Practical quantum digital signatures
Lead Research Organisation:
Heriot-Watt University
Department Name: Sch of Engineering and Physical Science
Abstract
Digital signature schemes enable a message to be securely signed, so that one or more recipients can be sure of its authenticity. R. Rivest, one of the inventors of the widely used RSA algorithm for public key cryptography, wrote in 1990 that "The notion of a digital signature may prove to be one of the most fundamental and useful inventions of modern cryptography". Indeed, digital signature schemes are today used extensively e.g. in internet commerce, and are of immense economic importance. Unfortunately all known classical digital signature schemes rely on unproven computational assumptions for their security. Quantum digital signature schemes, on the other hand, can be made unconditionally secure based only on the validity of quantum mechanics, similar to how the security of quantum key distribution is guaranteed. Distribution of a secret cryptographic key ensures the privacy of an encrypted message. Authentication and digital signature schemes, on the other hand, ensure the integrity of a message. This is different but no less important. Key distribution for cryptography also requires some kind of separate authentication scheme in order to work, since otherwise one cannot know that one is talking to the right person (a so-called "man-in-the-middle attack" becomes possible).
Quantum key distribution is one of the very few applications of quantum technology that are already commercially available. In contrast to quantum key distribution, however, no experimentally feasible scheme for quantum digital signatures has been proposed, until now. Existing schemes for quantum digital signatures use non-orthogonal quantum states distributed as "quantum signatures". For a classical physical system, there is in principle no limit to how well we can determine its position, velocity, colour, and so on, only practical limitations depending on how good our measurement equipment is. In contrast, quantum states cannot even in principle be perfectly determined or distinguished from each other, no matter how technically perfect our equipment is. Only the distributing party has perfect knowledge of the quantum signatures, allowing only her to later sign messages by giving the full classical description of the states, which can then be tested against the signature states. The recipients must store the signature states in quantum memory until the distributing party wants to sign a message. This requirement for long-term quantum memory unfortunately makes existing protocols completely unfeasible in practice. Quantum states are very fragile and rapidly deteriorate, usually on a scale of milliseconds or faster.
I propose a setting where the recipients measure the quantum signature states immediately after distribution. The quantum measurement they should use sometimes identifies the state perfectly, but sometimes fails. Integrity of a signed message is now guaranteed since no adverse party (including other recipients) can provide the correct description of the signature states for all the cases where identification succeeded. Only the distributing party can do this. Transferrability of messages can be guaranteed if the recipients "compare" the signature states they receive. Comparing quantum states is not as straightforward as comparing classical systems, but is feasible. This project will address the important task of investigating the information-theoretic security of such digital signature schemes which crucially do not require quantum memory, and identify the best scheme(s) in terms of scaling of key length versus level of security, and experimental feasibility of measurements and other components required. In addition to this theoretical work, a proof-of-principle experimental implementation will then be made.
The ultimate technological, societal and economical impact of this work is potentially very large, due to the importance and wide use of digital signature schemes.
Quantum key distribution is one of the very few applications of quantum technology that are already commercially available. In contrast to quantum key distribution, however, no experimentally feasible scheme for quantum digital signatures has been proposed, until now. Existing schemes for quantum digital signatures use non-orthogonal quantum states distributed as "quantum signatures". For a classical physical system, there is in principle no limit to how well we can determine its position, velocity, colour, and so on, only practical limitations depending on how good our measurement equipment is. In contrast, quantum states cannot even in principle be perfectly determined or distinguished from each other, no matter how technically perfect our equipment is. Only the distributing party has perfect knowledge of the quantum signatures, allowing only her to later sign messages by giving the full classical description of the states, which can then be tested against the signature states. The recipients must store the signature states in quantum memory until the distributing party wants to sign a message. This requirement for long-term quantum memory unfortunately makes existing protocols completely unfeasible in practice. Quantum states are very fragile and rapidly deteriorate, usually on a scale of milliseconds or faster.
