Cao Yuan, Zhao Yongli, Wang Jianquan, Yu Xiaosong, Ma Zhangchao, Zhang Jie
Opt Express. 2019 Mar 4;27(5):6892-6909. doi: 10.1364/OE.27.006892.
Quantum key distribution (QKD) holds the potential of providing long-term integrity and confidentiality for data and communications. Currently, many fiber-based QKD systems have been commercialized and several QKD networks have been deployed. Given the high cost and complexity of QKD network deployment, QKD as a service (QaaS) becomes a promising pattern for future QKD networks. The QaaS concept is that multiple users can apply for QKD services to obtain their required secret-key rates (SKRs) from the same QKD network infrastructure instead of deploying their dedicated QKD networks. Accordingly, how to provide efficient and flexible QaaS for fulfilling the SKR requirements of multiple users over a QKD network infrastructure becomes a new challenge. This study introduces the software defined networking (SDN) technique to overcome this challenge, since SDN can add flexibility together with efficient QKD network management. A new framework of SDN for QaaS (SDQaaS) is proposed, where the QaaS functions are developed in the SDN controller. We present the protocol extension, intercommunication workflow, and routing and SKR assignment strategy for QaaS implementation in the SDQaaS framework. We also establish a SDQaaS experimental testbed and perform the numerical simulation to verify our presented approaches. Experimental results demonstrate that our presented approaches can achieve efficient and flexible QaaS over the QKD network. Moreover, simulation results indicate that the success probability of QKD service requests can be increased via lowering the flexibility of SKR requirements for QKD service creation, sacrificing more cost to produce higher SKR over the QKD network, or gradually reducing SKR requirements with the modification of QKD service.
量子密钥分发（QKD）有望为数据和通信提供长期的完整性和保密性。目前，许多基于光纤的QKD系统已经商业化，并且已经部署了几个QKD网络。鉴于QKD网络部署的高成本和复杂性，QKD即服务（QaaS）成为未来QKD网络的一种有前景的模式。QaaS的概念是多个用户可以申请QKD服务，以从同一个QKD网络基础设施中获得他们所需的密钥率（SKR），而不是部署他们专用的QKD网络。因此，如何在QKD网络基础设施上提供高效且灵活的QaaS以满足多个用户的SKR需求成为了一项新的挑战。本研究引入软件定义网络（SDN）技术来克服这一挑战，因为SDN可以增加灵活性以及实现高效的QKD网络管理。提出了一种用于QaaS的SDN新框架（SDQaaS），其中QaaS功能在SDN控制器中开发。我们展示了用于在SDQaaS框架中实现QaaS的协议扩展、互通工作流程以及路由和SKR分配策略。我们还建立了一个SDQaaS实验测试平台并进行数值模拟，以验证我们提出的方法。实验结果表明，我们提出的方法可以在QKD网络上实现高效且灵活的QaaS。此外，模拟结果表明，通过降低创建QKD服务时SKR要求的灵活性、在QKD网络上牺牲更多成本以产生更高的SKR或者随着QKD服务的修改逐渐降低SKR要求，可以提高QKD服务请求的成功概率。
