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Browse Prior Art Database

Data Security for Modems with Cellular Capability

IP.com Disclosure Number: IPCOM000116191D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Massman, LL: AUTHOR [+2]

Abstract

Disclosed is the implementation of an encryption method, in modems capable of transmitting and receiving data over a cellular telephone network.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 93% of the total text.

Data Security for Modems with Cellular Capability

      Disclosed is the implementation of an encryption method, in
modems capable of transmitting and receiving data over a cellular
telephone network.

      Encryption is especially useful in applications where
confidential data, such as passwords and charge account numbers, are
to be sent over a cellular network, on which the surreptitious,
unauthorized reception of information is much easier than on the
wired Public Switched Telephone Network (PSTN).

      The use of Hayes "AT" commands provides in-line operation in a
data mode and in a command mode, using a small amount of  modem
controller resources.  This method is easy to implement and change,
with both secure and non-secure data being transmitted in full
duplex.  The encryption process can be active only in the data phase,
avoiding interference with the command phase or the escape phase.

      Due to a wide range of protocols and data formats, a
programmable XOR mask function with the data and parity bits is
acceptable for scrambling the data.  When a message is received by a
modem not implementing the security feature, this method causes line
parity errors, invalid ASCII characters, and invalid escape protocol
commands.

      The table shows how, with this method, the level of security
for the &pname mode is enabled using the IBM Security Enable Command
(AT_ESn) and disabled using the IBM Security Disable Command
(AT_DSn).  The receive an...