Design and Implementation of a Lightweight Security-Enhanced Scheme for Modbus TCP Protocol

Table 2

Symbol used in the proposed scheme.

Symbols	Description
PSK	Preshared key between the client and the server
Rm	Random number generated by the client
Rs	Random number generated by the server
Key	Session key negotiated between the client and the server
||	Connect function
	SM4 encryption
	SM4 decryption
	SM3 hash algorithm
16	The first 16 bytes of the SM3 hash value
Cm	Ciphertext encrypted by the client using preshared key
Cs	Ciphertext encrypted by the server using preshared key
Hm1, Hm2, Hm3	Hash value generated by the client
Hs1, Hs2, Hs3	Hash value generated by the server
CPT	Ciphertext encrypted by the negotiated session key