Continuing the discussion from Introduce yourself:
By security, do you mean preventing the file from being and proving that it hasn’t been changed?
If so, you could notarize the file in the Bitcoin blockchain by hashing it and storing that hash in the Bitcoin blockchain.
Or do you mean preventing a 3rd party from access the contents of the file?
In this case you could use public key cryptography with or without a blockchain component to protect your files.
Without knowing more about your specific situation, it’s difficult to give more specific advice