• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.155-160
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• 2010

Since the RSA cryptosystem based on Chinese Remainder Theorem is vulnerable to many fault insertion attacks, some countermeasures against them were proposed. Recently, Kim et al. or Ha et al. respectively proposed each countermeasure scheme based on fault propagation method. Unfortunately, Hur et al. insist that these countermeasures are vulnerable to their opcode modification fault attack. In this paper, we show that the proposed attack can not apply to almost CRT-RSA countermeasures which use multi-precision operations in long bit computation. Therefore, the countermeasure against fault attack proposed by Kim et al. or Ha et al. are still secure.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.1 no.1
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• pp.3-15
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• 1991

in 1984 Shamir proposed the concept of ID(identity)-based cryptosystem and digital signature scheme wich does not require any public file for storing the user' s public keys. In this paper, the concept of the ID-based cryptosystem based on discrete logarithm problem using the conven-tional public-key cryptosystems is described, and the implementation method of the ID-based cryptosystem is also presented. The new digital signaturw schme based on the ID-based crypto-system is proposed and possible atacks are considered and analyzed for the security of digital signature scheme. The proposed ID-based schemes are particularrly useful for smart card and personal identification card application.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1089-1097
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• 2016

It is well-known that, if additional information other than a plaintext-ciphertext pair is available, breaking the RSA cryptosystem may be much easier than factorizing the RSA modulus. For example, Coppersmith showed that, given the 1/2 fraction of the least or most significant bits of one of two RSA primes, the RSA modulus can be factorized in a polynomial time. More recently, Henecka et. al showed that the RSA private key of the form (p, q, d, $d_p$, $d_q$) can efficiently be recovered whenever the bits of the private key are erroneous with error rate less than 23.7%. It is notable that their algorithm is based on counting the matching bits between the candidate key bit string and the given decayed RSA private key bit string. And, extending the algorithm, this paper proposes a new RSA private key recovery algorithm using a generalized probabilistic measure for measuring the consistency between the candidate key bits and the given decayed RSA private key bits.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1991.11a
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• pp.204-214
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• 1991

개별통신 및 방송통신시스팀에 적합한 암호방식으로서 동일한 통신시스팀 내에 가입된 모든 이용자의 개별키에 공통으로 대치할 수 있는 마스터키 방식을 적용하였다. 사용된 암호방식으로는 키관리가 편리하고 인중기능이 좋은 RSA 공개키 암호방식을 사용하여 RSA마스터키의 생성법을 제시하고 실제 마스터키를 생성하여 개별암호통신 및 방송암호 통신의 방법을 보였다.

• Journal for History of Mathematics
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• v.16 no.3
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• pp.101-108
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• 2003

The RSA cryptosystem is most commonly used for providing privacy and ensuring authenticity of digital data. 1'his system is based on the difficulty of integer factoring. Many attacks had been done, but none of them devastating. They mostly illustrate the dangers of improper use of RSA. Improper use implies many aspects, but here we imply the misuse of the parameters of RSA. Specially, sizes of parameters give strong effects on the efficiency and the security of the system. Parameters are also related each other. We analyze the relation of them. Recently many researchers are interested in side-channel attacks. We also investigate partial key exposure attacks, which was motivated by side-channel attacks. If a fraction of tile secret key bits is revealed, the private key will be reconstructed. We also study mathematical background of these attacks, solving modular multivariate polynomial equations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.2
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• pp.65-72
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• 2005

Quite recently, Zhou, Lu and Cao proposed a proxy-protected signature scheme based on the RSA assumption and two proxy-protectcd schemes based on the hardness of integer factorization. Dey also provided a security proof for each signature scheme in the random oracle model. In this paper, we show that their schemes do not satisfy a security requirement necessary for proxy signature schemes. This results in generating proxy signature without fay Permission from an original signer.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.2
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• pp.335-344
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• 2016

It is known that power analysis is one of the most powerful attack in side channel analysis. Among power analysis single trace attack is widely studied recently since it uses one power consumption trace to recover secret key of public cryptosystem. Recently Sim et al. proposed new exponentiation algorithm for RSA cryptosystem with higher attack complexity to prevent single trace attack. In this paper we analyze the vulnerability of exponentiation algorithm described by Sim et al. Sim et al. applied message blinding and random exponentiation splitting method on $2^t-ary$ for higher attack complexity. However we can reveal private key using information exposed during pre-computation generation. Also we describe modified algorithm that provides higher attack complexity on collision attack. Proposed algorithm minimized the reuse of value that are used during exponentiation to provide security under single collision attack.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.4
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• pp.51-57
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• 2003

The development of the communication network and the other network method can generate serious social problems. So, it is highly required to control security of network. These problems related security will be developed and keep up to confront with anti-security field such as hacking, cracking. The way to preserve security from hacker or cracker without developing new cryptographic algorithm is keeping the state of anti-cryptanalysis in a prescribed time by means of extending key-length. In this paper, we proposed M3 algorithm for the reduced processing time in the montgomery multiplication part. Proposed M3 algorithm using the matrix function M(.) and lookup table perform optionally montgomery multiplication with repeated operation. In this result, modified repeated operation part produce 30% processing rate than existed montgomery multiplicator. The proposed montgomery multiplication structured unit array method in carry generated part and variable length multiplication for eliminating bottle neck effect with the RSA cryptosystem. Therefore, this proposed montgomery multiplier enforce the real time processing and prevent outer cracking.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1154-1157
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• 2010

최근 물리적인 보안이 큰 위협이 되는 가운데 물리적 공격 중에서도 오류 주입을 통한 공격이 국내에서도 본격적으로 연구가 시작되고 있다. 특히 중국인의 나머지 정리를 이용한 RSA-CRT 알고리즘은 오류 주입 공격을 통해서 비밀 값 p, q가 쉽게 추출 되어 취약하다는 것이 실험적으로 검증이 되었다. 본 논문에서는 레이저를 통한 광학적 오류 주입 공격을 시도 했으며 외부 버퍼를 이용해서 정확하게 원하는 시점에 오류를 주입함으로 레이저 장비 특성에 따른 오류 주입 값의 변화를 확인하였다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.318-326
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• 2011

Public key cryptosystem applications are very difficult in Ubiquitos environments due to computational complexity, memory and power constrains. HECC offers the same of levels of security with much shorter bit-lengths than RSA or ECC. Scalar multiplication is the core operation in HECC. T.Lange proposed inverse free scalar multiplication on genus 2 HECC. However, further coordinate must be access to SCA and need more storage space. This paper developed secure scalar multiplication algorithm with simultaneous inversion algorithm in HECC. To improve the over all performance and security, the proposed algorithm adopt the comparable technique of the simultaneous inversion algorithm. The proposed algorithm is resistant to DPA and SPA.