IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Communications Remarks
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that the e-mail functionality offered on mobile phones is severely restricted
compared with other e-mail applications. Like SMS, e-mail should be viewed
here as primarily a means of transmitting short messages with a short life. It is
not possible to implement security measures such as encryption or digital
signatures (unless additional modules or special devices are used).
The boundaries between the various types of message such as SMS, fax and email
are relatively fluid. What distinguishes them as far as the user is
concerned is generally not the type of data input but the transmission format.
Here the network provider may also offer other formats such as X.400 or
paging.
Data transmission
If the mobile phone is linked to another IT system (e.g. a notebook or
organiser), it is also possible to transmit larger quantities of data. Coupling of
the devices may be effected in a number of ways, depending on the
technologies supported by the two devices.
Plug-in card. A plug-in card (PC card or PCMCIA) is the conventional
solution for connecting mobile phone and notebook. However, most plugin
cards can only be connected to mobile phones of a particular
manufacturer.
Soft modem. Under this solution, special software is installed on the
notebook instead of a plug-in card. The mobile phone is then simply
connected to the notebook over the serial interface. This solution is cheaper
than a plug-in card.
Infra-red. With an infra-red interface, data can be transmitted from the
mobile phone to an IT system (e.g. a laptop or organiser) without any
cables. This requires that both the mobile phone and also the IT system
support Infrared Data Association (IrDA). IrDA is a world-wide standard
for data transmission by infra-red.
Bluetooth. Bluetooth is a more recent standard which enables devices to
exchange data with each other over short distances by radio. The Bluetooth
technology uses the freely available Industrial Scientific Medical (ISM)
radio network, which operates in the 2.45 GHz band.
Where data is to be transmitted e.g. from a laptop over GSM, it should be
encrypted on the terminal device prior to transmission. A number of programs
are available for achieving this relatively simply. Encryption of the
information prior to transmission protects it over the entire route between
originator and recipient. This goes beyond protection of the radio interface
between mobile phone and base station, as is standard with GSM. Moreover,
the messages can then also be digitally signed. Section 3.7 Crypto concept
describes how to select cryptographic procedures and systems that are
suitable.
There are a number of sites on the Internet from where additional ring tones,
display icons or similar can be downloaded for the various mobile phones. It
should, however, be noted that loading such data can sometimes render a
mobile phone inoperable.
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IT-Baseline Protection Manual: Oktober 2000
Encrypt data
transmissions
Downloading data