Side-channel attacks have become a significant threat to cryptographically protected devices, exploiting information leaks through physical parameters like power consumption and electromagnetic (EM) radiation.
These attacks do not target the cryptographic algorithm itself but rather the external physical characteristics of a device.
Recent advancements in technology have made such attacks more accessible and affordable, with tools like antennas costing less than £10 and modern computers enabling faster processing times.
Analysis of the PRESENT Cipher
A recent study focused on the PRESENT lightweight cipher, an ultra-lightweight symmetric block cipher introduced in 2007 and approved by ISO/IEC.
It features a Substitution-Permutation Network (SPN) with a 64-bit block size and offers 80-bit and 128-bit key versions.
The research aimed to investigate the EM side-channel robustness of PRESENT using a correlation attack model, specifically targeting the Substitution box (S-box) due to its non-linear properties.
The study successfully retrieved 8 bytes of the 10-byte encryption key using a minimum of 256 EM waveforms, significantly reducing the processing time compared to previous studies that required thousands of waveforms.
The methodology involved capturing EM waveforms using Near Field (NF) EM Compatibility (EMC) probes and analyzing them through simple EM analysis (SEMA), simple EM frequency analysis (SEMFA), and correlation EM analysis (CEMA).
The results showed that the induced voltage increases with the diameter of the probe, and the H10 probe was found to be the most suitable for the task.
Filtering specific frequencies enhanced the correlation magnitudes, leading to more accurate key retrieval.
This breakthrough reduces the time required for brute force analysis, as only two bytes remain to be determined after retrieving eight.
Implications and Future Directions
The study highlights the importance of side-channel analysis in ensuring the security of cryptographic algorithms before their deployment.
While PRESENT appears robust against EM side-channel attacks when used in its full-round version, the potential for leakage remains a concern.
Future research may explore using different hardware, such as Field Programmable Gate Arrays (FPGAs), and other coefficient types to further evaluate the strength of PRESENT.
Additionally, implementing countermeasures against EM leakages is crucial for manufacturers to protect devices from such vulnerabilities.
