2024-04-14
Compact selective opening security from LWE
Publication
Publication
Selective opening (SO) security is a security notion for public- key encryption schemes that captures security against adaptive corrup- tions of senders. SO security comes in chosen-plaintext (SO-CPA) and chosen-ciphertext (SO-CCA) variants, neither of which is implied by standard security notions like IND-CPA or IND-CCA security. In this paper, we present the first SO-CCA secure encryption scheme that combines the following two properties: (1) it has a constant ciphertext expansion (i.e., ciphertexts are only larger than plaintexts by a constant factor), and (2) its security can be proven from a standard assumption. Previously, the only known SO-CCA secure encryption scheme achieving (1) was built from an ad-hoc assumption in the RSA regime. Our construction builds upon LWE, and in particular on a new and sur- prisingly simple construction of compact lossy trapdoor functions (LTFs). Our LTF can be converted into an “all-but-many LTF” (or ABM-LTF), which is known to be sufficient to obtain SO-CCA security. Along the way, we fix a technical problem in that previous ABM-LTF-based con- struction of SO-CCA security.
| Additional Metadata | |
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| doi.org/10.1007/978-3-031-57728-4_5 | |
| Lecture Notes in Computer Science | |
| 27th IACR International Conference on Practice and Theory of Public-Key Cryptography | |
| Organisation | Cryptology |
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Hofheinz, D., Hostáková, K., Kastner, J., Klein, K., & Ünal, A. (2024). Compact selective opening security from LWE. In Public-Key Cryptography (pp. 127–160). doi:10.1007/978-3-031-57728-4_5 |
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