Whenpartiesshareasecretsymmetrickey(e.g.,uponasuccessfulexecutionofakey-establishmentschemeasspecifiedin[1]and[2]),itisoftenthecasethatadditionalkeyswillbeneeded(e.g.asdescribedin[3]).Separatekeysmaybeneededfordifferentcryptographicpurposes–forexampl