Secure communication method and system for double-CPU POS terminal

The invention provides a secure communication method and system for a POS terminal with double CPUs in the technical field of payment security, and the method comprises the steps: S1, a universal CPU creates a pair of AP public key and AP private key based on an ECDH algorithm, and transmits the AP public key to a secure CPU; s2, the security CPU receives the AP public key, creates a pair of SP public key and SP private key based on an ECDH algorithm, and negotiates a first session key with the AP public key based on the SP private key; s3, the security CPU calculates a first verification value of the first session key, and sends the SP public key and the first verification value to the universal CPU; s4, the general CPU receives the SP public key and the first verification value, and negotiates a second session key based on the SP public key and the AP private key; and step S5, the general CPU calculates a second verification value of the second session key, and after the first verification value is verified