International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Security Proof of Sakai-Kasahara's Identity-Based Encryption Scheme

Liqun Chen
Zhaohui Cheng
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Abstract: Identity-based encryption (IBE) is a special asymmetric encryption method where a public encryption key can be an arbitrary identifier and the corresponding private decryption key is created by binding the identifier with a system's master secret. In 2003 Sakai and Kasahara proposed a new IBE scheme, which has the potential to improve performance. However, to our best knowledge, the security of their scheme has not been properly investigated. This work is intended to build confidence in the security of the Sakai-Kasahara IBE scheme. In this paper, we first present an efficient IBE scheme that employs a simple version of the Sakai-Kasahara scheme and the Fujisaki-Okamoto transformation, which we refer to as SK-IBE. We then prove that SK-IBE has chosen ciphertext security in the random oracle model based on a reasonably well-explored hardness assumption.
  title={Security Proof of Sakai-Kasahara's Identity-Based Encryption Scheme},
  booktitle={IACR Eprint archive},
  keywords={public-key cryptography / Identity-based encryption, provable security, bilinear pairings},
  note={ 13026 received 12 Jul 2005, last revised 31 Aug 2005},
  author={Liqun Chen and Zhaohui Cheng},