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:
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:
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.
Stay up to date on the latest developments in Internet terminology with a free weekly newsletter from Webopedia. Join to subscribe now.
Like everything in technology, AI touches on so many other trends, like self-driving cars and automation, and Big Data and the Internet of Things... Read More »DevOp's Role in Application Security
As organizations rush to release new applications, security appears to be getting short shrift. DevSecOps is a new approach that holds promise. Read More »Slideshow: Easy Editorial SEO Tips to Boost Traffic
This slideshow reviews five easy on-page editorial SEO tips to help drive organic search engine traffic, including the page title, heading,... Read More »
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 »Java Basics, Part 2
This second Study Guide describes the basics of Java, providing an overview of operators, modifiers and control Structures. Read More »The 7 Layers of the OSI Model
The Open System Interconnection (OSI) model defines a networking framework to implement protocols in seven layers. Use this handy guide to compare... Read More »