Secure symmetric key distribution

A first node of a communication system, the first node comprising:

• a random number generator generating master keying material comprising at least a first master key;
• a first transmitter sharing the master keying material between the first node and the second node using a physical layer security method on a key-generation channel;
• the random number generator generating a first amount of random numbers as local keying material whereby the local keying material and the master keying material are available on the first node;
• an encryptor encrypting the local keying material using the first master key;
• and
• a second transmitter sending the encrypted local keying material to the second node over a communication channel for decrypting the encrypted local keying material on the second node using the master key to recover the local keying material at the second node whereby the local keying material and the master keying material are available on the second node as symmetric keying material shared between the first node and the second node, wherein the communication channel has a higher throughput than the key-generation channel.

A second node of a communication system, the second node comprising:

• a first receiver receiving master keying material comprising at least a first master key from a first node using physical layer security on a key-generation channel;
• a second receiver receiving encrypted local keying material comprising an encrypted first amount of random numbers from the first node over a communication channel, wherein the communication channel has a higher throughput than the key-generation channel;
• and
• a decryptor decrypting the encrypted local keying material using the first master key to recover the local keying material, whereby the local keying material and the master keying material are available on the second node as symmetric keying material shared between the first node and the second node.