Multiple different credentials and/or signatures based on different credentials may be included in a header portion of a single electronic message. Different recipients of intermediary computing systems may use the different credentials/signatures to identify the signer. The electronic message may include an encoding algorithm and a type identification of a credential included in the electronic message, allowing the recipient to decode and process the credential as appropriate given the type of credential. Also, the electronic message may include a pointer that references a credential associated with a signature included in the electronic message. That referenced credential may be accessed from the same electronic message, or from some other location. The recipient may then compare the references credential from the credentials used to generate the signature. If a match occurs, the integrity of the electronic message has more likely been preserved.