Non-Committing Encryption with Constant Ciphertext Expansion from Standard Assumptions.

Non-committing encryption (NCE) introduced by Canetti et al. (STOC ’96) is a central tool to achieve multi-party computation protocols secure in the adaptive setting. Recently, Yoshida et al. (ASIACRYPT ’19) proposed an NCE scheme based on the hardness of the DDH problem, which has ciphertext expansion \(\mathcal {O}(\log \lambda )\) and public-key expansion \(\mathcal {O}(\lambda ^2)\).