New Software and Platforms
Bilateral Contracts and Grants with Industry
Partnerships and Cooperations
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## Section: Partnerships and Cooperations

### International Research Visitors

#### Visits of International Scientists

• Diego Aranha from Aarhus University visited the team one week in May and presented his work on the Brazilian voting machines at the SSL seminar, and his work on fast pairing implementation at the team's seminar. As a result, some of the new secure pairing-friendly curves of  [21], [22] are implemented in the C++ library RELIC (https://github.com/relic-toolkit/relic) (free software).

• Santanu Sarkar from IIT Madras, Chennai, India is visiting the team from December 2019 to the end of February 2020.

##### Internships
• Hamid Boukerrou (Université Paris 8, from March 2019 until September 2019). Subject: cryptanalysis of LBlock.

• Félix Breton (ÉNS Paris, from June 2019 until July 2019). Félix Breton has formally proven in Coq the GNU MPFR subtraction routine in the case where all three operands (the two inputs and the result) have the same precision $p$, and $1\le p, where $w$ is the machine bit-size. This extends previous work done by Jianyang Pan in 2018 on the addition and multiplication routines.

• Émilien Failly (CPP Nancy, from April 2019 until June 2019). Émilien Failly studied the Multiple Polynomial General Number Field Sieve (MNFS). He compared the use of 2, 3, and 4 polynomials on three test numbers: a 60-digit number, a 70-digit number, and a 96-digit number. In each case, the sieving time was estimated, because Cado-NFS cannot currently fully deal with MNFS polynomials.

• Liwei Liu (Peking University, from June 2019 until September 2019). In the context of the computation of discrete logarithms in finite field extensions of small degree, using the Number Field Sieve, Liwei Liu worked on the individual logarithm step, in order to make it faster and more robust.

• Rémi Piau (ÉNS Rennes, from May 2019 until July 2019). Rémi Piau worked on the implementation in Python of our attack against ECDSA using wNAF representation. He was able to improve it by making it cleaner, and using small tricks to make it faster too.