Is there any way we can implement asymmetric encryption?
To illustrate the purpose more easily, let me give you a simple example.
There is A purchase list in the smart contract, and after user A purchases it can get the content, which comes from an IPFS address or a web address.
If the smart contract returns the address directly, then the owner can know that address without authorization (no purchase required).
How should we let only A can get the data correctly, while other users can not read it properly?
I expect it to be implemented using smart contracts alone, without the need for additional servers.
(The following is in Chinese, you do not need to pay attention to it, its content is the same as English.)