Securing API <> Smart Contract data exchange

Our use case is that we have an API that we’ve developed that will reside on a conventional server (that we host) that transmits a data object to a smart contract on the Ethereum blockchain. What I am trying to figure out is how we can secure the transmission of that data object. Of course, we need to affirm the data object source (perhaps by signing it) and its integrity in transit (perhaps by hashing it).

These are transactions that will most likely occur thousands of times per day per server. I’ve looked at the work Chain Link has developed for API <> Smart Contract communications (what they refer to as “Oracles”), but I have not found how they secure these transaction.

Quite frankly, I haven’t found any discussion re: securing these types of communications between conventional and blockchain architectures. Am I missing something very basic here, as in there is an obvious simple solution, or is this an area that simply has been skirted to date?

Would like to understand if Hashi’s product line can help address tihs use case. Thanks