PRESENT, step by step

How the lightweight block cipher PRESENT works: one 4-bit S-box, one bit permutation and a simple key schedule, 31 rounds

Fundamentals of Cryptography · Ali Huseynli, Teaching Assistant · AzTU Cybersecurity Department · Fall 2026

Example

Plaintext 64 bits = 16 hex digits

Key 80 or 128 bits = 20 or 32 hex digits