Secure network accessing method for POS terminal, and system thereof

A method for initializing secure network access for POS terminals, which is used to connect a POS terminal to a terminal backend system, the method comprising:

• loading a terminal default public key certificate, a default private key file, and a CA public key certificate of the terminal backend system into the POS terminal when leaving factory, wherein said terminal default public key certificate comprises a terminal transaction unique identifier;
• after the POS terminal leaves factory and when initializing secure network access for the POS terminal, establishing a terminal transaction certificate secure downloading channel,
• wherein the terminal transaction certificate secure downloading channel is a mutual authenticated secure channel based on a secure socket layer (SSL)/transport layer security (TLS) protocol that utilizes said terminal default public key certificate, said default private key file, and said CA public key certificate of the terminal backend system for authentication, and the terminal transaction certificate secure downloading channel is used for downloading a terminal transaction certificate, between the POS terminal and the terminal backend system;
• generating, by the POS terminal, a terminal transaction public/private key pair, storing the transaction private key within the POS terminal;
• uploading, by the POS terminal, at least said terminal transaction public key and said terminal transaction unique identifier as a certificate signing request to the terminal backend system via the terminal transaction certificate secure downloading channel;
• signing and issuing, by the terminal backend system, a terminal transaction certificate, wherein the terminal backend system generates the terminal transaction certificate based on the certificate signing request uploaded from the POS terminal via the terminal transaction certificate secure downloading channel, and returning the terminal transaction certificate to the POS terminal via the terminal transaction certificate secure downloading channel for downloading the terminal transaction certificate by the POS terminal;
• after the terminal transaction certificate is downloaded by the POS terminal, establishing a secure channel for transaction for executing financial transactions between the POS terminal and the terminal backend system, according to the terminal transaction certificate, the transaction private key of said terminal transaction public/private key pair, and the CA public key certificate of the terminal backend system;
• executing a first transaction between the POS terminal and the terminal backend system via the secure channel;
• after executing the first transaction, receiving, by the POS terminal via the terminal transaction certificate secure downloading channel that utilizes said terminal default public key certificate, an updated terminal transaction certificate generated by the terminal backend system;
• establishing an updated secure channel for the financial transactions between the POS terminal and the terminal backend system, according to the updated terminal transaction certificate;
• and
• executing a second transaction between the POS terminal and the terminal backend system via the updated secure channel;
• wherein the terminal default public key certificate and the private key file is only used for accessing the terminal backend system and performing terminal management directed to the terminal transaction certificate secure downloading channel, and not used for executing the first transaction or the second transaction between the POS terminal and the terminal backend system.