Abstract: A communication apparatus performs encryption on data transmitted from another communication apparatus by using first or second cryptographic algorithm, or performs decryption on the data that has been encrypted using the first or second cryptographic algorithm, by using one of the first and second cryptographic algorithms used for the encryption, where the second cryptographic algorithm provides a higher security level than the first cryptographic algorithm. The communication apparatus includes an encryption unit configured to perform, upon receiving the data including a cryptographic class identifying a parameter to be used for performing the encryption or the decryption, the encryption or the decryption by using one of the first and second cryptographic algorithms, based on the cryptographic class.

Abstract: A communication apparatus performs encryption on data transmitted from another communication apparatus by using first or second cryptographic algorithm, or performs decryption on the data that has been encrypted using the first or second cryptographic algorithm, by using one of the first and second cryptographic algorithms used for the encryption, where the second cryptographic algorithm provides a higher security level than the first cryptographic algorithm. The communication apparatus includes an encryption unit configured to perform, upon receiving the data including a cryptographic class identifying a parameter to be used for performing the encryption or the decryption, the encryption or the decryption by using one of the first and second cryptographic algorithms, based on the cryptographic class.

Abstract: A communication apparatus performs encryption on data transmitted from another communication apparatus by using first or second cryptographic algorithm, or performs decryption on the data that has been encrypted using the first or second cryptographic algorithm, by using one of the first and second cryptographic algorithms used for the encryption, where the second cryptographic algorithm provides a higher security level than the first cryptographic algorithm. The communication apparatus includes an encryption unit configured to perform, upon receiving the data including a cryptographic class identifying a parameter to be used for performing the encryption or the decryption, the encryption or the decryption by using one of the first and second cryptographic algorithms, based on the cryptographic class.

Abstract: A ring trip deciding method in a ring trip circuit detects voltage change in the on-hook state and the on-hook state of a terminal when the terminal such as telephone set connected to the telephone line is called.

Abstract: A two-wire termination impedance generation circuit of a subscriber circuit including differential amplifiers, which is provided with a network circuit including capacitors and resistors, an input point, and current sources, the capacitor being comprised of series connected first and second capacitors, the resistor being comprised of series connected first and second resistors and having a high band bypass capacitor connected at the intermediate connecting point of the same, and the resistor being comprised of a complex termination resistor forming an internal termination impedance and a series connected complex termination resistor and complex termination capacitor being connected directly to the telephone line as an external termination impedance, wherein the frequency characteristics can be improved in three ways.

Abstract: A battery feed circuit supplies a feed current to a telephone set via a 2-wire telecommunication line formed of a TIP line and a RING line.

Abstract: A ring trip detection circuit detects an OFF-hooked state of a telephone receiver during ringing of a telephone set by detecting a change in a voltage across two terminals of a transmission resistor through which a ringing signal is supplied to the telephone set from a ringing signal source.