Quantum fingerprinting explained

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 -bit strings x and y . Their goal and a referee's is to obtain the correct value of f(x,y) = \begin{cases} 1 & if x = y, \\ 0 & if x ≠ y. \\ \end{cases} . To do this, 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.

See also

• Quantum cryptography
• Quantum digital signature
• Swap test

Notes and References

1. . Quantum Fingerprinting . Physical Review Letters . 87 . 16 . 2001 . 167902 . 10.1103/PhysRevLett.87.167902 . 11690244 . quant-ph/0102001 . 2001PhRvL..87p7902B . 1096490 .