Fast-md5 is faster than the build-in md5 support in java standard toolkit. it can be used if one or more of following applies:
* java's built-in md5 support is a bottleneck for your program's performance
and you want something faster.
* you are using a version of java which doesn't have md5 support, such as
j2me midp/cldc.
* you want the extra convenience methods for hashing a file, hashing a
string, converting the hash to a hex string, etc.