Encyclopedia of Database Systems

2009 Edition

Hash Functions

  • Marina Blanton
Reference work entry
DOI: https://doi.org/10.1007/978-0-387-39940-9_1482



A hash function is a well-defined deterministic algorithm that takes as input data of arbitrary length and produces a short fixed-length digital representation of the data, or a digest, as its output. The output of a hash function can serve the role of a digital “fingerprint” of the input data, as an important design property of hash functions is that of collision resilience: two hashes produced on different inputs are very unlikely to result in the same value. Furthermore, given a hash function output, it is normally infeasible to find a (previously unseen) input that matches that output (this property is called preimage resistance).

Key Points

Hash functions have many uses, and in cryptography they are widely used because of their collusion resistance and preimage resistance properties. In particular, hash functions are used to verify integrity of messages and can be used to construct message authentication...

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Recommended Reading

  1. 1.
    Eastlake D. and Jones P. US Secure Hash Algorithm 1 (SHA1). IETF RFC 3174, 2001. http://www.ietf.org/rfc/rfc3174.txt.
  2. 2.
    National Institute of Standards and Technology (NIST). FIPS 180-2: Secure Hash Standard (SHS), Current version of the Secure Hash Standard (SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512), 2004.Google Scholar
  3. 3.
    Rivest R. The MD5 message-digest algorithm. IETF RFC 1321, 1992. http://www.ietf.org/rfc/rfc1321.txt.
  4. 4.
    Schneier B. Applied Cryptography: Protocols, Algorithms, and Source Code (2nd edn.). Wiley, New York, NY, 1996.Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Marina Blanton
    • 1
  1. 1.University of Notre DameNotre DameUSA