MD5 hash

In cryptography, MD5 (Message-Digest algorithm 5) is a widely used cryptographic hash function with a 128-bit hash value. As an Internet standard (RFC 1321), MD5 has been employed in a wide variety of security applications, and is also commonly used to check the integrity of files. An MD5 hash is typically a 32-character hexadecimal number. Recently, a number of projects have created MD5 "rainbow tables" which are easily accessible online, and can be used to reverse many MD5 strings into their original meanings.

MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function, MD4. In 1996, a flaw was found with the design of MD5; while it was not a clearly fatal weakness, cryptographers began to recommend using other algorithms, such as SHA-1. In 2004, more serious flaws were discovered making further use of the algorithm for security purposes questionable, but it's still very useful for simple data integrity purposes.

Linux

On any Unix-like OS you can simply use the following command

md5sum filename

Windows

On windows you can download one of the many available free MD5 hashing utilities, such as MD5Win32 by Kenneth Ballard. After installing you can just right-click on a file and select "hash" from the context menu to obtain the MD5 hash of the file.

Perl Module

Digest::MD5::Perl is a perl implementation of Ronald Rivests md5 hash algorithm. It is written in perl only and because of this it is slow but it works without C-Code. You should use Digest::MD5 instead of this module if it is available.