I'm trying to find a way to use an ethereum address/solidity/web3 for text encryption , but i'm not even sure it's possible to get the public key from the address(hash of the pubkey) using secp256k1 to get the publickey ? or if there is any other way to access it client side? if so, would the user be able to decrypt the data using it's passphrase(ethereum passphrase )? so that everything would happen client side but the data would be stored encrypted on the chain ?
I know none of this is really meant to do any of that but i'm trying to store encrypted data on the blockchain without having to rely on a server to store keys as much as possible but can't seems to find a way.
Ethereum + data = encrypted data
encrypted data + ethereum + passphrase = data