I propose a setting where the recipients measure the quantum signature states immediately after distribution. The quantum measurement they should use sometimes identifies the state perfectly, but sometimes fails. Integrity of a signed message is now guaranteed since no adverse party (including other recipients) can provide the correct description of the signature states for all the cases where identification succeeded. Only the distributing party can do this. Transferrability of messages can be guaranteed if the recipients "compare" the signature states they receive. Comparing quantum states is not as straightforward as comparing classical systems, but is feasible. This project will address the important task of investigating the information-theoretic security of such digital signature schemes which crucially do not require quantum memory, and identify the best scheme(s) in terms of scaling of key length versus level of security, and experimental feasibility of measurements and other components required. In addition to this theoretical work, a proof-of-principle experimental implementation will then be made.
The ultimate technological, societal and economical impact of this work is potentially very large, due to the importance and wide use of digital signature schemes.
Planned Impact
Understanding how to manipulate quantum systems is of tremendous technological importance and may lead to huge economic payoffs. The investment in basic research by companies such as IBM, Lucent technologies (Bell Labs), Microsoft research, Hitachi, Fujitsu, and Toshiba is testament to the potential impact of quantum technologies. The proposed research contributes to this challenge. Quantum communication is an emerging technology which could provide security and authentication protocols for the digital economy. Quantum cryptography is already commercially available, and the proposed work paves the way for bringing quantum digital signatures to a similar level.
There is also a shortage of STEM skilled employees in the UK, and it appears that young people are being put off science before they enter higher education. Enthusing the public about STEM subjects is one way to counter this. It is also essential that the public knows about relevant research results in order to make informed decisions about important issues. Especially levels of female students are low in STEM subjects, and the 'leaky pipeline' is of great concern, i.e. the fact that a higher proportion of women than men abandon a career in STEM subjects even after obtaining an undergraduate or postgraduate degree, or further along. This represents a great loss to the UK economy. The proportion of female students continuing with a PhD in Physics is actually higher than for male students, which indicates that the issue most likely is not lack of motivation among female students and researchers. The proposed research has great potential to enthuse the general public, and the applicant and her team have a strong track record in outreach activities. The applicant has also led the Athena Swan effort for Physics at Heriot-Watt (www.athenaswan.org). The Athena Swan Charter is committed to the advancement of the careers of women in science, engineering and technology.
There is also a shortage of STEM skilled employees in the UK, and it appears that young people are being put off science before they enter higher education. Enthusing the public about STEM subjects is one way to counter this. It is also essential that the public knows about relevant research results in order to make informed decisions about important issues. Especially levels of female students are low in STEM subjects, and the 'leaky pipeline' is of great concern, i.e. the fact that a higher proportion of women than men abandon a career in STEM subjects even after obtaining an undergraduate or postgraduate degree, or further along. This represents a great loss to the UK economy. The proportion of female students continuing with a PhD in Physics is actually higher than for male students, which indicates that the issue most likely is not lack of motivation among female students and researchers. The proposed research has great potential to enthuse the general public, and the applicant and her team have a strong track record in outreach activities. The applicant has also led the Athena Swan effort for Physics at Heriot-Watt (www.athenaswan.org). The Athena Swan Charter is committed to the advancement of the careers of women in science, engineering and technology.
