Efficient public key encryption with smallest ciphertext expansion from factoring

摘要: For public key encryption schemes, adaptive chosen ciphertext security is a widely accepted notion since it captures wide range of attacks. SAEP and SAEP+ are asymmetric schemes which were proven to achieve semantic against However, the bandwidth for message essentially worse, that expansion (the length difference between plaintext) too large. In most mobile networks constrained communication systems, necessary securely send as many messages possible. this article, we propose two chosen-ciphertext secure schemes. The first scheme generic padding based on trapdoor permutations. second one its application Rabin-Williams function has very fast algorithm. These both optimal w.r.t. expansion, namely with smallest expansion. Further, tight reductions shown prove these