FOR IMMEDIATE RELEASE:

Concerned Telecom and Network Security Specialists Respond to Claims of
GSM Cellular Phone Cloning

New York, Monday, April 13, 1998 -- Crossbar Security, Inc., a Telecom
and Network security consultancy, has reviewed the technical findings of
the Smartcard Developer Association (SDA) concerning their ability to
clone GSM cellular phones. Crossbar Security is offering solutions for
GSM providers and equipment manufacturers. Having examined the details
of the SDA's attack on the GSM standard for subscriber authentication,
Mark Abene, President of Crossbar Security says, "Although we have found
their discovery to be wholly factual, reproducible, and technically
sound there is no immediate threat of GSM phones being monitored or
cloned over the air.  Phones can only be cloned by physically obtaining
a subscribers SIM card."

GSM, the Global System for Mobile communications, is a standard for
digital cellphones, used by over 200 cellphone carriers in over 100
countries around the world, including the United States. Among the GSM
standards are the specifics of two cryptographic algorithms. One is used
to authenticate subscribers to their GSM carrier, to ensure that the
subscriber is a valid, paying customer. The other algorithm is used to
protect the subscriber's conversation from passive eavesdroppers, a large
privacy problem with older cellular phone networks. The details of these
algorithms are closely guarded by the GSM Memorandum of Understanding
(MoU), a European organization from which this technology must be licensed
by GSM carriers and equipment manufacturers.

"In the academic community, it is widely held that cryptographic
algorithms should be readily available and put under public scrutiny to
prove their strength. This has been the de facto process for algorithms
used by banks for electronic funds transfer, as well as electronic
commerce on the Internet. The secrecy around GSM's algorithms may have
been their undoing," says David Buchwald, Vice President, of Crossbar
Security. "The United States is a relative newcomer to GSM technology,
and although our domestic GSM carriers are members of the MoU, they
were not involved in its creation, nor in the creation or review of the
algorithms meant to ensure privacy and prevent fraud", adds Abene.

Using readily available hardware and software tools along with the help of
skilled mathematicians, the SDA was able to extract the unique secret key
that identifies a GSM subscriber. This secret key is stored on seemingly
tamper-proof smart cards called "SIMs" (Subscriber Identity Modules)
-- small computer chips mounted on credit-card-like plastic for easy
transportability by their owners, the GSM subscribers.

Until these flaws in GSM security are fully addressed, GSM subscribers
can still protect themselves from fraud. "GSM cloning depends on
physical access to a  SIM card," says Buchwald, adding, "We caution
subscribers against lending their SIM cards to anyone for any reason,
and strongly recommend that they report lost or stolen phones to their
carriers immediately. Even if a lost or stolen phone later turns up, the
possibility exists that the phone's SIM card could have been compromised.
"Eavesdropping or other over-the-air network snooping still presents
major obstacles for potential fraudsters, as they currently would require
rather expensive equipment."

Crossbar Security, Inc., has worked with GSM carriers in the past on
issues of security, and welcomes the opportunity to work with carriers,
equipment manufacturers and the MoU to resolve the problems the industry
is currently facing.

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Contact:
Crossbar Security, Inc.
Phone: 212-969-0573
E-mail: crossbar@crossbar.com
Or visit our website at www.crossbar.com