Organisations
- Heriot-Watt University (Lead Research Organisation)
- NICT National Institute of Information and Communications Technology (Collaboration)
- University of St Andrews (Collaboration)
- University of Padova (Collaboration)
- Heinrich Heine University Düsseldorf (Collaboration)
- Toshiba Research Europe Ltd (Collaboration)
- UNIVERSITY OF CAMBRIDGE (Collaboration)
- National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS) (Collaboration)
- University of Waterloo (Collaboration)
- Max Planck Society (Collaboration)
- University of Geneva (Collaboration)
- University of Vigo (Collaboration)
- ID Quantique (Collaboration)
- UNIVERSITY OF LEEDS (Collaboration)
People |
ORCID iD |
Erika Andersson (Principal Investigator) | |
Robert Collins (Researcher) |
Publications
Amiri R
(2015)
Secure Quantum Signatures Using Insecure Quantum Channels
Amiri R
(2021)
Imperfect 1-Out-of-2 Quantum Oblivious Transfer: Bounds, a Protocol, and its Experimental Implementation
in PRX Quantum
Amiri R
(2015)
Unconditionally Secure Quantum Signatures
in Entropy
Amiri R
(2016)
Secure quantum signatures using insecure quantum channels
in Physical Review A
Amiri R
(2015)
Unconditionally Secure Quantum Signatures
Buller G
(2018)
Progress in experimental quantum digital signatures
Collins R
(2013)
Photonic Quantum Digital Signatures: An Experimental Test-Bed
Collins RJ
(2017)
Experimental demonstration of quantum digital signatures over 43 dB channel loss using differential phase shift quantum key distribution.
in Scientific reports
Collins RJ
(2014)
Realization of quantum digital signatures without the requirement of quantum memory.
in Physical review letters
Croal C
(2016)
Free-Space Quantum Signatures Using Heterodyne Measurements.
in Physical review letters
Donaldson R
(2016)
Experimental demonstration of kilometer-range quantum digital signatures
in Physical Review A
Donaldson R
(2013)
An approach to experimental photonic quantum digital signatures in fiber
Donaldson R
(2015)
Experimental demonstration of kilometer-range quantum digital signatures
Dowker F
(2013)
A histories perspective on characterising quantum non-locality
Dowker F
(2014)
A histories perspective on characterizing quantum non-locality
in New Journal of Physics
Dunjko V
(2013)
Quantum Digital Signatures without quantum memory
Dunjko V
(2014)
Quantum digital signatures without quantum memory.
in Physical review letters
Puthoor I
(2016)
Measurement-device-independent quantum digital signatures
in Physical Review A
Roberts GL
(2017)
Experimental measurement-device-independent quantum digital signatures.
in Nature communications
Wallden P
(2013)
Minimum-cost quantum measurements for quantum information
Description | We have developed schemes for digital signatures, for which the security is guaranteed by the laws of quantum mechanics. We have theoretically investigated the security of such schemes, and built experimental prototypes to demonstrate viability in principle. The methods we have developed can in fact be implemented with the same experimental equipment as quantum key distribution, which is already commercially available, thus extending the usefulness of setups for quantum key distribution to provide also the functionality of digital signatures. Digital signatures are widely used in electronic communications and commerce, and enable the sending of signed messages such that the messages cannot be tampered with, and so that the messages are transferrable. This is different from encryption of a message, but no less important. All key findings are available open access. Some journal papers are gold open access, and for all papers, an equivalent version is available on www.arXiv.org and/or on the Heriot-Watt PURE web site. |
Exploitation Route | Further work is required e.g. on the security of quantum digital signatures, on finding the best quantum digital signature protocols, and how to best implement them. We are taking first steps to commercialise our most efficient signature protocol (filed a patent Feb 2016, patent published 2017), in collaboration with Swedish company IT Secured. |
Sectors | Aerospace Defence and Marine Digital/Communication/Information Technologies (including Software) Financial Services and Management Consultancy Healthcare Government Democracy and Justice Security and Diplomacy |
