Embedded Systems Academy

Today, EmSA released a software update for both the freely downloadable and the commercial version of CANcrypt. The update implements multiple recommendations from a security assessment.

As part of the NXP secure bootloader project, the experts at MathEmbedded did a security assessment of CANcrypt. The 43-page report examined possible attack vectors and potential weaknesses. Even to the original release the report stated: “We have not identified a straightforward attack that would allow an unauthorized attacker to easily accomplish all the steps [above].” But the latest update now fixes the discovered weaknesses or adds security notes and comments for application-specific configurations that need less security.

Just in time for the Embedded World 2018 in Nuremberg we can now show a first CANcrypt adaptation to CANopen FD. As CANopen FD already provides a direct, flexible communication method with USDO (Universal Service Data Object) supporting both broadcast and point-to-point communication, the easiest way to port the CANcrypt control messages to CANopen FD is to turn them into CANopen FD objects in the Object Dictionary. The CANcrypt control messages thus are “tunneled” through CANopen using dedicated Objects and USDO services. This allows implementing the CANcrypt grouping mechanism (similar to pairing, but for multiple devices). Authenticated messages are then exchanged based on a dynamically changing key. Each data transfer includes a random value that is used to continuously update the dynamic key.

Visit the CiA (CAN in Automation) at the Embedded World 2018 (hall 1, booth 1-630) to see the CANopen FD demonstrator and to learn more about CANcrypt. To download the free evaluation software or learn more about CANcrypt, visit our web pages for download and CANcrypt.net.

It was a lengthy process. Along with other experts we from Embedded Systems Academy participated in the CANopen FD definition group for more than 2 years now. Initially some only wanted a few changes. However as CAN FD is not backward compatible to CAN (classic CAN controllers produce error frames when they see a CAN FD message) the majority saw the chance to “dump complete backward compatibility” and add new and advanced features. The previous SDO communication (request-response scheme between one master and multiple devices) was replaced with the USDO communication – the Universal Service Data Object.

A first version of the definition of CANopen FD (CiA 1301) was released by the CiA in October this year. It is available from the CiA on request (www.can-cia.org/services/publications/). Some of the new features include:

• TPDOs can now have up to 64 bytes of data (previous 8)
• Full USDO mesh definition – every node can send client requests to every other node
• USDO communication may be a broadcast to all nodes

The USDO service allows any device to send service requests to any other device, without the need for a master or manager to be involved. This greatly improves plug-and-play support and self-configuring systems, as now each device independently can analyse its surroundings: which devices are on this network and what kind of communication objects do they have available.

We at Embedded Systems Academy are now adding CANopen FD support to all our CANopen products. The first line of products supporting CANopen FD is our CANopen Magic software for the analysis and test of networks. As of the latest release (V9.0) all CANopen Magic products support both CANopen and CANopen FD. For CANopen FD an appropriate CAN FD interface must be connected. All of our current tests have been made with the PCAN-USB FD and PCAN-USB Pro FD interfaces from PEAK System.

We are currently in the process of contacting all current CANopen Magic users to inform them about their upgrade options. If you are using CANopen Magic and have not yet received an email from us about your upgrade options, please contact us.

The last two weeks were very exciting for us: We held several papers at the International CAN Conference and Embedded World (both in Nuremberg, Germany), participated in the first CANopen FD demonstrator at both events – with the new NXP LPC54618 – and finally released our book “Implementing scalable CAN security with CANcrypt”.

The CANopen FD demonstrator at the CiA (CAN in Automation) booth showed one of the new features of CANopen FD: segmented broadcast of larger data blocks with “Universal Service Data Objects” (USDOs). This feature can be used to broadcast images, configuration tables or even firmware updates. Here, any participant could be commanded to broadcast an image to all other participants. Such use cases were almost unthinkable with classic CANopen communication.

At Embedded World, PHYTEC showed a Nano Dimension 3D printer for PCBs. Prototyping your printed circuit boards just became a lot easier and faster. The circuits are printed with a highly conductive ink. It looks like the machine can directly produce boards from Gerber files.

At the NXP booth, one of the demos featured the NXP LPC54618 microcontroller with two CAN FD interfaces. The “FD” (Flexible Data rate) allows the data portion of a CAN message to be transmitted at higher bit rates. So far, classical CAN was limited to 1 Mbps. With currently available transceivers the data rate can now be up to 5 Mbps. Also in CAN FD, the maximum payload for each message is 64 bytes compared to eight bytes in traditional CAN. The demo compared different firmware download speeds. Using CAN FD, updates can now be transferred multiple times faster than before.

The release of our book about CANcrypt (www.cancrypt.net) stirred a lot of interest and we had many engaged discussions, also with some security experts. CANcrypt is a security framework and the security level actually used is configurable. As usually, there is a trade-off: the more security you require, the more resources both in CPU time as well as in memory space you need. For a configuration on the upper end of security, proven encryption methods like AES-128 can be used. It will be interesting to see if the lower-end lightweight “Speck” cipher reaches adequate security levels, too.

A first potential weak spot in one of the initial published configurations (user section, where user’s are setting up their own security configuration) was already discovered and is currently improved. The encryption of the secure heartbeat accidentally used only limited parts of the shared dynamic key, reducing the effective key to 32-bit. However, CANcrypt supports key sizes of up to 1024-bit. The next release will use a demo where a larger key is applied properly.

To learn about our bounty program, stay tuned by joining our mailing list or following us on twitter . Within the next few weeks we will start such a program to encourage others to search for possible flaws in the CANcrypt implementation.