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.
Because nothing says "I Love You" Like an open source app. Read More »Guarding your Data against Cyber Attacks
In this new era of heightened stakes comes an increased need for a comprehensive security strategy. Let's take a look at how cyber-threats have... Read More »The Great Data Storage Debate: Is Tape Dead?
Tape clearly is on the decline. But remember, legacy systems can hang for a shockingly long time. Read More »
A network is a group of two or more computer systems or devices, linked together to share resources, exchange files and electronic communications.... Read More »Computer Architecture Study Guide
This Webopedia study guide describes the different parts of a computer system and their relations. Read More »Webopedia Polls
The trend for the past two years has been for shoppers to spend more online during the holiday season. How do you typically shop for holiday... Read More »
Stay up to date on the latest developments in Internet terminology with a free weekly newsletter from Webopedia. Join to subscribe now.
- Watch Datamation's editor James Maguire moderate roundtable discussions with tech experts from companies such as Accenture, Dell, Blue Jeans Network, Microsoft and more »