Description | We have had interest from commercial providers of quantum key distribution (Toshiba Research, Cambridge and IdQuantique, Geneva) to implement our protocol. Toshiba research have implemented some of our protocols, but commercial application is however some time away still. There is also emerging interest from other researchers, mainly from the quantum cryptography research community and from computer scientists, to work on quantum digital signatures. Outside the scientific community there is however still, at this time, limited impact. Our work on quantum signatures is continuing as WP4 of the UK Quantum Technology Hub on Quantum Communication, and it is a little hard to say whether outcomes in the transition period between grants should be associated to one or the other grant, or both. In Feb 2016 we filed a patent for an efficient signature protocol, and the patent was published in 2017. Ryan Amiri, who started his PhD studies in September 2014, supervised by Erika Andersson, was awarded one of only 5 places in the Nature/Entrepreneur First Innovation Forum in Quantum Technologies, to work on an efficient signature protocol that can use quantum key distribution technology. |
First Year Of Impact | 2016 |
Description | Blackett Review on Quantum Technologies |
Geographic Reach | National |
Policy Influence Type | Contribution to a national consultation/review |
URL | https://www.gov.uk/government/publications/quantum-technologies-blackett-review |
Description | MSCA-ITN-2015-ETN - Marie Sklodowska-Curie Innovative Training Networks (ITN-ETN) |
Amount | € 3,924,884 (EUR) |
Funding ID | QCALL 675662 |
Organisation | European Commission |
Sector | Public |
Country | European Union (EU) |
Start | 12/2016 |
End | 11/2020 |
Description | UK Quantum Technology Hubs |
Amount | £24,093,966 (GBP) |
Funding ID | EP/M013472/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 12/2014 |
End | 11/2020 |
Description | MPL, Erlangen |
Organisation | Max Planck Society |
Department | Max Planck Institute for the Science of Light |
Country | Germany |
Sector | Academic/University |
PI Contribution | Collaboration on extending and realising quantum signature protocols. Experimental realisation of a protocol using homodyne measurements has been carried out at MPL, with theoretical support from the groups at Heriot-Watt and St Andrews. |
Collaborator Contribution | Collaboration on extending and realising quantum signature protocols. Experimental realisation of a protocol using homodyne measurements has been carried out at MPL, with theoretical support from the groups at Heriot-Watt and St Andrews. |
Impact | Results are reported in Croal et al., Physical Review Letters 117, 100503 (2016). |
Start Year | 2015 |
Description | NICT |
Organisation | NICT National Institute of Information and Communications Technology |
Country | Japan |
Sector | Academic/University |
PI Contribution | NICT and Heriot-Watt both have long-standing research interests in quantum communication technology. Although this collaboration started before EP/K022717/1 ended, it is associated with this grant, as it arose through our work in this grant. We are continuing our work on quantum signatures, within this collaboration in the form of several research visits and a staff exchange in January 2016 (R Collins and R Amiri, both from Heriot-Watt, visited NICT to work on quantum signatures). On 14-19 March 2016, Gerald Buller and Erika Andersson visited Tokyo, funded by the Government Department for Business, Innovation and Skills (BIS) for a Quantum Technology Workshop and to discuss a possible research agreement between UK and Japan, on Quantum Communication. |
Collaborator Contribution | NICT have acted as hosts, providing accommodation for UK visiting researchers at no cost to the UK team members. |
Impact | A formal MoU on research collaboration has been put in place between NICT and Heriot-Watt. |
Start Year | 2015 |
Description | QCALL partnership |
Organisation | Heinrich Heine University Düsseldorf |
Country | Germany |
Sector | Academic/University |
PI Contribution | Based on our work on quantum signatures, we were invited to be an associated partner in the EU project QCALL (EU project 675662), which is an ITN (Innovative Training Network) funded by the Marie Sklodowska Curie Call H2020-MSCA-ITN-2015. This project runs 1 Dec 2016-30 Nov 2020. |
Collaborator Contribution | We have agreed to host visits by PhD students funded by the ITN. |
Impact | None yet (grant started Dec 2016). |
Start Year | 2016 |
