In this article we test an Erlang implementation of the Noise Protocol Framework, using a novel form of white-box testing. We extend interoperability testing of an Erlang enoise imple- mentation against an implementation of Noise in C. Testing typically performs a noise protocol handshake between the two implementations. If successful, then both implementa- tions are somehow compatible. But this does, for example, not detect whether we reuse keys that have to be newly gen- erated. Therefore we extend such operability testing: During the handshake the Erlang noise implementation is traced. The resulting protocol trace is refactored, obtaining as the end result a symbolic description (a functional term) of how key protocol values are constructed using cryptographic op- erations and keys. Therafter, this symbolic term is compared, using term rewriting, with a symbolic term representing the ideal symbolic execution of the tested noise protocol hand- shake (i.e., the “semantics” of the handshake). The semantic symbolic term is obtained by executing a symbolic imple- mentation of the noise protocol that we have developed.