Mikhail Kudinov
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error024.bsky.social
Mikhail Kudinov
@error024.bsky.social
77 followers 100 following 28 posts
PhD, Post-Quantum cryptography.

https://error0024.github.io/
Posts Replies Media Videos
error024.bsky.social
Thought HB schemes were running out of surprises, but new ideas keep coming. We recently looked at the “At the Top of the Hypercube” encoding for faster Winternitz-style verification, and now Abri & Katz show new optimizations for few-time signatures eprint.iacr.org/2025/2069! Still room to improve!
eprint.iacr.org
November 13, 2025 at 11:55 AM
error024.bsky.social
🎓 After 4 years, 7 papers, countless joyful moments, and meeting so many great people along the way, I’m excited to share that I’ve officially obtained my PhD!

It’s been an incredible journey of learning, persistence, and growth.

My thesis is now available here:
🔗 pure.tue.nl/ws/portalfil...
October 28, 2025 at 10:17 AM
Reposted by Mikhail Kudinov
signal.org
We are alarmed by reports that Germany is on the verge of a catastrophic about-face, reversing its longstanding and principled opposition to the EU’s Chat Control proposal which, if passed, could spell the end of the right to privacy in Europe. signal.org/blog/pdfs/ge...
signal.org
October 3, 2025 at 4:14 PM
Reposted by Mikhail Kudinov
matthewdgreen.bsky.social
I’m flagging this nice book/paper on FHE schemes not necessarily because it’s correct and I endorse it, but because it looks pretty useful. arxiv.org/pdf/2503.05136
arxiv.org
September 22, 2025 at 7:21 PM
error024.bsky.social
CryptoCorgi
September 20, 2025 at 8:22 PM
Reposted by Mikhail Kudinov
getnews-me.bsky.social
Over 500 cryptographers warn the EU draft “Chat Control” could weaken end‑to‑end encryption. The EU council votes on the Danish text on Sep 12, 2025. https://getnews.me/eu-chat-control-criticized-by-500-cryptographers-over-privacy-risks/ #euchatcontrol #privacy #cryptography
EU Chat Control criticized by 500 cryptographers over privacy risks
September 9, 2025 at 3:37 PM
Reposted by Mikhail Kudinov
nadim.computer
I'm thrilled to announce that after months of intensive work, the complete materials for my Applied Cryptography course at the American University of Beirut are now finished: both Part 1 (Provable Security) and Part 2 (Real-World Cryptography)!
August 6, 2025 at 8:01 AM
Reposted by Mikhail Kudinov
nadim.computer
I made a video about my upcoming applied cryptography course: youtu.be/z6kK7rIbyB0
Nadim Kobeissi's Applied Cryptography Course
YouTube video by Nadim Kobeissi
youtu.be
July 28, 2025 at 8:51 AM
error024.bsky.social
July 26, 2025 at 8:56 PM
error024.bsky.social
Crypto 2025 is just around the corner! Check out the full program here:
crypto.iacr.org/2025/program...

Join us on Monday for our talk where we explore the tradeoffs of hash-based signatures.

We then apply these findings to propose post-quantum Ethereum PoS signatures:
eprint.iacr.org/2025/1332
July 25, 2025 at 6:00 PM
Reposted by Mikhail Kudinov
eprint.ing.bot
Technical Note: LeanSig for Post-Quantum Ethereum (Justin Drake, Dmitry Khovratovich, Mikhail Kudinov, Benedikt Wagner) ia.cr/2025/1332
Abstract. In this note, we present a new instantiation of the hash-based multi-signature framework introduced by Drake, Khovratovich, Kudinov, and Wagner (CiC Vol 2 Issue 1, eprint 2025/055) for Ethereum’s consensus layer. Inspired by a recent work of Khovratovich, Kudinov, and Wagner (Crypto 2025, eprint 2025/889), we instantiate the framework with a novel incomparable encoding that improves the tradeoff between signature size and verification hashing. The purpose of this document is to make explicit how to use the ideas of the latter work within the framework of Drake, Khovratovich, Kudinov, and Wagner.
July 22, 2025 at 10:05 PM
Reposted by Mikhail Kudinov
matthewdgreen.bsky.social
This battle will keep playing out over and over again until they achieve something that their own citizens have made it clear they don’t want. www.techradar.com/vpn/vpn-priv...
The EU wants to decrypt your private data by 2030
The EU Commission unveiled the first step in its security strategy to ensure "lawful and effective" law enforcement access to data
www.techradar.com
July 5, 2025 at 5:39 PM
error024.bsky.social
PewDiePie’s evolution into a tech geek is so cool! His recent video dives deep into privacy concerns and surveillance issues, while being still fun to watch. I think these are the topics that couldn’t be more relevant today. Highly recommend watching his take on it:

🔗 youtu.be/u_Lxkt50xOg?...
I'm DONE with Google
YouTube video by PewDiePie
youtu.be
June 29, 2025 at 8:50 AM
Reposted by Mikhail Kudinov
krijn.isogeni.es
Single author, fifteen pages, reduces the bit complexity of millenia-old UOV instances!!
eprint.ing.bot ePrint Updates @eprint.ing.bot · Jun 19
Wedges, oil, and vinegar – An analysis of UOV in characteristic 2 (Lars Ran) ia.cr/2025/1143
Abstract. The Unbalanced Oil and Vinegar construction (UOV) has been the backbone of multivariate cryptography since the fall of HFE-based schemes. In fact, 7 UOV-based schemes have been submitted to the NIST additional call for signatures, and 4 of these made it to the second round. For efficiency considerations, most of these schemes are defined over a field of characteristic 2. This has as a side effect that the polar forms of the UOV public maps are not only symmetric, but also alternating. In this work, we propose a new key-recovery attack on UOV in characteristic 2 that makes use of this property. We consider the polar forms of the UOV public maps as elements of the exterior algebra. We show that these are contained in a certain subspace of the second exterior power that is dependent on the oil space. This allows us to define relations between the polar forms and the image of the dual of the oil space under the Plücker embedding. With this, we can recover the secret oil space using sparse linear algebra. This new attack has an improved complexity over previous methods and reduces the security by 4, 11, and 20 bits for uov-Ip, uov-III, and uov-V, respectively. Furthermore, the attack is applicable to MAYO₂ and improves on the best attack by 28 bits. Image showing part 2 of abstract.
June 19, 2025 at 12:39 PM
Reposted by Mikhail Kudinov
durumcrustulum.com
Apple announces that TLS client connections in version 26+ will be using hybrid PQ X25519MLKEM768 by default

support.apple.com/en-us/122756
Prepare your network for quantum-secure encryption in TLS - Apple Support
Learn about quantum-secure encryption in TLS and how to check if your organization's web servers are ready.
support.apple.com
June 9, 2025 at 10:34 PM
Reposted by Mikhail Kudinov
eprint.ing.bot
At the Top of the Hypercube – Better Size-Time Tradeoffs for Hash-Based Signatures (Dmitry Khovratovich, Mikhail Kudinov, Benedikt Wagner) ia.cr/2025/889
Abstract. Hash-based signatures have been studied for decades and have recently gained renewed attention due to their post-quantum security. At the core of the most prominent hash-based signature schemes, XMSS and SPHINCS+, lies a one-time signature scheme based on hash chains due to Winternitz. In this scheme, messages are encoded into vectors of positions (i.e., vertices in a hypercube) in the hash chains, and the signature contains the respective chain elements. The encoding process is crucial for the efficiency and security of this construction. In particular, it determines a tradeoff between signature size and computational costs. Researchers have been trying to improve this size-time tradeoff curve for decades, but all improvements have been arguably marginal. In this work, we revisit the encoding process with the goal of minimizing verification costs and signature sizes. As our first result, we present a novel lower bound for the verification cost given a fixed signature size. Our lower bound is the first to directly apply to general encodings including randomized, non-uniform, and non-injective ones. Then, we present new encodings and prove their security. Inspired by our lower bound, these encodings follow a counterintuitive approach: we map messages non-uniformly into the top layers of a much bigger hypercube than needed but the encoding itself has (hard to find) collisions. With this, we get a 20 % to 40 % improvement in the verification cost of the signature while keeping the same security level and the same size. Our constructions can be directly plugged into any signature scheme based on hash chains, which includes SPHINCS+ and XMSS. Image showing part 2 of abstract.
May 19, 2025 at 10:27 AM
error024.bsky.social
Excited to be heading to #Eurocrypt2025 in Madrid soon!

