Comment on “Secure quantum private information retrieval using phase-encoded queries”
Runhua Shi, Yi Mu, Hong Zhong, Shun Zhang · Physical Review A · 2016
In this Comment, we reexamine the security of phase-encoded quantum private query (QPQ). We find that the current phase-encoded QPQ protocols, including their applications, are vulnerable to a probabilistic entangle-and-measure attack performed by the owner of the database. Furthermore, we discuss how to overcome this security loophole and present an improved cheat-sensitive QPQ protocol without losing the good features of the original protocol.