A wireless transmit/receive unit (WTRU) and a Node B, respectively, perform joint randomness not shared by others (JRNSO) measurement to generate JRNSO bits based on a channel estimate between the WTRU and the Node B. The WTRU and the Node B then perform a reconciliation procedure to generate a common JRNSO bits. The Node B sends the common JRNSO bits to a serving network. The WTRU and the SN secure a session key (such as an integrity key, a cipher key and an anonymity key), using the common JRNSO bits. The JRNSO measurements are performed on an on-going basis, and the session key is updated using a new set of common JRNSO bits. The JRNSO bits may be expanded by using a pseudorandom number generator (PNG) or a windowing technique. A handover may be intentionally induced to increase the JRNSO bits generation rate.