A method for shared key generation with authentication in a gateway node includes generating, generating a first set of pseudo-random data corresponding to expected transmissions from a first node that communicates with a second node through a shared communication medium, identifying, with the gateway node, bits transmitted from the second node based on a signals received by the gateway node corresponding to simultaneous transmissions from the first node and the second node, identifying, with the gateway node, expected bit values for the bits from the second node based on a combination of shared secret data stored in a memory of the gateway node with another set of random or pseudo-random data generated by the second node, and authenticating the second node in response to the plurality of bits transmitted from the second node matching the plurality of expected bit values.