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I have files on the server that is encrypted with AES. I am developing iOS and Android apps to decrypt and process those files in the phone or tablet. To decrypt files on the client apps, I have to use/store the same AES keys in the app. That means I have to put my AES keys in the code so I can directly use from source or ship to client device so I can store there. Keeping/Shipping Encryption keys in the code is bad idea but I need those keys to process files.
How can I securely keep keys in my code? Or is there any other way to obtain my AES keys in the client so I can decrypt files?