ETH Zürich » Computer Science » Theory » Cryptography

Publications: Abstract

Quantum Cryptography with Finite Resources

Valerio Scarani and Renato Renner

The security of a key generated from finite resources is always finite. We present a lower bound for the security of finite keys in quantum cryptography, with respect to a definition of security thatis composable and has an operational meaning – two crucial requirements for practical applications. For single-qubit implementations of the Bennett-Brassard 1984 and the six-statesprotocols, the secret key rate becomes positive when at least N 10^5 signals are exchanged and processed, and reaches the asymptotic value only for N 10^{15}.