Fault-tolerant and error-correcting 4-bit S-boxes for cryptography applications with multiple errors detection

In this paper, fault-tolerant and error-correcting 4-bit S-boxes for cryptography applications with multiple error detection and correction are presented. Here, we consider three applicable 4-bit S-boxes, which are used in lightweight block ciphers PRESENT and PRINCE and lightweight hash function SPONGENT as basic circuits for the error-correcting method. The proposed design does not require two-rail checkers for detecting the error and the redundant S-box for repairing the S-box. This reduces the overall area consumption of the proposed design. In the proposed approach, the error-correcting part of the circuit is implemented concurrently with the main circuit of the S-box. Therefore, the four output bits of the S-box are tested individually to improve the efficiency of fault diagnosis. The proposed fault-tolerant S-box method can detect and repair transient and permanent faults simultaneously. In other words, the structure can detect and repair single, double, triple, and quadruple faults at a time. The comparison with the famous fault-tolerant and error-correcting methods shows that the ability of the proposed method to create error-correcting 4-bit S-boxes is acceptable. The performance of S-boxes with error and with our error-correcting method has been investigated in the image encryption. The analyzes show that the proposed method has the desirable results. Also, the area and timing results, in 180 nm CMOS technology, show the proposed structures are comparable in terms of area and delay overheads than those of the other methods.