Luca De Feo
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bsky.defeo.lu
Luca De Feo
@bsky.defeo.lu
230 followers 100 following 48 posts
Researcher in cryptography @ IBM Research, chief isogenista, SageMath developer, DevOps in my spare time. Opinions my own.
On Mastodon: @[email protected]
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Reposted by Luca De Feo
gro-tsen.bsky.social
IIUC, having a passenger dressed as batman causes other passengers to be more willing to give up their seats to a pregnant woman in the subway (in a statistically very significant way). www.nature.com/articles/s44...

Pagnini &al, “Unexpected events and prosocial behavior: the Batman effect”
Unexpected events and prosocial behavior: the Batman effect - npj Mental Health Research
npj Mental Health Research - Unexpected events and prosocial behavior: the Batman effect
www.nature.com
November 24, 2025 at 9:21 PM
Reposted by Luca De Feo
benadida.com
The International Association for Cryptologic Research has used heliosvoting.org – my online voting system – for a number of years.

This year, a trustee lost their secret key. The election has to be re-run.

Below, a few thoughts that didn't fit in the NYT piece.

www.nytimes.com/2025/11/21/w...
Cryptographers Held an Election. They Can’t Decrypt the Results.
www.nytimes.com
November 22, 2025 at 2:40 AM
bsky.defeo.lu
Yes! It was me!

I stole the key from Moti's hard drive and wiped it 😈

You'll never get it back. MUAHAHAHAHAH!
November 22, 2025 at 8:13 PM
Reposted by Luca De Feo
gro-tsen.bsky.social
These very nice slides by Marie Farge on how researchers can regain control of publication have been brought to my attention: openscience.ens.fr/MARIE_FARGE/... — I think they're worth spreading more widely!
Slide titled “How can researchers regain control of publication?” by Marie Farge (from a talk given on 2025-09-02 in Milan at the International Conference on Optimization and Decision Science).
November 17, 2025 at 11:26 AM
bsky.defeo.lu
Got an invitation to review for a journal that charges > 3 k$ in APC. How much should I charge for the review?
November 17, 2025 at 1:08 AM
Reposted by Luca De Feo
bsky.gay
holy shiiiiiiiiiiiiiiit
eprint.ing.bot ePrint Updates @eprint.ing.bot · 25d
On Reed–Solomon Proximity Gaps Conjectures (Elizabeth Crites, Alistair Stewart) ia.cr/2025/2046
Abstract. We disprove a range of conjectures for Reed-Solomon codes underpinning the security and efficiency of many modern proof systems, including SNARKs based on FRI (Ben-Sasson-Bentov-Horesh-Riabzev, ICALP’18), DEEP-FRI (Ben-Sasson-Goldberg-Kopparty-Saraf, ITCS’20), STIR (Arnon-Chiesa-Fenzi-Yogev, CRYPTO’24), and WHIR (Arnon-Chiesa-Fenzi-Yogev, preprint). Concretely, we prove that the following conjectures are false: 1. The correlated agreement up-to-capacity conjecture of Ben-Sasson-Carmon-Ishai-Kopparty-Saraf (J. ACM’23), 2. The mutual correlated agreement up-to-capacity conjecture of WHIR, 3. The list-decodability up-to-capacity conjecture of DEEP-FRI, which follows from existing results in the literature. We then propose minimal modifications to these conjectures up to the list-decoding capacity bound. Our second main contribution is a proof that correlated agreement with small enough error probability implies list decoding of Reed-Solomon codes. Thus, any future results on our correlated agreement conjectures with small enough error probability would imply similar results in classical list decoding. A reduction from proximity gaps to list-decodability was heretofore a natural open problem. Image showing part 2 of abstract.
November 5, 2025 at 9:03 PM
Reposted by Luca De Feo
cosic.bsky.social
Valerio Ardizio is the newest member of Frederik Vercauteren's team!
"I chose COSIC because of its welcoming, inspiring, and stimulating research environment, as well as the outstanding expertise of the researchers who are part of this group."
#choosecosic
November 3, 2025 at 4:01 PM
Reposted by Luca De Feo
nadim.computer
I wrote a long post about my experiences so far in teaching applied cryptography at the American University of Beirut: www.linkedin.com/pulse/teachi...
Teaching Applied Cryptography in Beirut: Field Update
Two months ago, I began what colleagues politely called an "ambitious" undertaking: teaching Applied Cryptography to fifty students at the American University of Beirut while the country navigates war...
www.linkedin.com
October 28, 2025 at 8:03 AM
Reposted by Luca De Feo
jonathan.isogeny.club
TL;DR: See title 🥳
eprint.ing.bot ePrint Updates @eprint.ing.bot · Oct 8
qt-Pegasis: Simpler and Faster Effective Class Group Actions (Pierrick Dartois, Jonathan Komada Eriksen, Riccardo Invernizzi, Frederik Vercauteren) ia.cr/2025/1859
Abstract. In this paper, we revisit the recent PEGASIS algorithm that computes an effective group action of the class group of any imaginary quadratic order R on a set of supersingular elliptic curves primitively oriented by R. Although PEGASIS was the first algorithm showing the practicality of computing unrestricted class group actions at higher security levels, it is complicated and prone to failures, which leads to many rerandomizations. In this work, we present a new algorithm, qt-Pegasis, which is much simpler, but at the same time faster and removes the need for rerandomization of the ideal we want to act with, since it never fails. It leverages the main technique of the recent qlapoti approach. However, qlapoti solves a norm equation in a quaternion algebra, which corresponds to the full endomorphism ring of a supersingular elliptic curve. We show that the algorithm still applies in the quadratic setting, by embedding the quadratic ideal into a quaternion ideal using a technique similar to the one applied in KLaPoTi. This way, we can reinterpret the output of qlapoti as four equivalent quadratic ideals, instead of two equivalent quaternion ideals. We then show how to construct a Clapoti-like diagram in dimension 2, which embeds the action of the ideal in a 4-dimensional isogeny. We implemented our qt-Pegasis algorithm in SageMath for the CSURF group action, and we achieve a speedup over PEGASIS of 1.8× for the 500-bit parameters and 2.6× for the 4000-bit parameters. Image showing part 2 of abstract.
October 8, 2025 at 8:17 AM
Reposted by Luca De Feo
pierreb.bsky.social
Pétition "non à #ChatControl" à signer sur le site de l'assemblée nationale. petitions.assemblee-nationale.fr/initiatives/...
Non à Chat Control, outil de surveillance de masse - Non à Chat Control, outil de surveillance de masse - Plateforme des pétitions de l’Assemblée nationale
Chers Représentants, Je vous écris pour exprimer mes graves préoccupations concernant la proposition de législation Chat Control (Règlement CSAM) actuellement reconsidérée sous la Présidence danoise ...
petitions.assemblee-nationale.fr
October 9, 2025 at 9:22 AM
Reposted by Luca De Feo
chrispeikert.bsky.social
We will Make this deadline, very strongly, because we are WINNERS—but Europe and the Rest of the world will have to pay up BIGLY with the strongest and Most polished Best Paper awards! That is the least these low IQ individuals can do to Pay back what we Americans so richly deserve!
October 3, 2025 at 3:37 AM
Reposted by Luca De Feo
chrispeikert.bsky.social
Other countries in Europe are LAUGHING at us, with their “Midnight Anywhere on Earth” conference submission Deadlines!!

