It can be seen that based on the homomorphic encryption/decryption solutions in the present specification, it can be ensured that an account balance of a user, a transaction amount of a blockchain transaction, etc. are kept private, and each amount can be correctly calculated and maintained based on the homomorphic feature, thereby implementing a confidential transaction in a blockchain network scenario. In addition, especially when a blockchain transaction involves a plurality of transaction objects or a large quantity of blockchain transactions are involved, based on the homomorphic encryption/decryption solutions in the present specification, an execution speed of each encryption/decryption operation can be increased while security is ensured, which helps improve transaction efficiency in a blockchain network.

The previous homomorphic encryption/decryption solutions can be applied to a multi-party computation scenario, to implement secure interaction in the multi-party computation scenario. For example, the target user can send homomorphic ciphertext c₀ to c_s respectively corresponding to data m₀ to m_s to a specified user, so that the specified user can perform predetermined operation f( ) that satisfies additive homomorphism on homomorphic ciphertext c₀ to c_s. In addition, operation result f(c₀?c_s) returned by the specified user can be decrypted by using private key sk, and a value obtained after the decryption is f(m₀?m_s).