An extension is provided to the SEND protocol without requiring a CGA or third party trust anchor. A shared key is provided to both a sender and receiver of a neighbor discovery (ND) message. A digital signature option is contained in the ND message. A digital signature field is determined by the algorithm field in the option. When the ND message is received, the receiver may verify the digital signature field using the pre-shared key according to the algorithm field. If the ND message passes verification, the receiver may process the message.