Cryptanalysis of an Eliptic Curve Based Threshold Proxy Signature Scheme

In 2006, Pomykala et al. proposed an elliptic curve based threshold proxy signature scheme as well as a proxy-protected version. They claimed that their scheme had the properties of secrecy, unforgeability, non-repudiation and signer’s identification, and the proxy-protected version could assure the proxy-protection property. In this paper, we show attacks on the basic scheme and we also point out that even if the central authority is engaged, the basic model is not proxy-protected.