• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.4
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• pp.1944-1956
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• 2016

The Digital Video Broadcasting-Common Scrambling Algorithm is an ETSI-designated algorithm designed for protecting MPEG-2 signal streams, and it is universally used. Its structure is a typical hybrid symmetric cipher which contains stream part and block part within a symmetric cipher, although the entropy is 64 bits, there haven't any effective cryptanalytic results up to now. This paper studies the security level of CSA against impossible differential cryptanalysis, a 20-round impossible differential for the block cipher part is proposed and a flaw in the cipher structure is revealed. When we attack the block cipher part alone, to recover 16 bits of the initial key, the data complexity of the attack is O(2^44.5), computational complexity is O(2^22.7) and memory complexity is O(2^10.5) when we attack CSA-BC reduced to 21 rounds. According to the structure flaw, an attack on CSA with block cipher part reduced to 21 rounds is proposed, the computational complexity is O(2^21.7), data complexity is O(2^43.5) and memory complexity is O(2^10.5), we can recover 8 bits of the key accordingly. Taking both the block cipher part and stream cipher part of CSA into consideration, it is currently the best result on CSA which is accessible as far as we know.

• Journal of the Korea Computer Industry Society
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• v.10 no.4
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• pp.167-176
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• 2009

In this paper, we propose an improved SHACAL-1 of the same encryption and decryption with a simple symmetric layer. SHACAL-1 has 4 rounds, and each round has 20 steps. Decryption is becoming inverse function of encryption, In this paper, we proposed SHACAL-1 are composed of the first half, symmetry layer and the last half. The first half with SHACAL-1 encryption algorithm 1 round does with 10 steps and composes of 4 round. The last half identically with SHACAL-1 decryption algorithm, has a structure. On the center inserts a symmetry layer, encryption and decryption algorithm identically, composes. In the experiments, the proposed SHACAL-1 algorithm showed similar execution time to that of the SHACAL-1. Thanks to the symmetric layer, the proposed algorithm makes it difficult for the attacks which take advantages of high probability path such as the linear cryptanalysis, differential cryptanalysis. The proposed algorithm can be applicable to the other block cipher algorithms which have different encryption and decryption and useful for designing a new block cipher algorithm.

• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.359-366
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• 2008

As the use of Internet and information communication technology is being generalized, the SSL protocol is essential in Internet because the important data should be transferred securely. While the SSL protocol is designed to defend from active attack such as message forgery and message alteration, the cipher suite setting can be easily modified. If the attacker draw on a malfunction of the client system and modify the cipher suite setting to the symmetric key algorithm which has short key length, he should eavesdrop and cryptanalysis the encrypt data. In this paper, we examine the domestic web site whether they generate the security session through the symmetric key algorithm which has short key length and propose the solution of the cipher suite setting problem.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1495-1500
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• 2011

Dynamic cipher has the property that the key-size, the number of round, and the plain text-size are scalable simultaneously. In this paper we propose the block cipher algorithm which is symmetrical in the dynamic network. We present the method for designing secure Dynamic cipher against meet-in-the-middle attack and linear crytanalysis. Also, we show that the differential cryptanalysis to Dynamic cipher is hard.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.164-168
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• 2023

As our community has become increasingly dependent on technology, security has become a bigger concern, which makes it more important and challenging than ever. security can be enhanced with encryption as described in this paper by combining RC6 symmetric cryptographic algorithms with RSA asymmetric algorithms, as well as the Vigenère cipher, to help manage weaknesses of RC6 algorithms by utilizing the speed, security, and effectiveness of asymmetric algorithms with the effectiveness of symmetric algorithm items as well as introducing classical algorithms, which add additional confusion to the decryption process. An analysis of the proposed encryption speed and throughput has been conducted in comparison to a variety of well-known algorithms to demonstrate the effectiveness of each algorithm.

• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.568-573
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• 2013

In this paper, we propose a differential fault analysis on symmetry structured SPN block cipher proposed in 2008. The target algorithm has the SPN structure and a symmetric structure in encryption and decryption process. To recover the 128-bit secret key of the target algorithm, this attack requires only one random byte fault and an exhaustive search of $2^8$. This is the first known cryptanalytic result on the target algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1519-1527
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• 2007

In order to combat the security threats that sensor networks are exposed to, a cryptography protocol is implemented at sensor nodes for point-to-point encryption between nodes. Given that nodes have limited resources, symmetric cryptography that is proven to be efficient for low power devices is implemented. Data protection is integrated into a sensor's packet by the means of symmetric encryption with the Dragon stream cipher and incorporating the newly designed Dragon-MAC Message Authentication Code. The proposed algorithm was designed to employ some of the data already computed by the underlying Dragon stream cipher for the purpose of minimizing the computational cost of the operations required by the MAC algorithm. In view that Dragon is a word based stream cipher with a fast key stream generation, it is very suitable for a constrained environment. Our protocol regarded the entity authentication and message authentication through the implementation of authenticated encryption scheme in wireless sensor nodes.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.171-179
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• 2011

Feistel and SPN are the two main structures in a block cipher. Feistel is a symmetric structure which has the same structure in encryption and decryption, but SPN is not a symmetric structure. Encrypt round function and decrypt round function in SPN structure have three parts, round key addition and substitution layer with S-box for confusion and permutation layer for defusion. Most SPN structure for example ARIA and AES uses 8 bit S-Box at substitution layer, which is vulnerable to Square attack, Boomerang attack, Impossible differentials cryptanalysis etc. In this paper, we propose a SPN which has a symmetric structure in encryption and decryption. The whole operations of proposed algorithm are composed of the even numbers of N rounds where the first half of them, 1 to N/2 round, applies a right function and the last half of them, (N+1)/2 to N round, employs an inverse function. And a symmetry layer is located in between the right function layer and the inverse function layer. The symmetric layer is composed with a multiple simple bit slice involution S-Boxes. The bit slice involution S-Box symmetric layer increases difficult to attack cipher by Square attack, Boomerang attack, Impossible differentials cryptanalysis etc. The proposed symmetric SPN block cipher with bit slice involution S-Box is believed to construct a safe and efficient cipher in Smart Card and RFID environments where electronic chips are built in.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.199-206
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• 2010

Society of digital information becomes gradually advancement, and it is a situation offered various service, but it is exposed to a serious security threat by a fast development of communication such as the internet and a network. There is required a research of technical encryption to protect more safely important information. And we require research for application of security technology in environment or a field to be based on a characteristics of market of an information security. The symmetric key cipher algorithm has same encryption key and decryption key. It is categorized to Block and Stream cipher algorithm according to conversion ways. This study inspects safety and reliability of proposed SEED, Stream cipher algorithm. And it confirms possibility of application on the communication environments. This can contribute to transact information safely by application of suitable cipher algorithm along various communication environmental conditions.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.2
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• pp.64-69
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• 2010

This paper designs the ABC(Advanced Block Cipher) algorithm which is a 64byte block encryption algorithm, improves the performance of encryption process time, and makes an key exchange using EC-DH. The ABC algorithm reduces basic memory occupation rates using the original data position exchange method which is a data swap key without S-Box, IP-Box and etc. Also, it prepares the exposure of symmetric key using the unfixed encryption(decryption) key excepting the fixed encryption(decryption) key. Therefore, the proposed ABC algorithm in this paper is a proper encryption algorithm in lower memory environment and mobile banking.