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Hash function

Hash function

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

Ultimate digital security