I think Chainlink enables the "holy grail" of cryptography known as online one-time padding.
One time padding involves all parties sharing a key used to encrypt a message but it's a bit of a chicken and egg problem since you first need a secure way for everyone involved to share the key. For this reason it's been relegated to an offline encryption method only (I write the key down and walk it over to your house).
Buuuut now with Chainlink data provider oracles on a blockchain it seems you can just enter a smart contract with all involved parties and the Chainlink node will generate a key for all parties to use through the contract which distributes it securely via the blockchain.
Now you might say, well in this case you're trusting a third party, namely the Chainlink node operator, that he/she won't snoop on the key generated for you and look at your data... Very valid concern. But, Chainlink nodes can implement Intel SGX enclaves where nothing, not even the OS can see what's being processed by the node. No way for the node operator to see the key that his/her computer generated for you.
Seems to me we've arrived at a way for secure online distribution of symmetric keys (vs the current public/asymmetric system)... And that's huge.
