Forward Secure Proxy Signature Scheme

Abstract

In this paper, we adopt the concept of forward-secure property for proxy signatures. Proxy signature is a kind of signature schemes in which an original signer delegates his signing capability to a designated signer called a proxy signer. Then, the proxy signer creates a digital signature on behalf of the original signer. We describe the problems of exposing of the secure key in proxy signature scheme. The key exposure problem in distributed environments is also a serious problem. To address the weaknesses we propose a proxy signature scheme with forward-secure based on 2l-root signature scheme. The proposed scheme with forward-secure property that renews the proxy key in each period and deletes the previous keys to prevent the secret against key exposure and conforms strong proxy signature requirements. We also mention that the forward proxy signature scheme can be applied to limitation on time duration of delegation.