Some Results on Anonymity in Hybrid Encryption
Anonymity(key privacy) as well as security(data privacy) are all important features in public key encryption applications. In this paper two new and general concepts, named "relevant anonymity" and "relevant security" are defined. Based upon these concepts some general results on anonymity in public key encryption are proved, which fall in three categories. The first results are two general relationships between anonymity and security; the second are a sufficient and necessary condition for chosen plaintext anonymity in Fujisaki Okamoto hybrid construction and a sufficient condition for its chosen ciphertext anonymity; the third is a sufficient condition for chosen ciphertext anonymity in Okamoto Pointcheval hybrid construction (REACT) All these conditions are also easy to use criteria in practice. By examples such general consequences are applied to some specific schemes and as a result anonymity of some well known schemes are re established in a simpler way. Furthermore, NISSIE scheme PSEC /1/2/3's chosen ciphertext anonymity are proved.
IACR Cryptol. ePrint Arch.