IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
05 March 2023
R Radheshwar, Meenakshi Kansal, Pierrick Méaux, Dibyendu Roy
Cas Cremers, Julian Loss, Benedikt Wagner
To this end, we provide the first holistic security model for Monero's RingCT. In our model, we then prove the security of RingCT. Our framework is modular in that it allows to view RingCT as a combination of various different sub-protocols. This has the benefit that these components can be easily updated in future versions of RingCT with only minor modifications to our analysis. At a technical level, we introduce several new techniques that we believe to be of independent interest. First, we need to make several subtle modifications to the syntax and security properties of existing building blocks (e.g., linkable ring signatures), which result from the unusual way in which they are combined within RingCT. Then, we show how these building blocks can be combined in order to argue security of the top level transaction scheme. As a technical highlight of our proof, we show that our security goals can be mapped to a suitable graph problem. This allows us to take advantage of ideas from the theory of network flows in our analysis.
Fabrice Benhamouda, Mariana Raykova, Karn Seth
Delft, Paesi Bassi, 7 July 2023
Submission deadline: 15 March 2023
Notification: 17 April 2023
TU Wien, Vienna, Austria
We are looking for a candidate with strong scientific foundations and demonstrated expertise in the design of innovative privacy-enhancing technologies that fulfill the needs of our digital society. Desired core areas of competence include but are not limited to:
- Data Privacy
- Privacy in analytics and machine learning
- Theoretical foundations of and formal methods for privacy
- Privacy-preserving protocols, applications, and systems
- Anonymous communication, censorship-resistance
- Cryptographic techniques for privacy
- Human-centered design and usability of privacy technologies
Application deadline: 4 May 2023
For all details and to apply, see: jobs.tuwien.ac.at/Job/203700
Closing date for applications:
Contact: Carmen Keck
More information: https://jobs.tuwien.ac.at/Job/203700
Input Output Global - remote work opportunity
As a Senior Cryptography Engineer in Applied Cryptography at IOG you must be an engineer, an architect, an applied cryptographer and leader - it’s a multifaceted role. You have the exciting challenge of working with bleeding-edge research and technology, always with a focus on the market's needs. You will be a leader to an exceptional team. Working on everything from Post-Quantum prototypes to hand-optimisation of existing primitives to completely new products.
Your mission
- Champion of the applied cryptography team
- Captain end to end development and delivery of new products
- Spearhead prototyping of cryptographic products
- Translate research into rigorous engineering specifications & implementations
- Meticulously review cryptographic protocols and proposed primitives
- Expert knowledge of ZK protocols, including PlonK and IPA commitment scheme
- Expert knowledge of elliptic curve cryptography
- Familiarity with blockchain cryptography and constructions
- Practical experience with implementation of cryptographic primitives
- Expert in terms of secure design (constant time, operational security, management of key material)
- Document code and APIs concisely and unambiguously
- Pragmatically adhere to software engineering principles (modularity, incremental development, no premature optimization, no feature creep, no speculative generality, ...)
- Security sensibility related to cryptographic implementation
- Good theoretical cryptography and mathematical knowledge
- Ability to read cryptographic papers, explain them, and manage delivery of their implementation
Your expertise
Degree in Computer Science/Engineering or Applied Mathematics is desirable but not essential
A minimum of 4-5 years development experience (professional or otherwise) in Rust
Experience working with Git and version control
Expert knowledge of applied cryptographic engineering & best practices
Closing date for applications:
Contact: Marios Nicolaides
Input Output Global - remote work opportunity
As Cryptographic Engineer at IO Global, you will have the exciting challenge of working on cutting-edge research and technology focusing on the market’s needs. You will be working on Midnight, specifically on the zero-knowledge proofs that power Midnight.
The Cryptography Engineering team is growing with the goal of bringing recent academic papers into production. In this team, you will work closely with researchers and engineers, being the bridge between both teams. As Cryptography Engineer you are responsible for writing high-quality code. To support you, our products have software architects, product managers, delivery managers, formal methods specialists, and QA test engineers, with whom you must communicate professionally, effectively, and efficiently.
Your mission
- Working with teams across time zones
- Working independently on software development tasks
- Being proactive and requiring minimal supervision or mentoring to complete tasks
- Reviewing specifications produced by architects and formal methods specialists
- Contributing to the design of algorithms
- Troubleshooting, debugging, and upgrading software
- Writing documentation for the code
- Writing technical user manuals
- Understanding complex cryptographic concepts from academic papers
- Bridging ideas from academic papers to production-ready systems
Requirements
Your expertise
- Excellent Mathematical and Analytical skills.
- Experience with Rust. Not necessarily in industry.
- Knowledge of basic cryptographic concepts (Hash Functions,
- Signature Schemes or Elliptic Curves).
- Degree in computer science or mathematics is desirable, but not essential.
- Experience with systems programming (Rust)
- Skilled in software development methods such as agile programming and test-driven development
- Experience in developing cryptography protocols would be a bonus, as would blockchain experience.
Location IOG is a distributed organization and therefore this is a remote position.
Closing date for applications:
Contact: Marios Nicolaides marios.nicolaides@iohk.io
More information: https://apply.workable.com/io-global/j/4437128D09/
Télécom Paris, Paris, France
Closing date for applications:
Contact: If you want to apply or have more information, please contact Sébastien Canard (sebastien.canard@telecom-paris.fr) or Duong Hieu Phan (hieu.phan@telecom-paris.fr).
