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The Difference Between one-way authentication and Mutual authentication/

The Difference Between one-way authentication and Mutual authentication

One-way authentication only requires the server to have a certificate, and the client doesn't need to have one. Mutual authentication requires both the client and the server to have certificates, and both parties must verify each other successfully to complete the SSL handshake.

SSL One-way Authentication

In SSL one-way authentication, only the server identity but not the client identity needs to be verified. The process of SSL one-way authentication is as shown below:



1. A client initiates an HTTPS connection request to the server together with the supported SSL protocol versions, encryption algorithms, generated random numbers, and other information.
2. The server returns an SSL protocol version, encryption algorithm, generated random number, server certificate (server.crt), and other information to the client.
3. The client verifies the validity of the certificate (server.crt) for the factors below and obtains the server's public key from the certificate.
4. After the certificate is verified, the client will generate a random number (the key K; which is used as the symmetric encryption key for the communication), encrypt it with the public key obtained from the server certificate, and then send it to the server.
5. After receiving the encrypted information, the server will use its private key (server.key) to decrypt it to obtain the symmetric encryption key (the key K).The symmetric encryption key (the key K) will be used by the server and client for communication to guarantee information security.

SSL Mutual Authentication

In SSL mutual authentication, the server identity and the client identity both need to be verified. The process of SSL mutual authentication is as shown below:



1. A client initiates an HTTPS connection request to the server together with the supported SSL protocol versions, encryption algorithms, generated random numbers, and other information.
2. The server returns an SSL protocol version, encryption algorithm, generated random number, server certificate (server.crt), and other information to the client.
3. The client verifies the validity of the certificate (server.crt) for the factors below and obtains the server's public key from the certificate.
4. The server requires the client to send the client certificate (client.crt), and the client does so as required.
5. The server verifies the client certificate (client.crt). After it is verified, the server will use the root certificate to decrypt the client certificate and obtain the client's public key.
6. The client sends the supported symmetric encryption schemes to the server.
7. The server selects the encryption scheme with the highest encryption level from the schemes sent from the client, uses the client's public key to encrypt it, and returns it to the client.
8. The client uses its private key (client.key) to decrypt the encryption scheme and generate a random number (the key K; which is used as the symmetric encryption key for the communication), encrypts it with the public key obtained from the server certificate, and then sends it to the server.
9. After receiving the encrypted information, the server will use its private key (server.key) to decrypt it to obtain the symmetric encryption key (the key K).The symmetric encryption key (the key K) will be used by the server and client for communication to guarantee information security.