International Association
for Cryptologic Research

We are looking for a bright and motivated PhD student to work in the topics of information security and cryptography The student is expected to work on topics that include security and privacy issues for resource-constrained devices (e.g., sensors) that rely on external untrusted servers in order to perform computations. More precisely, the student shall be working on investigating efficient authentication and verifiable delegation of computation mechanisms that provide: i) provable security guarantees, and ii) rigorous privacy guarantees. The overall aim of the PhD position will be to design and evaluate provably secure cryptographic protocols for privacy-preserving authentication and verifiable delegation of computation protocols. The research shall also consider the case where multiple clients outsource jointly computations to untrusted cloud servers. Key Responsibilities: Perform exciting and challenging research in the domain of information security and cryptography. Support and assist in teaching computer security and cryptography courses.

Your profile

• The PhD student is expected to have a MSc degree or equivalent, and strong background in cryptography, network security and mathematics.
• Experience in one or more domains such as cryptography, design of protocols, secure multi-party computation and differential privacy is beneficial.

Deadline for applications: 30 October 2021
Apply online: https://jobs.unisg.ch/offene-stellen/phd-position-in-applied-cryptography-and-information-security-m-w-d/09f75f22-649c-48a6-9aa4-659bbd686a84

Closing date for applications:

Contact: Katerina Mitrokotsa

More information: https://jobs.unisg.ch/offene-stellen/phd-position-in-applied-cryptography-and-information-security-m-w-d/09f75f22-649c-48a6-9aa4-659bbd686a84

University of Luxembourg, Computer Science department and Centre for Security, Reliability and Trust (SnT) invite applications from Ph.D. holders in the general area of Applied Cryptography. SnT is carrying out interdisciplinary research in secure, reliable and trustworthy ICT. CryptoLux/SnT team is currently doing research in cryptography, distributed ledgers and privacy.

Your role
The successful candidate will join the CryptoLux research team led by Prof. Alex Biryukov. He or she will contribute to a research project on future directions in cryptography and IT security and is expected to perform the following tasks:

• Shaping research directions and producing results in one or more of the following topics:
  • Applied Cryptography (symmetric, lightweight, AE, White-box etc.)
  • Financial cryptography, cryptocurrencies, blockchain technologies
  • Privacy enhancing technologies (Tor, zero-knowledge, eID, etc)
• Disseminating results through scientific publications
• Providing guidance to Ph.D. and M.Sc. students

Requirements

• a Ph.D. degree in Computer Science, Applied Mathematics, Electrical Engineering, or a related field;
• Competitive research record in applied cryptography or information security (at least one paper in top 10 IT security conferences)
• Strong mathematical and algorithmic CS background
• Fluent written and verbal communication skills in English

The University offers a one year employment contract (extendable based on performance). The University offers highly competitive salaries and is an equal opportunity employer. You will work in an exciting international environment together with more than 300 people working on all aspects of cryptography, IT security from very theoretical to very applied ones.

Starting date 1-Feb-2022 or later upon agreement. Early submission is encouraged; applications will be processed upon receipt.

Closing date for applications:

Contact: Prof. Alex Biryukov

More information: https://cryptolux.org

The project involves developing a secure USB dongle and standardization of Elliptic Curve Cryptography for Smart Card Platforms. Further details will be provided during the online interview for shortlisted candidates.

Number of positions: 2

Qualifications: Bachelor’s Degree in Engineering or Technology or MSc in Computer Science or MCA from a recognized university or equivalent

Desired Qualifications:

• Degree in Computer Science with highly coding proficiency
• A good knowledge of Cryptography, Security, Embedded Systems, Programming.
• Preference will be given to candidates having NET/GATE scores and working experience relevant to the project

How to Apply:
Candidates should only apply using the application form given in the link (https://iitbhilai.ac.in/index.php?pid=adv_oct21_3) and send it to deciphered.recruitment@gmail.com.

Last Date of Application: 31st October 2021

Closing date for applications:

Contact:
Dr. Dhiman Saha
Assistant Professor
Department of EECS IIT Bhilai
Research Group: http://de.ci.phe.red/

