A method and apparatus for secure direct link communication between multiple wireless transmit/receive units (WTRUs) are disclosed. The WTRUs may exchange nonces that are used for generating a common nonce. Group identification information may be generated from at least the common nonce and is forwarded to an authentication server. The authentication server may generate a master key from the group identification information to match WTRUs as part of a key agreement group. The common nonce may be a session key and be refreshed during communication with the second WTRU. A group key encryption key (GKEK) and a group key confirmation key (GKCK) may also be generated based on the common nonce and used to encrypt and sign the master key so that base stations do not have access to the master key. A first WTRU may generate a group direct link temporal key (GDLTK) for communicating with the second WTRU.
