Define PCASM in terms of indistinguishability #5
Description
Leaving aside the precise length stuff, I believe that it would be better to define PSCAM in terms of indistinguishability as used in the cryptographic information.
The idea is that it would be any thing that would give an attacker the ability to make a better than 50/50 guess at any bit of the message. You could think of it as any information that would give the attacker an advantage in determining which of two plaintexts is more likely.
For example, an attacker might already have a fair guess that a message is in English, but nothing that is revealed through the system should give them any help in refining that guess. (Again, leaving length aside). The way cryptographers define indistinguishability captures this.