An unified approach on security evaluation against sidechannel attacks on cryptographic algorithms

智能卡等移动设备正在渗透到我们的日常生活中，以使我们更舒适。当在诸如智能卡之类的计算机上实现加密方案时，侧信道攻击是对它们的特别威胁。由于电力是从外部提供的，因此攻击者可以在执行加密操作时观察到功耗。在侧信道攻击中，攻击者利用功耗来揭示秘密，因为功耗通常与与密钥相关的操作相关联。本研究的目的是建立有效的对抗侧信道攻击的对策。为此，我们首先尝试攻击已知的对抗措施，并研究了侧信道攻击的本质。然后，我们利用其中的精华构造适合于移动设备的有效对策。(1)针对已知对策，我们提出了两种新的攻击方法。一种是针对…More Oswald对抗的侧信道攻击，另一种是针对M″oller对抗的二阶差分功率分析。Oswald提出了一种随机加减链对策，该对策利用整数的符号数表示和随机化。并利用预计算表说明了对策的脆弱性。我们还提出了两种新的对抗侧信道攻击的方法。一种是采用椭圆曲线蒙哥马利形式的对抗，另一种是采用宽度为w的非相邻形式的对抗。Montgomery为了加速椭圆标量乘法，提出了椭圆曲线的Montgomery形式。(2)讨论了针对“随机二进制有符号数字”的一种可能的攻击，并给出了针对这种保护的一些攻击。我们还研究了XRT密码系统，并与传统的离散对数密码系统进行了比较。(3)从侧通道密码分析的角度讨论了基于koblitz曲线的密码系统的安全性，并针对已知攻击提出了两种对策。未来的研究方向是对侧信道攻击及其对策的研究。少

Mobile devices such as smartcards are penetrating in our daily life in order for us to be comfortable. When cryptographic schemes are implemented on computers such as smartcards, side channel attacks are particular menaces to them. Since electric power is provided from the outside of them, the attacker can observe the power consumption while they perform cryptographic operations. In side channel attacks, the attacker utilizes the power consumption for revealing the secret, since the power consumption is usually linked to the operations associated with the secret key.The aim of this research to construct efficient countermeasures against side channel attacks. For this purpose, we first attempt to attack the known countermeasures, and study the essence of side channel attacks. Then, we utilizes the essence for constructing efficient countermeasures which are suitable for the mobile devices.(1)We propose two novel attacks against known countermeasures. One is a side channel attack against … More Oswald's countermeasure, and the other is a second-order differential power analysis against M″oller's countermeasure. Oswald proposed a randomized addition-subtraction chains countermeasure, which utilizes a signed digit representation of an integer together with randomization. And we also show the vulnerability of countermeasures with pre-computation table. We also propose two novel countermeasures against side channel attacks. One is a countermeasure using the Montgomery form of elliptic curves, and the other is a countermeasure using the width-w non-adjacent form. Montgomery proposed the Montgomery form of elliptic curves in order to accelerate the elliptic scalar multiplication.(2)We discuss a possible attack against "Randomized Binary Signed Digits", and give some attack on this protection. We also study the cryptosystem XRT with comparision to conventional discrete-log cryptosystems.(3)Security of Koblitz-curve based cryptosystems is discussed from the view point of sidechannel cryptoanalysis, and proposed two counter measures against known attacks. A future research topic is study on sidechannel attacks and their counter measures. Less