Page 71 - Cyber Warnings

Post-Quantum Information Security

By Hunter Bannister, East Carolina University

As long as there is sensitive data there is always going to be another person out there who
wants to have it which is why it is necessary to make that data readable only to the authorized
parties. This is accomplished by utilizing encryption which renders the information useless to
anyone without the capabilities to unencrypt the data. The origin of the word “encryption” is from
the Greek language derived from the word kryptos meaning hidden and use of encryption can
be dated back thousands of years. Around 1900 BC ancient Egyptians would utilize hieroglyphs
not normally seen to hide the meaning of a tablet.

Spartans, around 700 BC, would write messages onto a thin leather strip while it was wrapped
around a stick (imagine the leather strip being wrapped around a stick in a similar fashion to
stripes on a candy cane or barber pole). When the leather strip was received it would be
wrapped around a stick of the same diameter and the characters would line up side by side and
form the message. With humanity soon entering the quantum age the majority of our current
encryption methods will be obsolete. Forcing us to adapt to the computational strength of those
quantum computers and make strong methods of encryption for the post-quantum age.

The type of encryption we use today accomplishes the same goal as the methods used by the
Egyptians and Spartans but is more complicated. There are two major types - asymmetric and
symmetric encryption. Asymmetric encryption, or public-key encryption, utilizes private and
public keys to encrypt and decrypt data. The public key can be distributed to anyone and is
used to encrypt messages that can only be decrypted by the private key which is supposed to
be kept a secret and not given out to anyone. On the other hand, symmetric encryption uses the
same key for encryption and decryption. The two keys being the same it is relatively easy to
produce a strong key.

Quantum computing is not a new idea and has been tossed around quite frequently but many
people do not actually know how they work. It operates in a vaguely similar fashion to our
current computers that use zeros and ones as bits but instead of trying to avoid quantum
mechanics the computer is built upon them. The base of a quantum computer is a quantum bit,
qubit for short. They are physical particles such as a photon, nucleus, or electron.

Quantum gates take the place of transistors in quantum computers and these quantum gates
measure the spin of the qubit by looking at the magnetic field. The two states can either be spin
up or spin down comparable to the ones and zeros of current computers. Qubits are in a state
called quantum super position which means the qubit is simultaneously in spin up and spin
down.

Another theory is called quantum entanglement which states that the only thing we know about
two qubits that are paired together is that they are opposite of each other. When one qubit is
measured you know the state of its pair without measuring it. With multiple states, four

71 Cyber Warnings E-Magazine – June 2017 Edition
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