Hash function definition

A hash function refers to a mathematical function that takes an input (often a large amount of data) and produces a fixed-size output, called a hash value or hash code. Any change in the input data will result in a different hash value. Hash functions are commonly used in cryptography, data integrity checking, and data storage.

See also: hash chain, file hash, integrity checking

Hash function features:

• Deterministic. It always produces the same hash value for the same input data.
• One-way. It is difficult or impossible to reverse a hash function.
• Collision-resistant. Two different inputs should not produce the same hash value.
• Fixed output size. Regardless of the input data size, the size of the hash value is fixed.

Hash function uses:

• In cryptography, they provide data integrity, message authentication, and digital signatures.
• In password management, hash values can be stored instead of passwords.
• In data indexing, they can help quickly locate and access data in large data sets.
• In data integrity checking, they are used to verify that data has not been corrupted or modified during transmission or storage.
• In digital forensics, they can help identify known files or to identify unique characteristics of files.

Further reading