Abstract: A cryptographic apparatus comprises a linear feedback shift register for providing a pseudo-random code, coupled to a ciphering device, which is in turn coupled to an adder. The ciphering device encrypts the pseudo-random code. One adder circuit input is coupled to a ciphering device, and the other adder circuit input is coupled to the data input. The adder circuit adds data input signals to ciphering device signals to provide output signals. A method for operation of a ciphering engine is described comprising the steps of providing a random number and setting tap weights for a linear feedback shift register, obtaining a pseudo-random bit stream therefrom, and then encrypting the pseudo-random bit stream to generating a traffic key stream. The traffic key stream is added to a data stream to produce encrypted data from plain-text data or, alternatively, the traffic key stream is added to an encrypted data stream to produce plain-text data.