IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
19 July 2019
Yuhei Watanabe, Hideki Yamamoto, Hirotaka Yoshida
ePrint ReportAbhishek Jain, Zhengzhong Jin
ePrint ReportChristian Badertscher, Peter Gaži, Aggelos Kiayias, Alexander Russell, Vassilis Zikas
ePrint ReportWe design and analyze a PoS blockchain protocol that we prove UC-secure without assuming access to a global time functionality. Central to our construction is a novel clock synchronization mechanism that enables joining parties to adjust their local clocks correctly, relying only on knowledge of the genesis block and the assumption that their local, initially desynchronized clocks advance at approximately the same speed. This is particularly challenging as we work in the dynamic availability setting which addresses optimal resilience under arbitrary and potential adversarial participation patterns. As a corollary of our construction, we obtain a permissionless PoS implementation of a global clock that may be used whenever access to global time is a requirement in a higher level protocol.
Daniel Cervantes-Vázquez, Mathilde Chenu, Jesús-Javier Chi-Domínguez, Luca De Feo, Francisco Rodríguez-Henríquez, Benjamin Smith
ePrint ReportMarkus Brandt, Claudio Orlandi, Kris Shrishak, Haya Shulman
ePrint ReportTransport layer: Although significantly improved, the performance of 2PC is still prohibitive for practical systems. Contrary to the common belief that bandwidth is the remaining bottleneck for 2PC implementation, we show that the network is under-utilised due to the use of standard TCP sockets. Nevertheless, using other sockets is a nontrivial task: the developers of secure computation need to integrate them into the operating systems, which is challenging even for systems experts. To resolve this issue, and break the efficiency barrier of 2PC, we design and develop a framework, we call Transputation, which automates the integration of transport layer sockets into 2PC implementations. The goal of Transputation is to enable developers of 2PC protocols to easily identify and use the optimal transport layer protocol for the given computation task and network conditions and hence to improve performance of secure computation.
We integrated selected transport layer protocols into Transputation and evaluated the performance for a number of computational tasks. As a highlight, even a general purpose transport layer protocol, such as SABUL, improves the run-time of 2PC over TCP on EU-Australia connection for circuits with $ > 10^6 $ Boolean gates by a factor of $ 8 $.
Evaluations of 2PC: Evaluations of 2PC implementations do not reflect performance in real networks since they are typically done on simulated environments and even more often on a single host. To address this issue, we provide a testbed platform for evaluation of 2PC implementations in real life settings on the Internet.
Karl Wüst, Sinisa Matetic, Silvan Egli, Kari Kostiainen, Srdjan Capkun
ePrint ReportIn this paper, we propose a novel system called ACE whose main goal is to enable more complex smart contracts on permissionless blockchains. ACE is based on an off-chain execution model where the contract issuers appoint a set of service providers to execute the contract code independent from the consensus layer. The primary advantage of ACE over previous solutions is that it allows one contract to safely call another contract that is executed by a different set of service providers. Thus, ACE is the first solution to enable off-chain execution of interactive smart contracts with flexible trust assumptions. Our evaluation shows that ACE enables several orders of magnitude more complex smart contracts than standard Ethereum.
Alessandro Chiesa, Peter Manohar, Nicholas Spooner
ePrint ReportIn this work we provide the first such evidence by proving that the SNARG construction of Micali is unconditionally secure in the *quantum* random oracle model. We also prove that, analogously to the classical case, the SNARG inherits the zero knowledge and proof of knowledge properties of the PCP underlying the Micali construction. We thus obtain the first zero knowledge SNARG of knowledge (zkSNARK) that is secure in the quantum random oracle model.
Our main tool is a new lifting lemma that shows how, for a rich class of oracle games, we can *generically* deduce security against quantum attackers by bounding a natural classical property of these games. This means that in order to prove our theorem we only need to establish *classical* properties about the Micali construction. This approach not only lets us prove post-quantum security but also enables us to prove explicit bounds that are tight up to small factors.
We additionally use our techniques to prove that SNARGs based on interactive oracle proofs (IOPs) with round-by-round soundness are unconditionally secure in the quantum random oracle model. This result establishes the post-quantum security of many SNARGs of practical interest.
Alexander Maximov
ePrint ReportAnnouncement
In-between a memorable Eurocrypt in Darmstadt and an exciting Crypto coming up in August, let me share some recent developments in the IACR.
Cryptology ePrint Archive
After four years of serving as one of two editors, Alexandra Boldyreva has stepped down. Approving the eprints according to minimal acceptance criteria is an important task that benefits everyone in the field. Speaking for IACR, I thank her for all the work with this and wish her a well-deserved break from the flood of submissions.
The Board has appointed Joppe Bos to new co-editor; he shares this position with Tancrède Lepoint.
Communications Secretary
A second change has taken place with the responsible for communications: Mike Rosulek has driven publicity for IACR during the last five years. On behalf of the organization, I thank him for all his efforts, his diligence, and many late-night shifts.
The Board has appointed Foteini Baldimtsi as new Communications Secretary; she oversees a growing team of multiple people who operate the online and communication services. Welcome to the Board!
