Quantum fingerprinting

Quantum fingerprinting is a proposed technique that uses a quantum computer to generate a string with a similar function to the cryptographic hash function. Alice and Bob hold  n {\displaystyle n} -bit strings  x {\displaystyle x} and  y {\displaystyle y} . Their goal and a referee's is to obtain the correct value of  f ( x , y ) = { 1 if x = y , 0 if x ≠ y . {\displaystyle f(x,y)={\begin{cases}1&{\text{if }}x=y,\\\0&{\text{if }}x\neq y.\\\\\end{cases}}} . To do this,  2 n {\displaystyle 2^{n}} quantum states are produced from the O(logn)-qubit state fingerprints and sent to the referee who performs the Swap test to detect if the fingerprints are similar or different with a high probability.[1]

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 quantum computer with 5 to 10 qubits. 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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1. ^ Harry Buhrman, Richard Cleve, John Watrous, Ronald de Wolf (2001). "Quantum Fingerprinting". Physical Review Letters. 87 (16): 167902. arXiv:quant-ph/0102001. Bibcode:2001PhRvL..87p7902B. doi:10.1103/PhysRevLett.87.167902. PMID 11690244. S2CID 1096490.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)

## See also

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* Quantum cryptography
* Quantum digital signature
* Swap test