Key sharing device and method

Abstract

A network device arranged to determine a shared key with a second network device is presented. The first network device is arranged to substitute an identity number of the second network device into a univariate private key polynomial to obtain an intermediate key. The network device comprises - a key derivation unit arranged to - extract from the intermediate key multiple bit-strings, the multiple bit-strings being non-overlapping, consecutive substrings of the intermediate key, each two adjacent bit-strings of the multiple bit-strings are separated in the intermediate key by at least one bit which does not belong to any of the multiple bit-strings, and - derive the shared key from the multiple bit-strings.