Security Analysis on “SPKSE: Secure Public Key Searchable Encryption Withstand Keyword Guessing Attacks”

Shi et al. (Scientific Reports 2025 (SJR Q1 Journal)) proposed a public key searchable encryption scheme, which they call secure public key searchable encryption (SPKSE). In this short note, we show that a trapdoor can be generated from a ciphertext without using the receiver's secret key. We also show that the test algorithm can be run without using the server's secret key, although the scheme employs a designated tester setting. Our analysis indicates that the scheme must be completely redesigned.