The paper addresses the problem of allowing a user ($\mathcal{U}$) to store encrypted files on a remote server ($\mathcal{S}$) and later retrieve specific files containing or indexed by certain keywords while maintaining the privacy of the keywords and the security of the stored files. The authors propose two efficient schemes that do not require public-key cryptosystems and are independent of the encryption method used for the files. The schemes are incremental, meaning that new files can be submitted securely against previous queries but remain searchable against future queries. The first scheme, *Scheme1*, assumes that a dictionary can be stored on the user's mobile device. It involves a non-interactive setup phase where the user prepares a keyword index and masks it using pseudo-random bits. In the retrieval phase, the user sends a masked index string to the server, which recovers the index and returns the encrypted files. The scheme ensures that the server learns nothing more than the shared keywords among the encrypted files. The second scheme, *Scheme2*, assumes that the dictionary cannot be stored on the mobile device. Instead, the user sends an encrypted dictionary to the server. The retrieval phase is interactive, involving two rounds where the user sends a masked index string and a key to the server, which then decodes the encrypted index and returns the files. Both schemes are secure against a malicious server and support secure updates. The paper also discusses potential security improvements and open problems, such as handling Boolean queries and general pattern matching, and the challenge of secure deletion of previously submitted files.The paper addresses the problem of allowing a user ($\mathcal{U}$) to store encrypted files on a remote server ($\mathcal{S}$) and later retrieve specific files containing or indexed by certain keywords while maintaining the privacy of the keywords and the security of the stored files. The authors propose two efficient schemes that do not require public-key cryptosystems and are independent of the encryption method used for the files. The schemes are incremental, meaning that new files can be submitted securely against previous queries but remain searchable against future queries. The first scheme, *Scheme1*, assumes that a dictionary can be stored on the user's mobile device. It involves a non-interactive setup phase where the user prepares a keyword index and masks it using pseudo-random bits. In the retrieval phase, the user sends a masked index string to the server, which recovers the index and returns the encrypted files. The scheme ensures that the server learns nothing more than the shared keywords among the encrypted files. The second scheme, *Scheme2*, assumes that the dictionary cannot be stored on the mobile device. Instead, the user sends an encrypted dictionary to the server. The retrieval phase is interactive, involving two rounds where the user sends a masked index string and a key to the server, which then decodes the encrypted index and returns the files. Both schemes are secure against a malicious server and support secure updates. The paper also discusses potential security improvements and open problems, such as handling Boolean queries and general pattern matching, and the challenge of secure deletion of previously submitted files.