A system, method, and computer program product are provided for end-to-end security of centrally accessible group membership information. In use, membership information defining a user group in a messaging system is accessed from a central server, where the membership information includes (1) at least one change to members of the user group, and (2) for each change of the at least one change, a digital signature of a user that made the change. Additionally, a verification process on the membership information is performed, including: for each change of the at least one change, verifying the digital signature of the user that made the change. Further, members of the user group are determined, as a result of the verification process, and at least one action is performed in association with the members of the user group.