Cryptography - Public Key Authentication (Certificate-based, Sender Verification)

With the public key scheme, the Authentication is based on digital signature where the digital signature verification proves that a message came from a particular sender.

There is two type of authentication:

• public key authentication based where the server authorizes only messages that can be decrypted by a authorized public key
• cert-based authentication where the server authorizes only client that are in possession of certificate signed by authorized CA.

See also:

• Security - Identity Assertions
• and message authentication codes.

• the private key remains (only) with the user (The possession of this key is proof of the user's identity. Only a user in possession of a private key that corresponds to the public key located at the server will be able to authenticate successfully.
• the public keys are stored on the server in a file known as the SSH - Authorized Keys file (on Server)

For the procedure. see Digital signature procedure

The KeyManager is a program (or function) that decides which authentication credentials should be sent to the remote host for authentication during SSL handshake.

• Mutual Authentication, in addition to server authentication, the client also has to present its certificate to the server.
• The server verifies it
• If both server and client authenticated themselves, then authentication is a success.

See the dedicated page: What is a certification base authentication (also known as Client certification / Mutual TLS authentication) ?

• http://logicoy.com/blogs/ssl-keystore-truststore-and-mutual-authentication/
• https://winscp.net/eng/docs/public_key