The exemplary inventive instant messaging system may include a sending client that accesses encryption data associated with a receiving client on a distributed mesh network where the encryption data is signed by a receiver public key of the receiving client, forms a non-interactive message exchange session on the distributed mesh network, generates a first session key based on the encryption data and a sender secret key, encrypts a message using the first session key, encrypts session information using the receiver public key, produces a session state including the encrypted message and the encrypted session information and stores the session state in the non-interactive message exchange session. The receiving client accesses the session state, decrypts the encrypted session information with a receiver secret key, generates a second session key using the session information and a sender public key, and decrypts the message using the second session key.