Hash functions are extremely useful and appear in almost all information security applications.
A hash function is a mathematical function that converts a numerical input value into another compressed numerical value. The input to the hash function is of arbitrary length but output is always of fixed length.
Values returned by a hash function are called message digest or simply hash values. The following picture illustrated hash function −
Features of Hash Functions
The typical features of hash functions are −
- Fixed Length Output (Hash Value)
- Hash function coverts data of arbitrary length to a fixed length. This process is often referred to as hashing the data.
- In general, the hash is much smaller than the input data, hence hash functions are sometimes called compression functions.
- Since a hash is a smaller representation of a larger data, it is also referred to as a digest.
- Hash function with n bit output is referred to as an n-bit hash function. Popular hash functions generate values between 160 and 512 bits.
- Efficiency of Operation
- Generally for any hash function h with input x, computation of h(x) is a fast operation.
- Computationally hash functions are much faster than a symmetric encryption.
