With the enlargement of wireless technology, Internet of Things (IoT) is emerging as a promising approach to realize smart cities and address lots of serious problems such as safety, convenience and efficiency. In order to avoid any possible rancorous attacks, employing lightweight cryptosystems is most effective to implement encryption/decryption, message authentication and digital signature for security of the IoT. LED is such a lightweight cipher with two flexible keysize variants in the IoT. Since its designing, a multitude of fault analysis techniques in chosen plaintext attacks focus on provoking faults on LED to derive the 64-bit and 128-bit secret keys. It is vital to investigate whether injecting faults allows breaking LED while the attackers have the weakest ciphertext-only attacking ability. This study presents ciphertext-only fault analysis with six different distinguishers on LED. The simulating experiments show that our analysis can recover its 64-bit and 128-bit secret keys with over 99 percent probability using the SEI, GF, GF-SEI, ML, HW and MAP distinguishers. The attack can not only improve the attacking efficiency, but also decrease the number of faults. The fault locations can be injected into the deeper round. It provides vital reference for security analysis of other lightweight ciphers in the IoT.

Differential power analysis (DPA), as a very practical type of side-channel attacks, has been widely studied and used for the security analysis of cryptographic implementations. However, as the development of the chip industry leads to smaller technologies, the leakage of cryptographic implementations in nanoscale devices tends to be nonlinear (i.e., leakages of intermediate bits are no longer independent) and unpredictable. These phenomena make some existing side-channel attacks not perfectly suitable, i.e., decreasing their performance and making some common used prior power models (e.g., Hamming weight) to be much less respected in practice. To solve the above issues, we introduce the regularization process from statistical learning to the area of side-channel attack and propose the ridge-based DPA. We also apply the cross-validation technique to search for the most suitable value of the parameter for our new attack methods. In addition, we present theoretical analyses to deeply investigate the properties of ridge-based DPA for nonlinear leakages. We evaluate the performance of ridge-based DPA in both simulation-based and practical experiments, comparing to the state-to-the-art DPAs. The results confirm the theoretical analysis. Further, our experiments show the robustness of ridge-based DPA to cope with the difference between the leakages of profiling and exploitation power traces. Therefore, by showing a good adaptability to the leakage of the nanoscale chips, the ridge-based DPA is a good alternative to the state-to-the-art ones.

Side-channel attacks are an increasingly important concern for the security of cryptographic embedded devices, such as the SIM cards used in mobile phones. Previous works have exhibited such attacks against implementations of the 2G GSM algorithms (COMP-128, A5). In this paper, we show that they remain an important issue for USIM cards implementing the AES-based MILENAGE algorithm used in 3G/4G communications. In particular, we analyze instances of cards from a variety of operators and manufacturers, and describe successful Differential Power Analysis attacks that recover encryption keys and other secrets (needed to clone the USIM cards) within a few minutes. Further, we discuss the impact of the operator-defined secret parameters in MILENAGE on the difficulty to perform Differential Power Analysis, and show that they do not improve implementation security. Our results back up the observation that physical security issues raise long-term challenges that should be solved early in the development of cryptographic implementations, with adequate countermeasures.

Differential fault analysis is one of the most efficient side channel attack techniques that threat the security of block cipher. However, it often requires a penultimate or an antepenultimate round faulty encryption and is not suitable for middle round fault. This paper presents attacks combining differential fault analysis with statistical cryptanalysis techniques against lightweight ciphers. The analysis makes use of statistical cryptanalysis techniques in practice rather than theoretically, and exploits the weakness of bit-permutation adopted by many lightweight block ciphers under fault attack. Specific attacks against PRESENT and PRINT\scriptsize{CIPHER} \normalsize are given to prove the validity. The result shows that about one fifth of the iterative rounds are needed to be protected for these lightweight ciphers with bit-permutation.