# What's the difference between perfect security and unconditional security?

This paper refers to two distinct security models: perfect security and unconditional security. Until now, I knew of them as the same thing and equivalent to information-theoretic security.

From the paper, it's obvious that perfect security is the same as information-theoretic security. In this case, what exactly is unconditional security?

## 1 Answer

According to the references, both perfect security and unconditional security consider adversaries that have unlimited computational power, i.e., information-theoretic security. I think the only difference is that unconditional security allows for negligible failure while perfect security requires zero failure.