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Adaptively Secure Streaming Functional Encryption
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| Conference: | TCC 2025 |
| Abstract: | This paper presents the *first adaptively secure* streaming functional encryption (sFE) scheme for P/Poly. sFE extends traditional FE to vast and/or dynamically evolving data sets, enabling incremental encryption of streaming inputs and iterative partial decryption over encrypted prefixes. The proposed sFE scheme is built from indistinguishability obfuscation for P/Poly and injective PRGs. We achieve this result via two core technical contributions which may be of independent interest. First, we introduce a novel "gluing" mechanism to achieve adaptive security by intertwining two schemes, each possessing one aspect of adaptive security. Second, we enhance the powerful Koppula-Lewko-Waters [STOC 2015] framework with a "sliding window" technique, enabling authenticated iterative computation with fresh inputs at each iteration. Prior work by Guan, Korb, and Sahai [CRYPTO 2023] constructed sFE but only under a (semi-adaptive) function-selective security model, requiring all functional keys to be queried before observing any ciphertext. This severe limitation precludes practical scenarios and leaves adaptive security as a crucial *open challenge* — explicitly highlighted by their work — which we address in this paper. |
BibTeX
@inproceedings{tcc-2025-36271,
title={Adaptively Secure Streaming Functional Encryption},
publisher={Springer-Verlag},
author={Pratish Datta and Jiaxin Guan and Alexis Korb and Amit Sahai},
year=2025
}