Abstract: Lightweight block cipher is usually used in “Internet of Thing” to protect confidentiality as well as to authentication. LBlock is a lightweight block cipher designed for tiny computing devices, such as RFID tags and sensor network nodes. The cipher algorithm iterates a Feistel structure with SP type round function by 32 rounds. Its block size is 64 bits and key size is 80 bits. The designers show that LBlock is resistant against most classical attacks, such as differential and linear cryptanalysis. This paper proposed differential fault analysis on LBlock based on different depth of fault model, the theoretical analysis demonstrates that LBlock is vulnerable to deep differential fault attack due to its Feistel structure and diffusion layer. By injecting faults in the 27th round to the 29th round, a differential fault analysis on LBlock based on a nibble-oriented random fault model is presented. The experiment shows that 4.3 faults on average could recover a round key. For reveal the whole key information, 13.3 faults on average are needed. This indicates that cryptographic devices supporting LBlock should be carefully protected.
