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Paolo Santini

@palli-santini.bsky.social

Researcher in cryptography, coding theory and whatever I find interesting

6 Posts43 Follower 40 Folgt

Paolo Santini @palli-santini.bsky.social · last mo.

We show how decoding of QC-MDPC codes can be improved, with only a very mild computational overhead 💪 Moreover, our decoder BF-Max seems to be the one with the lowest failure rate 👀

ePrint Updates@eprint.ing.bot · last mo.

Flip a Failure into a Success: Improved Bit Flipping Decoding for QC-MDPC Codes (Paolo Santini, Davide De Zuane, Alessio Baldelli, Marco Baldi) ia.cr/2026/1616

Abstract. Quasi-Cyclic Moderate-Density Parity-Check (QC-MDPC) codes are a family of error correcting codes admitting parity-check matrices composed of sparse circulant blocks. QC-MDPC codes have been used for the design of BIKE, one of the finalists in the NIST competition for the standardization of post-quantum cryptography. Decoding of QC-MDPC codes with cryptographically relevant parameters is intrinsically bound to fail, resulting in a decoding failure rate (DFR) that is nonzero. To achieve INDistinguishability under Adaptively Chosen Ciphertext Attacks (IND-CCA2), the DFR must not exceed 2^(−λ), with λ being the security parameter. QC-MDPC codes are customarily decoded with a Bit Flipping (BF) algorithm. Especially at very low DFR values, error patterns having a large intersection with near-codewords (which are vectors corresponding to columns of the parity-check matrix, up to some shift) are the main cause of decoding failures.

In this paper, we show how a BF decoder can be tweaked to exploit the knowledge about near-codewords. Since error vectors that cause decoding failures are likely making the decoder converge to the closest near-codeword (i.e., to the near-codeword with the largest amount of overlapping positions with the error vector), we exploit such a harmful but predictable behavior: we let the decoder recognize, and consequently correct, syndromes of near-codewords. This modification comes with a very mild computational overhead and can be applied to any BF decoder. As a concrete application, we focus on BIKE parameters for NIST security category 1. We show that a recently proposed BF variant called BF-Max outperforms significantly the two decoders used by BIKE within the NIST competition, achieving a significantly lower DFR with a comparable computational complexity.

Matthew Green @matthewdgreen.bsky.social · last mo.

I wrote up a short blog post giving my thoughts on the new Anthropic cryptanalysis results against HAWK and AES. blog.cryptographyengineering.com/2026/07/29/s...

Some notes about Anthropic’s new results

Yesterday Anthropic published two new cryptanalysis results, both outputs of Claude Mythos, their (still) unreleased advanced model. The first of these results attacks a signature scheme called HAW…

blog.cryptographyengineering.com

Paolo Santini @palli-santini.bsky.social · 2mo ago

📢 Upcoming online seminar organized by the "UMI Crittografia e Codici" Group 🗣️ Giuseppe D'Alconzo (Telsy S.p.A.) 📅 July 22, 3:00 PM (CEST) Title: Invariants and Group Actions: An Algebraic Attack Framework for Isomorphism Problems More information on 👉 sites.google.com/view/crittog...

Gianluca Stringhini @gianlucastringhini.com · 4mo ago

I like this. If the paper contains hallucinated references, how can we trust anything else in it? By the way, I'll present our experience developing and using the hallucinator tool next week at MetaCrisp (co-located with IEEE S&P)! 📄 seclab.bu.edu/people/gianl... 💾 github.com/gianlucasb/h...

seclab.bu.edu

anil oza@aniloza.bsky.social · 4mo ago

wow — the preprint host, arxiv, is banning authors for a year if they submit papers with hallucinated citations 🤖

Luca De Feo @bsky.defeo.lu · 6mo ago

We still have a few spots left at MaGIC! Registration closes this week... Hurry up if you want to be on top of all the latest news on Cryptographic Group Actions! magic-workshop.github.io

MaGIC 2026 - Marche Workshop on Group Actions in Cryptography

A workshop dedicated to the study of cryptographic group actions, a rapidly evolving area at the intersection of algebraic geometry, number theory, and post-quantum cryptography. The workshop will bri...

magic-workshop.github.io

Andrea Basso @andreavbasso.bsky.social · 6mo ago

We're organizing a workshop on cryptographic group actions bringing together the isogeny and code communities. The workshop is just before Eurocrypt, a quick train away from Rome in the beautiful Marche. Early registration ends this week, so grab your spot soon! magic-workshop.github.io

MaGIC 2026 - Marche Workshop on Group Actions in Cryptography

magic-workshop.github.io

Paolo Santini @palli-santini.bsky.social · 7mo ago

After MaGIC 2026, let's all head together to CBCrypto 2026 (and the other Eurocrypt affiliated events !)

