This has similar security properties to a salted password based key derivation scheme. Given the output, and assuming a function with effective preimage resistance, the best way to find the global password is brute force it by trying lots of master passwords. The security is a function of the forward difficulty of the KDF (in space and time) and the quality of the master password. Use the password &#x27;password&#x27; and MD5 and you don&#x27;t have much security except through obscurity. Use an 8 word diceware password and scypt and you are doing great security wise (assuming of course no implementation problems, a big assumption!)