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IACR Transactions on Symmetric Cryptology
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2519-173X
Published by Ruhr-Universit├Ąt Bochum Homepage  [4 journals]
  • The DRACO Stream Cipher

    • Authors: Matthias Hamann, Alexander Moch, Matthias Krause, Vasily Mikhalev
      Pages: 1 - 42
      Abstract: Stream ciphers are vulnerable to generic time-memory-data tradeoff attacks. These attacks reduce the security level to half of the cipher’s internal state size. The conventional way to handle this vulnerability is to design the cipher with an internal state twice as large as the desired security level. In lightweight cryptography and heavily resource constrained devices, a large internal state size is a big drawback for the cipher. This design principle can be found in the eSTREAM portfolio members Grain and Trivium.
      Recently proposals have been made that reduce the internal state size. These ciphers distinguish between a volatile internal state and a non-volatile internal state. The volatile part would typically be updated during a state update while the non-volatile part remained constant. Cipher proposals like Sprout, Plantlet, Fruit and Atom reuse the secret key as non-volatile part of the cipher. However, when considering indistinguishability none of the ciphers mentioned above provides security beyond the birthday bound with regard to the volatile internal state. Partially this is due to the lack of a proper proof of security.
      We present a new stream cipher proposal called Draco which implements a construction scheme called CIVK. In contrast to the ciphers mentioned above, CIVK uses the initial value and a key prefix as its non-volatile state. Draco builds upon CIVK and uses a 128-bit key and a 96-bit initial value and requires 23 % less area and 31 % less power than Grain-128a at 10 MHz. Further, we present a proof that CIVK provides full security with regard to the volatile internal state length against distinguishing attacks. This makes Draco a suitable cipher choice for ultra-lightweight devices like RFID tags.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.1-42
  • New Key-Recovery Attack on Reduced-Round AES

    • Authors: Navid Ghaedi Bardeh, Vincent Rijmen
      Pages: 43 - 62
      Abstract: A new fundamental 4-round property of AES, called the zero-difference property, was introduced by Rønjom, Bardeh and Helleseth at Asiacrypt 2017. Our work characterizes it in a simple way by exploiting the notion of related differences which was introduced and well analyzed by the AES designers. We extend the 4-round property by considering some further properties of related differences over the AES linear layer, generalizing the zero-difference property. This results in a new key-recovery attack on 7-round AES which is the first attack on 7-round AES by exploiting the zero-difference property.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.43-62
  • Improved MITM Cryptanalysis on Streebog

    • Authors: Jialiang Hua, Xiaoyang Dong, Siwei Sun, Zhiyu Zhang, Lei Hu, Xiaoyun Wang
      Pages: 63 - 91
      Abstract: At ASIACRYPT 2012, Sasaki et al. introduced the guess-and-determine approach to extend the meet-in-the-middle (MITM) preimage attack. At CRYPTO 2021, Dong et al. proposed a technique to derive the solution spaces of nonlinear constrained neutral words in the MITM preimage attack. In this paper, we try to combine these two techniques to further improve the MITM preimage attacks. Based on the previous MILP-based automatic tools for MITM attacks, we introduce new constraints due to the combination of guess-and-determine and nonlinearly constrained neutral words to build a new automatic model.
      As a proof of work, we apply it to the Russian national standard hash function Streebog, which is also an ISO standard. We find the first 8.5-round preimage attack on Streebog-512 compression function and the first 7.5-round preimage attack on Streebog-256 compression function. In addition, we give the 8.5-round preimage attack on Streebog-512 hash function. Our attacks extend the best previous attacks by one round. We also improve the time complexity of the 7.5-round preimage attack on Streebog-512 hash function and 6.5-round preimage attack on Streebog-256 hash function.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.63-91
  • Integral Cryptanalysis of WARP based on Monomial Prediction

