• Journal of Internet Computing and Services
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• v.16 no.2
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• pp.27-40
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• 2015

Inferring firewall policy is to discover firewall policy by analyzing response packets as results of active probing without any prior information. However, a brute-force approach for generating probing packets is unavailable because the probing packets may be regarded as attack traffic and blocked by attack detection threshold of a firewall. In this paper, we propose a firewall policy inference method using an efficient probing algorithm which considers the number of source IP addresses, maximum probing packets per second and interval size of adjacent sweep lines as inference parameters to avoid detection. We then verify whether the generated probing packets are classified as network attack patterns by a firewall, and present the result of evaluation of the correctness by comparing original firewall policy with inferred firewall policy.

• Journal of Korea Multimedia Society
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• v.21 no.8
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• pp.909-916
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• 2018

Cloud storage services have many advantages. As a result, the amount of data stored in the storage of the cloud service provider is increasing rapidly. This increase in demand forces cloud storage providers to apply deduplication technology for efficient use of storages. However, deduplication technology has inherent security and privacy concerns. Several schemes have been proposed to solve these problems, but there are still some vulnerabilities to well-known attacks on deduplication techniques. In this paper, we examine some of the existing schemes and analyze their security weaknesses.

• Journal of Communications and Networks
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• v.14 no.1
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• pp.10-14
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• 2012

When tag privacy is required in radio frequency identification (ID) system, a reader needs to identify, and optionally authenticate, a multitude of tags without revealing their IDs. One approach for identification with lightweight tags is that each tag performs pseudo-random function with his unique embedded key. In this case, a reader (or a back-end server) needs to perform a brute-force search for each tag-reader interaction, whose cost gets larger when the number of tags increases. In this paper, we suggest a simple and efficient identification technique that reduces readers computation to $O$(${\sqrt{N}}$ log$N$) without increasing communication cost. Our technique is based on the well-known "meet-in-the-middle" strategy used in the past to attack symmetric ciphers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.6161-6176
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• 2018

Pseudorandom numbers are useful in cryptographic operations for using as nonce, initial vector, secret key, etc. Security of the cryptosystem relies on the secret key parameters, so a good pseudorandom number is needed. In this paper, we have proposed a new approach for generation of pseudorandom number. This method uses the three dimensional combinational puzzle Rubik Cube for generation of random numbers. The number of possible combinations of the cube approximates to 43 quintillion. The large possible combination of the cube increases the complexity of brute force attack on the generator. The generator uses cryptographic hash function. Chaotic map is being employed for increasing random behavior. The pseudorandom sequence generated can be used for cryptographic applications. The generated sequences are tested for randomness using NIST Statistical Test Suite and other testing methods. The result of the tests and analysis proves that the generated sequences are random.

• Journal of the Korea Society of Computer and Information
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• v.24 no.1
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• pp.107-113
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• 2019

Along with the development of IOT, the number of people using IOT devices has enormously increased and the IOT era has come. Especially, people using the IP cameras among Internet devices have been drastically increasing. It is because the IP cameras are well networked and comparatively cheap compared with CCTVs, and they can also be monitored and controlled in real time through PCs and smart phones for the purposes of general theft prevention and shop surveillance. However, due to the user's serious lack of security awareness and the fact that anyone can easily hack only with simple hacking tools and hacking sites information, security crimes that exploit those have been increasing as well. Therefore, this paper describes how easily the IP cameras can be hacked in the era of IOT, what kind of security incidents occurred, and also suggests possible government measures and new technical solutions to those problems.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.97-99
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• 2022

