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Non-Committing Identity based Encryption: Constructions and Applications
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| Conference: | PKC 2025 |
| Abstract: | A receiver non-committing encryption (RNCE) scheme [Canetti et al., STOC 1996; Canetti et al., TCC 2005] allows one to sample a public key pk and (dummy) ciphertext ct without knowing the message m. Later, when the message is known, one can sample a secret key sk that looks like the secret key corresponding to pk, and decryption of ct produces m. In this work, we study receiver non-committing identity-based encryption (RNC-IBE). We give constructions based on standard assumptions on bilinear groups (prior works [Hiroka et al., ASIACRYPT 2021] require indistinguishability obfuscation). Our RNC-IBE constructions have important implications for incompressible identity based encryption. This notion was recently introduced by Goyal et al., ITCS 2025. However, there were no constructions for the strongest security definitions in Goyal et al., ITCS 2025. Our RNC-IBE scheme also leads to the first incompressible IBE scheme with optimal ciphertext size, which was another open question in Goyal et al., ITCS 2025. We also give constructions for relaxed RNC-IBE (where the identity space is polynomial in the security parameter, but the public key is compact) that are based on DDH, LWE. This leads to a relaxed incompressible IBE scheme with strong security from the same assumptions. |
BibTeX
@inproceedings{pkc-2025-35195,
title={Non-Committing Identity based Encryption: Constructions and Applications},
publisher={Springer-Verlag},
author={Rishab Goyal and Fuyuki Kitagawa and Venkata Koppula and Ryo Nishimaki and Mahesh Sreekumar Rajasree and Takashi Yamakawa},
year=2025
}