Boris Fouotsa
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borisfouotsa.bsky.social
Boris Fouotsa
@borisfouotsa.bsky.social
100 followers 58 following 10 posts
Postdoc at EPFL, isogenies, and more...

https://borisfouotsa.com
Posts Replies Media Videos
Reposted by Boris Fouotsa
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 Boris Fouotsa
mccurley.bsky.social
I spent two years building a piece of infrastructure for open access publishing in CS arxiv.org/abs/2504.10424. I've gotten positive feedback from authors, but most are quite ignorant about how publishing works (even in computer science). Thankfully we don't have to accept Microsoft Word.😁
Lowering the Cost of Diamond Open Access Journals
Many scholarly societies face challenges in adapting their publishing to an open access model where neither authors nor readers pay any fees. Some have argued that one of the main barriers is the actu...
arxiv.org
October 25, 2025 at 4:49 PM
Reposted by Boris Fouotsa
durumcrustulum.com
let's read some legal agreements

www.youtube.com/watch?v=nmvf...
Is ML-KEM Patent-Encumbered?
YouTube video by Deirdre Connolly
www.youtube.com
October 10, 2025 at 6:09 PM
Reposted by Boris Fouotsa
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 Boris Fouotsa
eprint.ing.bot
WaterSQI and PRISMO: Quaternion Signatures for Supersingular Isogeny Group Actions (Tako Boris Fouotsa) ia.cr/2025/1737
Abstract. Isogeny group action based signatures are obtained from a sigma protocol with high soundness error, say $\frac{1}{2}$ for its most basic variant. One needs to independently repeat the sigma protocol O(λ) times to reduce the soundness error to negligible (with λ being the security parameter). These repetitions come with a considerable efficiency and size overhead. On the other hand, quaternion isogeny-based signatures such as SQIsign and PRISM are directly obtained from a sigma protocol with a negligible soundness error. The secret key in the SQIsign and PRISM is a random supersingular isogeny, and both schemes are insecure when the secret isogeny arises from the supersingular isogeny group action setting. In this paper, we propose WaterSQI and PRISMO, variants of SQIsign and PRISM respectively, suited for secret isogenies that arise from the supersingular isogeny group action setting. They use a sigma protocol whose soundness error is negligible without requiring parallel repetitions. They are hence more compact and O(λ) times more efficient compared to Generalised CSI-FiSh (the generalisation of CSI-FiSh to large parameters using generic isogeny group action evaluation algorithms such as Clapotis/KLaPoTi/PEGASIS). For example, for our proof of concept implementation with a 2000 bits prime in sagemath, PRISMO, when compared to Generalised CSI-FiSh with the same public key size, is about 3x faster for key generation, 273x faster for signing and 4900x faster for verification, while also being 29x more compact (signature size). Image showing part 2 of abstract.
September 24, 2025 at 12:37 AM
borisfouotsa.bsky.social
Quaternion signatures for isogeny group actions: showing how to adapt SQIsign and PRISM to the group actions setting, unleashing WaterSQI and PRISMO signatures that come with a tremendous speed-up over CSI-FiSh style signatures.
eprint.ing.bot ePrint Updates @eprint.ing.bot · Sep 24
WaterSQI and PRISMO: Quaternion Signatures for Supersingular Isogeny Group Actions (Tako Boris Fouotsa) ia.cr/2025/1737
Abstract. Isogeny group action based signatures are obtained from a sigma protocol with high soundness error, say $\frac{1}{2}$ for its most basic variant. One needs to independently repeat the sigma protocol O(λ) times to reduce the soundness error to negligible (with λ being the security parameter). These repetitions come with a considerable efficiency and size overhead. On the other hand, quaternion isogeny-based signatures such as SQIsign and PRISM are directly obtained from a sigma protocol with a negligible soundness error. The secret key in the SQIsign and PRISM is a random supersingular isogeny, and both schemes are insecure when the secret isogeny arises from the supersingular isogeny group action setting. In this paper, we propose WaterSQI and PRISMO, variants of SQIsign and PRISM respectively, suited for secret isogenies that arise from the supersingular isogeny group action setting. They use a sigma protocol whose soundness error is negligible without requiring parallel repetitions. They are hence more compact and O(λ) times more efficient compared to Generalised CSI-FiSh (the generalisation of CSI-FiSh to large parameters using generic isogeny group action evaluation algorithms such as Clapotis/KLaPoTi/PEGASIS). For example, for our proof of concept implementation with a 2000 bits prime in sagemath, PRISMO, when compared to Generalised CSI-FiSh with the same public key size, is about 3x faster for key generation, 273x faster for signing and 4900x faster for verification, while also being 29x more compact (signature size). Image showing part 2 of abstract.
September 24, 2025 at 12:20 PM
Reposted by Boris Fouotsa
claucece.bsky.social
Come to the ASCrypto school, affiliated with Latincrypt2025!
🗓️ Sept 29–30 | Medellín, Colombia
👨‍🏫 Learn 𝐦𝐨𝐝𝐞𝐫𝐧 𝐩𝐫𝐨𝐯𝐢𝐧𝐠 𝐬𝐲𝐬𝐭𝐞𝐦𝐬 from top experts
💥 2 days, 3 modules: IVC, STARKs, MPC
👥 With Benedikt Bünz, Sophia Yakoubov, Alan Szepieniec

