All it does is to form a "practically unique" key of any data. MD5 Hash Extractor MD5 Hash Extractor is a free and powerful 128-bit hashing algorithm extractor utility This tiny MD5 extractor has a Windows (any 32-bit) GUI and can extract MD5 out of files of gigabytes size.

MD5 is a 128-bit hashing algorithm. All it does is to form a "practically unique" key of any data. This tiny MD5 extractor has a Windows (any 32-bit) GUI and can extract MD5 out of files of gigabytes size. Now, version 1.3 supports files with up to 64-bit size!
From Webopedia.com, the definition of MD5:
"An algorithm created in 1991 by Professor Ronald Rivest that is used to create digital signatures. It is intended for use with 32 bit machines and is safer than the MD4 algorithm, which has been broken. MD5 is a one-way hash function, meaning that it takes a message and converts it into a fixed string of digits, also called a message digest.
When using a one-way hash function, one can compare a calculated message digest against the message digest that is decrypted with a public key to verify that the message hasn't been tampered with. This comparison is called a 'hashcheck'."
v2.0+ supports Unicode and Windows XP/Vista/7 themes as it is compiled with BCB2010 and ICSv7.
The SHA (Secure Hash Algorithm) hash functions refer to five FIPS-approved algorithms for computing a condensed digital representation (known as a message digest) that is, to a high degree of probability, unique for a given input data sequence (the message). These algorithms are called "secure" because (in the words of the standard), "for a given algorithm, it is computationally infeasible 1) to find a message that corresponds to a given message digest, or 2) to find two different messages that produce the same message digest. Any change to a message will, with a very high probability, result in a different message digest.

The license of this software is Freeware, you can free download and free use this file compare software.