Sadegh Sadeghi :: Homepage

About Me

I am an Assistant Professor in the Cryptography group within the Mathematics Department at the Institute for Advanced Studies in Basic Sciences (IASBS). Before this, I held a position as a Postdoctoral Researcher in the Department of Electrical Engineering at Sharif University of Technology, where I was a member of the ISSL research group. During my time there, my research focused on the security of lightweight ciphers in the context of the Internet of Things (IoT), with a particular emphasis on analyzing authentication schemes and protocols used in IoT systems.

Before joining Sharif University, I completed my PhD thesis on Automated Cryptanalysis of Lightweight Symmetric Ciphers at Kharazmi University in 2019. Additionally, during my doctoral studies, I had the opportunity to work as a visiting researcher at KU Leuven, collaborating with Prof. Vincent Rijmen as part of the COSIC research group.

Research Interests

My passion lies in advancing the field of cryptography through a comprehensive approach that encompasses both theoretical research and practical applications. Specifically, my research interests revolve around cryptology, with a focus on the design and analysis of symmetric schemes. This includes exploring lightweight ciphers, such as block ciphers, hash functions, authenticated encryption schemes, and cryptographic protocols tailored for constrained environments like IoT edge devices.

Network Visualization of keywords in IACR TOSC papers.

News

August 2024: Our paper “Cryptanalysis of DBST, a lightweight block cipher" is published in Front. Comput. Sci. 18, 184819. (Access Link). This is a joint work with Nasour Bagheri

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In this work, we provide the first third-party analysis of the DBST cipher, challenging its security claims. The analysis reveals significant vulnerabilities within the cipher's structure, allowing the identification of distinguishers that can differentiate all 32 rounds of the cipher from a random permutation with a probability of one. This contradicts the designers' claim that the probability of a successful differential attack on any 32-round characteristic is bounded by $2^{-170}$. Additionally, the existence of differential distinguishers for the full round implies the existence of full-round impossible differential distinguishers, contradicting the designers' claim that the best impossible differential characteristic would require at most 6 rounds.

January 2024: Our paper “Improved Search for Integral, Impossible-Differential and Zero-Correlation Attacks, Application to Ascon, ForkSKINNY, SKINNY, MANTIS, PRESENT and QARMAv2 ” is accepted in ToSC 2024/1 (FSE2024). (Access Link). This is a joint work with Hosein Hadipour , Simon Gerhalter, Maria Eichlseder.

This paper will be presented at the FSE 2024 in Leuven, Belgium.

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In this work, we have made significant advancements in our EUROCRYPT 2023 project (https://ia.cr/2022/1147) through three key improvements. Firstly, we have eliminated the need to determine the contradiction location in advance. Secondly, we have introduced a new bit-wise model that considers the internal structure of S-boxes. Lastly, we have introduced the CP model for the partial-sum technique for the first time. Applying our enhanced method to six different block ciphers has yielded impressive results. Some notable achievements include enhancing the integral distinguishers of QARMAv2-128 (QARMAv2-64) by 7 (5) rounds, improving ForkSKINNY integral distinguishers by 1 round, enhancing ForkSKINNY-64-192 ID distinguishers by 5 rounds, and improving integral key recovery on all SKINNY variants. Additionally, we have discovered numerous new ID/ZC distinguishers for Ascon, surpassing the speed of previous methods.

April 2023: Our paper “Finding the Impossible: Automated Search for Full Impossible-Differential, Zero-Correlation, and Integral Attacks ” is published in Eurocrypt-2023. (Access Link). This is a joint work with Hosein Hadipour , Maria Eichlseder.

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This paper has been published in the Eurocrypt-2023 conference. We introduced a unified method to fully automate three important cryptographic attacks on block ciphers. We invite you to explore our work here.

May 2023: Our paper “$\Xi$perbp: a cloud-based lightweight mutual authentication protocol” is published in Peer-to-Peer Networking and Applications. (Access Link). This is a joint work with Morteza Adeli, Nasour Bagheri , Saru Kumari.

