Main » TERM » H »

hashing

Producing hash values for accessing data or for security. A hash value (or simply hash), also called a message digest, is a number generated from a string of text. The hash is substantially smaller than the text itself, and is generated by a formula in such a way that it is extremely unlikely that some other text will produce the same hash value.

Hashes play a role in security systems where they're used to ensure that transmitted messages have not been tampered with. The sender generates a hash of the message, encrypts it, and sends it with the message itself. The recipient then decrypts both the message and the hash, produces another hash from the received message, and compares the two hashes. If they're the same, there is a very high probability that the message was transmitted intact.

Hashing is also a common method of accessing data records. Consider, for example, a list of names:

  • John Smith
  • Sarah Jones
  • Roger Adams
  • To create an index, called a hash table,for these records, you would apply a formula to each name to produce a unique numeric value. So you might get something like:

  • 1345873 John smith
  • 3097905 Sarah Jones
  • 4060964 Roger Adams
  • Then to search for the record containing Sarah Jones,you just need to reapply the formula, which directly yields the index key to the record. This is much more efficient than searching through all the records till the matching record is found.







    TECH RESOURCES FROM OUR PARTNERS
    LATEST ARTICLES
    Text Messaging & Chat Abbreviations

    This chat guide lists more than 1,460 text message and online chat abbreviations to help you translate today's texting lingo. Read More »

    SEO Dictionary

    From keyword analysis to backlinks and Google search engine algorithm updates, our search engine optimization glossary lists 85 SEO terms you need... Read More »

    Slideshow: History of Microsoft Operating Systems

    Microsoft Windows is a family of operating systems for personal computers. In this article we look at the history of Microsoft operating... Read More »

    STUDY GUIDES
    Computer Architecture Study Guide

    Computer architecture provides an introduction to system design basics for most computer science students. Read More »

    Network Fundamentals Study Guide

    Networking fundamentals teaches the building blocks of modern network design. Learn different types of networks, concepts, architecture and... Read More »

    Java Basics, Part 1

    Java is a high-level programming language. This guide describes the basics of Java, providing an overview of syntax, variables, data types and... Read More »