vulcan-cryptanalysis

known how vulnerable this cipher actually was. We strongly suspect that many
other proprietary ciphers are similarly weak and we warn against their use.
Third, we wish to assist budding cryptographers and reverse-engineers in
learning the basic skills. Vulcan, being both simple and weak, offers an excellent
learning opportunity for a beginning cryptographer. We believe that breaking
a Vulcan-encrypted message would be a suitable homework assignment for
students enrolled in an undergraduate cryptography course. Other suitable assignments
might include investigating ways of making simple changes to Vulcan
in order to improve its cryptographic strength.
Fourth, we undertook this effort for sheer enjoyment. This project required
us to learn many new skills and overcome many technical difficulties. Nothing
beats the satisfaction gained from solving a giant puzzle. Nothing more
thoroughly whets the appetite for knowledge than a secret.
We imagine that Motorola would prefer that this paper did not exist, and
we would not be surprised if they seek to remove it from the public eye, presumably
under the feeble justification that our work threatens the security of
their customers. No doubt the real reason they might object to our work is to
avoid embarrassment resulting from the disclosure that DVP is far from secure.
In spite of these imagined protests, we are completely confident that no harm
will come to any end users for the simple reason that Vulcan and DVP are long
obsolete and have not been used to protect sensitive communications in decades.
For these same reasons, we are equally confident that no harm will be done to
any active NSA signal intelligence efforts. Furthermore, we are confident that
we have broken no laws in the course of our work, and we believe that this paper
is both legally and technically legitimate.
We want to make it perfectly clear that we do not wish to disparage Motorola
with our comment that Vulcan is weak; quite the contrary, in its era DVP
was revolutionary. We commend Motorola for developing the first digitally
encrypted two-way radio available to non-military customers at a time when
simple analog frequency inversion scrambling was considered “high tech”.
Furthermore, we wish to allay any concerns that our revelations will in any
way harm Motorola’s intellectual property. Had this paper been published in
1976, such a concern would have been legitimate, but in 2014 the technology
underlying Vulcan and DVP is not only long obsolete, but absolutely archaic.
None of Motorola’s competitors have anything to gain, or even learn, from our
disclosures.
1.5 Technique
We were surprised at how easy it was for us to learn the details of Vulcan.
Although the Vulcan cipher is implemented in a custom CMOS integrated circuit,
techniques for reverse-engineering ICs are well known. We do not know
why the myth still persists that reverse-engineering hardware is more difficult
than reverse-engineering software. We caution that secrets cannot be hidden in
silicon or software; only a fool believes otherwise.
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