    • Authors: Hosein Hadipour, Maria Eichlseder
      Pages: 92 - 112
      Abstract: WARP is a 128-bit block cipher published by Banik et al. at SAC 2020 as a lightweight alternative to AES. It is based on a generalized Feistel network and achieves the smallest area footprint among 128-bit block ciphers in many settings. Previous analysis results include integral key-recovery attacks on 21 out of 41 rounds. In this paper, we propose integral key-recovery attacks on up to 32 rounds by improving both the integral distinguisher and the key-recovery approach substantially. For the distinguisher, we show how to model the monomial prediction technique proposed by Hu et al. at ASIACRYPT 2020 as a SAT problem and thus create a bit-oriented model of WARP taking the key schedule into account. Together with two additional observations on the properties of WARP’s construction, we extend the best previous distinguisher by 2 rounds (as a classical integral distinguisher) or 4 rounds (for a generalized integral distinguisher). For the key recovery, we create a graph-based model of the round function and demonstrate how to manipulate the graph to obtain a cipher representation amenable to FFT-based key recovery.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.92-112
  • Automatic Search of Rectangle Attacks on Feistel Ciphers: Application to

    • Authors: Virginie Lallemand, Marine Minier, Loïc Rouquette
      Pages: 113 - 140
      Abstract: In this paper we present a boomerang analysis of WARP, a recently proposed Generalized Feistel Network with extremely compact hardware implementations. We start by looking for boomerang characteristics that directly take into account the boomerang switch effects by showing how to adapt Delaune et al. automated tool to the case of Feistel ciphers, and discuss several improvements to keep the execution time reasonable. This technique returns a 23-round distinguisher of probability 2−124, which becomes the best distinguisher presented on WARP so far. We then look for an attack by adding the key recovery phase to our model and we obtain a 26-round rectangle attack with time and data complexities of 2115.9 and 2120.6 respectively, again resulting in the best result presented so far. Incidentally, our analysis discloses how an attacker can take advantage of the position of the key addition (put after the S-box application to avoid complementation properties), which in our case offers an improvement of a factor of 275 of the time complexity in comparison to a variant with the key addition positioned before. Note that our findings do not threaten the security of the cipher which iterates 41 rounds.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.113-140
  • Truncated Differential Attacks on Contracting Feistel Ciphers

    • Authors: Tim Beyne, Yunwen Liu
      Pages: 141 - 160
      Abstract: We improve truncated differential attacks on t-branch contracting Feistel ciphers with a domain size of Nt. Based on new truncated differentials, a generic distinguisher for t2 + t − 2 rounds using O(Nt−1) data and time is obtained. In addition, we obtain a key-recovery attack on t2 + 1 rounds with Õ(Nt−2) data and Õ(Nt−1) time. Compared to previous results by Guo et al. (ToSC 2016), our attacks cover more rounds with a lower data-complexity. Applications of the generic truncated differential to concrete ciphers include full-round attacks on some instances of GMiMC-crf, and the best-known key-recovery attack on 17 rounds of the Chinese block cipher standard SM4. In addition, we propose an automated search method for truncated differentials using SMT, which is effective even for trails with probability below the probability of the truncated differential for a random permutation.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.141-160
  • Revisiting the Extension of Matsui’s Algorithm 1 to Linear Hulls:
           Application to TinyJAMBU

    • Authors: Muzhou Li, Nicky Mouha, Ling Sun, Meiqin Wang
      Pages: 161 - 200
      Abstract: At EUROCRYPT ’93, Matsui introduced linear cryptanalysis. Both Matsui’s Algorithm 1 and 2 use a linear approximation involving certain state bits. Algorithm 2 requires partial encryptions or decryptions to obtain these state bits after guessing extra key bits. For ciphers where only part of the state can be obtained, like some stream ciphers and authenticated encryption schemes, Algorithm 2 will not work efficiently since it is hard to implement partial encryptions or decryptions. In this case, Algorithm 1 is a good choice since it only involves these state bits, and one bit of key information can be recovered using a single linear approximation trail. However, when there are several strong trails containing the same state bits, known as the linear hull effect, recovering key bits with Algorithm 1 is infeasible. To overcome this, Röck and Nyberg extended Matsui’s Algorithm 1 to linear hulls. However, Röck and Nyberg found that their theoretical estimates are quite pessimistic for low success probabilities and too optimistic for high success probabilities. To deal with this, we construct new statistical models where the theoretical success probabilities are in a good accordance with experimental ones, so that we provide the first accurate analysis of the extension of Matsui’s Algorithm 1 to linear hulls. To illustrate the usefulness of our new models, we apply them to one of the ten finalists of the NIST Lightweight Cryptography (LWC) Standardization project: TinyJAMBU. We provide the first cryptanalysis under the nonce-respecting setting on the full TinyJAMBU v1 and the round-reduced TinyJAMBU v2, where partial key bits are recovered. Our results do not violate the security claims made by the designers.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.161-200
  • Accelerating the Best Trail Search on AES-Like Ciphers