They’re finishing their papers and taking off for the Weekend at 2pm Friday, while we Americans have to pull ALL-NIGHTERS!

Not on my (your favorite PC chair) watch—MAGTBAARHA!
October 3, 2025 at 12:14 AM
Reposted by Luca De Feo
tiborj.bsky.social
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
September 25, 2025 at 5:53 PM
Reposted by Luca De Feo
nadim.computer
Hot on the heels of this week's invited talk, I'm pleased to announce that we will soon be following up with a fantastic upcoming talk by the inimitable @kennyog.bsky.social!
September 24, 2025 at 1:58 PM
Reposted by Luca De Feo
maria.isogeny.club
The Isogeny Club Season 7 starts today! At 5pm CEST, Bruno Sterner will talk about finding large smooth twins from short lattice vectors. More details at isogeny.club
September 23, 2025 at 7:23 AM
bsky.defeo.lu
And so it ends where it all started (well, some 50km upstream of that first picture). Thanks for following and see you at the next #IsogenyCycle!
#LID6
Zürisee
September 21, 2025 at 4:53 PM
Reposted by Luca De Feo
nbcnews.com
BREAKING: The U.K., Canada and Australia officially recognize a Palestinian state, a significant shift away from alignment with the U.S.
U.K, Canada and Australia formally recognize a Palestinian state, breaking with the U.S.
The announcements Sunday marked a significant shift in foreign policy, with several other European nations and U.S. allies set to follow suit in the coming days.
nbcnews.to
September 21, 2025 at 1:26 PM
bsky.defeo.lu
You never know when you'll make it
#LID6 #IsogenyCycle
999.99km in 49:58
September 21, 2025 at 9:37 AM
bsky.defeo.lu
Alsace welcomed me with some of the most spectacular views!
#LID6 #IsogenyCycle
Col du Bonhomme 949m View in Kaysersberg Vineyards in Alsace Petite Venise in Colmar
September 20, 2025 at 9:27 PM
bsky.defeo.lu
Last leg of the trip. The sun is back and it's even too hot!
Here's the Château de Lunéville this morning. Now finishing a siesta before crossing the Vosges.
#LID6 #IsogenyCycle
Château de Lunéville
September 20, 2025 at 12:19 PM
Reposted by Luca De Feo
dfaranha.bsky.social
The impact of Alfred Menezes in cryptography is profound. Francisco RH and I are organizing an afternoon session in Latincrypt to celebrate Alfred's career:

menezesfest.info

If you're coming to Medellín, consider attending!
MenezesFest 2025
MenezesFest brings together researchers, colleagues, and friends to celebrate the career and impact of Alfred Menezes.
menezesfest.info
September 18, 2025 at 6:17 AM
Reposted by Luca De Feo
krijn.isogeni.es
Announcing The Isogeny Problems!

A curated list of the seven foremost unsolved problems in isogeny-based cryptography. Solving one of these profound questions would mark a monumental advance, and as a resolver you'd get eternal honor and epic rewards!

Full list: isogeni.es/problems
The Isogeny Problems
isogeni.es
September 15, 2025 at 7:43 AM
bsky.defeo.lu
Found a bunch of researchers at the French border, they dragged me to Nancy 🇫🇷
#LID6 #IsogenyCycle
4 cyclists in front of some French monument
September 14, 2025 at 5:28 PM
bsky.defeo.lu
I have plenty of questions...
#LID6 #IsogenyCycle
"Beetroots"
September 13, 2025 at 9:20 AM
bsky.defeo.lu
Thought for a moment of swapping the bike for a canoe, but I finally reached my first destination yesterday!
Next chapter coming this weekend...
#LID6 #IsogenyCycle
Stadhuis in Leuven
September 10, 2025 at 10:52 AM