Abstract: A method of encryption and decryption applied to a transmitted plaintext message in a communication network containing multiple subscriber nodes is provided. The method comprises the steps of: processing an Integrity check value (ICV); using a private key at the first subscriber node; providing a random initialization vector (W) executing a first operation on the random IV to obtain a sum IV; using the sum IV to process an encryption on the plaintext to obtain the ciphertext; transmitting the ciphertext to the second subscriber node wherein the second node receives the ciphertext; identifies the IV; utilizes the private key and the IV to process the decryption of the ciphertext to obtain the plaintext; generates a feedback message, the feedback message is then used to generate future sum IVs.