Alfred's New Ramblings

Hash and large files

You need to send off several large files.  These may be the parts of a very a large zip file or multiple individual files.  The receiver tried to open or merge the files together and get a bad data error message.  How do you know what is bad?

The answer is simple.  Use a hash.  A hash or hash checksum is a unique pattern created from the contents of your file.  This is a one way process.  It is commonly used to validate if two files are identical.  When the file is in the pc or smartphone, create a hash and save it.  A simple Windows tool for creating hash is FCIV.  Upload your desired file and the hash in 2 separate files.

The receiver, will again hash the file you sent.  Compare the hash signature generated versus your hash.  If the hashes match, the file has not been modified and is identical to the source.

Note there is no mention on the type of file or its contents.  It does not matter, if is a zip, msi, text, audio or video file.

File verification fciv

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