Set of servers for “machine-to-machine” communications using public key infrastructure

What is this patent about?

’464 is related to the field of Machine-to-Machine (M2M) communications, specifically addressing the challenges of maintaining secure and energy-efficient links between remote modules and application servers. In typical M2M environments, devices frequently enter sleep states to conserve battery, causing intermediate firewalls to tear down connection states. The background context involves the need for a robust Public Key Infrastructure (PKI) that can handle dynamic IP addresses and the secure rotation of cryptographic keys without requiring manual intervention like swapping SIM cards.

The underlying idea behind ’464 is the use of an intermediate server set that acts as a secure bridge, managing the asymmetric cryptographic lifecycle of remote modules while shielding them from the overhead of complex server-side protocols. The core insight is to allow a module to internally derive new public/private key pairs based on server-provided parameters and then authenticate these new keys using a previously established trust anchor. This enables the system to update security postures and rotate keys over the air while ensuring that instructions from an application server are only delivered when the module is active and reachable.

The claims of ’464 focus on a multi-step handshake and key derivation sequence performed by a set of servers to manage a module located behind a firewall. The process involves verifying a module's identity via an initial public key, providing specific cryptographic parameters to the module for the generation of a new key pair, and then authenticating a second module public key derived from those parameters. The independent claims specifically cover the logic of receiving a module instruction from an application server and waiting to transmit it until the module reconnects from a new, different source IP:port number, ensuring the data is encrypted with the newly verified key.

In practice, the invention operates by utilizing a shared module database and a module controller that monitors for incoming UDP datagrams. When a module wakes from a dormant state, it may have a different network-assigned address; the server detects this change and uses the most recent source IP:port to bypass firewall restrictions. The server set manages two distinct security layers: a secure connection (such as TLS) with the application server using one set of keys, and a more efficient, potentially ECC-based encryption layer with the module using the derived keys. This dual-layer approach allows the module to remain low-power while the application interface remains compatible with enterprise standards.

’464 differs from prior approaches by eliminating the need for persistent, high-overhead security tunnels like IPSec or standard TLS between the module and the final application. Instead of requiring the module to re-negotiate complex handshakes after every sleep cycle, the server set maintains the stateful association between the module identity and its current cryptographic keys. By allowing the module to derive its own keys and authenticating them through a shared secret or prior key, the system provides a scalable way to refresh security without the logistical burden of physical credential management or the energy drain of traditional session establishment.