What is the principle and process of the SSH framework?

SSH, or Secure Shell, is a protocol used for securely transmitting data over insecure networks. Its principles and processes are as follows:

1. The client initiates a connection request: The client first reaches out to the server to establish a connection and sends its own identity authentication information.
2. The server responds to the connection request by verifying the client’s identity and sending a random number (referred to as a “challenge”) to the client.
3. The client creates a session key: After receiving a challenge from the server, the client encrypts the challenge with its own private key and sends it back to the server.
4. The server verifies the session key: by decrypting the challenge from the client using the client’s public key and comparing it with the previously sent random number, the server confirms the authenticity of the client.
5. The client generates an encryption key: Once a secure connection has been established between the client and server, the client uses a random number and some other parameters sent by the server to create a key known as a “session key,” which is then sent to the server.
6. Data transmission encryption: The communication between the client and the server is encrypted and decrypted using a session key to ensure the security and integrity of data transmission.

In summary, the principles and process of SSH can be roughly summarized into a few steps: the client initiates a connection request, the server responds and verifies the client’s identity, the client generates a session key and sends it to the server, the server verifies the session key, and both parties establish a secure connection and encrypt data transmission.