How to design the cryptosystem of the next venture?

Question

Encryption

Hello!

I'm developing a pet-project - password manager in Web'e. Therefore, the browser is a client, and a server is somewhere far away.
At the moment, I have thought of the following:
Store in the database not only the hashed user password, but also the login. Then the login will be only on the client side and will not be transmitted over the network. And by hashing it with a salt, I can use it as a secret.
But as soon as I looked at this idea a little more closely, I realized that I need to store the login somewhere on the client side use cookies that the server generates, therefore the login will be transmitted in clear text over the network and the option disappears.
Already broke my head over this question, tell me

Answer 1

Encrypt all information with the other party's public key prior to transmission