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Protecting Against Side Channels with Re-keying: Meet Isap
There have been many examples of systems being cracked through side-channel analysis. One of these methods is differential power analysis (DPA) and where an intruder can obverse the operation of the encryption key through electrical disturbances. One way to overcome these problems is to only use a key for a short time, and then to generate a new one. If an intruder finds one of the keys, it will only be relevant for a short-time, before they have to rediscover the new key. This is likely to be expensive in cost and time. We thus need a way to have a pre-shared secret key and then derive our session keys from these. The pre-shared secret key can then be kept secure, and the process for generating the session key can be protected against side-channel leakage. The re-key method is fairly standard in TLS and tunnelling but has struggled in its implementation on devices. Here is Dr Owen Lo doing a live DPA attack on an embedded device:
