Quantum Computing and Cryptography Vishal Bilagi Kennesaw State University

Modern Day Cryptography Relies on mathematical formula to secure data Easy to create cryptographic keys, but hard to randomly guess because of the integer factorization problem Pretty good at keeping data encrypted since classical computers can take forever to guess the encryption keys What can crack such cryptographic keys easily? Quantum computers are very efficient at doing this task Kennesaw State University

Quantum Computing Impact on Modern Day Cryptography Poses a threat to asymmetric key cryptographic systems Proven theory exists that a quantum computer can factorize integers that form an encryption key In 2001, Shor’s algorithm factorized 15 = 5 x 3 and in 2012, 21 = 3 x 7 A quantum computer with sufficient qbits can actually crack RSA encryption one day. Quantum computing is not a serious threat to symmetric key cryptographic systems Grover’s algorithm offered a quadratic speed up to crack a 128-bit encryption key in 264 iterations. Since there is no basis on where to begin guessing the key, it is harder to crack symmetric encryption keys Doubling the key size should still keep the currently used symmetric key encryption pretty unbreakable Building and maintaining a Quantum computer is very expensive and there is really low chance in the given years that it poses a serious threat to cryptosystems Kennesaw State University

Post Quantum Cryptography In the coming decades, when quantum computing advancements reach new level, only then will it be a threat to existing cryptosystems In order to tackle such a case, a new way to securely store and transmit data needs to be employed A transmission medium that quantum computers can securely communicate in Such a paradigm shift is termed as Post Quantum Cryptography New algorithms that harness the power of quantum mechanics to secure data Communication medium that works well between quantum computers Kennesaw State University

Post Quantum Cryptography Approach Lattice-based Cryptography Multivariate cryptography Hash-based cryptography Code-based cryptography Supersingular elliptic curve isogeny cryptography Symmetric key quantum resistance Kennesaw State University

Quantum Key Distribution A new medium of communication needs to be established and agreed upon the quantum computers that are in it For this new network medium, keys need to be shared with the authorized parties on the network Transmitting quantum data across this medium and making some sort of handshake involves a protocol called Quantum Key Distribution (QKD) Keys are randomly generated and agreed between two parties that want to communicate with each other One major advantage of quantum key exchange is that it allows the parties to detect intruders in the system by analyzing any anomaly caused by eavesdropping – this is based on the ‘No Cloning Theorem’ Kennesaw State University

Quantum Cryptography Algorithm – BB84 In 1984, Charles Bennett and Gilles Brassard published a paper, outlining a protocol for sharing/generating random secret keys on a quantum communication network Keys are random because both the parties are unaware of what the key will be until they have a discussion after transmission and reception bits In this protocol each bit is encoded using photons. Specifically in two polarization bases – Rectilinear or Diagonal For rectilinear bases bit 0 is polarized as 0 degrees, bit 1 is polarized as 90 degrees For diagonal bases bit 0 is polarized as 45 degrees, bit 1 is polarized as 135 degrees 90, bit 1 45, bit 0 135, bit 1 0, bit 0 Kennesaw State University

BB84 – How It Works Kennesaw State University

Thank you Kennesaw State University