Quantum Software Consortium

III - Cryptography in a Quantum World

In Research Theme III, the QSC will develop and analyze novel cryptographic protocols to achieve security against a fully quantum adversary.



To develop and analyze both classical and quantum cryptographic protocols to achieve security against a fully quantum adversary.   

Theme leader

Prof. dr. Ronald Cramer (Mathematics Institute, CWI)


Overview and Motivation

Cryptography is a key enabling technology for today’s digital world. If present-day cryptographic systems were to be broken, then we can no longer perform online banking, digital commerce, access control, secure communication, secure mobile devices, the internet of things, medical applications, and many more.


Challenge III.1: How can digital information be protected from quantum attackers using classical communication? Cryptographic systems that use classical communication are widely deployed and form the cornerstone of digital technologies, ranging from the internet to mobile phones. Typically such systems are rendered insecure once a quantum computer becomes available, for example RSA can be broken using Shor’s algorithm. RSA is widely deployed, and forging RSA signatures on operating-system updates would allow an attacker to gain control of billions of computers around the world.


Challenge III.2: How can we exploit the laws of physics to build cryptographic schemes? In contrast to classical information, quantum information has several inherent properties that can be exploited to achieve cryptographic security. One of these is the no-cloning principle, which says that the laws of physics prohibit the copying of qubits. Qubits can thus not be intercepted and copied without detection, which is a physical constraint on any form of attack. This is the cryptographic potential that enables QKD.



In order to address these challenges, we will lay out a solid theoretical foundation for the security of cryptographic schemes both in the conventional setting of cryptography based on classical communication, as well as for cryptography that exploits quantum communication.