How to Terminate Service Requests in Outsourcing: A Seamless Solution From Withdrawable Signatures

Outsourcing is an essential strategy for enterprises, and leveraging it can offer advantages such as saving costs, improving efficiency, and allowing them to concentrate on their primary business activities. Therefore, announcing and managing service requests is paramount for obtaining suitable quotes and partnering with the right outsourcing service providers. To achieve this, enterprises can employ digital signatures to ensure the authenticity and security of these service requests. However, the irrevocable nature of traditional digital signatures poses challenges, particularly when canceling the service requests is necessary. A withdrawable signature scheme provides a novel property for signers to initially create “withdrawable” signatures, which they can later confirm into additional conventional signatures. Withdrawable signatures can be regarded as withdrawn when the signer has not confirmed them yet. This property provided by the withdrawable signature mechanism can then be adopted as a solution to this problem, allowing the enterprise to retract announced signatures on service requests. However, to meet the demands in the outsourcing system, existing approaches on withdrawable signatures require further development since they only allow signers in outsourcing systems to confirm withdrawable signatures on service requests. This limitation prevents enterprises from accepting quotes for service requests simply by confirming the withdrawable signature. This paper focuses on this problem by applying the withdrawable signature to the outsourcing framework, identifying the limitations of existing withdrawable signature schemes, and proposing solutions. We demonstrate how revisiting of withdrawable signatures can lead to flexible outsourcing systems that ensure the cancellation of announced service requests. Additionally, we provide a performance evaluation demonstrating that our revised withdrawable signature scheme achieves acceptable efficiency and security within the outsourcing system.