Corona provides routines for calculating common message digests (hashes) and hash-based message authentication codes (HMAC).
The crypto library is an external library pre-installed into Corona apps. To speed up launch time, it is not automatically loaded by default. In order to use this library, you must explicitly load the library to make the library's functions available to your code. To do this, you should use require, i.e. placing local crypto = require("crypto") at the top of your Lua file.
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