Privacy protection infectious disease close contact person screening method and system

The invention provides a privacy-protected infectious disease close contact screening method and system, and the method comprises the following steps: carrying out the decryption through a Dec-represented decryption algorithm under the help of a trusted third party through a management department through a function decryption key, and obtaining a set intersection result, the result reflects whether the user and the infectious disease infected person appear at the same physical position at the same time or not. The intersection of the user physical position sets can be used as an important judgment basis for judging whether the user is in close contact with the infectious disease infected person or not, and the practicability is very high. After a plurality of mobile network operators encrypt the user physical location set, the encrypted user physical location set is sent to the storage party, and the storage party cannot recover privacy information of the user physical location from the ciphertext, so that pr