Which of the following are common hash functions?

Both MD5 and SHA are widely recognized and commonly used hash functions in cybersecurity. Hash functions are algorithms that take an input (or 'message') and return a fixed-size string of bytes. The output, often referred to as the hash value, is unique to the given input; even a small change in the input data will produce a significantly different hash.

MD5 (Message-Digest Algorithm 5) was developed in the early 1990s and is used to verify data integrity. Although it was once considered secure, vulnerabilities have since been discovered, making it less reliable for cryptographic purposes.

SHA (Secure Hash Algorithm), on the other hand, encompasses a family of hash functions, with several iterations that include SHA-1, SHA-256, SHA-512, etc. SHA was designed to address some of the vulnerabilities present in MD5 and to provide stronger security for data integrity and digital signatures.

Combining both MD5 and SHA demonstrates an understanding of the evolution of hashing techniques, highlighting their prevalence in various applications such as password storage, data integrity checking, and digital certificates. Therefore, selecting both is a reflection of the knowledge of these vital cryptographic elements in the realm of cybersecurity.