# The use of the term "sound" in cryptography [closed]

In the context of interactive proof systems, we often see the term "sound" used. What is the sense of this word?

• Context and/or reference, please. Nov 4 '14 at 10:34
• This definition is likely from interactive proof systems. Complete means verifying party would accept for a valid common input, sound means will reject for an invalid input. Unlike logic, both with some probability, resulting in "soundness error" being the probability of accepting a wrong answer. In the context of a proof of equality of two logarithms, "wrong" would mean no NP-witness exists, so response must being calculated with "arbitrary" algorithm. Jan 8 '15 at 22:04

This applies similarly to any decision procedure for example a program that has to declare whether $X$ is secure in some model $Y$.