Techniques for invocating a smart contract are described. One example method includes receiving a target transaction that is used to initiate an invocation of a smart contract, wherein the target transaction comprises invocation data, and wherein the invocation data comprises a data digest associated with target data stored in a third-party storage system interconnected with a blockchain; querying the target data from the third-party storage system; receiving a query result returned by the third-party storage system, wherein the query result comprises encrypted target data; obtaining a key to decrypt the encrypted target data to generate decrypted target data; performing a content verification on the decrypted target data; determining that the content verification succeeds; invoking the smart contract to perform a smart contract computation on the invocation data; and storing a computation result in a distributed database associated with the blockchain after the smart contract computation is completed.