Enhancing MD5 Hash Algorithm using Symmetric Key Encryption

Abstract

Traditionally, hash functions were designed in the keyless manner, where a hash function accepts a variable length input message and produces a fixed length digest as output. However, over the years, few significant weaknesses were found in some popular keyless hash functions. Many a few recent attacks have been successfully implemented on these traditional popular hash functions such as- SHA-1, MD5 etc. The proposed solution uses integration of keyed symmetric key block encryption algorithm in each step or round of hash compression function. Because symmetric key encryption algorithm works on use of single key, both sender and receiver use the same key. When comparing MD5 hash and proposed algorithm, the time taken by proposed algorithm raises by 15-20% for data below 50 KB while the number of operation to perform the brute force pre-image attack , second pre-image attack increases from 264 (for MD5) to 2192.