Access control encryption (ACE) enforces, through a sanitizer as the mediator, that only legitimate sender-receiver pairs can communicate, without the sanitizer knowing the communication metadata, including its sender and recipient identity, the policy over them, and the underlying plaintext. Any illegitimate transmission is indistinguishable from pure noise. Existing works focused on computational security and require trapdoor functions and possibly other heavyweight primitives. We present the first ACE scheme with information-theoretic security (unconditionally against unbounded adversaries). Our novel randomization techniques over matrices realize sanitization (traditionally via homomorphism over a fixed randomness space) such that the secret message in the hidden message subspace remains intact if and only if there is no illegitimate transmission.

翻译：访问控制加密（ACE）通过作为中介的清理器，确保只有合法的发送方-接收方对能够进行通信，同时清理器无法获知通信元数据，包括发送方和接收方的身份、通信策略以及底层明文。任何非法传输与纯噪声不可区分。现有工作专注于计算安全性，需要陷门函数以及其他可能的重型密码原语。我们提出了首个具有信息论安全性（针对无界敌手无条件安全）的ACE方案。我们基于矩阵的新型随机化技术实现了清理功能（传统上通过在固定随机空间上使用同态加密实现），使得隐藏消息子空间中的秘密消息在且仅在没有非法传输时保持完整。