Authentication method and system, a quantum communication network, and a node for quantum communication

A method for quantum communication between two nodes, the method comprising:

• exchanging a QKD key on a quantum communication channel, wherein information exchanged on the quantum communication channel is encoded on weak light pulses;
• exchanging a message on a classical communication channel;
• and
• authenticating the exchanged message, wherein authenticating the exchanged message comprises:
• applying a hash function to the message to obtain a hash code, wherein the hash function is a polynomial evaluation function, and wherein
• applying the hash function comprises:
• processing each block of the message, wherein the message comprises a plurality of blocks, accumulating each processed block in an accumulator, and deriving the hash code from the accumulator;
• applying a one-time pad cipher to the hash code to obtain a message authentication code (MAC);
• and
• authenticating the message exchanged between the two nodes using the MAC.

A node for quantum communication, the node comprising:

• a quantum key distribution system;
• and a
• an authentication engine,
• wherein the authentication engine is configured to:
• receive a message and a MAC;
• determine a further MAC from the received message, wherein determining the further MAC comprises:
• obtaining a further hash code by applying a hash function to the received message using a first key, wherein the hash function is a Poly1305;
• and
• applying a one-time pad cipher to the further hash code using a second key to obtain a further MAC;
• and,
• compare the further MAC with the received MAC, such that the message is authenticated when the further MAC corresponds to the received MAC.