With the ever-increasing demands on decentralization and transparency of cloud storage, CP-ABE (Ciphertext Policy-Attribute-Based Encryption) has become a promising technology for blockchain-enabled data sharing methods due to its flexibility. However, real-world blockchain applications usually have some special requirements like time restrictions or power limitations. Thus, decryption outsourcing is widely used in data sharing scenarios and also causes concerns about data security. In this paper, we proposed a secure access control scheme based on CP-ABE, which could share contents during a particular time slot in blockchain-enabled data sharing systems. Specifically, we bind the time period with both ciphertexts and the keys to archive the goal of only users who have the required attributes in a particular time slot can decrypt the content. Besides, we use time slots as a token to protect the data and access control scheme when users want to outsource the decryption phase. The security analysis shows that our scheme can provide collusion resistance ability under a time restriction, and performance evaluations indicate that our scheme uses less time in decryption compared to other schemes while ensuring security.

中文翻译：

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时间限制下解密外包的抗共谋区块链数据共享方案

随着对云存储去中心化和透明化需求的不断增加，CP-ABE（密文策略属性加密）因其灵活性而成为区块链数据共享方法的一种有前途的技术。但是，现实世界的区块链应用程序通常有一些特殊要求，例如时间限制或功率限制。因此，解密外包被广泛应用于数据共享场景，同时也引发了对数据安全的担忧。在本文中，我们提出了一种基于 CP-ABE 的安全访问控制方案，该方案可以在支持区块链的数据共享系统中的特定时间段内共享内容。具体来说，我们将时间段与密文和密钥绑定，以实现只有在特定时间段内具有所需属性的用户才能解密内容的目标。此外，当用户想要外包解密阶段时，我们使用时隙作为令牌来保护数据和访问控制方案。安全性分析表明，我们的方案可以在时间限制下提供抗合谋能力，性能评估表明，与其他方案相比，我们的方案在保证安全性的同时，使用更少的解密时间。