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Quantum Cheque: Difference between revisions
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'''Tags:''' [[Quantum Digital Signature]], Private key protocol. | '''Tags:''' [[Quantum Digital Signature]], Private key protocol. | ||
== Assumptions == | |||
* The protocol assumes the account holder and the bank, to be honest. The bank is a trusted party, however, the branches may or may not be trusted. | |||
* This protocol assumes perfect state preparations, transmissions, and measurements. | |||
* The protocol takes the assumption that the Quantum Digital Signature scheme and the Quantum key distribution is unconditionally secure. | |||
* The digital signature scheme must satisfy the following security conditions of unforgeability and non-repudiation | |||
==Outline== | ==Outline== | ||
This protocol allows a quantum cheque to be issued using quantum | This protocol allows a quantum cheque to be issued using quantum cheque books to the bank customers. The customers can then carry forward transactions in a perfectly secure manner and these cheques can be en-cashed after being verified by the trusted bank or its branches, which communicate with the main branch securely. The quantum cheque follows all the property of a classical cheque - verifiable by a trusted bank, cannot be disavowed by the issuer and cannot be counterfeited by an adversary. </br> | ||
The entire bank transaction process can be divided into three stages, Gen, where the cheque book is generated for the account holder, Sign, where the account holder prepares a cheque and issues it to the third party and Verify, where the third party en-cashes the cheque depending upon its validity. | The entire bank transaction process can be divided into three stages, Gen, where the cheque book is generated for the account holder, Sign, where the account holder prepares a cheque and issues it to the third party and Verify, where the third party en-cashes the cheque depending upon its validity. | ||
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==Properties== | ==Properties== | ||
* In the signing process, the quantum one-way function used to create the cheque for the account holder is assumed to take polynomial time to compute and is hard to invert. | * In the signing process, the quantum one-way function used to create the cheque for the account holder is assumed to take polynomial time to compute and is hard to invert. | ||
* In the verification process, the bank sets a thresholding security parameter <math>\kappa</math>. The swap test is passed if <math>\{ \langle\psi^{(i)}|\psi^{,(i)}\rangle \geq \kappa\}_{i=1:l}</math> | * In the verification process, the bank sets a thresholding security parameter <math>\kappa</math>. The swap test is passed if <math>\{ \langle\psi^{(i)}|\psi^{,(i)}\rangle \geq \kappa\}_{i=1:l}</math> | ||
* No quantum memory would be required for the account holder to store the quantum check if the transaction is occurring in real time. | * No quantum memory would be required for the account holder to store the quantum check if the transaction is occurring in real time. | ||
* This protocol can be realized, efficiently, with few qubit systems, without compromising on the security | |||
* Security: This protocol is impossible to counterfeit and non-repudiation by signatory is impossible here. | |||
==Notation== | ==Notation== | ||