Biblio

Homomorphic encryption enables computation on encrypted data while maintaining secrecy. This leads to an important open question whether quantum computation can be delegated and verified in a non-interactive manner or not. In this paper, we affirmatively answer this question by constructing the quantum homomorphic encryption scheme with quantum obfuscation. It takes advantage of the interchangeability of the unitary operator, and exchanges the evaluation operator and the encryption operator by means of equivalent multiplication to complete homomorphic encryption. The correctness of the proposed scheme is proved theoretically. The evaluator does not know the decryption key and does not require a regular interaction with a user. Because of key transmission after quantum obfuscation, the encrypting party and the decrypting party can be different users. The output state has the property of complete mixture, which guarantees the scheme security. Moreover, the security level of the quantum homomorphic encryption scheme depends on quantum obfuscation and encryption operators.

Due to the importance of securing electronic transactions, many cryptographic protocols have been employed, that mainly depend on distributed keys between the intended parties. In classical computers, the security of these protocols depends on the mathematical complexity of the encoding functions and on the length of the key. However, the existing classical algorithms 100% breakable with enough computational power, which can be provided by quantum machines. Moving to quantum computation, the field of security shifts into a new area of cryptographic solutions which is now the field of quantum cryptography. The era of quantum computers is at its beginning. There are few practical implementations and evaluations of quantum protocols. Therefore, the paper defines a well-known quantum key distribution protocol which is BB84 then provides a practical implementation of it on IBM QX software. The practical implementations showed that there were differences between BB84 theoretical expected results and the practical implementation results. Due to this, the paper provides a statistical analysis of the experiments by comparing the standard deviation of the results. Using the BB84 protocol the existence of a third-party eavesdropper can be detected. Thus, calculations of the probability of detecting/not detecting a third-party eavesdropping have been provided. These values are again compared to the theoretical expectation. The calculations showed that with the greater number of qubits, the percentage of detecting eavesdropper will be higher.

The Internet of things (IoT) has experienced rapid development these years, while its security and privacy remains a major challenge. One of the main security goals for the IoT is to build secure and authenticated channels between IoT nodes. A common way widely used to achieve this goal is using authenticated key exchange protocol. However, with the increasing progress of quantum computation, most authenticated key exchange protocols nowadays are threatened by the rise of quantum computers. In this study, we address this problem by using ring-SIS based KEM and hash function to construct an authenticated key exchange scheme so that we base the scheme on lattice based hard problems believed to be secure even with quantum attacks. We also prove the security of universal composability of our scheme. The scheme hence can keep security while runs in complicated environment.