SHA (Secure Hashing Algorithm) is a cryptographic hash, which is like a signature for a text or datafile. Hashes are convenient for situations where computers may want to identify, compare, or otherwise run calculations against files and strings of data. It is easier for the computer to first compute a hash and then compare the values than it would be to compare the original files.
SHA 1 and SHA 256 are two different algorithms, SHA 256 being more recent and more secure than its predecessor. This is the recommended option.
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