An Improved Construction for Universal Re-encryption

Golle et al recently introduced universal re-encryption, defining it as re-encryption by a player who does not know the key used for the original encryption, but which still allows an intended player to recover the plaintext. Universal re-encryption is potentially useful as part of many information-hiding techniques, as it allows any player to make ciphertext unidentifiable without knowing the key used. Golle et al’s techniques for universal re-encryption are reviewed, and an improved hybrid universal re-encryption construction which permits indefinite re-encryptions with better efficiency and an almost-optimally small increase in file size is presented. Some implementational issues and optimisations are discussed.