A computer-implemented method for identifying transactions in multiple blockchain networks using data mining, the transactions related to a cross-chain transaction across the multiple blockchain networks, the computer-implemented method comprising: accessing, by a computing system, transaction data stored in the multiple blockchain networks, wherein accessing the transaction data comprises searching for transactions published in a first blockchain network and transactions published in a second blockchain network, the second blockchain network being different from the first blockchain network; identifying, by the computing system, using data mining on the transaction data, a first Hash Time Locked Contract, HTLC, transaction in the first blockchain network and a second HTLC transaction in the second blockchain network, wherein the first HTLC transaction is associated with the second HTLC transaction in the second blockchain network; identifying, by the computing system, using data mining on the transaction data, a third HTLC transaction in the second blockchain network that is associated with the second HTLC transaction in the second blockchain network; identifying, by the computing system, using data mining on the transaction data, a fourth HTLC transaction in the first blockchain network that is associated with the first, second, and third HTLC transactions; storing, by the computing system, identified transaction information of the first, second, third, and fourth HTLC transactions and associations of the first, second, third, and fourth HTLC transactions in a data structure; identifying, by the computing system, using data mining and the data structure, that the first, second, third, and fourth HTLC transactions are related to a same cross-chain transaction across the first blockchain network and the second blockchain network; and deriving, by the computing system, using data mining and the data structure, hidden information of the cross-chain transaction from the identified transaction information of the first, second, third, and fourth HTLC transactions based on the associations of the first, second, third, and fourth HTLC transactions, wherein the hidden information of the cross-chain transaction comprises at least one of i) a first party of the cross-chain transaction, ii) a second party of the cross-chain transaction, iii) a swap value, and iv) an exchange ratio. accessing, by a computing system, transaction data stored in the multiple blockchain networks, wherein accessing the transaction data comprises searching for transactions published in a first blockchain network and transactions published in a second blockchain network, the second blockchain network being different from the first blockchain network; identifying, by the computing system, using data mining on the transaction data, a first Hash Time Locked Contract, HTLC, transaction in the first blockchain network and a second HTLC transaction in the second blockchain network, wherein the first HTLC transaction is associated with the second HTLC transaction in the second blockchain network; identifying, by the computing system, using data mining on the transaction data, a third HTLC transaction in the second blockchain network that is associated with the second HTLC transaction in the second blockchain network; identifying, by the computing system, using data mining on the transaction data, a fourth HTLC transaction in the first blockchain network that is associated with the first, second, and third HTLC transactions; storing, by the computing system, identified transaction information of the first, second, third, and fourth HTLC transactions and associations of the first, second, third, and fourth HTLC transactions in a data structure; identifying, by the computing system, using data mining and the data structure, that the first, second, third, and fourth HTLC transactions are related to a same cross-chain transaction across the first blockchain network and the second blockchain network; and deriving, by the computing system, using data mining and the data structure, hidden information of the cross-chain transaction from the identified transaction information of the first, second, third, and fourth HTLC transactions based on the associations of the first, second, third, and fourth HTLC transactions, wherein the hidden information of the cross-chain transaction comprises at least one of i) a first party of the cross-chain transaction, ii) a second party of the cross-chain transaction, iii) a swap value, and iv) an exchange ratio.