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→Algorithms
== Algorithms ==
A cryptographic algorithm (also known as a ''cypher'') is a step by step sequence of mathematical calculations used to encrypt and decrypt information. There are currently three different types of cryptographic algorithms, hashing algorithms, symmetric-key algorithms and asymmetric key algorithms.
== Hashing Algorithms ==
A ''hash'' is a mathematical algorithm designed to perform ''one-way encryption''. When we say ''one-way'' we mean that once the information has been encrypted there is no way to retrieve the original information from the hashed form. Hashing is commonly used in password files and for ensuring that the integrity of data. As an example, a hash may be created for an email message in the form of a Message Authentication Code (MAC). When the message is received the receiver would also generate a hash from the message. If the recipient's hash matches the code which accompanied the message the receiver knows the mesasge is authentic and has not been tampered with during transmission.
The two most common hash methods are as follows:
* '''Message Digest Service Algorithm''' - The message digest family of encryption algorithms provide encryption of 128-bits in strength and are designed to be fast and simple. Current standards are MD2, MD4 and MD5.
* '''Secure Hash Algorithm''' - SHA is used extensively by the US government and was developed by the National Security Agency (NSA). Two version of SHA have so far been developed - SHA and SHA1. SHA1 provides 160-bit hashing. SHA-1 is more secure than MD5 but involves a slower encryption process.
== Symmetric Encryption Algorithms ==
Symmetric encryption is one of the most basic forms of cryptography and are based on the premise that both the sending and receiving parties are in possession of the key ued to encrypt the data (otherwise known as ''share secret'' encryption).
Symmetric key encryption is performed using two methods, ''block cipher'' and ''stream cipher''. As the names suggest, block ciphers encrypt data in sections of bits whereas a stream cipher encrypts data one bit at a time until the entire message is encrypted.
A wide variety of symmetric key algorithms are currently in use, the most prevalent of which are described below.
== Data Encryption Standard (DES) ==
DES was originally developed in the 1970's at the behest of the National Bureau of Standards (NBS), now knoen as the National Institute of Standards and Technology.
DES is a block cipher and encrypts data in 64-bit units using a key length of 56-bits. As with other symmetric encryption algorithms, DES uses the same key and algorithm for both encyption and decryption.
== Triple DES (3DES) ==
As may be infered from the name, 3DES (pronounced Triple Des) is an adaptation of DES. Unlike DES, 3DES uses either 2 or 3 keys executes three passes through the algorithm to provide ''muliple encrytion'' resulting is a total bit strength of 168-bits.
== Advanced Encryption Standard (AES) ==
