5Smart N. The discrete logamithm problem on elliptic curves of trace one[J]. Journal of Cryptology, 1999, (12):193-196.
6Dangard I B, Pedersen T P. New Convertible Undeniable Signature, Advances in Cryptology - Eurocrypt' 96 [ Z].New York : LNCS, Spring - Verlag, 1996. 372--386.
