SFTP (SSH File Transfer Protocol) works by providing a secure method for transferring files between computers over a network. It uses the SSH (Secure Shell) protocol to establish a secure connection between a client and a server. Unlike FTP (File Transfer Protocol), which is not encrypted by default, SFTP encrypts both commands and data exchanged between the client and server, ensuring confidentiality and integrity of file transfers.
SFTP operates over the SSH protocol, specifically using the SSH transport layer to secure communications between the client and server. SSH provides mechanisms for authentication, encryption, and data integrity verification. When a client connects to an SFTP server, it establishes a SSH connection using public key, password-based, or other authentication methods supported by SSH. Once authenticated, the client and server can exchange SFTP commands and transfer files securely.
SFTP encryption works by encrypting both commands and data transferred between the client and server using symmetric encryption algorithms negotiated during the SSH handshake. Typically, SFTP supports encryption algorithms like AES (Advanced Encryption Standard) for data encryption and HMAC (Hash-based Message Authentication Code) algorithms for verifying data integrity. These encryption algorithms ensure that files transferred via SFTP cannot be intercepted or modified by unauthorized parties during transmission over the network. This robust encryption mechanism is a key feature of SFTP, making it a preferred choice for secure file transfers in environments where data security is paramount.