Security is a foundational component of Wi-SUN networks. From initial device authentication to ongoing communication, every interaction in a Wi-SUN network is protected by strong cryptographic methods designed to ensure data integrity, device authenticity, and network privacy.

This section provides an overview of the key security principles built into the Wi-SUN protocol. It explains the high-level architecture, the trust model, and the mechanisms that secure device access and communication.

Trust Model and Security Objectives

Wi-SUN security is based on a public key infrastructure (PKI) and a mutual authentication model. Every device in the network must prove its identity before it can join or communicate.

The main objectives of the security model are:

  • Device Authentication: Ensure only trusted devices can join the network

  • Data Confidentiality: Encrypt data during transmission to protect against eavesdropping

  • Message Integrity: Prevent tampering or replay of network messages

  • Network Isolation: Prevent unauthorized devices from interfering with operations

Key Security Phases

Wi-SUN defines multiple stages of secure interaction between a device and the network. These include:

1. Authentication and Onboarding

Devices must authenticate with the network before joining. This is typically done using EAP-TLS (Extensible Authentication Protocol Transport Layer Security).

  • Devices present a digital certificate to prove identity

  • The network (via the Border Router) validates this certificate using a trusted Certificate Authority (CA)

  • Mutual authentication occurs: both sides confirm each other’s identity

This process ensures only authorized devices can join the mesh.

Authentication is not based on passwords or MAC address filtering it is cryptographic and certificate-based, providing high assurance even in untrusted environments.

After authentication, all communications within the mesh are encrypted using AES-128 at the link layer.

  • Ensures that data in transit cannot be read or modified by third parties

  • Keys are derived through secure key agreement processes during onboarding

  • Traffic between any two devices is encrypted hop-by-hop

This encryption is mandatory and enforced at the protocol level.

3. Ongoing Key Management

Wi-SUN networks support key rotation and rekeying to improve security over time.

  • Session keys can be rotated periodically or in response to events

  • Devices can re-authenticate or be removed from the network if needed

  • Broadcast traffic (e.g., advertisements) is also secured using group keys

This supports long-lived and secure mesh deployments.

Root of Trust

The entire security model depends on a trusted Certificate Authority (CA). Devices are provisioned with:

  • A unique private key

  • A public certificate signed by the CA

  • Trust anchors (CA public keys)

The Border Router and other devices use these credentials to verify identities and establish trust during onboarding.

Threat Protection

Wi-SUN security mechanisms are designed to defend against:

  • Unauthorized access (spoofing, rogue devices)

  • Passive listening (eavesdropping)

  • Message injection or alteration (tampering)

  • Replay attacks (delayed re-use of valid messages)

  • Denial of Service (limited by strict join/auth policies)

By combining strong cryptographic foundations with layered protections, Wi-SUN enables secure mesh networks in untrusted or public spaces.