduce your attack surface
2026 is the year to build your internal security capacity
Most protocols spend a lot on audits and bug bounties but have zero internal security
Launching whohassecurity.com to highlight the ones that do
Having an internal security team should be in every protocol's New Year's resolutions for 2026
Andreas Renz retweeted
Google says breaking Bitcoin's ECDSA signatures takes 500,000 physical qubits. That is ~20x fewer than prior estimates.
But the paper is not a timeline forecast. It is a cost estimate.
Full breakdown, 16 min: youtube.com/watch?v=wj3Y0V_h…
#PostQuantumCryptography #Bitcoin
Andreas Renz retweeted
We’ve identified a security incident that involved unauthorized access to certain internal Vercel systems, impacting a limited subset of customers. Please see our security bulletin:
vercel.com/kb/bulletin/verce…
