CRC (“cyclic redundancy check”) is an early data integrity check standard (a.k.a. “hash”). Most CRC codes are 32-bit numbers and are usually represented in hexadecimal format (e.g., “567890AB”). CRC was commonly used with modem-based data transfer systems because it was cheap to calculate and fast on early computers. Its use[..]

## MD4

MD4 (“Message Digest [algorithm] #4”) is best known as the data integrity check standard (a.k.a. “hash”) that inspired modern hashes such as MD5, SHA-1 and SHA-2. MD4 codes are 128-bit numbers and are usually represented in hexadecimal format (e.g., “9508bd6aab48eedec9845415bedfd3ce”). Use of MD4 in modern file transfer applications is quite[..]

## MD5

MD5 (“Message Digest [algorithm] #5”) is the most common data integrity check standard (a.k.a. “hash”) used throughout the world today. MD5 codes are 128-bit numbers and are usually represented in hexadecimal format (e.g., “9508bd6aab48eedec9845415bedfd3ce”). MD5 was created in 1991 as a replacement for MD4 and its popularity exploded at the[..]

## SHA-1

SHA-1 (“Secure Hash Algorithm #1”, also “SHA1”) is the second most common data integrity check standard (a.k.a. “hash”) used throughout the world today. SHA-1 codes are 160-bit numbers and are usually represented in hexadecimal format (e.g., “de9f2c7f d25e1b3a fad3e85a 0bd17d9b 100db4b3”). SHA-1 is the least secure hash algorithm NIST currently[..]

## SHA-2

SHA-2 (“Secure Hash Algorithm #2”) is the most secure hash algorithm NIST currently supports in its FIPS validated cryptography implementations. SHA-2 is really a collection of four hashes (SHA-224, SHA-256, SHA-384 and SHA-512), all of which are stronger than SHA-1. Complete SHA-2 implementations in file transfer are still uncommon but[..]

## SHA-224

SHA-224 is the 224-bit component of the “SHA-2” data integrity check standard (a.k.a. “hash”). It is not a unique hash algorithm within the SHA-2 standard but is instead a truncated version of SHA-256. See “SHA-2” for more information.

## SHA-256

SHA-256 is the 256-bit component of the “SHA-2” data integrity check standard (a.k.a. “hash”). Like SHA-512, it is one of two unique algorithms that make up a SHA-2 hash, but SHA-256 is optimized for 32-bit calculations rather than 64-bit calculations. See “SHA-2” for more information.

## SHA-3

SHA-3 refers to the new hash algorithm NIST will choose to someday replace SHA-2. A contest to select the new hash is scheduled to conclude in 2012.

## SHA-384

SHA-384 is the 384-bit component of the “SHA-2” data integrity check standard (a.k.a. “hash”). It is not a unique hash algorithm within the SHA-2 standard but is instead a truncated version of SHA-512. See “SHA-2” for more information.

## SHA-512

SHA-512 is the 512-bit component of the “SHA-2” data integrity check standard (a.k.a. “hash”). Like SHA-256, it is one of two unique algorithms that make up a SHA-2 hash, but SHA-512 is optimized for 64-bit calculations rather than 32-bit calculations. See “SHA-2” for more information.