Organised by the amazing Arantxa Zapico and Javier Verbel.
June 25, 2025 at 3:48 PM
Reposted by Boris Fouotsa
cosic.bsky.social
Registration for the Leuven Isogeny Days 6 is now open!
📅 10–12 Sept 2025 @ KU Leuven
Morning: research talks
Afternoon: brainstorming sessions
More info: www.esat.kuleuven.be/cosic/projec...
#isogeny #isocrypt #erc #postquantum
June 16, 2025 at 6:17 AM
borisfouotsa.bsky.social
AFRICACRYPT'25 accepted papers (africacrypt2025.sciencesconf.org/resource/page/…) & invited speakers (https://africacrypt2025.sciencesconf.org/resource/page/id/11) are online.
Early registration deadline is May 30th (africacrypt2025.sciencesconf.org/resource/page/���).
See you in Rabat 🇲🇦 in July! 😉
May 22, 2025 at 7:46 AM
borisfouotsa.bsky.social
Isogenies @ Eurocrypt 2025 in Madrid!
May 3, 2025 at 12:12 PM
Reposted by Boris Fouotsa
bsky.defeo.lu
The SQIparty starts on Monday, but it's still time to register!

We prepared an exciting program for you with a balanced mix of talks, coding sprints, skillshares and other activities!

www.cig.udl.cat/SQIparty2025...

See you in Lleida!
bsky.defeo.lu Luca De Feo @bsky.defeo.lu · Mar 13
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
Cathedral of La Seu Vella in Lleida
April 25, 2025 at 2:14 PM
Reposted by Boris Fouotsa
maria.isogeny.club
Good news is that we're still accepting brainstorm topics!! If you have a brainstorm idea, send us a short description by email !
April 23, 2025 at 11:00 AM
Reposted by Boris Fouotsa
maria.isogeny.club
Season 6 of the Isogeny Club is officially done! You can catch up with all the talks here: isogeny.club

If, like us, you haven't had enough isogenies for the term, be sure to join us at the Brainstorm Sessions affiliated with Eurocrypt: isogeny.club/eurocrypt
The Isogeny Club
isogeny.club
April 23, 2025 at 10:58 AM
Reposted by Boris Fouotsa
smartcryptology.bsky.social
Congratulations to the new IACR fellows....

Joan Daemen,
Thomas Johansson,
Anna Lysyanskaya,
Pascal Paillier,
J.R. Rao,
Alon Rosen,
Elaine Shi,
Bo-Yin Yang.

iacr.org/fellows/

#cryptography
IACR Fellows
iacr.org
April 14, 2025 at 6:16 PM
borisfouotsa.bsky.social
Higher dimensions everywhere ! #isogenies
April 7, 2025 at 11:28 AM
Reposted by Boris Fouotsa
bsky.defeo.lu
Registration to the SQIparty is open, free, and we have a first sketch of a program!

www.cig.udl.cat/SQIparty2025...

Register and plan your travel quickly: the rooms are reserved only until Thursday!

