Encryption based security for ISDN communication: technique and application

The current evolution of the public integrated services digital network (ISDN) with its complete end to end digital connectivity provides an excellent platform for networking and reliable data communications. The primary objective of the present work is to develop and implement methodologies for successful data encryption schemes which can be embedded into the ISDN customer premises equipment (CPE) and require no software upgrades of the switching equipment. This will make the public ISDN network look like a private network to the security conscious user. Furthermore, secure data communication is provided over circuit switched voice or data channels. Widely used encryption and keying schemes based upon the data encryption standard (DES), secret key cryptography, and Rivest-Shamir-Adleman (RSA) public key cryptography algorithms are being investigated for their applicability in the ISDN environment. Initial investigations show that a HYBRID cryptographic approach, RSA for authentication, and DES for encryption, may be most appropriate. Efforts are underway to develop a hardware and software implementation for the HYBRID approach. In the paper, the authors discuss possible standards for ISDN security that will allow data (including voice) transmitted over the ISDN basic rate interface (BRI) line to be encrypted so that only the intended receiver can decipher it. The ideas presented can easily be transported to the packet switched channels, primary rate interface (PRI) and possibly to broadband ISDN (BISDN)