I have two keys (K1 and K2) at both the client and the server. I hope to use HKDF in both client and server side to concatenate the keys. I will use the same salt value at both the client ad the server. Then will I be able to arrive at the same key by applying HKDF at both the client and the server to K1 and K2?
HKDF is deterministic, that is, given the same input; IKM (Input Keying Material), salt, and contextual info (these last two are optional, but recommended), and provided that the same underlying hash function is used (SHA256, for example), the output will always be the same.