Quantum fingerprinting is a proposed technique that uses a

quantum computer A quantum computer is a computer that exploits quantum mechanical phenomena. On small scales, physical matter exhibits properties of both particles and waves, and quantum computing takes advantage of this behavior using specialized hardware. ...

to generate a string with a similar function to the

cryptographic hash function A cryptographic hash function (CHF) is a hash algorithm (a map (mathematics), map of an arbitrary binary string to a binary string with a fixed size of n bits) that has special properties desirable for a cryptography, cryptographic application: ...

. Alice and Bob hold

n

-bit strings

x

and

y

. Their goal and a referee's is to obtain the correct value of

f(x,y) = \begin
  1 & \text x = y, \\
  0 & \text x \neq y. \\
 \end

. To do this,

2^

quantum states are produced from the O(logn)-qubit state fingerprints and sent to the referee who performs the

Swap test The swap test is a procedure in quantum computation that is used to check how much two quantum states differ, appearing first in the work of Barenco et al. and later rediscovered by Harry Buhrman, Richard Cleve, John Watrous, and Ronald de Wol ...

to detect if the fingerprints are similar or different with a high probability. If unconditional guarantees of security are needed, and if it is impractical for the communicating parties to arrange to share a secret that can be used in a Carter–Wegman MAC, this technique might one day be faster than classical techniques given a

with 5 to 10

qubit In quantum computing, a qubit () or quantum bit is a basic unit of quantum information—the quantum version of the classic binary bit physically realized with a two-state device. A qubit is a two-state (or two-level) quantum-mechanical syste ...

s. However, these circumstances are very unusual and it is unlikely the technique will ever have a practical application; it is largely of theoretical interest.

References

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References

See also