A method of identifying invalid participants in a synchronization group. The method generates a device synchronization group identifier (DSGI) for a first device from a device-specific key of the first device. The method joins the first device in the synchronization group by using the DSGI of the first device. Prior to the joining of the first device, the synchronization group stores a set of DSGIs of a set of devices that have joined the synchronization group. The method determines that a particular DSGI stored in the synchronization group is the same as the DSGI of the first device. The method identifies the particular DSGI stored in the synchronization group as a DSGI of an invalid participant of the synchronization group.