INTL JOURNAL OF ELECTRONICS AND TELECOMMUNICATIONS, 2020, VOL. 66, NO. 4, PP. 647-653 Manuscript received August 18, 2020; revised October, 2020. DOI: 10.24425/ijet.2020.134023 © The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0, https://creativecommons.org/licenses/by/4.0/), which permits use, distribution, and reproduction in any medium, provided that the Article is properly cited. Abstract—Currently, the Republic of Kazakhstan is developing a new standard for symmetric data encryption. One of the candidates for the role of the standard is the Qamal encryption algorithm developed by the Institute of Information and Computer Technologies (Almaty, Republic of Kazakhstan). The article describes the algorithm. Differential properties of the main operations that make up the Qamal cypher are considered in the questions of stability. We have shown that for a version with a 128-bit data block and the same secret key size for three rounds of encryption it is difficult to find the right pairs of texts with a probability of 2 –120 , which makes differential cryptanalysis not applicable to the Qamal cypher. Keywords—cryptography, block cypher, difference, differential cryptanalysis, probability I. INTRODUCTION HE first of the well-known government standards for data encryption was the DES standard adopted in the United States in the early 1970s. It was the time when the first computers (electronic computers) gradually ceased to be exotic and began to enter the life and work of small firms and research laboratories. This led to the fact that the problem of data protection, stored and processed on them, was recognized by a growing number of specialists. Many large corporations, not to mention public services, have conducted their own research in this area. As a result, various encryption algorithms began to appear. One of the most famous research centres of this kind at that time was the IBM science laboratory, headed by Dr Horst Feistel [1]. As a result, a system of encryption called Lucifer was created. For this encryption system, Horst Feistel proposed a mathematical model, which is now called the "Feistel scheme". The principle of the Feistel scheme is that only half or part of the text is encrypted in one round. A This work was supported by a targeted funding program “Development of software and hardware and software for cryptographic protection of information during its transmission and storage in infocommunication systems and general purpose networks” from the Committee of Science of the Ministry of Education and Science of the Republic of Kazakhstan (registration number 0118РК01064). Kunbolat Algazy (e-mail: kunbolat@mail.ru), Rustem Biyashev (e-mail: brg@ipic.kz), Nursulu Kapalova (e-mail: kapalova@ipic.kz), Saule Nysynbaeva (e-mail: sultasha1@mail.ru) are with Institute of Information and Computational Technologies of the Committee of Science of the Ministry of Education and Science of the Republic of Kazakhstan, Almaty; Ludmila Babenko (e-mail: lkbabenko@sfedu.ru). Evgeniya Ishchukova (e-mail: uaishukova@sfedu.ru) are with Institute of Computer Technologies and Information Security of the Southern Federal University, Taganrog, Russia Ryszard Romaniuk (e-mail: r.romaniuk@ise.pw.edu.pl) is with Warsaw University of Technology, Poland. Andrzej Smolarz (e-mail: a.smolarz@pollub.pl) is with Lublin University of Technology, Lublin, Poland. block of text is divided into parts. One part goes through some mathematical transformation. And the result of this transformation is added up by modulo two with the second part of the text. After that, the parts of the text are swapped. Another advantage of the scheme was the fact that by using the “Exclusive-OR” operation or, as it is also called the modulo- two addition operation, it becomes possible to use the same scheme for both data encryption and data decryption, it is enough just to change the order of the round subkeys. Initially, the DES standard was adopted for a period of 5 years, but later it was repeatedly extended as a standard [2]. By the end of the 20th century, computers were already widespread and computing power increased significantly. Therefore, the U.S. government has thought about changing the standard. As a result, a tender was announced for the adoption of a new data encryption standard – the AES (Advanced Encryption Standard) competition. The competition was announced in 1997 by the National Institute of Standards and Technologies (NIST) [3]. Fifteen encryption algorithms created by scientists from different countries were announced for participation in the contest. As a result of a five-year study, the Rijndael encryption algorithm developed by two mathematicians from Belgium, Vincent Rijmen (V. Rijmen) and Joan Damen, was chosen as the new US standard. The Rijndael algorithm is built on a network scheme based on substitutions and permutations (SPN) and has the architecture of "Square". At that time, the "Square" architecture and the SP-network were an innovative solution. Now many algorithms are AES-like and follow the structure of the Rijndael cypher. In parallel with the AES competition in January 2000, a very similar competition began in Europe, involving the selection of cryptographic standards of the European Union. This competition was called NESSIE (New European Schemes for Signature, Integrity and Encryption) [3]. As a result of the work on the NESSIE competition, a great work entitled "NESSIE security report" [3] was written by scientists- cryptographers, but the European standard was never chosen. Under the influence of the US and European sentiment, the CRYPTREC project was created in Japan. CRYPTREC is an acronym from the Cryptography Research and Evaluation Committee [4]. The project was created to study cryptographic algorithms and then recommend specific algorithms for use in public and private organizations. As a result of the CRYPTREC project, a number of recommended encryption algorithms have been identified. CIPHERUNICORN-E, Hierocrypt-L1, MISTY1 and a three-key version of the Triple DES algorithm were recommended for 64-bit ciphers. For 128- bit: AES, Camellia, CIPHERUNICORN-A, Hierocrypt-3, SC2000. Differential Cryptanalysis of New Qamal Encryption Algorithm Kunbolat T. Algazy Ludmila K. Babenko Rustem G. Biyashev Evgeniya A. Ishchukova, Ryszard Romaniuk, Nursulu A. Kapalova, Saule E. Nysynbaeva, and Andrzej Smolarz T