At a node device associated with a blockchain as a received target transaction, a target transaction published by a user is received, where the received target transaction includes transaction content, and where at least a part of the transaction content includes a content summary associated with target content that is stored in a third-party storage system connected to the blockchain. By the node device and to the third-party storage system, the target content corresponding to the content summary is queried. By the node device, whether the target content is verified is determined. In response to determining that the target content is verified, by the node device, the received target transaction is executed based on the transaction content. By the node device, the received target transaction is stored in a distributed database associated with the blockchain.