    • Authors: Seonggyeom Kim, Deukjo Hong, Jaechul Sung, Seokhie Hong
      Pages: 201 - 252
      Abstract: In this study, we accelerate Matsui’s search algorithm to search for the best differential and linear trails of AES-like ciphers. Our acceleration points are twofold. The first exploits the structure and branch number of an AES-like round function to apply strict pruning conditions to Matsui’s search algorithm. The second employs permutation characteristics in trail search to reduce the inputs that need to be analyzed. We demonstrate the optimization of the search algorithm by obtaining the best differential and linear trails of existing block ciphers: AES, LED, MIDORI-64, CRAFT, SKINNY, PRESENT, and GIFT. In particular, our search program finds the fullround best differential and linear trails of GIFT-64 (in approx. 1 s and 10 s) and GIFT-128 (in approx. 89 h and 452 h), respectively.
      For a more in-depth application, we leverage the acceleration to investigate the optimal DC/LC resistance that GIFT-variants, called BOGI-based ciphers, can achieve. To this end, we identify all the BOGI-based ciphers and reduce them into 41,472 representatives. Deriving 16-, 32-, 64-, and 128-bit BOGI-based ciphers from the representatives, we obtain their best trails until 15, 15, 13, and 11 rounds, respectively. The investigation shows that 12 rounds are the minimum threshold for a 64-bit BOGIbased cipher to prevent efficient trails for DC/LC, whereas GIFT-64 requires 14 rounds. Moreover, it is shown that GIFT can provide better resistance by only replacing the existing bit permutation. Specifically, the bit permutation variants of GIFT-64 and GIFT-128 require fewer rounds, one and two, respectively, to prevent efficient differential and linear trails.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.201-252
  • Differential Trail Search in Cryptographic Primitives with Big-Circle Chi:

    • Authors: Alireza Mehrdad, Silvia Mella, Lorenzo Grassi, Joan Daemen
      Pages: 253 - 288
      Abstract: Proving upper bounds for the expected differential probability (DP) of differential trails is a standard requirement when proposing a new symmetric primitive. In the case of cryptographic primitives with a bit-oriented round function, such as Keccak, Xoodoo and Subterranean, computer assistance is required in order to prove strong upper bounds on the probability of differential trails. The techniques described in the literature make use of the fact that the non-linear step of the round function is an S-box layer. In the case of Keccak and Xoodoo, the S-boxes are instances of the chi mapping operating on l-bit circles with l equal to 5 and 3 respectively. In that case the differential propagation properties of the non-linear layer can be evaluated efficiently by the use of pre-computed difference distribution tables.
      Subterranean 2.0 is a recently proposed cipher suite that has exceptionally good energy-efficiency when implemented in hardware (ASIC and FPGA). The non-linear step of its round function is also based on the chi mapping, but operating on an l = 257-bit circle, comprising all the state bits. This making the brute-force approach proposed and used for Keccak and Xoodoo infeasible to apply. Difference propagation through the chi mapping from input to output can be treated using linear algebra thanks to the fact that chi has algebraic degree 2. However, difference propagation from output to input is problematic for big-circle chi. In this paper, we tackle this problem, and present new techniques for the analysis of difference propagation for big-circle chi.
      We implemented these techniques in a dedicated program to perform differential trail search in Subterranean. Thanks to this, we confirm the maximum DP of 3-round trails found by the designers, we determine the maximum DP of 4-round trails and we improve the upper bounds for the DP of trails over 5, 6, 7 and 8 rounds.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.253-288
  • Fast MILP Models for Division Property

    • Authors: Patrick Derbez, Baptiste Lambin
      Pages: 289 - 321
      Abstract: Nowadays, MILP is a very popular tool to help cryptographers search for various distinguishers, in particular for integral distinguishers based on the division property. However, cryptographers tend to use MILP in a rather naive way, modeling problems in an exact manner and feeding them to a MILP solver. In this paper, we show that a proper use of some features of MILP solvers such as lazy constraints, along with using simpler but less accurate base models, can achieve much better solving times, while maintaining the precision of exact models. In particular, we describe several new modelization techniques for division property related models as well as a new variant of the Quine-McCluskey algorithm for this specific setting. Moreover, we positively answer a problem raised in [DF20] about handling the large sets of constraints describing valid transitions through Super S-boxes into a MILP model. As a result, we greatly improve the solving times to recover the distinguishers from several previous works ([DF20], [HWW20], [SWW17], [Udo21], [EY21]) and we were able to search for integral distinguishers on 5-round ARIA which was out of reach of previous modeling techniques.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.289-321
  • Vectorial Decoding Algorithm for Fast Correlation Attack and Its
           Applications to Stream Cipher Grain-128a

