Yamin Liu

Efficient Lossy Trapdoor Functions Based on Subgroup Membership Assumptions

We propose a generic construction of lossy trapdoor function from the subgroup membership assumption. We present three concrete constructions based on the k-DCR assumption over

Improved efficiency of chosen ciphertext secure encryption from factoring

\mathbb{Z}^*_{N^2}

Improved tradeoff between encapsulation and decapsulation of HK09

, the extended p-subgroup assumption over

Efficient CCA-secure CDH based KEM balanced between ciphertext and key

\mathbb{Z}^*_{N^2}

(Deterministic) Hierarchical Identity-based Encryption from Learning with Rounding over Small Modulus

, and the decisional RSA subgroup membership assumption over

Lossy Trapdoor Relation and Its Applications to Lossy Encryption and Adaptive Trapdoor Relation

\mathbb{Z}^*_{N}

How to Remove the Exponent GCD in HK09

. Our constructions are more efficient than the previous construction from the DCR assumption over

On the Lossiness of 2k-th Power and the Instantiability of Rabin-OAEP

\mathbb{Z}^*_{N^{s}}

Improving the Message-Ciphertext Rate of Lewko’s Fully Secure IBE Scheme

(s ≤ 3).

A User-Friendly Centrally Banked Cryptocurrency

We propose a new variant of HK09 (proposed by Hofheinz and Kiltz in Eurocrypt 2009) which improves the decapsulation efficiency at the price of a slightly increased key size. Compared with the original HK09 scheme the decapsulation efficiency is improved by 32% (instantiated over the quadratic residuosity group) or 57.6% (instantiated over the semi-smooth subgroup) and the encapsulation efficiency remains the same.