The Research And Implementation Of Message Digest Technology

Message Digest that is used as a basic part in cryptology has always been aresearch hotspot in that area since it was proposed. The situation that Message-Digestalgorithms which are in used suffer from breaking has become a reality because thecheap and high-performance cloud computing resources are more and more accessiblein nowadays. As application behaviors in network are getting richer and richer andmore and more complex, people’s requirements for authentication of identity andinformation are becoming more urgent, especially in integrity, confidentiality,usability, nonrepudiation, and other aspects. With the amount of the analysis, collisionattacks and breaking methods to the message-digest algorithms which are in used nowgetting bigger and bigger and the attacks to the objects of algorithms getting more andmore targeted and effective, people’s pressing needs can not be met and they have toface the threat of being attacked on their algorithms in used. So the research task ofthe message digest technology is becoming more important and it’s progress and fruitwill influence the security of information resources directly and even influence thesecurity of individuals and society indirectly.In order to satisfy people’s security requirement at present, this paper proposes akind of virtual word technology, extends and improves message-digest algorithmMD5on the basis of the research of MD structure, and generates the MD5-alikealgorithms of words which are stretch and of rounds which are tailorable, which keepthe advantages of the original algorithm and have more safety and application value.Meanwhile, this paper proposes a kind of message-digest model which improvesapplication security of algorithms obviously and can adapt itself to the changes ofdigest algorithms now rather than depend on the security of one algorithm unduly andrealizes a tool for verifying files based on message-digest model with salt on the basisof the study above, combining the problem that message-digest algorithms encountertargeted attacks in practice. Specific content as follows:(1) Study the principle, technology and development situation at home andabroad of the message digest. (2) Study the design principle of message-digest algorithms and the main attackmethods on them.(3) On the basis of the study above, the dissertation focuses on themessage-digest algorithm of MD structure, proposes a kind of virtual wordtechnology to remedy the defect of MD5and puts forward the MD5-alike algorithmsof words which are stretch and of rounds which are tailorable by applying thattechnology.(4) On the basis of the study above, the dissertation proposes a kind ofmessage-digest model which improves application security of algorithms obviouslyand can randomly select digest algorithm by adding random number to it.(5) Build OpenSSL environment on the windows platform and realize a tool forverifying files based on message-digest model with salt.