"Most of the ISO images and other software you grab off the
Internet come with a message digest--a cryptographic hash value
that you can use to verify their integrity. While almost all Linux
distributions come with utilities to read and generate digests
using MD5 and SHA1 hash functions, the md5deep utilities can do
that and more.
"md5deep computes MD5, SHA-1, SHA-256, Tiger, and Whirlpool
digests across Linux, Windows, Mac OS X, *BSD, Solaris, and other
operating systems. It can recursively traverse directories,
computing sums for files under subdirectories as well. When
traversing directories, you can control md5deep to process only
files of certain types, such as text files, and ignore other files,
such as block devices and symbolic links..."