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.