Applying Fujisaki-Okamoto to Identity-Based Encryption
- Cite this paper as:
- Yang P., Kitagawa T., Hanaoka G., Zhang R., Matsuura K., Imai H. (2006) Applying Fujisaki-Okamoto to Identity-Based Encryption. In: Fossorier M.P.C., Imai H., Lin S., Poli A. (eds) Applied Algebra, Algebraic Algorithms and Error-Correcting Codes. AAECC 2006. Lecture Notes in Computer Science, vol 3857. Springer, Berlin, Heidelberg
The Fujisaki-Okamoto (FO) conversion is widely known to be able to generically convert a weak public key encryption scheme, say one-way against chosen plaintext attacks (OW-CPA), to a strong one, namely, indistinguishable against adaptive chosen ciphertext attacks (IND-CCA). It is not known that if the same holds for identity-based encryption (IBE) schemes, though many IBE and variant schemes are in fact specifically using the FO conversion. In this paper, we investigate this issue and confirm that the FO conversion is generically effective also in the IBE case. However, straightforward application of the FO conversion only leads to an IBE scheme with a loose (but polynomial) reduction. We then propose a simple modification to the FO conversion, which results in considerably more efficient security reduction.
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