In a distributed computing architecture, a method and system for authenticating a message as originating from an unaltered or unmodified node is provided. Prior to sending a messages, a black box software module in a node validates the node to determine whether the node has been altered or modified without authorization. Once validated, the black box alters a message, using a black box protection scheme, in such a manner that the message can be subsequently authenticated. The black box module sends the altered message to a peer node, whose own black box authenticates the message using an authentication scheme corresponding to the protection scheme. Because validation is performed, each node may assume that the message originated from an unaltered node. The protection and/or validation scheme can be changed in regular intervals so that attackers do not have time to reverse engineer the black box. Alternatively, validation may be skipped and the key used to alter/protect each message may be based on the environment of the node performing the alteration/protection, so that nodes that have been altered will generate different keys than unaltered nodes, and will not be able to communicate.