Description | QCALL partnership |
Organisation | ID Quantique |
Country | Switzerland |
Sector | Private |
PI Contribution | Based on our work on quantum signatures, we were invited to be an associated partner in the EU project QCALL (EU project 675662), which is an ITN (Innovative Training Network) funded by the Marie Sklodowska Curie Call H2020-MSCA-ITN-2015. This project runs 1 Dec 2016-30 Nov 2020. |
Collaborator Contribution | We have agreed to host visits by PhD students funded by the ITN. |
Impact | None yet (grant started Dec 2016). |
Start Year | 2016 |
Description | QCALL partnership |
Organisation | National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS) |
Country | France |
Sector | Academic/University |
PI Contribution | Based on our work on quantum signatures, we were invited to be an associated partner in the EU project QCALL (EU project 675662), which is an ITN (Innovative Training Network) funded by the Marie Sklodowska Curie Call H2020-MSCA-ITN-2015. This project runs 1 Dec 2016-30 Nov 2020. |
Collaborator Contribution | We have agreed to host visits by PhD students funded by the ITN. |
Impact | None yet (grant started Dec 2016). |
Start Year | 2016 |
Description | QCALL partnership |
Organisation | Toshiba Research Europe Ltd |
Country | United Kingdom |
Sector | Private |
PI Contribution | Based on our work on quantum signatures, we were invited to be an associated partner in the EU project QCALL (EU project 675662), which is an ITN (Innovative Training Network) funded by the Marie Sklodowska Curie Call H2020-MSCA-ITN-2015. This project runs 1 Dec 2016-30 Nov 2020. |
Collaborator Contribution | We have agreed to host visits by PhD students funded by the ITN. |
Impact | None yet (grant started Dec 2016). |
Start Year | 2016 |
Description | QCALL partnership |
Organisation | University of Geneva |
Department | Department of Physics |
Country | Switzerland |
Sector | Academic/University |
PI Contribution | Based on our work on quantum signatures, we were invited to be an associated partner in the EU project QCALL (EU project 675662), which is an ITN (Innovative Training Network) funded by the Marie Sklodowska Curie Call H2020-MSCA-ITN-2015. This project runs 1 Dec 2016-30 Nov 2020. |
Collaborator Contribution | We have agreed to host visits by PhD students funded by the ITN. |
Impact | None yet (grant started Dec 2016). |
Start Year | 2016 |
Description | QCALL partnership |
Organisation | University of Leeds |
Department | School of Electronic and Electrical Engineering Leeds |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Based on our work on quantum signatures, we were invited to be an associated partner in the EU project QCALL (EU project 675662), which is an ITN (Innovative Training Network) funded by the Marie Sklodowska Curie Call H2020-MSCA-ITN-2015. This project runs 1 Dec 2016-30 Nov 2020. |
Collaborator Contribution | We have agreed to host visits by PhD students funded by the ITN. |
Impact | None yet (grant started Dec 2016). |
Start Year | 2016 |
Description | QCALL partnership |
Organisation | University of Padova |
Department | Department of Information Engineering |
Country | Italy |
Sector | Academic/University |
PI Contribution | Based on our work on quantum signatures, we were invited to be an associated partner in the EU project QCALL (EU project 675662), which is an ITN (Innovative Training Network) funded by the Marie Sklodowska Curie Call H2020-MSCA-ITN-2015. This project runs 1 Dec 2016-30 Nov 2020. |
Collaborator Contribution | We have agreed to host visits by PhD students funded by the ITN. |
Impact | None yet (grant started Dec 2016). |
Start Year | 2016 |
Description | QCALL partnership |
Organisation | University of Vigo |
Department | School of Telecommunications Engineering |
Country | Spain |
Sector | Academic/University |
PI Contribution | Based on our work on quantum signatures, we were invited to be an associated partner in the EU project QCALL (EU project 675662), which is an ITN (Innovative Training Network) funded by the Marie Sklodowska Curie Call H2020-MSCA-ITN-2015. This project runs 1 Dec 2016-30 Nov 2020. |
Collaborator Contribution | We have agreed to host visits by PhD students funded by the ITN. |
Impact | None yet (grant started Dec 2016). |
Start Year | 2016 |
Description | St Andrews University |
Organisation | University of St Andrews |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Collaboration on quantum signatures, realising and extending previous work. |
