IfAliceandBobeachknowtheirownprivatekeyandtheother'spublickey,theycancommunicatesecurely,throughanynumberofpublickeybasedprotocolssuchasIPSec,PGP,S/MIME,orSSL.However,howdotheyknoweachother'spublickeys?Thegoalofapublickeyinfrastructure(PKI)istoena