Files MD5 SHA1 Calculate & Compare oleh Moris Papasmadov

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Some relevant links:
Wikipedia - https://en.wikipedia.org/wiki/Cryptographic_hash_function
OpenSSL - https://www.openssl.org/docs/man1.1.0/apps/dgst.html
Microsoft File Checksum Integrity Verifier - https://www.microsoft.com/en-us/download/details.aspx?id=11533
Apple Mac Computer, Checking an MD5 Checksum on - http://www.resourcesforlife.com/docs/item1428