More information: https://iitbhilai.ac.in/index.php?pid=adv_oct21_3

We’re looking for a Cryptographic subject matter expert to join our newly established Applications team and be responsible for developing algorithms for the development of core crypto primitives. We are looking to develop our expertise in this area and our aspiration is to develop a world-class internal team over the next couple of years so we are interested in applications from people looking for permanent, fixed term and contract positions. Our head office is located in Bristol but we can consider remote working for the right person. We can also sponsor work visas for those who are not currently UK based but are looking to relocate. Reporting to the Chief Applications Officer, the Senior Cryptographic Engineer’s main responsibilities will be: Work with the applications team to design and evaluate modification of existing communications protocols to provide robust security against the threat of quantum computers. Support the team to develop proof of concept implementations that can be evaluated with KETS’ trusted client base. Contribute to the wider cyber security culture within KETS. Design and evaluate modifications to common layer 2/3 communication protocols (e.g. MACsec, MPLS) to incorporate quantum-safe cryptographic primitives. Collaborating with your team to develop prototype implementations of quantum-safe communications protocols. Produce technical design specifications and documentation. Deliver research papers & patents where appropriate. Engage with the wider community (conferences, industry seminars, standards bodies) where appropriate. Supporting the wider team in implementing best practice for secure software development.

Closing date for applications:

Contact: careers@kets-quantum.com

More information: https://ketsquantum.livevacancies.co.uk/#/job/details/14?target=frame

The mathematical department IRMAR, part of Rennes 1 University in the west of France, is advertising a 2-year post-doctoral position in the area of computational number theory and algebraic geometry for code-based or isogeny-based post-quantum cryptography.
See link for further information.

Closing date for applications:

Contact: David Lubicz (DGA) or Jade Nardi (IRMAR)

More information: http://jnardi.perso.math.cnrs.fr/fichiers/fichierspageweb/postdoc_offer.pdf

We introduce non-interactive distributionally indistinguishable arguments (NIDI) to address a significant weakness of NIWI proofs: namely, the lack of meaningful secrecy when proving statements about $\mathsf{NP}$ languages with unique witnesses.

NIDI arguments allow a prover P to send a single message to verifier V, given which V obtains a sample d from a (secret) distribution D, together with a proof of membership of d in an NP language L. The soundness guarantee is that if the sample d obtained by the verifier V is not in L, then V outputs $\bot$. The privacy guarantee is that secrets about the distribution remain hidden: for every pair of distributions $D_0$ and $D_1$ of instance-witness pairs in L such that instances sampled according to $D_0$ or $D_1$ are (sufficiently) hard-to-distinguish, a NIDI that outputs instances according to $D_0$ with proofs of membership in L is indistinguishable from one that outputs instances according to $D_1$ with proofs of membership in L.

- We build NIDI arguments for sufficiently hard-to-distinguish distributions assuming sub-exponential indistinguishability obfuscation and sub-exponential one-way functions.

- We demonstrate preliminary applications of NIDI and of our techniques to obtaining the first (relaxed) non-interactive constructions in the plain model, from well-founded assumptions, of:

1. Commit-and-prove that provably hides the committed message

2. CCA-secure commitments against non-uniform adversaries.

The commit phase of our commitment schemes consists of a single message from the committer to the receiver, followed by a randomized output by the receiver (that need not necessarily be returned to the committer).

We investigate the communication complexity of Byzantine agreement protocols for long messages against an adaptive adversary. In this setting, prior results either achieved a communication complexity of $O(nl\cdot\poly(\kappa))$ or $O(nl + n^2 \cdot \poly(\kappa))$ for $l$-bit long messages. We improve the state of the art by presenting protocols with communication complexity $O(nl + n \cdot \poly(\kappa))$ in both the synchronous and asynchronous communication models. The synchronous protocol tolerates $t \le (1-\epsilon) \frac{n}{2}$ corruptions and assumes a VRF setup, while the asynchronous protocol tolerates $t \le (1-\epsilon) \frac{n}{3}$ corruptions under further cryptographic assumptions. Our protocols are very simple and combine subcommittee election with the recent approach of Nayak et al. (DISC `20). Surprisingly, the analysis of our protocols is \emph{all but simple} and involves an interesting new application of Mc Diarmid's inequality to obtain {\em optimal} corruption thresholds.

First posed as a challenge in 1978 by Rivest et al., fully homomorphic encryption—the ability to evaluate any function over encrypted data— was only solved in 2009 in a breakthrough result by Gentry. After a decade of intense research, practical solutions have emerged and are being pushed for standardization.

This guide is intended to practitioners. It explains the inner-workings of TFHE, a torus-based fully homomorphic encryption scheme. More exactly, it describes its implementation on a discretized version of the torus. It also explains in detail the technique of the programmable bootstrapping.

Payment channels effectively move the transaction load off-chain thereby successfully addressing the inherent scalability problem most cryptocurrencies face. A major drawback of payment channels is the need to ``top up'' funds on-chain when a channel is depleted. Rebalancing was proposed to alleviate this issue, where parties with depleting channels move their funds along a cycle to replenish their channels off-chain. Protocols for rebalancing so far either introduce local solutions or compromise privacy.

