Adaptive Secure-Channel Free Public-Key Encryption with Keyword Search Implies Timed Release Encryption

摘要

As well-known results, timed-release encryption (TRE) and public key encryption scheme with keyword search (PEKS) are very close to identity-based encryption (IBE), respectively. It seems natural that there is a close relationship between TRE and PEKS. However, no ex plicit bridge has been shown between TRE and PEKS so far. In this paper, we show that TRE can be generically constructed by PEKS with extended functionalities, called secure-channel free PEKS (SCF-PEKS) with adaptive security, and discuss the reason why PEKS and (non adaptive) SCF-PEKS are not suitable for constructing TRE. In addition to this result, we also show that adaptive SCF-PEKS can be generically constructed by anonymous IBE only. That is, for constructing adaptive SCF-PEKS we do not have to require any additional cryptographic prim itive compared to the Abdalla et al. PEKS construction (J. Cryptology 2008), even though adaptive SCF-PEKS requires additional functionali ties. This result seems also independently interesting.