    • Authors: Zhaocun Zhou, Dengguo Feng, Bin Zhang
      Pages: 322 - 350
      Abstract: Fast correlation attack, pioneered by Meier and Staffelbach, is an important cryptanalysis tool for LFSR-based stream cipher, which exploits the correlation between the LFSR state and key stream and targets at recovering the initial state of LFSR via a decoding algorithm. In this paper, we develop a vectorial decoding algorithm for fast correlation attack, which is a natural generalization of the original binary approach. Our approach benefits from the contributions of all correlations in a subspace. We propose two novel criteria to improve the iterative decoding algorithm. We also give some cryptographic properties of the new FCA which allows us to estimate the efficiency and complexity bounds. Furthermore, we apply this technique to the well-analyzed stream cipher Grain-128a. Based on a hypothesis, an interesting result for its security bound is deduced from the perspective of iterative decoding. Our analysis reveals the potential vulnerability for LFSRs over matrix ring and also for nonlinear functions with biased multidimensional linear approximations such as Grain-128a.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.322-350
  • More Inputs Makes Difference: Implementations of Linear Layers Using Gates
           with More Than Two Inputs

    • Authors: Qun Liu, Weijia Wang, Ling Sun, Yanhong Fan, Lixuan Wu, Meiqin Wang
      Pages: 351 - 378
      Abstract: Lightweight cryptography ensures cryptography applications to devices with limited resources. Low-area implementations of linear layers usually play an essential role in lightweight cryptography. The previous works have provided plenty of methods to generate low-area implementations using 2-input xor gates for various linear layers. However, it is still challenging to search for smaller implementations using two or more inputs xor gates. This paper, inspired by Banik et al., proposes a novel approach to construct a quantity of lower area implementations with (n + 1)- input gates based on the given implementations with n-input gates. Based on the novel algorithm, we present the corresponding search algorithms for n = 2 and n = 3, which means that we can efficiently convert an implementation with 2-input xor gates and 3-input xor gates to lower-area implementations with 3-input xor gates and 4-input xor gates, respectively.
      We improve the previous implementations of linear layers for many block ciphers according to the area with these search algorithms. For example, we achieve a better implementation with 4-input xor gates for AES MixColumns, which only requires 243 GE in the STM 130 nm library, while the previous public result is 258.9 GE. Besides, we obtain better implementations for all 5500 lightweight matrices proposed by Li et al. at FSE 2019, and the area for them is decreased by about 21% on average.
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.351-378
  • On the Quantum Security of OCB

    • Authors: Varun Maram, Daniel Masny, Sikhar Patranabis, Srinivasan Raghuraman
      Pages: 379 - 414
      Abstract: The OCB mode of operation for block ciphers has three variants, OCB1, OCB2 and OCB3. OCB1 and OCB3 can be used as secure authenticated encryption schemes whereas OCB2 has been shown to be classically insecure (Inoue et al., Crypto 2019). Even further, in the presence of quantum queries to the encryption functionality, a series of works by Kaplan et al. (Crypto 2016), Bhaumik et al. (Asiacrypt 2021) and Bonnetain et al. (Asiacrypt 2021) have shown how to break the unforgeability of the OCB modes. However, these works did not consider the confidentiality of OCB in the presence of quantum queries.
      We fill this gap by presenting the first formal analysis of the IND-qCPA security of OCB. In particular, we show the first attacks breaking the IND-qCPA security of the OCB modes. Surprisingly, we are able to prove that OCB2 is IND-qCPA secure when used without associated data, while relying on the assumption that the underlying block cipher is a quantum-secure pseudorandom permutation. Additionally, we present new quantum attacks breaking the universal unforgeability of OCB. Our analysis of OCB has implications for the post-quantum security of XTS, a well-known disk encryption standard, that was considered but mostly left open by Anand et al. (PQCrypto 2016).
      PubDate: 2022-06-10
      DOI: 10.46586/tosc.v2022.i2.379-414
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