When part of your system becomes flawed (part or whole), the whole can be attacked. Thus, adding more deterministic behavior doesn't add more randomness (i.e.

When part of your system becomes flawed (part or whole), the whole can be attacked. Thus, adding more deterministic behavior doesn't add more randomness (i.e. more safety). Generally, when crypto falls down, it falls somewhat gracefully (i.e. there are a class of known attacks under certain particular situations.) As Crypto is an on-going war between those creating the security and those trying to break it, expect to have to change your crypto over time.