What's your security/cryptography background?

Instead of stenography, I simply appended the encrypted data/payload to the end of a JPG file in my photo library. The file opens and displays normally.

Part of the photo/carrier file is used as salt for decryption. The part that is used changes randomly based on the last modification time/attribute of the file. The file creation time is maintained/doesn't change with payload modifications.

Encryption is also tied to disk parameters so a simple file copy makes the data unreadable. The access utility can be used to move the file and re-encrypt the data on a different disk.

A labeled section of the payload data/vault holds TOTP keys so the access utility can also function as a 2FA authenticator.