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% 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.

QARMA is a new tweakable block cipher used for memory encryption, the generation of short tags and the construction of the keyed hash functions in future. It adopts a three-round Even-Mansour scheme and supports 64 and 128 bits of block size, denoted by QARMA-64 and QARMA-128, respectively. Their tweak lengths equal the block sizes and their keys are twice as long as the blocks. In this paper, we improve the security analysis of reduced-version QARMA against impossible differential and meet-in-the-middle attacks. Specifically, first exploit some properties of its linear operations and the redundancy of key schedule. Based on them, we propose impossible differential attacks on 11-round QARMA-64/128, and meet-in-the-middle attacks on 10-round symmetric QARMA-128 and the last 12 rounds of asymmetric QARMA-128. Compared with the previously best known results on QARMA-64, our attack can recover 16 more bits of master key with the almost complexities. Compared with the previously best known results on symmetric QARMA-128, the memory complexity of our attack in Section IV is reduced by a factor of 2 ⁴⁸ . Moreover, the meet-in-the-middle attack on 12-round QARMA-128 is the best known attack on QARMA-128 in terms of the number of rounds.

The multi-factor authentication (MFA) protocol requires users to provide a combination of a password, a smart card and biometric data as verification factors to gain access to the services they need. In a single-server MFA system, users accessing multiple distinct servers must register separately for each server, manage multiple smart cards, and remember numerous passwords. In contrast, an MFA system designed for multi-server architecture allows users to register once at a registration center (RC) and then access all associated servers with a single smart card and one password. MFA with an offline RC addresses the computational bottleneck and single-point failure issues associated with the RC. In this paper, we propose a post-quantum secure MFA protocol for a multi-server architecture with an offline RC. Our MFA protocol utilizes the post-quantum secure Kyber key encapsulation mechanism and an information-theoretically secure fuzzy extractor as its building blocks. We formally prove the post-quantum semantic security of our MFA protocol under the real or random (ROR) model in the random oracle paradigm. Compared to related protocols, our protocol achieves higher efficiency and maintains reasonable communication overhead.