Privacy protection methods, systems, and apparatus, including computer programs encoded on computer storage media, are provided. One of the methods is performed by a second computing device and includes: receiving a data request for object data from a first computing device, wherein the object data is associated with an object and is stored in the second computing device; performing encryption of the object data using a public key associated with the object based on the data request to generate a first ciphertext; obtaining verification data based on the first ciphertext for verifying whether a ciphertext to be verified corresponds to the object data; and sending the verification data to the first computing device for the first computing device to execute a cryptography protocol with a third computing device based on the verification data.