MD5 (Message Digest Five) is the algorithm developed by Rivest (of the RSA fame). It is also documented in the RFC1321. In order for the completely free use, L. Peter Deutsch wrote his own implementation according to the specification of the RFC. Currently, his implementation can be found on Sourceforge.

I transformed Deutsch’s implementation into C++. So that you can call the MD5 in the following way:

#include "md5.h"

md5* MD5 = new md5();
cout << "MD5 of string 'hello' is " << MD5->digest('hello') << endl;
MD5->append('hello ');
cout << "MD5 of string 'hello world!' is " << MD5->getDigest() << endl;

The code is here: C++ source and header file