Intrusion-Resilient Key-Evolving Schnorr Signature
Kwangjo Kim, Jihwan Kim · 2003
Exposure of secret keys is one of the most critical issues in a cryptographic system. It seems to be unavoidable. Recently, the notion of key-evolving paradigm was proposed as a means of mitigating the harmful e#ects that key exposure can cause. In this model, the whole lifetime is divided into distinct periods (e.g., days) such that at time period j, the signer holds the secret key SK j and updates it periodically, while the public key PK is fixed during its lifetime. We present an intrusion-resilient key-evolving Schnorr signature based on this notion. It has the following property: If secret keys of all periods are not compromised, it is not possible to forge signatures relating to non-exposed secret keys. Our scheme is constructed from unforgeably secure Schnorr signature scheme, which is based on the Discrete Logarithm Problem.