International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Madars Virza

Publications

Year
Venue
Title
2020
TOSC
Cryptanalysis of Curl-P and Other Attacks on the IOTA Cryptocurrency 📺
We present attacks on the cryptography formerly used in the IOTA blockchain, including under certain conditions the ability to forge signatures. We developed practical attacks on IOTA’s cryptographic hash function Curl-P-27, allowing us to quickly generate short colliding messages. These collisions work even for messages of the same length. Exploiting these weaknesses in Curl-P-27, we broke the EUCMA security of the former IOTA Signature Scheme (ISS). Finally, we show that in a chosen-message setting we could forge signatures and multi-signatures of valid spending transactions (called bundles in IOTA).
2019
EUROCRYPT
Aurora: Transparent Succinct Arguments for R1CS
We design, implement, and evaluate a zero knowledge succinct non-interactive argument (SNARG) for Rank-1 Constraint Satisfaction (R1CS), a widely-deployed NP language undergoing standardization. Our SNARG has a transparent setup, is plausibly post-quantum secure, and uses lightweight cryptography. A proof attesting to the satisfiability of n constraints has size $$O(\log ^2 n)$$O(log2n); it can be produced with $$O(n \log n)$$O(nlogn) field operations and verified with O(n). At 128 bits of security, proofs are less than $${250}\,\mathrm{kB}$$250kB even for several million constraints, more than $$10{\times }$$10× shorter than prior SNARGs with similar features.A key ingredient of our construction is a new Interactive Oracle Proof (IOP) for solving a univariate analogue of the classical sumcheck problem [LFKN92], originally studied for multivariate polynomials. Our protocol verifies the sum of entries of a Reed–Solomon codeword over any subgroup of a field.We also provide $$\texttt {libiop}$$libiop, a library for writing IOP-based arguments, in which a toolchain of transformations enables programmers to write new arguments by writing simple IOP sub-components. We have used this library to specify our construction and prior ones, and plan to open-source it.
2017
EUROCRYPT
2016
TCC
2015
EUROCRYPT
2014
CRYPTO
2013
CRYPTO