Analysis of EM emission from cryptographic devices

Electromagnetic information leakage is an attack against secret information in an information-processing circuit, and realized by observing electromagnetic radiation around the circuit. When a cryptographic module works, electrical fluctuation in it can be conducted to peripheral circuits by ground bounce, resulting in electromagnetic radiation. The authors demonstrate the mechanism through experiments with an FPGA board which processes the standard cipher AES (Advanced Encryption Standard). Measurement of electromagnetic radiation from a power cable showed that correlation electromagnetic analysis (CEMA) reveals the secret keys. The leakage is possible even if voltage regulators are placed as a disturbing factor between the module and the measurement points. Circuit-level countermeasures against CEMA are also discussed, and an information suppression technique is proposed by the authors.