• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.4
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• pp.99-114
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• 2002

Improved algorithms for elliptic scalar multiplication secure against side-channel attacks, such as timing and power analysis, are presented and analyzed. We first point out some potential security flaws often overlooked in most previous algorithms and then present a simple $\pm$1-signed encoding scheme that can be used to enhance the security and performance of existing algorithms. More specifically, we propose concrete signed binary and window algorithms based on the proposed $\pm$ 1-signed encoding and analyze their security and performance. The proposed algorithms are shown to be more robust and efficient than previous algorithms.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.57-64
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• 2003

Recently, it has been shown that cryptographic devices such as smart cards are vulnerable to power attacks. In this paper, by mixing the randomization concept and the folding in half for secret scalar integer on ECCs, we propose an efficient and fast scalar multiplication algorithm to resist against simple power analysis(SPA) and differential power analysis(DPA) attacks. Our proposed algorithm as a countermeasure against SPA and DPA is estimated as a 33% speedup compared to the binary scalar multiplication.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.4
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• pp.59-68
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• 2006

Although the cryptographic algorithms in IC chip such as smart card are secure against mathematical analysis attack, they are susceptible to side channel attacks in real implementation. In this paper, we analyze the security of smart card using a developed experimental tool which can perform power analysis attacks and fault insertion attacks. As a result, raw smart card implemented SEED and ARIA without any countermeasure is vulnerable against differential power analysis(DPA) attack. However, in fault attack about voltage and clock on RSA with CRT, the card is secure due to its physical countermeasures.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.117-126
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• 2011

RSA-CRT algorithm is widely used to improve the performance of RSA algorithm. However, it is also vulnerable to side channel attacks like as general RSA. One of the power attacks on RSA-CRT, proposed by Boer et al., is a power analysis which utilizes reduction steps of RSA-CRT algorithm with equidistant chosen messages, called as ECMPA(Equidistant Chosen Messages Power Analysis) or MRED(Modular Reduction on Equidistant Data) analysis. This method is to find reduction output value r=xmodp which has the same equidistant patterns as equidistant messages. One can easily compute secret prime p from exposure of r. However, the result of analysis from a reduction step in [5] is remarkably different in our experiment from what Boer expected in [5]. Especially, we found that there are Ghost key patterns depending on the selection of attack bits and selected reduction algorithms. Thus, in this paper we propose several Ghost key patterns unknown to us until now, then we suggest enhanced and detailed analyzing methods.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.373-375
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• 2017

Side-channel attacks and in particular differential power analysis (DPA) attacks pose a serious threat to cryptographic implementations. One approach to counteract such attacks is cryptographic schemes based on fresh re-keying. In settings of pre-shared secret keys, such schemes render DPA attacks infeasible by deriving session keys and by ensuring that the attacker cannot collect side-channel leakage on the session key during cryptographic operations with different inputs. This paper present a study on rekeying approach against side channel attacks with current secure schemes and their rekeying functions.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1043-1050
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• 2014

Obsolescent control systems for power systems are evolving into intelligent systems and connecting with smart devices to give intelligence to the power systems. As networks of the control system are growing, vulnerability is also increasing. The communication network of distribution areas in the power system connects closely to vulnerable environments. Many cyber-attacks have been founded in the power system, and they could be more critical as the power system becomes more intelligent. From these environment, new communication network architecture and mitigation method against cyber-attacks are needed. Availability and Fault Tree analysis used to show that the proposed system enhances performance of current control systems.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.3
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• pp.117-121
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• 2007

Most existing countermeasures against classical DPA are vulnerable to new DPA, e.g., refined power analysis attack (RPA), zero-value point attack (ZPA), and doubling attack. More recently, Mamiya et al proposed a new countermeasure (so-called BRIP) against RPA, ZPA, classical DPA and SPA. This countermeasure, however, also has a vulnerability of scalar multiplication computations by exploiting specially chosen input message. Therefore, to prevent various power analysis attacks like DPA and new SPA, we propose an enhanced countermeasure by developing a new random blinding technique.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.6
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• pp.63-70
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• 2009

Many research results show that RSA system mounted using conventional binary exponentiation algorithm is vulnerable to some physical attacks. Recently, Schmidt and Hurbst demonstrated experimentally that an attacker can exploit secret key using faulty signatures which are obtained by skipping the squaring operations. Based on similar assumption of Schmidt and Hurbst's fault attack, we proposed new fault analysis attacks which can be made by skipping the multiplication operations or computations in looping control statement. Furthermore, we applied our attack to Montgomery ladder exponentiation algorithm which was proposed to defeat simple power attack. As a result, our fault attack can extract secret key used in Montgomery ladder exponentiation.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.155-158
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• 2008

In 1989, Kocher et al. introduced Differential Power Attack on block ciphers. This attack allows to extract secret key used in cryptographic computations even if these are executed inside tamper-resistant devices such as smart card. Since 1989, many papers were published to improve resistance of DPA. At FSE 2003 and 2004, Akkar and Goubin presented several masking methods to protect iterated block ciphers such as DES against Differential Power Attack. The idea is to randomize the first few and last few rounds(3 $\sim$ 4 round) of the cipher with independent random masks at each round and thereby disabling power attacks on subsequent inner rounds. This paper show how to combine truncated differential cryptanalysis applied to the first few rounds of the cipher with power attacks to extract the secret key from intermediate unmasked values.

• Proceedings of the IEEK Conference
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• 2003.07d
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• pp.1399-1402
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• 2003

Paul Hocker has developed new attacks based on the electric consumption of cryptographic device such as smartcard that performs cryptographic computation. Among those attacks, the Differential Power Analysis(DPA) is one of the most impressive and most difficult to avoid. By analysing the power dissipation of encryption in a device, the secret information inside can be deduced. This paper presents that Advanced Encryption Standard(AES) is highly vulnerable to DPA and readily leaks away all secret keys through the experimental results for DPA. After all, it is required an implementation of the AES algorithm that is not vulnerable to DPA. We also propose countermeasures that employ asynchronous circuit.