Collaborator Contribution | Collaboration on quantum signatures, realising and extending previous work. Realisation at Max Planck Institute of Light, Erlangen, Germany. |
Impact | Results are reported in Croal et al., Physical Review Letter 117, 100503 (2016). |
Start Year | 2015 |
Description | Toshiba Research |
Organisation | Toshiba Research Europe Ltd |
Department | Cambridge Research Laboratory - Toshiba |
Country | United Kingdom |
Sector | Private |
PI Contribution | Based on the work in EP/K022717/1, Dr Erika Andersson, Dr Robert Collins and Prof Gerald Buller visited Toshiba Research in Cambridge on 17 October 2014. Toshiba Research, are developing equipment for quantum key distribution. We have continued to develop quantum communication protocols to be implemented by Toshiba Research (currently as part of the UK Quantum Technology Hub on Quantum Communication). |
Collaborator Contribution | Toshiba Research, who are developing equipment for quantum key distribution, will implement the procedures for quantum digital signatures we have developed using their experimental setups. |
Impact | Visit to Toshiba Cambridge as mentioned above, and informal agreement to collaborate. A paper on an implementation by Toshiba of a scheme for measurement-device-independent signatures developed by our team has recently been submitted. This is funded by further collaboration through the UK Quantum Technology Hub on Quantum Communication. |
Start Year | 2014 |
Description | University of Cambridge |
Organisation | University of Cambridge |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Collaborative research on novel protocols for quantum digital signatures, with Adrian Kent from University of Cambridge. In particular, we have jointly proved that certain protocols are secure against general forging attacks, where recipients can use quantum entanglement. |
Collaborator Contribution | Collaborative research on novel protocols for quantum digital signatures, with Adrian Kent from University of Cambridge. In particular, we have jointly proved that certain protocols are secure against general forging attacks, where recipients can use quantum entanglement. |
Impact | Joint publications wit A Kent as reported under publications. |
Start Year | 2014 |
Description | University of Waterloo |
Organisation | University of Waterloo |
Country | Canada |
Sector | Academic/University |
PI Contribution | Staff time; Dr Erika Andersson and Dr Petros Wallden visited University of Waterloo in August 2014 to initiate a collaboration with the group of Prof Norbert Luetkenhaus. |
Collaborator Contribution | Staff time for Prof Norbert Luetkenhaus and Mr Juan Miguel Arrazola (PhD student at IQC, Waterloo). |
Impact | Dr Erika Andersson and Dr Petros Wallden visited University of Waterloo in August 2014 to initiate collaboration with the group of Prof Norbert Luetkenhaus. Joint publications with Juan Miguel Arrazola, who obtained his PhD with Prof Luetkenhaus as supervisor, are reported in the publications section. |
Start Year | 2014 |
Title | METHOD AND SYSTEM FOR ASSURANCE OF MESSAGE INTEGRITY |
Description | The present disclosure relates to a computer-implemented method for assurance of message integrity for a message transmitted within a network environment. The disclosure also relates to a corresponding communication system and to a computer program product. |
IP Reference | WO2017135866 |
Protection | Patent application published |
Year Protection Granted | 2017 |
Licensed | No |
Impact | A Swedish company, IT Secured, with whom one of the inventors is affiliated, is involved in developing the invention. |
Description | Kosmos article |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | I wrote an article on quantum computers, "Quantum computers - supercomputers in superposition", for the yearbook of the Swedish Physical Society. The level of the article, written in Swedish, is suitable for anybody with school-level physics. |
Year(s) Of Engagement Activity | 2017 |
URL | http://www.fysikersamfundet.se/kosmos/ |
Description | New Scientist Instant Experts event on the quantum world |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | I gave a well-received introductory talk at a New Scientist "Instant Experts" event in London on 14 October 2017 |
Year(s) Of Engagement Activity | 2017 |
URL | https://www.facebook.com/events/729470520568475/ |