Schematic representation of the quantum dual signature scheme which involves multiple participants in the network. Alice_i (2 ≤ i ≤ n) is a customer who signs her own two messages and generates a dual signature by applying entanglement swapping. Bob is the business who verifies the order information’s signature. Charlie _j (2 ≤ j ≤ m) is the bank who verifies the signature of payment information of the corresponding customer.