대규모 양자컴퓨터가 등장하면 기존 암호체계가 더 이상 안전하지 않을 것이라 예상한다. 양자 알고리즘인 Grover's brute-force 알고리즘은 대칭키 암호에 대한 attack을 가속화 시켜 보안강도를 감소시킨다. 따라서 양자컴퓨터의 가용 자원이 암호공격에 필요한 자원에 도달했을 때, 공격 대상 암호가 깨지는 시점으로 보고 있다. 많은 선행 연구들은 암호를 양자회로로 구현하여 공격에 필요한 자원을 추정하고 암호에 대한 양자 강도를 확인하였다. 본 논문에서는 이러한 연구동기로 ARX 구조의 SIMECK 경량암호에 대한 양자회로를 처음으로 제안한다. 우리는 SIMECK 양자회로에 대한 최적의 양자회로 구현을 제시하고 각 함수의 동작을 설명한다. 마지막으로 SIMECK 양자회로에 대한 양자자원을 추정하고 SIMON 양자회로와 비교하여 평가한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.43-53
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• 2015

Password-based authentication schemes for server-client system are convenient to use, but vulnerable to dictionary attack or brute-force attack. To solve this vulnerability, Cryptographic secret key is used for security, but difficult to memorize. So, for the first time, Das proposed a biometric-based authentication scheme to solve various problems but it has various vulnerabilities. Afterwards, Jiping et al. improved Das's scheme, but some vulnerabilities remain. In this paper, we analyze the cryptanalysis of Jiping et al.'s authentication scheme and then propose improved biometric based user authentication scheme to resolve the analyzed problem. Moreover, we conduct a security analysis for the proposed scheme and make a comparison between the proposed scheme and other biometric based user authentications.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.3
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• pp.85-95
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• 2011

Smart phones, greatly expanding in the recent mobile market, are equipped with various features compared to existing feature phones and provide the conveniences to in several ways. The camera, one of the features of a smartphone, creates the digital contents, such photos and videos, and plays a role for the media which transmits information, such as video calls and bar code reader. QR-Code recognition is also one of the camera features. It contains a variety of information in two-dimensional bar code type in matrix format, and makes it possible to obtain the information by using smart phones. This paper analyzes the method of QR-Code recognition, password method-the existing user-authentication technique, smart card, biometrics and voice recognition and so on and thenn designs a new user-authentication technique. The proposed user-authentication technique is the technique in which QR-Code, which can be simply granted is read by smart phones and transmitted to a server, for authentication. It has the advantages in view that it will simply the process of authentication and conteract the disadvantages, such as brute force attack, man-inthe-middle attack, and keyboard hacking, which may occur in other authentication techniques.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.5
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• pp.781-793
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• 2014

A Public Key Infrastructure (PKI) is security standards to manage and use public key cryptosystem. A PKI is used to provide digital signature, authentication, public key encryption functionality on insecure channel, such as E-banking and E-commerce on Internet. A soft-token private key in PKI is leaked easily because it is stored in a file at standardized location. Also it is vulnerable to a brute-force password attack as is protected by password-based encryption. In this paper, we proposed a new method that detects private key compromise and is probabilistically secure against a brute-force password attack though soft-token private key is leaked. The main idea of the proposed method is to use a genuine signature key pair and (n-1) fake signature key pairs to make an attacker difficult to generate a valid signature with probability 1/n even if the attacker found the correct password. The proposed method provides detection and notification functionality when an attacker make an attempt at authentication, and enhances the security of soft-token private key without the additional cost of construction of infrastructure thereby extending the function of the existing PKI and SSL/TLS.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.6
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• pp.181-188
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• 2023

Block cipher is not expected to be safe for quantum computer, as Grover's algorithm reduces the security strength by accelerating brute-force attacks on symmetric key ciphers. So it is necessary to check the post-quantum security strength by implementing quantum circuit for the target cipher. In this paper, we propose the optimal quantum circuit implementation result designed as a technique to minimize the use of quantum resources (qubits, quantum gates) for SIMECK lightweight cryptography, and explain the operation of each quantum circuit. The implemented SIMECK quantum circuit is used to check the estimation result of quantum resources and calculate the Grover attack cost. Finally, the post-quantum strength of SIMECK lightweight cryptography is evaluated. As a result of post-quantum security strength evaluation, all SIMECK family cipher failed to reach NIST security strength. Therefore, it is expected that the safety of SIMECK cipher is unclear when large-scale quantum computers appear. About this, it is judged that it would be appropriate to increase the block size, the number of rounds, and the key length to increase the security strength.