Patent ID: 8694774

Claim:
A method for authentication of a plurality of sites in a land mobile radio (LMR) system and for encryption of messages exchanged by the sites, the plurality of sites being connected by a data network, the method comprising: receiving, by one or more of the plurality of sites in the LMR system, a certificate transmitted by a first site, wherein the certificate is created by a trusted authority by encrypting at least a public key of the first site with the trusted authority's private key; decrypting, by the one or more of the plurality of sites, the certificate transmitted by the first site, wherein the certificate is decrypted using the trusted authority's public key; authenticating the first site; generating a shared session key that is valid across a group of sites in the LMR system; encrypting the shared session key with the public key of the first site; and transmitting the encrypted shared session key to the first site for decryption by the first site using the first site's private key, wherein the shared session key is used by the first site to encrypt a message for multicast transmission.