Method and apparatus for obtaining input of secure multiparty computation protocol

1. A method for privacy protection, wherein the method is performed by a second computing device and comprises:

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, the second computing device being associated with an authorized organization;

generating a random number;

generating a first ciphertext of the object data by performing homomorphic encryption of the object data using a public key of the object and the generated random number;

generating a hash value of the first ciphertext based on the first ciphertext;

generating a digital signature of the authorized organization that endorses the hash value;

storing, at a storage location in a blockchain, the hash value of the first ciphertext, and the authorized organization's digital signature that endorses the hash value;

obtaining, from the blockchain, verification data for verifying whether a ciphertext to be verified corresponds to the object data, the verification data comprising the storage location in the blockchain;

sending the generated random number to the first computing device for generating a second cipher text of the object data by performing homomorphic encryption based on the random number and object data stored in the first computing device; 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 and the second cipher text of the object data.

2. The method of claim 1 , wherein:

sending the verification data to the first computing device comprises sending the verification data and the first ciphertext to the first computing device.

3. The method of claim 1 , wherein:

the verification data comprises the authorized organization's digital signature.

4. The method of claim 1 , wherein:

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 comprises sending the verification data to the first computing device for the first computing device to execute a secure multiparty computation protocol for the object data with the third computing device based on the verification data.

5. The method of claim 4 , wherein:

sending the verification data to the first computing device for the first computing device to execute a secure multiparty computation protocol for the object data with the third computing device based on the verification data comprises:

causing the third computing device to obtain and verify the second ciphertext based on the verification data and to determine the second ciphertext as an input to the secure multiparty computation protocol in response to determining that the first ciphertext corresponds to the object data.

6. A system for privacy protection, wherein the system acts as a second computing device and comprises one or more processors and one or more non-transitory computer-readable memories coupled to the one or more processors and configured with instructions executable by the one or more processors to cause the system to perform operations comprising:

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, the second computing device being associated with an authorized organization;

generating a random number;

generating a first ciphertext of the object data by performing homomorphic encryption of the object data using a public key of the object and the generated random number;

generating a hash value of the first ciphertext based on the first ciphertext;

generating a digital signature of the authorized organization that endorses the hash value;

storing, at a storage location in a blockchain, the hash value of the first ciphertext, and the authorized organization's digital signature that endorses the hash value;

obtaining, from the blockchain, verification data for verifying whether a ciphertext to be verified corresponds to the object data, the verification data comprising the storage location in the blockchain;

sending the generated random number to the first computing device for generating a second cipher text of the object data by performing homomorphic encryption based on the random number and object data stored in the first computing device; 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 and the second cipher text of the object data.

7. The system of claim 6 , wherein:

sending the verification data to the first computing device comprises sending the verification data and the first ciphertext to the first computing device.

8. A method for privacy protection, wherein the method is performed by a first computing device and comprises:

sending a data request for object data to a second computing device, wherein the object data is associated with an object and is stored in the second computing device, the second computing device being associated with an authorized organization;

in response to sending the data request for object data to the second computing device, receiving verification data from the second computing device and a random number generated by the second computing device, wherein the verification data comprises a storage location in a blockchain of a hash value of a first ciphertext, and a digital signature of the authorized organization that endorses the hash value, the first ciphertext generated by performing homomorphic encryption using a public key of the object and the random number generated by the second computing device to encrypt the object data;

obtaining a second ciphertext corresponding to the object data, wherein the second ciphertext is generated by performing homomorphic encryption using a public key of the object and the random number received from the second computing device to encrypt the object data; and

sending the second ciphertext and the verification data to a third computing device to execute a cryptography protocol with the third computing device based on the verification data.

9. The method of claim 8 , wherein:

sending the second ciphertext and the verification data to the third computing device comprises sending the second ciphertext and the storage location to the third computing device.

10. The method of claim 8 , wherein:

sending the second ciphertext and the verification data to the third computing device to execute the cryptography protocol with the third computing device based on the verification data comprises sending the second ciphertext and the verification data to the third computing device to execute a secure multiparty computation protocol for the object data with the third computing device based on the verification data.

11. The method of claim 10 , wherein:

sending the second ciphertext and the verification data to the third computing device to execute the secure multiparty computation protocol for the object data with the third computing device based on the verification data comprises:

causing the third computing device to obtain and verify the second ciphertext based on the verification data and to determine the second ciphertext as an input to the secure multiparty computation protocol in response to determining that the second ciphertext corresponds to the object data.