Message perfect secrecy (Shannon spirit)
Read as: The ciphertext carries zero mutual information about the message.
Arguments
- M
- : message or protected value before observation
- C
- : ciphertext in the Shannon secrecy equation
Operators
- I
- : mutual information
- = 0
- : posterior belief does not change after observing ciphertext
Significance: It states the classical emptiness claim: ciphertext observation does not update beliefs about the message.
Computational contrast: The computational bargain replaces this emptiness requirement with a hardness clock so strangers can talk at scale without OTP logistics.
References:Perfect secrecy (Shannon)
