Purchases of electric vehicles have been increasing in recent years. These vehicles differ from traditional fossil-fuel-based vehicles especially in the time consumed to keep them running. Electric-Vehicle-charging Service Providers (EVSPs) must arrange reasonable charging times for users in advance. Most EVSP services are based on third-party platforms, but reliance on third-party platforms creates a lack of security, leaving users vulnerable to attacks and user-privacy leakages. In this paper, we propose an anonymous blockchain-based system for charging-connected electric vehicles that eliminates third-party platforms through blockchain technology and the establishment of a multi-party security system between electric vehicles and EVSPs. In our proposed system, digital certificates are obtained by completing distributed Public Key Infrastructure (distributed-PKI) identity registration, with the user registration kept separate from the verification process, which eliminates dependence on the EVSP for information security. In the verification process, we adopt smart contracts to solve problems associated with centralized verification and opaque services. Furthermore, we utilize zero-knowledge proof and ring-signature superposition to realize completely anonymous verification, which ensures undeniability and unforgeability with no detriment to anonymity. The evaluation results show that the user anonymity, information authenticity, and system security of our system fulfill the necessary requirements.

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Secure multi-party computation has been playing a fundamental role in terms of classical cryptography. Quantum homomorphic encryption (QHE) could compute the encrypted data without decryption. At present, most protocols use a semi-honest third party (TP) to protect participants' secrets. We use a quantum homomorphic encryption scheme instead of TP to protect the privacy of parties. Based on quantum homomorphic encryption, a secure multi-party quantum summation scheme is proposed in which N participants can delegate a server with strong quantum computing power to assist computation. By delegating the computation and key update processes to a server and a semi-honest key center, participants encrypt their private information data using Pauli operators to get the sum. Besides, the server can design and optimize the summation lines itself, and the correct results can be obtained even if the secret information is negative. The correctness analysis showed that the participants could correctly obtain the results of the calculation. The security analysis proves the scheme is resistant to both outside attack and participant's attack, and is secure against collusive attack by up to N-2 participants. From the theoretical point of view, our protocol can extend to other secure multi-party computing problems.

In the current E-healthcare scenarios, medical institutions are used to encrypt the information and store it in an Electronic Health Record (EHR) system in order to ensure the privacy of medical information. To realize data sharing, a Public-key Encryption with Keyword Search (PEKS) scheme is indispensable, ensuring doctors search for medical information in the state of ciphertext. However, the traditional PEKS scheme cannot resist the keyword guessing quantum computing attacks, and its security depends on the confidentiality of the secret key. In addition, classical PEKS hand over the search process to a third party, affecting the search results’ accuracy. Therefore, we proposed a postquantum Public-key Searchable Encryption scheme on Blockchain (PPSEB) for E-healthcare scenarios. Firstly, we utilized a lattice-based cryptographic primitive to ensure the security of the search process and achieve forward security to avoid key leakage of medical information. Secondly, we introduced blockchain technology to solve the problem of third-party untrustworthiness in the search process. Finally, through security analysis, we prove the correctness and forward security of the solution in the E-healthcare scenarios, and the comprehensive performance evaluation demonstrates the efficiency of our scheme compared with other existing schemes.

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