Public-private key pair account login and key manager

Embodiments of the invention provide improved account authentication using public-private key cryptography instead of passwords. Instead of registering a password and using that password to login to an account, an authentication server of an account provider registers a public key received from a user device. To authenticate the user device for logging into an account, the authentication server generates a challenge and encrypts using the registered public key. The encrypted challenge is sent to the user device, which can decrypt the challenge using the private key corresponding to the registered public key. The decrypted challenge is used for authentication instead of using a password. The private key corresponding to the public key is securely stored and not revealed to the authentication server.