CoAPs

Protocol Security

Establishing a secure connection requires a handshake that verifies the identity of the client and the server. This process in CoAPs involves negotiation of cipher suites that align with the processing limits of low-power microcontrollers. The protocol relies on pre-shared keys or raw public keys to establish trust.

Once the handshake completes, the session keys protect against eavesdropping and injection attacks.

Memory Management

The RAM overhead of holding cryptographic session states represents a major design constraint for constrained nodes. Since CoAPs runs over UDP, the application layer must handle packet retransmission and packet reordering. The integration must allocate sufficient memory buffers to handle fragmented datagrams during the handshake phase.

This constraint often dictates the selection of hardware with dedicated hardware acceleration for asymmetric cryptography. Engineers configure the maximum transmission unit size to prevent packet fragmentation on the wireless link.

Integration Handover

Compliance testing of the communication stack verifies that the security layer does not exceed the transmission timeout limits. Hardware developers run test sequences to measure the power consumption of CoAPs handshakes under poor signal conditions. This step is completed prior to the final qualification of the connected product.

The results verify the integrity of the data transfer across the product life cycle.