Copenhagen, Denmark, 24 August - 25 August 2023
Submission deadline: 15 April 2023
Notification: 15 June 2023
03 March 2023
Reza Ghasemi
Danilo Gligoroski
Additionally, we construct an Arithmetic for power indices and propose generic recipe guidelines that we call "Entropic-Lift" for transforming some of the existing classical cryptographic schemes that depend on the hardness of Discrete Logarithm Problem to post-quantum cryptographic schemes that will base their security on the hardness of the Exponential Congruences Problem.
As concrete examples, we show how to transform the classical Diffie-Hellman key exchange, DSA and Schnorr signature schemes.
We also post one open problem: From the perspective of provable security, specifically from the standpoint of security of post-quantum cryptographic schemes, to precisely formalize and analyze the potentials and limits of the Entropic-Lift transformation.
Razvan Barbulescu, Adrien Poulalion
Senpeng Wang, Dengguo Feng, Bin Hu, Jie Guan, Ting Cui, Tairong Shi, Kai Zhang
Thuat Do
Joseph Jaeger, Akshaya Kumar
The reductions carefully combine recent proof techniques introduced by Bhattacharyya’20 and Ghoshal- Ghosal-Jaeger-Tessaro’22. Our proofs for the augmented ECIES version of Hashed-ElGamal make use of a new computational Diffie-Hellman assumption wherein the adversary is given access to a pairing to a random group, which we believe may be of independent interest.
Sajin Sasy, Ian Goldberg
In this work we survey 31 systems targeting metadata-protected communications, and present a unified view of the current state of affairs. We provide two different taxonomies for existing MPCS, first into three different categories by the precise type of metadata protections they offer, and next into six families based on the core techniques that underlie them. By contrasting these systems we identify potential vulnerabilities, as well as subtle privacy implications of design choices of existing MPCS. Furthermore, we identify promising avenues for future research for MPCS, and desirable properties that merit more attention.
Poulami Das, Andreas Erwig, Sebastian Faust, Julian Loss, Siavash Riahi
In this work, we address this significant drawback of non-hardened nodes by laying out the design for the first hierarchical deterministic wallet scheme with thresholdized non-hardened nodes. We first provide a game-based notion of threshold signatures with rerandomizable keys and show an instantiation via the Gennaro and Goldfeder threshold ECDSA scheme (CCS'18). We further observe that the derivation of hardened child wallets according to the BIP32 specification does not translate easily to the threshold setting. Therefore, we devise a new and efficient derivation mechanism for hardened wallets in the threshold setting that satisfies the same properties as the original BIP32 derivation mechanism and therefore allows for efficient constructions of BIP32-compatible threshold wallets.
Léo Colisson, Garazi Muguruza, Florian Speelman
In particular, by instantiating our construction using Non-Interactive ZK (NIZK), we provide the first round-optimal (2-message) quantum OT protocol secure in the random oracle model, and round-optimal extensions to string and $k$-out-of-$n$ OT. At the heart of our construction lies a new method that allows us to prove properties on a received quantum state without revealing (too much) information on it, even in a non-interactive way and/or with statistical guarantees when using an appropriate classical ZK protocol. We can notably prove that a state has been partially measured (with arbitrary constraints on the set of measured qubits), without revealing any additional information on this set. This notion can be seen as an analog of ZK to quantum states, and we expect it to be of independent interest as it extends complexity theory to quantum languages, as illustrated by the two new complexity classes we introduce, ZKstateQIP and ZKstateQMA.
Lennart Braun, Mahak Pancholi, Rahul Rachuri, Mark Simkin
Asymptotically, our protocol requires a constant number of rounds and a amortized sublinear amount of communication and computation per memory access. In terms of concrete efficiency, our protocol outperforms previous solutions. For a memory of size $2^{26}$ our memory accesses are \(30\times\) faster in the LAN and \(8.7\times\) faster in the WAN setting, when compared to the previously fastest solution by Vadapalli, Henry, and Goldberg (ePrint 2022). Due to our superior asymptotic guarantees, the efficiency gap is only widening as the memory gets larger and for this reason Ramen provides the currently most scalable concretely efficient solution for securely computing RAM programs.
Rohann Bella, Xavier Bultel, Céline Chevalier, Pascal Lafourcade, Charles Olivier-Anclin
In 2019, X. Bultel and P. Lafourcade proposed a cryptographic protocol for Spades in the random oracle model allowing peer-to-peer trick-taking games to be played securely without the possibility of cheating, even by playing a card that does not respect the secret constraints. However, to simulate card shuffling, this protocol requires a custom proof of shuffle with quadratic complexity in the number of cards, which makes the protocol inefficient in practice. In this paper, we improve their work in several ways. First, we extend their model to cover a broader range of games, such as those implying a set of cards set aside during the deal (for instance Triomphe or French Tarot). Then, we propose a new efficient construction for Spades in the standard model (without random oracles), where cards are represented by partially homomorphic ciphertexts. It can be instantiated by any standard generic proof of shuffle, which significantly improves the efficiency. We demonstrate the feasibility of our approach by giving an implementation of our protocol, and we compare the performances of the new shuffle protocol with the previous one. Finally, we give a similar protocol for French Tarot, with comparable efficiency.