Paper 2024/798

Incompressible Functional Encryption

Rishab Goyal
Venkata Koppula
Mahesh Sreekumar Rajasree
Aman Verma
Abstract

Incompressible encryption (Dziembowski, Crypto'06; Guan, Wichs, Zhandry, Eurocrypt'22) protects from attackers that learn the entire decryption key, but cannot store the full ciphertext. In incompressible encryption, the attacker must try to compress a ciphertext within pre-specified memory bound $S$ before receiving the secret key. In this work, we generalize the notion of incompressibility to functional encryption. In incompressible functional encryption, the adversary can corrupt non-distinguishing keys at any point, but receives the distinguishing keys only after compressing the ciphertext to within $S$ bits. An important efficiency measure for incompressible encryption is the ciphertext-rate ( i.e., $\mathsf{rate} = \frac{|m|}{|\mathsf{ct}|}\;$). We give many new results for incompressible functional encryption: 1. Incompressible attribute-based encryption for circuits from standard assumptions, with $\mathsf{ct}$-rate-$\frac{1}{2}$ and short secret keys, 2. Incompressible functional encryption for circuits from (non-incompressible) functional encryption, with (a) $\mathsf{ct}$-rate-$\frac{1}{2}$ and short secret keys, (b) $\mathsf{ct}$-rate-$1$ and large secret keys. Our results achieve optimal efficiency, as incompressible attribute-based/functional encryption with $\mathsf{ct}$-rate-$1$ as well as short secret keys has strong implausibility barriers. Moreover, our assumptions are minimal as incompressible attribute-based/functional encryption are strictly stronger than their non-incompressible counterparts.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint.
Keywords
incompressiblefunctional-encryptionattribute-based-encryption
Contact author(s)
rishab @ cs wisc edu
kvenkata @ iitd ac in
srmahesh1994 @ gmail com
amanverma1729 @ gmail com
History
2024-05-24: approved
2024-05-23: received
See all versions
Short URL
https://ia.cr/2024/798
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/798,
      author = {Rishab Goyal and Venkata Koppula and Mahesh Sreekumar Rajasree and Aman Verma},
      title = {Incompressible Functional Encryption},
      howpublished = {Cryptology ePrint Archive, Paper 2024/798},
      year = {2024},
      note = {\url{https://eprint.iacr.org/2024/798}},
      url = {https://eprint.iacr.org/2024/798}
}
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