Abstract: An apparatus is provided for digital signal processing of telecommunication signals along respective transmit and receive paths of a two-way telecommunication link. The respective transmit and receive signals each include an audio data component and a timing component. Digital signal processing of at least one of the signals, such as an echo cancellation, employs information derived from the audio data component of the other signal. To compensate for differences between the respective timing components of the signals, resynchronization of each signal in terms of the timing component of the other signal is performed prior to modifying the audio data component of the other signal.

Abstract: Communications security between a host computer and another remote computer or terminal is ensured by a means of a two-tiered cryptographic communications security device and procedure. A master key is used to encrypt a first session key. The session key encrypted under the master key is transmitted from a remote facility to a host computer. At the host computer, the session key is decrypted and stored, a second and different session key is then generated, encrypted under the master key and transmitted to the remote facility where it is utilized as the facilities session decryptor key. Because the session key utilized for transmission of data between the remote facility and the host differs from the session key utilized for transmission of data between the host and the remote facility, communications security is increased.