See you in Lleida!
bsky.defeo.lu Luca De Feo @bsky.defeo.lu · Mar 13
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
Cathedral of La Seu Vella in Lleida
March 25, 2025 at 5:04 PM
borisfouotsa.bsky.social
It saddens to spend time reviewing a paper, then to neither be able to see the other reviews nor take part in the discussion on that paper! Program Chairs should always enable this (and choose a reviewing platform that allows them to).
March 29, 2025 at 7:54 AM
Reposted by Boris Fouotsa
malb.bsky.social
Update on crypto.iacr.org/2025/
Given recent instances of US visa holders and residents being detained or deported by US immigration authorities, we understand that some members of our community may not feel safe traveling to the US for Crypto this year. We want to assure everyone that we will provide the option to present and attend remotely.
March 21, 2025 at 7:26 PM
Reposted by Boris Fouotsa
krijn.isogeni.es
> claims no new results
> adds in a tiny new result anyway
> ???

anyway, enjoy the read!
eprint.ing.bot ePrint Updates @eprint.ing.bot · Mar 14
A Note on the Advanced Use of the Tate Pairing (Krijn Reijnders) ia.cr/2025/477
Abstract. This short note explains how the Tate pairing can be used to efficiently sample torsion points with precise requirements, and other applications. These applications are most clearly explained on Montgomery curves, using the Tate pairing of degree 2, but hold more generally for any degree or abelian variety, or even generalized Tate pairings. This note is explanatory in nature; it does not contain new results, but aims to provide a clear and concise explanation of results in the literature that are somewhat hidden, yet are extremely useful in practical isogeny-based cryptography.
March 14, 2025 at 8:07 AM
Reposted by Boris Fouotsa
andreavbasso.bsky.social
This workshop is gonna be great: cool people, interesting talks, and lots of great research on SQIsign and isogeny-based crypto. Mark it in your calendars!

And if you’re going to Eurocrypt, this is going to be convenient: the workshop is just the week before, and it’s not too far from Madrid
bsky.defeo.lu Luca De Feo @bsky.defeo.lu · Mar 13
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
Cathedral of La Seu Vella in Lleida
March 13, 2025 at 6:00 PM
Reposted by Boris Fouotsa
smartcryptology.bsky.social
Looking forward to speaking at this event.

Come and enjoy an autumn day in Rome talking #cryptography....

www.decifris.it/fcir25
Financial Cryptography in Rome 2025
L'associazione De Componendis Cifris si propone di animare la comunità crittografica italiana, favorendo lo studio, la ricerca e la divulgazione della crittografia.
www.decifris.it
March 13, 2025 at 6:41 PM
Reposted by Boris Fouotsa
bsky.defeo.lu
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
Cathedral of La Seu Vella in Lleida
March 13, 2025 at 5:30 PM
Reposted by Boris Fouotsa
icascudo.bsky.social
Registration for Eurocrypt 2025 is open!!
Register at eurocrypt.iacr.org/2025/registr...
Early bird registration deadline is 4th of April.
Note that registration will be temporarily closed between the 29th and the 31st of March, and we'll have to cancel previous invoices left unpaid by March 30th.
March 12, 2025 at 3:41 PM
Reposted by Boris Fouotsa
bsky.defeo.lu
And why not pair that with an isogeny workshop in Catalonia just before?

bsky.app/profile/bsky...
bsky.defeo.lu Luca De Feo @bsky.defeo.lu · Mar 13
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
Cathedral of La Seu Vella in Lleida
March 13, 2025 at 5:39 PM
Reposted by Boris Fouotsa
eprint.ing.bot
A Note on Zero-Knowledge Simulator of the CROSS Identification Protocol (Shai Levin) ia.cr/2025/359
Abstract. We point out flaw in zero-knowledge of the CROSS identification protocol, CROSS-ID, which allows a distinguisher to distinguish real and simulated transcripts given access to the witness. Moreover, we show that the real and simulated transcripts are not statistically indistinguishable, and therefore the protocol can only satisfy weak computational (rather than strong, statistical or perfect) Honest Verifier Zero-knowledge. This issue is still present in version 2.0 updated on January 31, 2025, which resolves the security losses attained via the attacks of [BLP+25]
March 4, 2025 at 7:44 AM