TY - UNPB

T1 - Almost Public Quantum Coins

AU - Behera, Amit

AU - Sattath, Or

PY - 2020

Y1 - 2020

N2 - In a quantum money scheme, a bank can issue money that users cannot
counterfeit. Similar to bills of paper money, most quantum money schemes
assign a unique serial number to each money state, thus potentially
compromising the privacy of the users of quantum money. However in a
quantum coins scheme, just like the traditional currency coin scheme,
all the money states are exact copies of each other, providing a better
level of privacy for the users. A quantum money scheme can be private,
i.e., only the bank can verify the money states, or public, meaning
anyone can verify. In this work, we propose a way to lift any private
quantum coin scheme -- which is known to exist based on the existence of
one-way functions, due to Ji, Liu, and Song (CRYPTO'18) -- to a scheme
that closely resembles a public quantum coin scheme. Verification of a
new coin is done by comparing it to the coins the user already
possesses, by using a projector on to the symmetric subspace. No public
coin scheme was known prior to this work. It is also the first
construction that is very close to a public quantum money scheme and is
provably secure based on standard assumptions. The lifting technique
when instantiated with the private quantum coins scheme, due to Mosca
and Stebila 2010, gives rise to the first construction that is very
close to an inefficient unconditionally secure public quantum money
scheme.

AB - In a quantum money scheme, a bank can issue money that users cannot
counterfeit. Similar to bills of paper money, most quantum money schemes
assign a unique serial number to each money state, thus potentially
compromising the privacy of the users of quantum money. However in a
quantum coins scheme, just like the traditional currency coin scheme,
all the money states are exact copies of each other, providing a better
level of privacy for the users. A quantum money scheme can be private,
i.e., only the bank can verify the money states, or public, meaning
anyone can verify. In this work, we propose a way to lift any private
quantum coin scheme -- which is known to exist based on the existence of
one-way functions, due to Ji, Liu, and Song (CRYPTO'18) -- to a scheme
that closely resembles a public quantum coin scheme. Verification of a
new coin is done by comparing it to the coins the user already
possesses, by using a projector on to the symmetric subspace. No public
coin scheme was known prior to this work. It is also the first
construction that is very close to a public quantum money scheme and is
provably secure based on standard assumptions. The lifting technique
when instantiated with the private quantum coins scheme, due to Mosca
and Stebila 2010, gives rise to the first construction that is very
close to an inefficient unconditionally secure public quantum money
scheme.

KW - Quantum Physics

KW - Computer Science - Cryptography and Security

M3 - פרסום מוקדם

T3 - Arxiv preprint

BT - Almost Public Quantum Coins

ER -