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In this paper, we first introduce $\Xi$per, as a new hardware/software friendly component that can be implemented using bit-wise operations and extensively analyze its security. Next, we propose $\Xi$perbp, a lightweight authentication protocol based on $\Xi$per component. To evaluate the performance efficiency of our proposed scheme, we implement the $\Xi$perbp scheme on an FPGA module Xilinx Kintex-7 using the hardware description language VHDL. Our security and cost analysis of the proposed protocol shows that the proposed protocol provides desired security against various attacks, at a reasonable cost. Also, formal security evaluation using BAN logic and the Scyther tool indicates its security correctness. Besides, we analyze the security of a related protocol which has been recently proposed by Fan et al. It is a cloud-based lightweight mutual authentication protocol for RFID devices in an IoT system. The authors have claimed that their scheme is secure against active and passive attacks, however, our detailed security analysis in this paper demonstrates the major drawbacks of this protocol. More precisely, the proposed attack discloses the tag’s secrets efficiently. Given the tag’s secrets, any other attack will be trivial.

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November 2023: Our paper “Cryptanalysis of full-round SFN Block Cipher a Lightweight Block Cipher, Targeting IoT Systems” is published in Scientia Iranica. (Access Link). This is a joint work with Sadegh Sadeghi, Majid Mahmoudzadeh Niknam, Nasour Bagheri, Mohammad Reza Aref.

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In this paper, we propose a deterministic related key distinguisher for 31 rounds of the SFN. we are able to use the proposed related key distinguisher to attack the SFN in the known-plaintext scenario with the time complexity of $2^{60.58}$ encryptions. The data and memory complexity of those attacks are negligible. In addition, we will extend it to a practical chosen-plaintext-ciphertext key recovery attack on full SFN (32 rounds) with the complexity of $2^{20}$. We also experimentally verified this attack. Also, in the single key mode, we present a meet in the middle attack against the full rounds block cipher for which the time complexity is $2^{80}$ the SFN calculations and the memory complexity is $2^{35.6}$ bytes. The data complexity of this attack is only two known plaintext and their corresponding ciphertext.

September 2022: Our paper “SIPFA: Statistical Ineffective Persistent Faults Analysis on Feistel Ciphers” is published in CHES 2022-IACR. (Access Link). This is a joint work with Nasour Bagheri, Prasanna Ravi, Shivam Bhasin, Hadi Soleimany.

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In this paper, we introduce a framework to utilize Statistical Ineffective Fault Analysis (SIFA) in the persistent fault setting by proposing Statistical Ineffective Persistent Faults Analysis (SIPFA) that can be efficiently applied to Feistel ciphers in a variety of scenarios. To demonstrate the effectiveness of our technique, we apply SIFPA on three widely used Feistel schemes, DES, 3DES, and Camellia. Our analysis reveals that the secret key of these block ciphers can be extracted with a complexity of at most 250 utilizing a single unknown fault. Furthermore, we demonstrate that the secret can be recovered in a fraction of a second by increasing the adversary’s control over the injected faults. To evaluate SIPFA in a variety of scenarios, we conducted both simulations and real experiments utilizing electromagnetic fault injection on DES and 3DES.

June 2022: Our paper “Improving RFID/IoT-based generalized ultra-lightweight mutual authentication protocols” is published in Journal of Information Security and Applications. (Access Link). This is a joint work with Masoumeh Safkhani, Samad Rostampour, Ygal Bendavid, Nasour Bagheri.

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In this project, we evaluate the security level of recent ultra-lightweight mutual authentication protocols and show their susceptibility to replay and desynchronization attacks. We also show that these protocols can be grouped into a generalized version of ultra-lightweight mutual authentication protocols (GUMAPs) and classify them into two categories. We then establish that both groups are vulnerable to replay and desynchronization attacks. To eliminate these vulnerabilities, we present a new message authentication code (MAC) function to propose a more secure generalized improved mutual authentication protocol (GIMAP).