An Efficient Verifiably Encrypted Signature Scheme Based on Half-Trust Private Key Generator

As many ID-based verifiably encrypted signature schemes have key escrow problem and low efficiency, we propose a new efficient verifiably encrypted signature scheme using pairing operation. The half-trust private key generator generates user´s private key components, and user generates another private key in the scheme, thus the key escrow is solved, the private key generator is prevented forging a legal user´s signatures and the user repudiates his signature is avoided. The scheme is analyzed to meet accuracy, unforgeability and opacity. By comparison, our scheme has higher efficiency than the existing schemes.