In this work, we present an opt-in rebalancing protocol that is both private and globally optimal, meaning our protocol maximizes the total amount of rebalanced funds. We study rebalancing from the framework of linear programming. To obtain full privacy guarantees, we leverage multi-party computation in solving the linear program, which is executed by selected participants to maintain efficiency. Finally, we efficiently decompose the rebalancing solution into incentive-compatible cycles which conserve user balances when executed atomically.

The linear layer, which is basically a binary non-singular matrix, is an integral part of cipher construction in a lot of private key ciphers. As a result, optimising the linear layer for device implementation has been an important research direction for about two decades. The Boyar-Peralta's algorithm (SEA'10) is one such common algorithm, which offers significant improvement compared to the straightforward implementation. This algorithm only returns implementation with XOR2 gates, and is deterministic. Over the last couple of years, some improvements over this algorithm has been proposed, so as to make support for XOR3 gates as well as make it randomised. In this work, we take an already existing improvement (Tan and Peyrin, TCHES'20) that allows randomised execution and extend it to support three input XOR gates. This complements the other work done in this direction (Banik et al., IWSEC'19) that also supports XOR3 gates with randomised execution. Further, noting from another work (Maximov, Eprint'19), we include one additional tie-breaker condition in the original Boyar-Peralta's algorithm. Our work thus collates and extends the state-of-the-art, at the same time offers a simpler interface. We show several results that improve from the lastly best-known results.

Let $p$ be a polynomial, and let $p^{(i)}(x)$ be the result of iterating the polynomial $i$ times, starting at an input $x$. The case where $p(x)$ is the homogeneous polynomial $x^2$ has been extensively studied in cryptography. Due to its associated group structure, iterating this polynomial gives rise to a number of interesting cryptographic applications such as time-lock puzzles and verifiable delay functions. On the other hand, the associated group structure leads to quantum attacks on the applications.

In this work, we consider whether inhomogeneous polynomials, such as $2x^2+3x+1$, can have useful cryptographic applications. We focus on the case of polynomials mod $2^n$, due to some useful mathematical properties. The natural group structure no longer exists, so the quantum attacks but also applications no longer immediately apply. We nevertheless show classical polynomial-time attacks on analogs of hard problems from the homogeneous setting. We conclude by proposing new computational assumptions relating to these inhomogeneous polynomials, with cryptographic applications.

Most existing work on secure multi-party computation (MPC) ignores a key idiosyncrasy of modern communication networks, that there are a limited number of communication paths between any two nodes, many of whom might even be corrupted. The work by Garay and Ostrovsky [EUROCRYPT'08] on almost-everywhere MPC (AE-MPC), introduced “best-possible security” properties for MPC over such incomplete networks, where necessarily some of the honest parties may be excluded from the computation—we call such parties “doomed.”

In this work we provide a universally composable definition of almost-everywhere security, which allows us to automatically and accurately capture the guarantees of AE-MPC (as well as AE-communication, the analogous “best-possible security” version of secure communication) in the Universal Composability (UC) framework of Canetti. Our result offers the first simulation-based treatment of this important but under-investigated problem, along with the first simulation-based proof of AE-MPC.

Non-interactive publicly verifiable secret sharing (PVSS) schemes allow parties to re-share a secret in a decentralized setting in the presence of malicious parties. A recently proposed application of PVSS schemes is to enable permissionless proof-of-stake blockchains to ``keep a secret" via a sequence of committees that share that secret. Such committees can use the secret to produce signatures on the blockchain's behalf, or to disclose hidden data conditioned on consensus that some event has occurred. Such a setting may involve thousands of parties, so the PVSS scheme that it uses must be very efficient, both in computation and communication. Yet, previous PVSS schemes have large proofs and/or require many exponentiations over large groups.

We present a non-interactive PVSS scheme in which the underlying encryption scheme is based on the learning with errors (LWE) problem. While lattice-based encryption schemes are very fast, they have issues with bandwidth (long ciphertexts and public keys). We deal with the bandwidth issue in two ways. First, we adapt the Peikert-Vaikuntanathan-Waters (PVW) encryption scheme to the multi-receiver setting so that the bulk of the parties' keys is a common random string, and so that we get good amortized communication: $\Omega(1)$ plaintext/ciphertext rate (rate $\approx 1/60$ for 100 parties, $\approx 1/8$ for 1000 parties, approaching 1/2 as the number of parties grows). Second, we use bulletproofs over a DL-group of order about 256 bits to get compact proofs of correct encryption of shares. Switching from the lattice setting to the DL setting is relatively painless, as we equate the LWE modulus with the order of the group, and apply dimension reduction to vectors before the switch to minimize the number of exponentiations in the bulletproof. An implementation of our PVSS for 1000 parties showed that it's quite practical, and should remain so with up to a two order of magnitude increase in the group size.

