An Efficient ID-KEM Based On The Sakai-Kasahara Key Construction

Sakai et. al in 2000 produced a method of construction identity based public/private key pairs using pairings on elliptic curves. In 2001, using the same key construction as Sakai et. al., Boneh and Franklin presented the first efficient and provably secure identity-based encryption scheme. In 2003 Sakai and Kasahara proposed another method of constructing identity based keys, also using pairings, which has the potential to improve performance. Later, Chen and Cheng gave a provably secure identity based scheme using this second construction. Both the Boneh–Franklin scheme and the scheme based on the second construction are not true hybrid encryption schemes in the traditional of the public key KEM/DEM approach. To address this issue, Bentahar et. al. extended the idea of key encapsulation mechanism to the identity based setting and presented three constructions in line with the original Sakai et. al. method of constructing identity based keys. In this paper we present another ID-KEM based on the second method of constructing identity based keys and prove its security. The new scheme has a number of advantages over all previous ID-based encryption schemes.