# Information Security and Cryptography Research Group

## Quantum Cryptography with Finite Resources

### Valerio Scarani and Renato Renner

Available on http://arxiv.org/abs/0708.0709, Aug 2007.

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}.

## BibTeX Citation

@unpublished{ScaRen07,
author       = {Valerio Scarani and Renato Renner},
title        = {Quantum Cryptography with Finite Resources},
year         = 2007,
month        = 8,
howpublished = {Available on http://arxiv.org/abs/0708.0709},
}