Access control schemes in predicate encryption can effectively reduce the risk of information leakage in the inner product function encryption (IPFE). However, when we try to transition from identity-based IPFE to attribute-based IPFE, the fine-grained nature of attributes induces some unprecedented access control problems. These problems not only lead to incorrect inner product computation results from attribute-based IPFE but also inevitable passive information leakage induced by large attribute set secret key. At the same time, since the above problems are not common in identity-based IPFE and traditional ABEs, they cannot be properly addressed by existing schemes. To address the above problems, we introduce a new scheme - Ciphertext Policy Based Inner Product Functional Encryption (CP-IPFE). In this scheme, we propose to use a “label vector” to label the attributes of n-dimensional vectors and encode them onto the relevant information, so as to ensure that the attribute-based IPFE will not output incorrect inner-product computation results; establishing a leaf node set-based “reverse access control policy” to realize reverse access control on “risky ciphertext”, ensures that “risky ciphertext” will not be leaked encrypted-information by the secret key of large attribute sets. In addition, CP-IPFE also has the characteristics of traditional attribute encryption and supports more fine-grained access control. Finally, we prove the CPA security of the CP-IPFE in the GGM model and show a detailed application of the CP-IPFE on a general-purpose platform.

中文翻译：

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CP-IPFE：基于密文策略的内积函数加密


谓词加密中的访问控制方案可以有效降低内积函数加密（IPFE）中信息泄露的风险。然而，当我们尝试从基于身份的IPFE过渡到基于属性的IPFE时，属性的细粒度性质会引发一些前所未有的访问控制问题。这些问题不仅会导致基于属性的IPFE的内积计算结果不正确，而且会导致大属性集密钥不可避免地导致被动信息泄露。同时，由于上述问题在基于身份的IPFE和传统ABE中并不常见，因此现有方案无法很好地解决这些问题。针对上述问题，我们引入了一种新的方案——基于密文策略的内积函数加密（CP-IPFE）。在该方案中，我们提出使用“标签向量”来标记n维向量的属性，并将其编码到相关信息上，以保证基于属性的IPFE不会输出错误的内积计算结果；建立基于叶节点集的“反向访问控制策略”，实现对“风险密文”的反向访问控制，保证“风险密文”不会因大属性集的密钥而泄露加密信息。此外，CP-IPFE还具有传统属性加密的特点，支持更细粒度的访问控制。最后，我们在GGM模型中证明了CP-IPFE的CPA安全性，并展示了CP-IPFE在通用平台上的详细应用。