As message authentication needs to be resistant to malicious insiders, following the outline of [GUVGC09], ''(n)sec'' signs each message using a public key signature scheme. The messages are signed with the ephemeral key of the sender. The authenticity of the origin can be verified by the public ephemeral key of the party distributed during the key exchange period.
== '''VII.5 4 Transcript Ordering and Consistency''' ==
Because Since each message sent by each any one participant is signed by the ephemeral private key generated for the that specific session, it is not possible for the internal or external adversary to forge a message on behalf of an uncorrupted participant.
However, if the adversary is controlling the network structure, denial or delay of service is always possible. Hence, the The consistency of the transcript (meaning that i.e. all participants see the same transcript in the same order) relies on the means of transport guaranteeing reliable delivery, with a single order, to every participant. Another way of viewing this is that In other words, we are verifying the ''recipients'' of a message.
The protocol offered in this document examines the transcript for such consistency. In the case that the underlying transport fails to provide this level of consistency, clearly the consistency test will fail. In this sense, failure of consistency does not distinguish between malicious activities or the absence of a reliable transport.