Method and apparatus for encrypting transmission traffic at separate protocol layers L1 (220), L2 (210), and L3 (200) so that separate encryption elements (204) can be assigned to separate types of transmission traffic (201, 203, 205), which allows the implementation of different levels of encryption according to service requirements. Encryption elements (204) use variable value inputs, called crypto-syncs, along with semi-permanent encryption keys to protect from replay attacks from rogue mobile stations. Since crypto-sync values vary, a method for synchronization and authentificated registration of crypto-syncs is also presented. Crypto-scancs can be built expediently for each different type of traffic frame by using different system resources. In one embodiment, a cyclic redundancy check (CRC) can be used to verify crypto-syncs.