An encryption function can be used to obfuscate pieces of information and later on retrieve them.
What is the yardstick for measuring how well the function encrypts the information ? Given any invertible function, which are the quantified parameters which measure how effective the function is to encrypt a message ?
I am assuming a finite domain for the function. Any other assumption may be stated.
Motivation: Is there any mathematical/set theoretic formulation at all... I ask this specially because I don't see this approach ever being used as has been rightly observed. My motivation is to find out weather the notion of 'encryption' can be captured fully in a mathematical formalism.-- or that we require other kind of 'concepts' to describe it fully. –