【作者】 崔岩；

【导师】 徐高潮；

【作者基本信息】 吉林大学 ， 软件工程， 2012， 硕士

【摘要】 当今社会的发展已经是一个每天都必须依赖信息通讯来交流的时代，距离已经不再是一个制约人与人能顺畅沟通的因素，而如何保障网络的安全在通讯过程中的重要性开始凸显出来。人们逐渐开始采用加密技术来保证通讯过程中信息的安全，而加密技术当中的一个重要应用就是数字签名。数字签名就是利用公钥密码体制对信息进行签名的一种确认方法，使发送者对消息保证合法性和真实性，接收者可以确认信息来源等。安全散列算法是实现数字签名的重要工具，它使得数字签名能够正确执行，而对安全散列算法的加速也相应地提高了数字签名的执行效率，所以如果能找到一种加速安全散列算法的途径，就会对电子商务、电子政务领域做出巨大的贡献。散列算法的主体思想是首先接受了一段明文，然后把它变换成一段密文，变换的方式是单向不可逆的，将转换后所得到的密文称做消息摘要。散列算法发展到SHA-1，已经具备了相当强的抗击主动攻击类型的能力，因为SHA-1输出的消息摘要是160位，而MD5加密算法的消息摘要则是128位，这两个不同长度的消息摘要在抵抗生日攻击这一重要的攻击类型时，就表现出了迥然不同的优势和劣势，SHA-1的抗攻击力比最初的MD5散列算法提升了232数量级，数量级的提升大大降低了被攻破的几率，所以说对SHA-1的改进具有十分重要的现实意义。本文对SHA-1算法从结构上和实现上都做了一些改进，这些改进包括对算法的输入分组的长度、算法的逻辑函数、算法的串行转换为并行。将算法原本规定的对小于2的64次方长度的输入进行分组，由原来的每一组512比特扩展至1024比特，目的在于减少冗余，提高对真正数据的处理；算法原本有两个具有相同表达式的逻辑函数，本文对其中一个表达式的定义进行重新表述，目的在于提高加密中逻辑函数变换的复杂度，使得攻击者不能获得两个逻辑函数其中之一以后，就轻而易举得知另一个与其相同的逻辑函数进一步实施攻击；将串行的算法转换为并行，这从效率上对算法进行了彻底的改进，原本串行的算法需要对每个分组进行串行处理，时间消耗大，尤其当面对输入数据量大的任务时，不能满足加密过程对速度的要求，将其转换为并行处理的方式，目的在于提高算法处理速度，进而提高加密效率。文中给出了这些改进的主要思想和流程，对每一个改进都进行了详细阐述，并做了相关的实验性质的测试，对改进思想进行验证。近些年里，图形处理器的浮点运算和带宽被发掘出来，GPU（Graphics ProcessingUnit）不再仅仅适用于图形处理方面，它本身所具有的这些特征非常适合做大规模密集型数据的处理。另一个近年来的重要的并行体系就是集群，本文首先简要介绍在集群下进行并行计算的原理，阐明了GPU相对于集群所具有的优势，再结合安全散列算法SHA-1本身的特质，说明采取GPU来实现SHA-1的并行化会更有效率。对SHA-1从运算效率上进行改进，并兼顾了算法的保密性和完整性，分别采取了在GPU上实现、增添分组、变换逻辑函数、数字签名等一系列的措施，改进后的算法虽然在结构上看起来比原来要复杂得多，但是在算法的实用性上比原算法更具优势，而且诸多的改进使得算法能更加有效的应用于当前的信息安全中来，为消息通讯保驾护航。本文以提高SHA-1加密算法的速度为宗旨，利用GPU这个潜力资源最大化地提高SHA-1的加密速度，借用GPU的并行能力将串行SHA-1以并行的方式来实现，为SHA-1的新发展开辟了方向。更多还原

【Abstract】 The development of today must rely on information and communication, the linksbetween people are more than ever too frequent, people had overcome geographical barriers,distance is no longer a constraint factors of human’s smooth communication, network securityissues began to stand out in the communication process. People gradually began to useencryption technology to ensure the security of the information in the communication process,and encryption technology which is an important application in the digital signature. Digitalsignature using public key cryptography to sign the information as a confirmation to ensurethe legitimacy and authenticity of the sender of the message, the recipient can confirm thesource of information. Secure Hash Algorithm is an important tool for digital signatures,which makes the digital signature can be executed correctly, the acceleration of the SecureHash Algorithm also improve the efficiency of the implementation of digital signature, so ifwe can find an accelerated Secure Hash Algorithm way, it will make a great contribution toe-commerce, e-government.The hash algorithm is to accept a period of clear text, and then convert it to a section ofciphertext, the conversion is an irreversible manner, the ciphertext is called the messagedigest, this conversion is a one-way irreversible. The hash algorithm SHA-1, already have avery strong resistance to cryptanalysis attacks. SHA-1has more anti-attack power than theoriginal MD5hash algorithm,about232magnitude, so that the improvement of the SHA-1hasa very important practical significance. Knowledge of the SHA-1, including the processes ofthe algorithm, the core compression function and the basic concepts and principles, do someimprovements to the algorithm, these improvements include the algorithm serial conversionof input, the logic function of the algorithm, the algorithm for parallel, gives the main ideaand process of each improvement are described in detail.In recent years, the graphics processor’s floating-point operations and bandwidth areuncovered, the GPU (Graphics Processing Unit) no longer applies only to the graphicsprocessing, these characteristics are very suitable for large-scale intensive data processing,the use of GPU parallel computing is a predictable very promising direction of development.Another recent years important parallel system is clustered, this article first cluster-basedparallel computing and GPU-based parallel computing for a brief introduction, indicating thatthe GPU the advantages relative to the cluster, and then for Secure Hash Algorithm SHA-1‘snature, the GPU-based parallelization is more efficient than the cluster-based. And SHA-1 algorithm for GPU-based parallel taking into account the confidentiality and integrity,respectively, to take on the GPU, adding grouping, transformation logic functions, digitalsignature and a series of measures, although the improved algorithm is much more than theoriginal complex structure become more advantages than the original algorithm, but thepracticality of the algorithm, and makes many improvements The algorithm can be applied tomore effective information security, escort for message communication.In this paper, the purpose is to improve the speed of SHA-1, I mainly want to use the GPU‘s potential of resources to improve the SHA-1encryption speed, to borrow the GPU’s parallelcapabilities,make the serial SHA-1’s implementation in parallel, a new direction has openedup for SHA-1’s development.更多还原