The Sign method provides a way to sign a given Aleph message using a Cosmos account. The full message is not used as the payload, only fields of the BaseMessage type are.
The signMessage method uses the amino SignDoc helpers to generate the signature
The Aleph message to sign, using some of its fields.
CosmosAccount implements the Account class for the Cosmos protocol. It is used to represent a Cosmos account when publishing a message on the Aleph network.