Design And Implementation Of Hash Functions Based On Composite Structures

In the age of information technology,the issue of information security has become increasingly prominent.Hash functions have a pivotal role in cryptography,computer networks and information security,they are used in essential areas such as message integrity check codes,digital signatures and blockchain technology.Today one can find collisions of MD4,MD5,SHA-1 and other algorithms in a relatively short period of time,the security of traditional hash functions has become a major concern.Improving the security proble m and efficiency of hash functions has become the focus of researchers in recent years.The commonly used hash functions are MD series,SHA series,etc.As a result of a series of successful attacks on hash functions in recent years,the existing hash functions have certain security flaws(e.g,not good collision resistance).Therefore,in this paper,in order to improve the operation efficiency as well as the security of the hash function,we propose random functions,chaotic mapping and other design methods to construct a composite structure-based secure hash function(SHF).First,a compression function with faster diffusion capability is designed.In this paper,we analyze the internal structure of existing hash functions and attack methods,and borrow the design concept of packet cipher IDEA,improve the MA(Multiplication-Addition)structure in packet cipher IDEA and apply it to the compression function,so that the designed hash function has the ability of fast diffusion and differential obfuscation.Second,the proposed random function-based hash function construction method.Since traditional hash functions have a fixed structure,this makes the existing generic attacks on hash functions also based on deterministic algorithms.Therefore,in order to increase the difficulty of the attack on the hash function,this paper breaks the inherent pattern of the traditional hash function,the specific form of the hash function is constantly changing according to the changes in the message.The attacker does not know the particular message and thus cannot learn the exact form of the hash function,thus making it more difficult to decipher.Finally,multi-chaotic mappings with variable parameters are introduced and applied to the hash function.During the message computation,the intermediate link variable values are controlled by multiple mixed iterations,which makes the structure of SHF a composite structure for the purpose of enhancing the avalanche of hash functions.In this paper,the security of the designed hash function is tested in various aspects,among which the statistical test experiment proves that SHF has good resistance to statistical analysis.The avalanche factor experiment verifies that SHF has fast diffusivity and confusion,making the hash function designed in this paper have good collision resistance.K-order diffusion experiments confirm that SHF has good second-order diffusion properties.In the avalanche effect experiments,SHF has a lower probability of bad points than the traditional hash functions SHA-256 and MD5.Performance testing experiments show that its computing efficiency is also slightly better than SHA-256.