• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.1
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• pp.99-107
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• 2005

ARIA is a 128-bit block cipher having 128-bit, 192-bit, or 256-bit key length. The cipher is a substitution and permutation encryption network (SPN) and uses an involutional binary matrix. This structure was efficiently developed into light weight environments or hardware implementations. This paper shows that a careless implementation of an ARIA on smartcards is vulnerable to a differential power analysis attack This attack is realistic because we can measure power consumption signals at two kinds of S-boxes and two types of substitution layers. By using the two round key, we extracted the master key (MK).

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.6
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• pp.1059-1068
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• 2022

A Post-Quantum Cryptographic algorithm NTRU, which is designed by considering the computational power of quantum computers, satisfies the mathematically security level. However, it should consider the characteristics of side-channel attacks such as power analysis attacks in hardware implementation. In this paper, we verify that the private key can be recovered by analyzing the power signal generated during the decryption process of NTRU. To recover the private keys, the Simple Power Analysis (SPA), Correlation Power Analysis (CPA) and Differential Deep Learning Analysis (DDLA) were all applicable. There is a shuffling technique as a basic countermeasure to counter such a power side-channel attack. Neverthe less, we propose a more effective method. The proposed method can prevent CPA and DDLA attacks by preventing leakage of power information for multiplication operations by only performing addition after accumulating each coefficient, rather than performing accumulation after multiplication for each index.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.11
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• pp.8-15
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• 2009

Side-channel attacks including the differential power analysis attack are often more powerful than classical cryptanalysis and have to be seriously considered by cryptographic algorithm's implementers. Various countermeasures have been proposed against such attacks. In this paper, we deal with the masking method, which is known to be a very effective countermeasure against the differential power analysis attack and propose new gate-level conversion methods between Boolean and arithmetic masks. The new methods require only 6n-5 XOR and 2n-2 AND gates with 3n-2 gate delay for converting n-bit masks. The basic idea of the proposed methods is that the carry and the sum bits in the ripple adder are manipulated in a way that the adversary cannot detect the relation between these bits and the original raw data. Since the proposed methods use only bitwise operations, they are especially useful for DPA-securely implementing cryptographic algorithms in hardware which use both Boolean and arithmetic operations. For example, we applied them to securely implement the block encryption algorithm SEED in hardware and present its detailed implementation result.

• 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 Internet of Things and Convergence
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• v.6 no.2
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• pp.25-29
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• 2020

The elliptic curve crypto-algorithm is widely used in authentication for IoT environment, since it has small key size and low communication overhead compare to the RSA public key algorithm. If the scalar multiplication, a core operation of the elliptic curve crypto-algorithm, is not implemented securely, attackers can find the secret key to use simple power analysis or differential power analysis. In this paper, an elliptic curve scalar multiplication algorithm using a randomized scalar and an elliptic curve point blinding is suggested. It is resistant to power analysis but does not significantly reduce efficiency. Given a random r and an elliptic curve random point R, the elliptic scalar multiplication kP = u(P+R)-vR is calculated by using the regular variant Shamir's double ladder algorithm, where l+20-bit u≡rn+k(modn) and v≡rn-k(modn) using 2^lP=∓cP for the case of the order n=2^l±c.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.35-43
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• 2003

The randomization of scalar multiplication in ECC is one of the fundamental concepts in defense methods against side-channel attacks. This paper proposes a countermeasure against simple and differential power analysis attacks through randomizing the transformed m-ary method based on a random m-ary receding algorithm. The proposed method requires an additional computational load compared to the standard m-ary method, yet the power consumption is independent of the secret key. Accordingly, since computational tracks using random window width can resist against SPA and DPA, the proposed countermeasure can improve the security for smart cards.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.2
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• pp.261-270
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• 2015

In information security devices, such as Smart Cards, vulnerabilities of the RSA algorithm which is used to protect the data were found in the Side Channel Analysis. The RSA is especially vulnerable to Power Analysis which uses power consumption when the algorithm is working. Typically Power Analysis is divided into SPA(Simple Power Analysis) and DPA(Differential Power Analysis). On top of this, there is a CA(Collision Analysis) which is a very powerful attack. CA makes it possible to attack using a single waveform, even if the algorithm is designed to secure against SPA and DPA. So Message blinding, which applies the window method, was considered as a countermeasure. But, this method does not provide sufficient safety when the window size is small. Therefore, in this paper, we propose a new countermeasure that provides higher safety against CA. Our countermeasure is a combination of message and exponent blinding which is applied to the window method. In addition, through experiments, we have shown that our countermeasure provides approximately 124% higher attack complexity when the window size is small. Thus it can provide higher safety against CA.

• Journal of the Korea Society of Computer and Information
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• v.27 no.1
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• pp.43-50
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• 2022

Correlation Power Analysis(CPA) is a sub-channel attack method that measures the detailed power consumption of attack target equipment equipped with cryptographic algorithms and guesses the secret key used in cryptographic algorithms with more than 90% probability. Since CPA performs analysis based on statistics, a large amount of data is necessarily required. Therefore, the CPA must measure power consumption for at least about 15 minutes for each attack. In this paper proposes a method of using a Convolutional Neural Network(CNN) capable of accumulating input data and predicting results to solve the data collection problem of CPA. By collecting and learning the power consumption of the target equipment in advance, entering any power consumption can immediately estimate the secret key, improving the computational speed and 96.7% of the secret key estimation accuracy.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.4
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• pp.607-615
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• 2022

The SITM (See-In-The-Middle) proposed in CHES 2020 is a methodology for side-channel assisted differential cryptanalysis. This technique analyzes the power traces of unmasked middle rounds in partial masked SPN block cipher implementation, and performs differential analysis with the side channel information. Blockcipher GIFT is a lightweight blockcipher proposed in CHES 2017, designed to correct the well-known weaknesses of block cipher PRESENT and provide the efficient implementation. In this paper, we propose SITM attacks on partial masked implementation of GIFT-128. This attack targets 4-round and 6-round masked implementation of GIFT-128 and time/data complexity is 2^14.01 /2^14.01, 2¹⁶ /2¹⁶. In this paper, we compare the masterkey recovery logic available in SITM attacks, establishing a criterion for selecting more efficient logic depending on the situation. Finally, We introduce how to apply the this attack to GIFT-COFB, one of the finalist candidates in NIST lightweight cryptography standardization process.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.2
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• pp.155-162
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• 2022

The SITM (See-In-The-Middle) attack proposed in CHES 2020 is a type of analysis technique that combines differential cryptanalysis and side-channel analysis, and can be applied even in a harsh environment with a low SNR (Signal-to-Noise Ratio). This attack targets partial 1^st or higher order masked block cipher, and uses unmasked middle round weakness. PRESENT is a lightweight blockcipher proposed in CHES 2007, designed to be implemented efficiently in a low-power environment. In this paper, we propose SITM attacks on 14-round masked implementation of PRESENT while the previous attacks were applicable to 4-round masked implementation of PRESENT. This indicates that PRESENT has to be implemented with more than 16-round masking to be resistant to our attacks.