中文摘要：

Concurrent signature was introduced as an efficient approach to solving the problem of fair exchange of signatures. Almost all fair exchange e-commerce protocols based on concurrent signature that have been proposed until now either do not provide message privacy protection or adopt the sign-then-encrypt scheme to provide confidentiality. However,confidentiality is an important requirement of fair exchange e-commerce protocol. In this paper,a new concept called concurrent signcryption which combines the con...

英文摘要：

Concurrent signature was introduced as an efficient approach to solving the problem of fair exchange of signatures. Almost all fair exchange e-commerce protocols based on concurrent signature that have been proposed until now either do not provide message privacy protection or adopt the sign-then-encrypt scheme to provide confidentiality. However, confidentiality is an important requirement of fair exchange e-commerce protocol. In this paper, a new concept called concurrent signcryption which combines the concepts of concurrent signature and signcryption together to resolve the confidentiality problem in e-commerce systems based on concurrent signature. We also propose a concurrent signcryption scheme using bilinear pairings and prove its security in the random oracle model. Compared with the sign-then-encrypt scheme using bilinear pairings, our scheme enjoys shorter message length and less operation cost. Moreover, in our scheme the two ambiguous signcryptions can be published in any order.