Using RFID to Protect System Firmware

Since the interrogator (tag reader) initiates communications in most RFID protocols, the tag needs to have a challenge always ready (Figure 1). The tag reader reads the cryptographic challenge and generates a response for the tag to validate. The tag updates its challenge upon a successful response, so that no challenge is used twice. Counterfeiters, not possessing the proper response to a challenge will not be able to obtain the labeling information from the device and, therefore, will not be able to clone the label.

Not all RFID solutions support this challenge-response scheme, so security minded engineers should verify that the RFID tags have this capability.

Managing interrogator side secrets (keys) allows authentic manufacturers to prevent counterfeiters from reading their product information, thus preventing illegal cloning of their productís label. Cloned products with unauthentic labels will be identified as fakes.

The double- challenge- response scheme is similar to the challenge-response scheme with the additional ability for the interrogator to also challenge the tag (Figure 2). This scheme requires both interrogators and tags to independently store asymmetric secrets to use in the process. This mutual authentication scheme guarantees the identity of both the host and the RFID tag. This is particularly useful where authentic interrogators need to provide field updates to authentic tags. For example, interrogators in a mobile electronic application, like smart phone firmware upgrade equipment at a supplier location may need to ascertain the authenticity of the tag (product) before issuing a firmware upgrade.

Adding Optional Security for Data Protection

The challenge-response and double challenge-response RFID security schemes provide effective anti-counterfeiting solutions. These solutions by themselves, however, do not offer data protection for data communication between the interrogator and the tag. An eavesdropper, for instance, can wait until completion of the challengeresponse process, and intercept information between interrogator and tag. Depending on the application, they may even modify the information to suit their needs.