In order to optimize the trade-off between performance and security of digital signature in electronic commerce; an electronic seal system based on elliptical curve cryptosystem is presented. Elliptical curve cryptosystem is adopted as it is an effective system which has the advantage of fast speed and high security. The identity-based scheme is introduced to protect the system from chosen-message attack and also identifies a forged signature at the same time. The safety of the whole system is assured by public-key infrastructure techniques. Analysis and application show that the scheme proposed in the paper has the quality of high security and high efficiency of implementation.