• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.6
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• pp.1103-1116
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• 2014

Collision attacks using side channel analysis confirm same intermediate value and restore sensitive data of algorithm using this point. In CHES 2011 Clavier and other authors implemented the improved attack using Blacklist so they carried out the attack successfully using less plaintext than before. However they did not refer the details of Blacklist method and just performed algorithms with the number of used plaintext. Therefore in this paper, we propose the specific method to carry out efficient collision attack. At first we define basic concepts, terms, and notations. And using these, we propose various methods. Also we describe facts that greatly influence on attack performance in priority, and then we try to improve the performance of this attack by analyzing the algorithm and structuring more efficient one.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.55-64
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• 2012

Until now, Side Channel Attack has been known to be effective to crack decrypt key such as smart cards, electronic passports and e-ID card based on Chip. Combination of Masking and shuffling methods have been proposed practical countermeasure. Newly, S.Tillich suggests biased-mask using template attack(TA) to attack AES with masking and shuffling. However, an additional assumption that is acquired template information previously for masking value is necessary in order to apply this method. Moreover, this method needs to know exact time position of the target masking value for higher probability of success. In this paper, we suggest new practical method called Biasing Power Analysis(BPA) to find a secret key of AES based on masking-shuffling method. In BPA, we don't use time position and template information from masking value. Actually, we do experimental works of BPA attack to 128bit secret key of AES based on masking-shuffling method performed MSP430 Chip and we succeed in finding whole secret key. The results of this study will be utilized for next-generation ID cards to verify physical safety.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.65-70
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• 2003

In this paper, we propose a scalar multiplication method and its hardware architecture which is resistant to SPA while its computation speed is faster than Colon's. There were SPA-resistant scalar multiplication method which has performance problem. Due to this reason, the research about an efficient SPA-resistant scalar multiplication is one of important topics. The proposed architecture resists to SPA and is faster than Colon's method under the assumption that Colon's and the proposed method use same fmite field arithmetic units(multiplier and inverter). With n-bit scalar multiple, the computation cycle of the proposed is 2n·(Inversion cycle)+3(Aultiplication cycle).

• Smart Media Journal
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• v.12 no.9
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• pp.9-18
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• 2023

Black box cryptography is a cryptographic scheme based on a hardware encryption device, operating under the assumption that the device and the user can be trusted. However, with the increasing use of cryptographic algorithms on unreliable open platforms, the threats to black box cryptography systems have become even more significant. As a consequence, white box cryptography have been proposed to securely operate cryptographic algorithms on open platforms by hiding encryption keys during the encryption process, making it difficult for attackers to extract the keys. However, unlike traditional cryptography, white box-based encryption lacks established specifications, making challenging verify its structural security. To promote the safer utilization of white box cryptography, CHES organizes The WhibOx Contest periodically, which conducts safety analyses of various white box cryptographic techniques. Among these, the Differential Computation Analysis (DCA) attack proposed by Bos in 2016 is widely utilized in safety analyses and represents a powerful attack technique against robust white box block ciphers. Therefore, this paper analyzes the research trends in white box block ciphers and provides a summary of DCA attacks and relevant countermeasures. adhering to the format of a research paper.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.5
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• pp.1001-1011
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• 2017

A lattice-based cryptography is known as one of the post-quantum cryptographies. Ring-LWE problem is an algebraic variant of LWE, which operates over elements of polynomial rings instead of vectors. It is already known that post-quantum cryptography has side-channel analysis vulnerability. In 2016, Park et al. reported a SPA vulnerability of the public key cryptosystem, which is proposed by Roy et al., based on the ring-LWE problem. In 2015 and 2016, Reparaz et al. proposed DPA attack and countermeasures against Roy cryptosystem. In this paper, we show that the chosen ciphertext SPA attack is also possible for Lyubashevsky cryptosystem which does not use NTT. And then we propose a countermeasure against CCSPA(Chosen Ciphertext SPA) attack and we also show through experiment that our proposed countermeasure is secure.

• The KIPS Transactions:PartC
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• v.18C no.4
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• pp.213-216
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• 2011

Differential Power Analysis is fully affected by various noises including temporal misalignment. Recently, Ryoo et al have introduced an efficient preprocessor method leading to improvements in DPA by removing the noise signals. This paper experimentally proves that the existing preprocessor method is not applied to all processor. To overcome this defect, we propose a Differential Trace Model(DTM). Also, we theoretically prove and experimentally confirm that the proposed DTM suites DPA.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.859-865
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• 2013

Esmbedded devices such as smart cards and electronic passports highly demand security of sensitive data. So, the secure implementation of the cryptographic system against various side-channel attacks are becoming more important. In particular, the fault injection attack is one of the threats to the cryptosystem and can destroy the whole system only with single pair of the plain and cipher texts. Therefore, the implementors must consider seriously the attack. Several techniques for preventing fault injection attacks were introduced to a variety of the cryptosystem, But the countermeasures are still inefficient to be applied to the classical RSA cryptosystem. This paper introduces an efficient countermeasure against the fault injection attack for the classical RSA cryptosystem, which is based on the famous Fermat's theorem. The proposed countermeasure has the advantage that it has less computational overhead, compared with the previous countermeasures.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.3
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• pp.69-77
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• 2008

In the recent years, power attacks were widely investigated, and so various countermeasures have been proposed. In the case of block ciphers, masking methods that blind the intermediate results in the algorithm computations(encryption, decryption, and key-schedule) are well-known. Applications of masking methods are able to vary in different block ciphers, therefore suitable masking methods about each ciphers have been researched. Existed methods of ARIA have many revisions of mask value. And because existed masking methods pay no regard for key schedule, secret information can be exposed. In the case of ARIA, this problem is more serious than different block ciphers. Therefore we proposes an efficient masking scheme of ARIA including the key-schedule. Our method reduces time-complexity of ARIA encryption, and solve table-size problem of the general ARIA masking scheme from 256*8 byte to 256*6 byte.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.1
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• pp.127-132
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• 2007

This paper proposed receding methods for a radix-${\gamma}$ representation of the secret scalar which are resistant to SPA. Unlike existing receding method, these receding methods are left-to-right so they can be interleaved with a left-to-right scalar multiplication, removing the need to store both the scalar and its receding. Hence, these left-to-right methods are suitable for implementing on memory limited devices such as smart cards and sensor nodes

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.2
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• pp.39-47
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• 2008

Among previous Side Channel Analysis (SCA) methods, Differential Power Analysis (DPA) based on the statistical characteristics of collected signals has been known as an efficient attack for uncovering secret key of cryptosystems. However, the attack performance of this method is affected very much by the temporal misalignment and noise of collected side channel signals. In this paper, we propose a new method to surmount the noise problem in DPA. The performance of the proposed method is then evaluated while analyzing the power consumption signals of Micro-controller chips during a DES operation. Its performance is then compared to that of the original DPA in the time and frequency domains. When we compare the experimental results with respect to the needed number of traces to uncover the secret key, our proposed method shows the performance enhancement 33% in the time domain and 50% in the frequency domain.