Multiple Hashing Using SHA-256 and MD5

Abstract

Message Digest 5 (MD5) is a hashing function with numerous vulnerabilities such as pre-image vulnerability and collision vulnerability which restrict the usage of MD5. Therefore, by using other hashing functions such as SHA prior to hashing with MD5, we can use MD5 for various applications such as data integrity without compromising the security of the hash. MD5 is widely used in file transfer or storage applications because it produces a smaller hash value of 128 bits when compared with other hashing algorithms. Also, it is simpler to implement in hardware and as a program. We propose a technique of hashing the original message (or string) with secure hashing algorithms such as SHA-256 followed by hashing the hash value of SHA-256 with MD5 to get the resultant hash which is less prone to various security attacks such as collision attacks. By hashing the string twice, we make it more secure and tackle the pre-image vulnerability and collision vulnerability of MD5. This makes the hashing algorithm more secure for file transfer applications. Multiple iterations will produce more secure hash values but our simulation uses two iterations, where we upload a file onto a cloud server and check if it has been tampered with or modified.