Eurocrypt 2021 in Norway and Asiacrypt 2021 in Singapore
Eurocrypt will return to Norway in 2021 (after 1993 in Lofthus) and take place Trondheim, with Colin Boyd serving as General Chair. For Asiacrypt 2021 the IACR has selected a proposal from Singapore, organized by Guo Jian of the Nanyang Technological University.
We thank them and all other conference organizers for creating the leading conferences in the field. It is a multi-year effort to organize an event attended by several hundred people and means a great investment of time and energy. But organizing an event also provides the rewarding opportunity to leave lasting memories with all attendees. Bringing together everyone, including newcomers, students, senior researchers and everyone else with a common interest in cryptologic research, is an important aspect that goes beyond the scientific progress. In this sense I invite everyone who is in a position to do so, to think about contributing to IACR and potentially organize a future event -- just approach any Board member with your ideas.
The Board has discussed many further topics at the recent Eurocrypt meeting and also earlier at virtual meetings; you can find the meeting minutes online at https://www.iacr.org/docs/minutes/
Website renewal
A few days ago the web team has upgraded the IACR website with a completely new, responsive design. I invite you to check it out at https://iacr.org/. The new implementation renders the content nicely on any platform, from mobile phone to tablet and desktop.
On behalf of the IACR, I sincerely thank Kevin McCurley for the tremendous effort he has put into the upgrade. As a former IACR treasurer, president, and creator of the initial website, his contributions and dedication are exemplary!
I am looking forward to seeing many of you at CRYPTO in Santa Barbara! Please note that the early-registration deadline is on July 19th.
Christian Cachin
IACR President
18 July 2019
Announcement
San Francisco, USA, 24 February - 28 February 2020
Event CalendarSubmission deadline: 20 September 2019
Notification: 15 November 2019
Cambridge, England, 6 November 2019
Event CalendarParis, France, 31 March - 1 April 2020
Event CalendarRonald Cramer, Matthieu Rambaud, Chaoping Xing
ePrint ReportUsing theory of AG-codes over finite fields and over rings, combined with nontrivial algebraic-geometric lifting techniques, we show that, for arbitrary fixed ring $R_\ell=\mathbb{Z}/p^{\ell}\mathbb{Z}$, there is a fixed integer $\hat{r}=\hat{r}(p)>0$ and a (dense) family of $R_\ell(\hat{r})$-linear codes $C$ of unbounded length such that:
-- Denoting the reduction of $C$ modulo $p$ (an $\mathbb{F}_{p^{\hat{r}}}$-linear code) by $\overline{C}$, each of $\overline{C}$, $(\overline{C})^{\bot}$ (dual), $(\overline{C})^{\ast 2}$ ("square under Schur-product'') is asymptotically good. -- Each of $C$, $C^{\bot}$, $C^{\ast 2}$ is free over $R_\ell(\hat{r})$, with the same dimension as its reduction. Therefore, each has the same minimum distance as its reduction. Particularly, each is asymptotically good.
-- All constructions are efficient.
This implies arithmetic secret sharing over the fixed ring $\mathbb{Z}/p^{\ell}\mathbb{Z}$ (rather, the constant-degree extension) with unbounded (dense) $n$, secret-space dimension $\Omega(n)$, share-space dimension $O(1)$, $t$-privacy $\Omega(n)$ with $t$-wise share-uniformity and $1/3 - t/n>0$ a constant arbitrarily close to 0, and, ---last-but-not-least---, ``multiplicativity-locality'' $n-t$. This extends Chen-Cramer (CRYPTO 2006), which only works over any (large enough) finite fields, significantly. Concrete parameters we show here are at least as large.
We also show a similar lifting result for asymptotically-good reverse multiplication-friendly embeddings (RFME) and we show how to get an asymptotically-good alternative for the functionality of "hyper-invertible matrices" (essential for efficient active-security MPC), as the latter are inherently asymptotically-bad.
Finally, we give two applications to general arithmetic MPC over $\mathbb{Z}/p^{\ell}\mathbb{Z}$ (in the BGW-model with active, perfect security) with communication complexity significantly better than the obvious approach based on combining MPC over $\mathbb{F}_p$ with added circuitry for emulation of the basic $\mathbb{Z}/p^{\ell}\mathbb{Z}$-operations over $\mathbb{F}_p$. Concretely, recent results by Cascudo-Cramer-Xing-Yuan on amortized complexity of MPC (CRYPTO 2018) are now achievable over these rings instead of finite fields, with the same asymptotic complexity and adversary rates.
Cristian Hristea, Ferucio Laurentiu Tiplea
ePrint ReportIn this paper, we introduce the class of stateful RFID schemes with constant tag identifiers, that ensure tag identification in no more than logarithmic time. In order to study their privacy, we propose an appropriate general model obtained by constraining Vaudenay's model. We then propose two symmetric-key cryptography based RFID schemes in this class that achieve weak and destructive privacy, respectively, in addition to mutual authentication. We also discuss on the degree of privacy provided by other schemes proposed in the literature, that fall in this class.