User's Manual

Description of integrity and authenticity measures
Mesh network
The SRT MN-01 communicates with other mesh-nodes using a proprietary protocol using either
frequencies in the 865-868MHz, 902-928MHz or 2,4-2,4834GHz range.
The protocol builds and maintains a Destination-Oriented Directed Acyclic Graph topology that
originates from a designated root node, which typically also serves as a border router to a computer.
Routing information is disseminated through broadcast beacons a-periodically using timers. The
topology is built according to ensure maximum stability in the network
The protocol supports different directions of traffic:
x Upward routing: from any node to a root.
x Downward routing: from the root to any node.
All upward routing is handled by having each node on the path toward the root forwarding traffic
through a preferred parent. Downward routing can be handled by maintain address information
stored in the nodes.
Authentication is handled by whitelisting of MAC addresses in combination with pre-shared key
material from fabric
Message integrity is handled by evaluating CRC checksums contained in each message.
Encryption is handled by using pre-shared key material from fabric
Bluetooth communication
The SRT PT-01 relies on the Bluetooth protocol for managing message integrity. The protocol
handles checksum validation for every received package (based on 3 bytes of CRC included in the
package itself). Regarding authentication, the SRT PT-01 will not accept any inbound connections
from other devices as the device is not connectable. Advertisements from SRT PT-01 includes a
unique identifier describing the SRT PT-01 as a type of device. This unique identifier is used by the
SRT MN-01 when filtering for SRT PT-01 devices. In addition, the system uses whitelisting of both SRT
PT-01 and SRT-MN-01 based on unique MAC addresses
2
. This ensures external or unknown devices
are not able to connect or join the network. Data from unrecognized mesh nodes or tags will be
discarded.
Mesh node and Personnel communication pattern
The SRT PT-01 (wearable tag) will typically be used in conjunction with SRT MN-01 (static located
mesh node). A mesh node will listen for advertisements from all nearby tags based on the unique
advertisement identifier. The mesh-node will forward the information from tag advertisements to an
upstream gateway where this information will be used to create value. If the gateway is not
reachable directly the mesh node will depend on other upstream mesh nodes to forward the
information. As already mentioned, whitelisting of both mesh nodes and tags is used ensuring
unwanted access.
2
https://en.wikipedia.org/wiki/MAC_address