Sharing of encrypted lock keys in the blockchain-based renting house system from time- and identity-based proxy reencryption

To design an efficient protocol for sharing the encrypted lock keys in the renting house system, we introduce a new notion called time- and identity-based, proxy reencryption (TIPRE) and the blockchain platform. Our CPA secure TIPRE scheme is constructed from Green et al.'s identity-based proxy reen-cryption scheme by adding the time property. In every time period, a time stamp authority generates a public key embedded with the current time stamp for each user. In our protocol for the renting house system, the TIPRE scheme is the primary building block, and the blockchain platform serves instead of a trusted third party, such as a real estate agency between landlords and tenants. The TIPRE scheme allows the landlord to change the lock key at each time period for safety. The blockchain platform allows the landlords and tenants to directly interact, and all of the interactions are recorded in the blockchain database to provide the desired security requirements, such as non-repudiation and unforgeability. Finally, we provide the secure analysis of our protocol and test its performance by implementing it in the MacBook Pro and the Intel Edison development platforms.