Techniques are provided for determining an updated session encryption key. According to one embodiment, a packet index can be computed using a sequence number received in a session data packet during a SRTP session and a predetermined value. The predetermined value can be, for example, a non-zero value from a roll-over-counter that has been set to the non-zero value. The updated session encryption key can then be determined using a master key received from a BCMCS controller and the packet index. The determined updated session key is used to encrypt or de-encrypt content provided by a content server.