Executes the next phase of this key agreement with the given key that was received from one of the other parties involved in this key agreement.
|the key for this phase. For example, in the case of Diffie-Hellman between 2 parties, this would be the other party's Diffie-Hellman public key.|
|flag which indicates whether or not this is the last phase of this key agreement.|
|if the given key is inappropriate for this phase.|
|if this key agreement has not been initialized.|