System and method for searching a database or data sharing system for the presence of data

A method for determining by a client whether a desired data item is stored in a database server having a list of data items stored therein, the method comprising:

• generating a search request message that includes an encryption of a desired data item by the client;
• transmitting the search request message to the database server, wherein the desired data item is kept secret from the database server;
• receiving from the database server a search response message, wherein the search response messaged is generated based on the search request message and based on the list of data items;
• and
• determining whether the desired data item is stored in the database server based on the search response message, wherein the presence of any other data items of the list of data items is not revealed to the client.

A system for searching a database server having a list of data items stored therein, the system comprising:

• a search request message generation unit that generates a search request message that includes an encryption of a desired data item transmitted from a client to the database server, wherein the desired data item is kept secret from the database server;
• a search response message generation unit that generates a search response message based on the search request message and based on the list of data items, wherein the search response message is used to determine whether the desired data item exists in the database server without revealing the presence of any other data items of the list of data items to the client, and wherein the search response message is transmitted from the database server to the client;
• and
• a search result determination unit that determines whether the desired data item is stored in the database server based on the search response message.

A system for determining by a client whether a desired data item is stored in a database server having a list of data items, the system comprising:

• a search request message generation unit that generates a search request message that includes an encryption of a desired data item transmitted to the database server, wherein the desired data item is kept secret from the database server;
• a search response message generation unit that generates a search response message based on the search request message and based on the list of data items, wherein the search response message is used to determine whether the desired data item exists in the database server without revealing the presence of any other data items of the list of data items to the client;
• and
• a search result determination unit that determines whether the desired data item is stored in the database server based on the search response message.