【摘要】：自Shannon1949年提出完善保密的概念并證明了一次性密碼本(One-time Pad:OTP)的安全性后,如何解決完善保密的可操作性則成了國(guó)內(nèi)外學(xué)者所關(guān)注的問題,而流密碼則是結(jié)合完善保密的安全性和可操作性所提出的實(shí)際可行的密碼體制。由于流密碼具有實(shí)現(xiàn)簡(jiǎn)單、易于硬件設(shè)計(jì)實(shí)施、加解密速度快等一系列優(yōu)點(diǎn),使得其在一些特殊的應(yīng)用場(chǎng)景中有著獨(dú)特的優(yōu)勢(shì),特別是在一些專用或機(jī)密機(jī)構(gòu)的通信系統(tǒng)中。實(shí)際應(yīng)用中,流密碼的實(shí)現(xiàn)通常是由較短的種子秘鑰經(jīng)過特定的算法得到隨機(jī)性質(zhì)良好的偽隨機(jī)密鑰流,所以偽隨機(jī)序列生成算法則是流密碼的核心部件。而布爾函數(shù)作為經(jīng)典的密鑰序列非線性組合生成器的一部分,它的邏輯結(jié)構(gòu)直接決定了生成算法的安全性。為了保障在某些特定的應(yīng)用場(chǎng)景中加密的安全性,布爾函數(shù)的一些指標(biāo)需要精心地設(shè)計(jì)以抵抗相應(yīng)場(chǎng)景下的某些攻擊。本文介紹了針對(duì)流密碼的一些主流攻擊和如何衡量一個(gè)布爾函數(shù)抵抗這些攻擊的能力,如最佳抵抗仿射逼近攻擊(BAA)或線性攻擊的非線性度、抵抗分別征服攻擊以及相關(guān)攻擊的彈性、抵抗差分攻擊的嚴(yán)格雪崩準(zhǔn)則(SAC)以及擴(kuò)散準(zhǔn)則(PC)和抵抗代數(shù)攻擊的代數(shù)免疫度等。所以為了抵抗某些特定的攻擊,構(gòu)造出滿足某些密碼學(xué)特性的布爾函數(shù)則是密碼學(xué)中的重要課題。而具有高非線性度,滿足彈性和嚴(yán)格雪崩準(zhǔn)則(SAC)的布爾函數(shù)則是其中一類,在流密碼、分組密碼設(shè)計(jì)中,特別是對(duì)稱密鑰算法的設(shè)計(jì)中,這些指標(biāo)都是必不可少的。為此,本文引入了一些經(jīng)典的設(shè)計(jì)方法來構(gòu)造滿足以上多個(gè)指標(biāo)的布爾函數(shù),如廣義Maiorana-McFarland構(gòu)造、Dillon構(gòu)造和Dobbertin構(gòu)造方法,并對(duì)這些構(gòu)造方法所得到的函數(shù)的各個(gè)指標(biāo)進(jìn)行了分析。本文還給出了一種構(gòu)造高非線性彈性函數(shù)的有效方法,并在該方法的基礎(chǔ)上進(jìn)行擴(kuò)展,使其滿足了嚴(yán)格雪崩準(zhǔn)則。該構(gòu)造方法可以構(gòu)造出n(偶數(shù))變?cè)獫M足SAC并且非線性度1 22 2n?n??的布爾函數(shù),這在之前是未曾得到過的。隨后對(duì)其進(jìn)行了一些改進(jìn),使得改進(jìn)后的非線性度在某些情況下得到了一定的提高。
[Abstract]:Since Shannon1949 put forward the concept of perfect security and proved the security of one-off cryptographic book (One-time Pad:OTP), how to solve the problem of how to improve the operation of security has become a concern of scholars at home and abroad. Stream cipher is a practical and feasible cryptosystem which combines the security and maneuverability of security. Because stream cipher has a series of advantages, such as simple implementation, easy hardware design and fast encryption and decryption, it has unique advantages in some special application scenarios, especially in some communication systems of special or confidential organizations. In practical applications, the implementation of stream cipher is usually from a short seed secret key through a specific algorithm to obtain a pseudorandom key stream of good random properties, so pseudorandom sequence generation algorithm is the core component of stream cipher. The Boolean function is a part of the classical key sequence nonlinear composition generator, its logical structure directly determines the security of the generation algorithm. In order to ensure the security of encryption in some specific application scenarios, some metrics of Boolean functions need to be carefully designed to resist some attacks in the corresponding scenarios. This paper introduces some mainstream attacks against stream ciphers and how to measure the ability of a Boolean function to resist these attacks, such as the best resistance to the nonlinear degree of affine approximation attack (BAA) or linear attack. To resist the elasticity of subjugation attack and related attack, the strict avalanche criterion (SAC) against differential attack, the diffusion criterion (PC) and the algebraic immunity of resisting algebraic attack, etc. Therefore, in order to resist some specific attacks, it is an important subject in cryptography to construct Boolean functions that satisfy some cryptographic characteristics. Boolean functions with high nonlinearity and satisfying elastic and strict avalanche criteria (SAC) are one of them. These parameters are essential in stream cipher and block cipher design, especially in the design of symmetric key algorithms. In this paper, some classical design methods are introduced to construct Boolean functions which satisfy the above indexes, such as generalized Maiorana-McFarland construction and Dobbertin construction, and the indexes of the functions obtained by these methods are analyzed. In this paper, an effective method for constructing high nonlinear elastic functions is presented, which is extended to satisfy the strict avalanche criterion. The method can construct n (even number) variables satisfying SAC and the degree of nonlinearity is 1 22 2 n? A Boolean function, which has not been obtained before. Then some improvements are made to improve the degree of nonlinearity in some cases.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN918.2

【共引文獻(xiàn)】

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本文編號(hào)：2150130