There are multiple ways to secure your key, but it depends upon how you create your key.
One way to create a dynamic key for encryption and decryption so there is no need to store it anywhere.
e.g. you can pick a HDD serial no and encrypt your key and use same for decryption (
In this case you do not need to store it any where, just fetch HDD serial no each time dynamically, or you can use Processor ID instead)
One possibility is to query the database for the encryption key, you can store it in database, it has its own encryption key. see below link
Encrypt a Column of Data[
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