In the new era of quantum computers, many daily life applications, such as home banking, are doomed to failure, and new forms of ensuring the confidentiality of our data are being study to overcome this threat. Researchers have taken a step further in this direction and propose a quantum blind signature scheme, a useful protocol for example in e-election, which ensures that signatures cannot be copied and that the sender must compromise to a single message. The security of the protocol also relies on perfect private quantum channels.
Digital signatures are mechanisms for authenticating the validity or authorship of a certain digital message, and they aim to be digital counterparts to real (or analog) signatures. The concept was introduced by Diffie and Hellman in 1976. Notice that, when certified, digital signatures have the same legal power as traditional signatures.
With the advent of quantum computation, new threats to security became a near-future reality, and all known digital signatures schemes are vulnerable, compromising fundamental properties of signature schemes: authenticity and authorship uniqueness. In order to overcome the potential threat of quantum computation, the community started to envisage the possibility of using quantum mechanics laws to develop new protocols that are resilient against quantum adversaries.
In the paper, “Quantum blind signature with an online repository,” the researchers show how to build such a digital blind signature scheme under the assumption that they have an offline repository and are using quantum information. A future work of this application would be the possibility of creating untraceable money, an ultimate goal of cryptography.
The research was partially supported, under the PQDR (Probabilistic, Quantum and Differential Reasoning) and Capri initiatives of SQIG at IT, CV-Quantum initiative of SQIG and Optical Communications and Photonics groups at IT, by FCT and EU FEDER, namely via the FCT PEst-OE/EEI/LA0008/2013 and UID/EEA/50008/ 2013 projects, as well as by the European Union’s Seventh Framework Programme for Research (FP7). Andre Souto also acknowledges the FCT postdoc grant SFRH/ BPD/76231/2011. Joao Ribeiro acknowledges the scholarship awarded by Fundacao Calouste Gulbenkian through the program Novos Talentos em Matematica for undergraduate students.
The paper can be found in http://www.worldscientific.com/doi/pdf/10.1142/S0219749915500161 in latest issue of the International Journal of Quantum Information (IJQI).