CBCrypto@cb-crypto.bsky.social · 7mo ago

Join us in Rome in May 9&10! The deadline for submitting your 2-page extended abstracts to CBCrypto 2026 is March 15, 2026. More information can be found at www.cb-crypto.org/home

Paolo Santini @palli-santini.bsky.social · 7mo ago

📢📢📢 𝐌𝐚𝐆𝐈𝐂 𝟐𝟎𝟐𝟔 𝐌𝐚𝐫𝐜𝐡𝐞 𝐖𝐨𝐫𝐤𝐬𝐡𝐨𝐩 𝐨𝐧 𝐆𝐫𝐨𝐮𝐩 𝐀𝐜𝐭𝐢𝐨𝐧𝐬 𝐢𝐧 𝐂𝐫𝐲𝐩𝐭𝐨𝐠𝐫𝐚𝐩𝐡𝐲 In May 5-8, let's all gather together to speak about Group Actions! Early registration until March 8! Organized with Marco Baldi, @bsky.defeo.lu, @giacomoborin.bsky.social, @andreavbasso.bsky.social magic-workshop.github.io

MaGIC 2026 - Marche Workshop on Group Actions in Cryptography

magic-workshop.github.io

Paolo Santini @palli-santini.bsky.social · 9mo ago

Reducing LESS public key size! Can we make it even shorter? 🤔 Big thanks to Marco Baldi, Riccardo Schiavoni and @rahmec.bsky.social

ePrint Updates@eprint.ing.bot · 9mo ago

On the representation of self-orthogonal codes and applications to cryptography (Marco Baldi, Rahmi El Mechri, Paolo Santini, Riccardo Schiavoni) ia.cr/2025/2279

$Abstract. The of a linear code is the intersection between the code and its dual. When the hull is equal to the code (i.e., the code is contained in the dual), the code is called (or ); if, moreover, the code is equal to its dual, then we speak of a code. For problems such as the Permutation Equivalence Problem (PEP) and (special instances of) the Lattice Isomorphism Problem (LIP) over q-ary lattices, codes with a sufficiently large hull provide hard-to-solve instances. In this paper we describe a technique to compress the representation of a self-orthogonal code. Namely, we propose an efficient compression (and decompression) technique that allows representing the generator matrix of a self-orthogonal code with slightly more than $k(n-k)-\binom{k+1}{2}$ finite field elements. The rationale consists in exploiting the relationships deriving from self-orthogonality to reconstruct part of the generator matrix entries from the others, thus reducing the amount of entries one needs to uniquely represent the code. For instance, for self-dual codes, this almost halves the amount of finite field elements required to represent the code. We first present a basic version of our algorithm and show that it runs in polynomial time and, moreover, its communication cost asymptotically approaches the lower bound set by Shannon’s source coding theorem. Then, we provide an improved version which reduces both the size of the representation and the time complexity, essentially making the representation technique as costly as Gaussian elimination. %Under plausible heuristic assumptions (which we have verified via intensive numerical simulations), we furthermore show that our encoding technique is asymptotically optimal (in the sense that the amount of required information bits matches with the theoretical lower bound from Shannon’s theorem). As concrete applications, we show that our technique can be used to reduce the public key size in cryptosystems based on PEP such as LESS and SPECK (achieving approximately a 50% reduction in the public key size), as well as in the Updatable Public Key Encryption Scheme recently proposed by Albrecht, Benčina and Lai, which is based on LIP.$

Signal @signal.org · 11mo ago

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

Tibor Jager @tiborj.bsky.social · 12mo ago

The call for papers for PKC 2026 is out: pkc.iacr.org/2026/callfor...

PKC 2026 call for papers

Public Key Cryptography

pkc.iacr.org

Paolo Santini @palli-santini.bsky.social · 12mo ago

So happy to have been a speaker for the "4th Training school on wireless & cyber-physical system security" held in Technical University of Braunschweig. Wonderful city, wonderful people and wonderful event! Thanks a lot for the invitation 😀 @tu-braunschweig.de @6g-physec.bsky.social

Diego F. Aranha @dfaranha.bsky.social · last yr.

The EU wants to spend your money to assemble a giant mass surveillance machine with little effect on harm against children. Chat Control is not effective, weakens security for all and does not respect privacy. Contact your EU representatives and let them know. csa-scientist-open-letter.org/Sep2025

csa-scientist-open-letter.org