MERIDIAN: A Toroid-Inspired Permutation Block Cipher for Constrained Environments

We introduce MERIDIAN, a 128-bit block cipher designed for resource-constrained environments as a lightweight alternative to AES-128. MERIDIAN retains the AES-128 interface, including a 128-bit block, 128-bit key, and 4×4 byte state, while reusing the standard AES S-box. This enables compatibility with existing AES-128 modes such as ECB, CBC, CFB, OFB, CTR, XTS, CMAC, CCM, and GCM, and allows implementations to reuse established S-box ROMs and GF(28) inverse circuits. The cipher is based on thre