Research On Design And Application Of Cryptographic Hash Functions

Cryptographic hash functions play an increaseingly important role in cryptography. Many primitives and protocols rely on the existence of secure cryptographic hash functions. Because of many successful attacks on hash functions, hash function has become a hotspot research field in the cryptographic world. We start a reseach on hash functions under this background. In this paper, we do main research on designing of new hash function; meanwhile, we do research on the applications of hash function. The mainly obtained results are as follows:1. Attack analysis methods of hash functions were summarized. In the author's opinion, the attack analysis of hash function can be seen from three different layers:1st the generalize attack technique; 2nd the one to iterated structure; 3rd the one to compression function. Moreover, the basic design infrastructure of hash function was analyzed. In addition, the ideas of designing hash function for resisting different attack was also summarized.2. We analyzed two massage expansion methods of MD4-family. From the consideration of security and efficiency, we proposed the third message expansion method: use step function which has a fast diffusion effect to do message expansion.3. A new compression function Shuttle was designed for construction of secure and efficient iterated hash function. Shuttle maps input of a 512-bit message block and a 256-bit chaining variable to a 256-bit output. The key innovations of Shuttle are its step function and structure. A new step function was designed to provide a fast avalanche effect and a novel two lines structure was designed to provide a high level of security. We conjecture that Shuttle is secure against known attacks on compression functions from our analysis up to now. Combining Shuttle with Merkle-Damgard iterated structure, we construct a hash function. Experiments show that new hash function is about 87% faster than that of SHA-256 in software.4. Based on coupled map lattice together with traditional Merkle-Damgard iterated structure, a new hash function OCMLHash construction was proposed. Through defining a new float point number storage presentation and corresponding basic operations, the proposed construction can complete chaos operation and output hash value on 32-bit word using basic operations such as shifter, adder etc. Compared with the existing chaotic hash functions, this construction cuts down time expansion on data type transformation between unsigned integers and float point numbers, and avoids the possibility of hashing the same message to different hash value in different computation environments. New hash function maintances properties of chaos such as irreversibility, sensitivity to initial values, etc.5. Hash chain and commitment based on hash chain were studied; Security flaws of a new electronic auction scheme based on hash chain were analyzed. We designed an improved scheme based on hash chain, and analyzed the the security of new scheme.6. We studied chameleon hash function, proposed a new strong multi-designated verifiers signature scheme, and analyed the security properties and efficiency of the scheme.