Using an example in the business or finance industry, describe how the following
cryptographic protocols work:
C. Secure shell (SSH).
In the business or finance industry, Secure Shell (SSH) is commonly used to secure remote logins and secure network services. Let's take the example of a financial institution that needs to securely access and manage its servers remotely.
SSH Protocol:
1. Server Authentication: When a client (e.g., an employee accessing a server remotely) initiates an SSH connection, the server first authenticates itself to the client. This is done using asymmetric encryption techniques. The server presents its public key, and the client verifies the authenticity of the key by checking its digital signature against a trusted list of known and verified public keys.
2. Client Authentication: Once the server is authenticated, the client needs to authenticate itself to the server to gain access. This can be done through multiple authentication methods, including password-based authentication or public key-based authentication. If using public key authentication, the client generates a key pair (public and private key) before initiating the connection. The client's public key is stored on the server, and during the connection, the client proves its identity by providing a valid private key that corresponds to the stored public key.
3. Encryption: After the authentication process, SSH establishes an encrypted connection between the client and the server. All data transmitted between them, including login credentials, commands, and data transfers, are encrypted to prevent eavesdropping and unauthorized access. SSH utilizes symmetric encryption algorithms, like AES (Advanced Encryption Standard), to secure the data transmitted during the session. The encryption keys are negotiated during the connection setup phase.
4. Data Integrity: Along with encryption, SSH ensures the integrity of the transmitted data. It uses hash functions like SHA (Secure Hash Algorithm) to generate message digests, which are sent along with the data. The server checks the digests received from the client to ensure the data has not been tampered with during transmission.
5. Port Forwarding: SSH also enables port forwarding, allowing secure connections to internal network services. For example, if a financial institution wants its employees to access a database server securely, SSH can tunnel the database connection through the encrypted SSH connection. This ensures the database communication remains secure and confidential.
Overall, SSH provides secure network communication, strong authentication, and encryption to protect sensitive data and ensure the integrity of transactions in the business or finance industry.