Pure signature check: verifies msg.signature covers JCS(msg without
signature) with the dacs-channelmsg:v1: prefix under the key encoded
in msg.sender. Membership (sender ∈ members) and sequence enforcement
are handled by ChannelSession — this function does crypto only.
Pure signature check: verifies
msg.signaturecovers JCS(msg without signature) with thedacs-channelmsg:v1:prefix under the key encoded inmsg.sender. Membership (sender ∈ members) and sequence enforcement are handled byChannelSession— this function does crypto only.