I’ll be speaking at Algebraic Hash Cryptanalysis Days on Security Requirements in the Context of Hash-Based Signatures.

Catch me at the affiliated events or during the main conference. Let’s connect! #Cryptography #Madrid
April 29, 2025 at 7:59 AM
error024.bsky.social
🎤 My talk from #PQCrypto2025 is now live on YouTube!

I discussed rejection types in KEMs. Why they matter, how they impact security and which one should you choose.

Check it out & let me know your thoughts! 👇
📺 youtu.be/W-gUd_qTUs4?...

#PostQuantum #Cryptography #KEMs
Treating Dishonest Ciphertexts in Post Quantum KEMs – Explicit vs Implicit Rejection in the FO T
YouTube video by PQCrypto conference videos
youtu.be
April 27, 2025 at 11:26 PM
error024.bsky.social
1/2 🔐 Exciting read: "A Survey on the Security of Lattice-Based NIST Finalists" (eprint.iacr.org/2025/304.pdf) provides a clear overview of modern security analysis for Lattice-based schemes. It dives into structured vs. unstructured attacks on LWE/NTRU assumptions and reduction algorithms like BKZ.
eprint.iacr.org
April 23, 2025 at 3:02 PM
error024.bsky.social
My Crypto Learning Journey: Helpful Resources

I’ve compiled a list of materials that helped me the most in my cryptography journey. The list will keep growing—feel free to suggest your favorites!

error0024.github.io/posts/2025/0...
Materials that I can suggest for Cryptography and Computer Science
These books and other materials helped my study of cryptography. If there is an English version of the book/paper - I first give a link to that book, if there is a Russian version - the link is given ...
error0024.github.io
April 17, 2025 at 8:03 PM
Reposted by Mikhail Kudinov
eprint.ing.bot
Hybrid-query bounds with partial input control - framework and application to tight M-eTCR (Andreas Hülsing, Mikhail Kudinov, Christian Majenz) ia.cr/2025/633
Abstract. In this paper, we present an improved framework for proving query bounds in the Quantum Random Oracle Model (QROM) for algorithms with both quantum and classical query interfaces, where the classical input is partially controlled by the adversary. By extending existing techniques, we develop a method to bound the progress an adversary can make with such partial-control classical queries. While this framework is applicable to different hash function properties, we decided to demonstrate the impact of the new techniques by giving an analysis of the multi-target extended target collision resistance property (m-eTCR). This new approach allows us to achieve an improved bound that significantly reduces the required function key size. Our proof is tight in terms of query complexity and has significant implications for cryptographic applications, especially for signature schemes in the hash & sign paradigm, enabling more efficient instantiations with reduced salt sizes and smaller signature lengths. For an example of multiple signatures aggregation, we achieve a signature size of 30 kB smaller.
April 11, 2025 at 7:14 AM
Reposted by Mikhail Kudinov
eprint.ing.bot
CAKE requires programming - On the provable post-quantum security of (O)CAKE (Kathrin Hövelmanns, Andreas Hülsing, Mikhail Kudinov, Silvia Ritsch) ia.cr/2025/458
Abstract. In this work we revisit the post-quantum security of KEM-based password-authenticated key exchange (PAKE), specifically that of (O)CAKE. So far, these schemes evaded a security proof considering quantum adversaries. We give a detailed analysis of why this is the case, determining the missing proof techniques. To this end, we first provide a proof of security in the post-quantum setting, up to a single gap. This proof already turns out to be technically involved, requiring advanced techniques to reason in the QROM, including the compressed oracle and the extractable QROM. To pave the way towards closing the gap, we then further identify an efficient simulator for the ideal cipher. This provides certain programming abilities as a necessary and sufficient condition to close the gap in the proof: we demonstrate that we can close the gap using the simulator, and give a meta-reduction based on KEM-anonymity that shows the impossibility of a non-programming reduction that covers a class of KEMs that includes Kyber / ML-KEM.
March 12, 2025 at 4:02 PM