We believe that in today’s world of connected devices and heightened security concerns, digitally signing the firmware that is loaded onto your embedded or mobile device has become a top priority. One of the reasons that embedded RTOS environments do not include digital signature functionality is because it has historically not been a requirement for most embedded applications. This is no longer true today – without secure firmware updates, even if a system has been secured, a malicious firmware update can undermine much of the work which was put into securing the device.
wolfSSL is a popular tool for digitally signing applications, libraries or files prior to loading them on embedded devices and as such, it is ideal for signing firmware updates. Because wolfSSL supports the key embedded and real time operating systems, encryption standards, and authentication functionality, it is a natural choice for embedded systems developers to use when signing firmware updates.
Generally, the process for setting up code and file signing on an embedded device are as follows:
1. The embedded systems developer will generate an RSA key pair.
2. A server side script based tool is developed
a. The server side tool will create a hash of the code to be loaded on the device with SHA-256 for example.
b. The hash is then digitally signed, also called a RSA private encrypt.
c. A package is created that contains the code along with the digital signature.
1. The package is loaded on the device along with a way to get the RSA public key. The hash is re-created on the device and then digitally verified (also called RSA public decrypt) against the existing digital signature.
Digitally securing your firmware updates can:
1. Protect against updates from unauthorized parties
2. Enable a secure method for allowing third parties to load files to your device
3. Ensure against malicious files finding their way onto your device
Do you need help setting up code signing for your firmware updates? Let us know as we can help in setting up server-side scripts as well as device-side requirements. Contact us at firstname.lastname@example.org.
More background on code signing:
A great article on the topic at embedded.com: http://embedded.com/design/216500493?printable=true
General information on code signing: http://en.wikipedia.org/wiki/Code_signing