8 research outputs found
Quantum boomerang attacks and some applications
In this paper, we study quantum key-recovery attacks on block ciphers. While it is well known that a quantum adversary can generically speed up an exhaustive search of the key, much less is known on how to use specific vulnerabilities of the cipher to accelerate this procedure. In this context, we show how to convert classical boomerang and mixing boomerang attacks into efficient quantum key-recovery attacks. In some cases, we can even obtain a quadratic speedup, the same as simple differential attacks. We apply this technique to a 5-round attack on SAFER++
Truncated Differential Attacks: New Insights and 10-round Attacks on QARMA
Truncated differential attacks were introduced by Knudsen in 1994 [1].
They are a well-known family that has arguably received less attention than some other variants of differential attacks. This paper gives some new insight on truncated differential attacks and provides the best-known attacks on both variants of the lightweight cipher QARMA, in the single tweak model, reaching for the first time 10 rounds while contradicting the security claims of this reduced version. These attacks use some new truncated distinguishers as well as some evolved key-recovery techniques
Improved Differential Meet-In-The-Middle Cryptanalysis
In this paper, we extend the applicability of differential meet-
in-the-middle attacks, proposed at Crypto 2023, to truncated differen-
tials, and in addition, we introduce three new ideas to improve this type
of attack: we show how to add longer structures than the original pa-
per, we show how to improve the key recovery steps by introducing some
probability in them, and we combine this type of attacks with the state-
test technique, that was introduced in the context of impossible differ-
ential attacks. Furthermore, we have developed a MILP-based tool to
automate the search for a truncated differential-MITM attack with op-
timized overall complexity, incorporating some of the proposed improve-
ments. Thanks to this, we can build the best known attacks on the cipher
CRAFT, reaching 23 rounds against 21 previously; we provide a new at-
tack on 23-round SKINNY-64-192, and we improve the best attacks on
SKINNY-128-384
Quantum linearization attacks
Recent works have shown that quantum period-finding can be used to break many popular constructions (some block ciphers such as Even-Mansour, multiple MACs and AEs...) in the superposition query model. So far, all the constructions broken exhibited a strong algebraic structure, which enables to craft a periodic function of a single input block. Recoverin
Internal symmetries and linear properties: Full-permutation distinguishers and improved collisions on Gimli
Gimli is a family of cryptographic primitives (both a hash function and an AEAD scheme) that has been selected for the second round of the NIST competition for standardizing new lightweight designs. The candidate Gimli is based on the permutation Gimli, which was presented at CHES 2017. In this paper, we study the security of both the permutation and the constructions that are based on it. We exploit the slow diffusion in Gimli and its internal symmetries to build, for the first time, a distinguisher on the full permutation of complexity 2^64. We also provide a practical distinguisher on 23 out of the full 24 rounds of Gimli that has been implemented. Next, we give (full state) collision and semi-free start collision attacks on Gimli-Hash, reaching, respectively, up to 12 and 18 rounds. On the practical side, we compute a collision on 8-round Gimli-Hash. In the quantum setting, these attacks reach 2 more rounds. Finally, we perform the first study of linear trails in Gimli, and we find a linear distinguisher on the full permutation
QCB: Efficient quantum-secure authenticated encryption
It was long thought that symmetric cryptography was only
mildly affected by quantum attacks, and that doubling the key length
was sufficient to restore security. However, recent works have shown that
Simon’s quantum period finding algorithm breaks a large number of MAC
and authenticated encryption algorithms when the adversary can query
the MAC/encryption oracle with a quantum superposition of messages.
In particular, the OCB authenticated encryption mode is broken in this
setting, and no quantum-secure mode is known with the same efficiency
(rate-one and parallelizable).
In this paper we generalize the previous attacks, show that a large class
of OCB-like schemes is unsafe against superposition queries, and discuss
the quantum security notions for authenticated encryption modes. We
propose a new rate-one parallelizable mode named QCB inspired by TAE
and OCB and prove its security against quantum superposition queries