Software implementations of the number-theoretic transform (NTT) method often leverage Harvey’s butterfly to gain speedups. This is the case in cryptographic libraries such as IBM’s HElib, Microsoft’s SEAL, and Intel’s HEXL, which provide optimized implementations of fully homomorphic encryption schemes or their primitives. We extend the Harvey butterfly to the radix-4 case for primes in the range [2^31, 2^52). This enables us to use the vector multiply sum logical (VMSL) instruction, which is available on recent IBM Z^(R) platforms. On an IBM z14 system, our implementation performs more than 2.5x faster than the scalar implementation of SEAL we converted to native C. In addition, we implemented a mixed-radix implementation that uses AVX512-IFMA on Intel’s Ice Lake processor, which happens to be ~1.1 times faster than the super-optimized implementation of Intel’s HEXL. Finally, we compare the performance of some of our implementation using GCC versus Clang compilers and discuss the results.

Homomorphic secret sharing (HSS) for a function $f$ allows input parties to distribute shares for their private inputs and then locally compute output shares from which the value of $f$ is recovered. HSS can be directly used to obtain a two-round multiparty computation (MPC) protocol for possibly non-threshold adversary structures whose communication complexity is independent of the size of $f$. In this paper, we propose two constructions of HSS schemes supporting parallel evaluation of a single low-degree polynomial and tolerating multipartite and general adversary structures. Our multipartite scheme tolerates a wider class of adversary structures than the previous multipartite one in the particular case of a single evaluation and has exponentially smaller share size than the general construction. While restricting the range of tolerable adversary structures (but still applicable to non-threshold ones), our schemes perform $\ell$ parallel evaluations with communication complexity approximately $\ell/\log\ell$ times smaller than simply using $\ell$ independent instances. We also formalize two classes of adversary structures taking into account real-world situations to which the previous threshold schemes are inapplicable. Our schemes then perform $O(m)$ parallel evaluations with almost the same communication cost as a single evaluation, where $m$ is the number of parties.

TCC'21 will take place will take place in Raleigh, United States on November 8-11 2021.

Early registration closes on October 24th. Visit: https://tcc.iacr.org/2021/registration.php to register.

If you have any questions or doubts, contact the General Chair Alessandra Scafuro

The 2021 Election for Directors of the IACR Board is now open.

You may vote as often as you wish now through November 16th using the Helios https://heliosvoting.org cryptographically-verifiable election system, but only your last vote will be counted.

Please see for a brief overview of how the Helios system works and https://www.iacr.org/elections/eVoting/ for information on the IACR decision to adopt Helios.

2021 members of the IACR (generally people who attended an IACR event in 2020) should shortly receive, or have already received, voting credentials from system@heliosvoting.org sent to their email address of record with the IACR. Please check your spam folder first if you believe that you haven't received the mail. Questions about this election may be sent to elections@iacr.org.

Information about the candidates can be found below and also at https://iacr.org/elections/2021/candidates.php.

The importance of efficient multi-exponen- tiation algorithms in a large spectrum of cryptographic applications continues to grow. Many of the algorithms proposed in the past pay attention exclusively on the minimization of the number of modular multiplications. However, a short reduction of the multiplicative com- plexity can be easily overshadowed by other figures of merit. In this article we demonstrate a large number of practical results aimed at concrete cryptographic tasks requiring multi-exponentiations and provide rec- ommendations on the best possible algorithmic strate- gies for different selection of security parameters.

Bulletproofs (Bünz et al. IEEE S&P 2018) are a celebrated ZK proof system that allows for short and efficient proofs, and have been implemented and deployed in several real-world systems. In practice, they are most often implemented in their non-interactive version obtained using the Fiat-Shamir transform, despite the lack of a formal proof of security for this setting.

Prior to this work, there was no evidence that malleability attacks were not possible against Fiat-Shamir Bulletproofs. Malleability attacks can lead to very severe vulnerabilities, as they allow an adversary to forge proofs re-using or modifying parts of the proofs provided by the honest parties. In this paper, we show for the first time that Bulletproofs (or any other similar multi-round proof system satisfying some form of weak unique response property) achieve simulation-extractability in the algebraic group model.

This implies that Fiat-Shamir Bulletproofs are non-malleable.

Block cipher DEFAULT has been proposed as a differential fault analysis immune cipher at Asiacrypt 2021. In this paper, we show that one can find the key of the initial version of DEFAULT with complexity $2^{16}$ by injecting 112 faults. However, our idea does not work in the modified version of the cipher.