YSM Issue 87.4

FEATURE
cryptography
Q
U A N T U M
C O M P U T I N G
An uncertain future for information security
BY JACOB MARKS
On September 10th, news broke that roughly five million Gmail
accounts had been hacked, and their passwords had been stolen .
This followed on the heels of a cyber attack against Community
Health System, Inc., in which personal data of more than four
million patients was compromised , and came soon after a credit card
theft that affected Home Depot locations all over the world, making
the home improvement store the largest retailer yet to succumb to
computerized security theft.
Every day, it seems,
governments and corporations
fall victim to data leaks caused by
anonymous online crusaders or
foreign terrorist organizations—
leaks which call into question the
efficacy of modern computer
security measures. But quantum
cryptography, the use of
quantum mechanical principles
to make and break codes,
could irrevocably alter the way
cyber crimes are committed
and defended against. If
recent advances in quantum
key distribution come to full
fruition, they could reconfigure
the cybercrime landscape,
and give renewed hope for
information security.
Deriving from the Greek
words kryptos, for ‘hidden’, and graphein, for ‘writing’, cryptography
is defined as the science of writing secret codes . For thousands
of years, the practice has been used to protect state secrets and to
transmit war strategies. The ancient Greeks wrote messages along
cloth wound around sticks of a specific diameter, and the Romans
developed the first substitution cipher, called the Caesar Shift, in
which each letter in a message was shifted forward a certain number
of places. Later ciphers, such as those produced by the Enigma
machines used by German forces in World War II, involved multiple
substitution schemes, or arrangements of the alphabet to encrypt
messages.
But the advent of the computer in the latter half of the twentieth
century spurred a cryptographic revolution couched in a new type of
security By allowing for the electronic transmission of large quantities
of data, the computer introduced the need to securely transmit
information at a distance. In the past, sender and receiver shared
special knowledge about how
the message was encrypted—
such as the diameter of
the stick. But computers
necessitated a cryptosystem
that could securely transmit
information between people
who did not share a previously
agreed upon key.
The solution, public-key
cryptography, makes use of a
one-way problem—something
that is easy to solve in one
direction, but hard to solve
in the other. RSA, one of the
IMAGE COURTESY OF WIKIPEDIA
D-wave: D-Wave Two, pictured above, is the world’s most complex
quantum computer. Created in 2013, D-Wave Two is comprised of 512
qubits, and performs an optimization algorithm orders of magnitude
faster than classical computers.
IMAGE COURTESY OF 33RD SQUARE
most widely-used public key
cryptosystems, is rooted in the
assumption that it is easy for a
computer to multiply two large
prime numbers, but much
harder for it to factor the result
into the two initial primes. However, public key systems like this rely
on the limited computing power of cryptanalysts, or code-breakers.
Although hard to solve, the problem of factorization is certainly
possible, and as computing power has increased, the key length
needed to ensure information security has increased as well. In 2009,
a 768 bit RSA key (an integer represented by a string of 768 0s and
1s), was successfully factored by Thorsten Kleinjung and colleagues
, and some people believe that the 1024 bit RSA keys now in use will
32 Yale Scientific Magazine October 2014 www.yalescientific.org