Say I want to make a smart contract that is able to save secret messages (strings). The messages should be stored only in encrypted form so no one can read them, but should be decrypt-able by a couple of users.
I can write basic Solidity, but I need some help on how to do this design wise.
I know it's possible to encrypt/decrypt strings offline and only send the encrypted data to the blockchain. But in the case there must be multiple users who need to be able to decrypting the same strings, how can this best be done?
Would this be possible with creating a multi-sig wallet contract comprised out of a few users? Will they all need to have the private key on their computers in order to use it? Isn't that dangerous?
Any advice much appreciated.