Identity-based threshold ring signcryption from pairing

This paper presents an identity-based threshold ring signcryption scheme. With this technique, any group of t entities can choose n - t entities to generate a t-out-of-n signcryption on behalf of the group of n members, yet the actual signcrypters remain anonymous. The scheme is proven to be indistinguishable against adaptive chosen ciphertext attacks, existentially unforgeable against adaptive chosen message and identity attacks, and unconditional signcrypter ambiguity under the random oracle model. To the best of authors' knowledge, the scheme is the first security ID-based threshold ring signcryption scheme.