Disclosed embodiments include a method for synchronizing a cryptosystem.
In one embodiment, the method uses existing control data that is
transmitted as part of a connection establishment process in a wireless
communication system. In one embodiment, messages that are normally sent
between a base station and a remote unit during the setup of both
originating and terminating calls are parsed to detect a particular
control message that indicates the start of telephony data transmission.
Detection of this message indicates a point at which
encryption/decryption can begin, and is used to synchronize the
cryptosystem. Synchronizing a cryptosystem involves generating an RC4
state space in a keyed-autokey ("KEK") encryption system. In one
embodiment, Lower Medium Access Channel ("LMAC") messages are used
according to a wireless communication protocol. This is convenient
because the LMAC messages are passed through the same Associated Control
Channel ("ACC") processing that encrypts and decrypts the telephony data.