Identity-Based Hierarchical Strongly Key-Insulated Encryption and Its Application

In this paper, we discuss non-interactive updating of decryption keys in identity-based encryption (IBE). IBE is a public key cryptosystem where a public key is an arbitrary string. In practice, key revocation is a necessary and inevitable process and IBE is no exception when it comes to having to manage revocation of decryption keys without losing its merits in efficiency. Our main contribution of this paper is to propose novel constructions of IBE where a decryption key can be renewed without having to make changes to its public key, i.e. user’s identity. We achieve this by extending the hierarchical IBE (HIBE). Regarding security, we address semantic security against adaptive chosen ciphertext attacks for a very strong attack environment that models all possible types of key exposures in the random oracle model. Straightforward extension of the HIBE, however, does not achieve our goal as such a scheme is completely insecure under our attack model. In addition to this, we show met...

• Type: Conference
• Year: 2005
• Where: ASIACRYPT
• Authors: Yumiko Hanaoka, Goichiro Hanaoka, Junji Shikata, Hideki Imai
• Keywords: Arbitrary Ibe, ASIACRYPT 2005, Cryptology, Decryption Key, Public Key