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Background SHA-256 is a cryptographic hash function developed by the US. National Security Agency (NSA) as a U.S. Federal Information Processing Standard (FIPS). The SHA acronym stands for Secure Hash Algorithm. A hash function operates on an arbitrary amount of data and returns a fixed-size bit string, the cryptographic hash value. So why would such an algorithm be useful? Its utility lies in the fact that attempts to change the original data will almost certainly change the hash value returned by the algorithm. An obvious application would be to apply such an algorithm to a file (text or binary) as a means of determining whether or not it has been tampered with. This post shows you how to use SHA-256 as implemented by the OpenSSL open source project, and use it within Windows / Visual C++ environments to produce digital signatures of strings or files.

A short and to-the-point C++ recipe for determining the status of your PC / laptop DVD. To study this area in more depth, follow this link for more information, which is where I got much of this inspiration for this code snippet. It works. http://ws0.org/windows-how-to-get-the-tray-status-of-the-optical-drive/ Full code listing