Tag
block-ciphers
- Aug 20, 2026 Key Schedules: Why Subkeys Cannot Be Independent The key expansion that derives a round key from a short master key, the nonlinearity it must add, and the related-key and slide attacks that punish weak expansion. cryptography
- Apr 28, 2026 Differential and Linear Cryptanalysis as Trail Counting The two classical attacks reduce to finding high-probability differentials and high-bias linear approximations, and both are bounded by the same active S-box count. cryptography
- Feb 13, 2026 Tweakable Block Ciphers and the Cost of Sector Independence How a public tweak makes one key behave like many, why the tweak must enter before the first round, and what XTS and Threefish give up to get it. cryptography
- Mar 22, 2025 Why a Feistel Round Function Need Not Be Invertible The two-branch construction that turns any function into a permutation, why decryption reuses the encryption circuit, and what the halved diffusion rate costs. cryptography
- Nov 2, 2024 CBC-MAC Ends at the Last Block, and That Is the Problem Chaining a block cipher over a message authenticates only the final block, so variable-length messages invite splicing attacks; CMAC adds two derived subkeys to close the hole. cryptography
- Dec 25, 2023 ARX Ciphers: Carry Chains as the Only Nonlinearity Why modular addition provides nonlinearity in add-rotate-xor designs, how carries propagate as a probabilistic process, and why diffusion is measured in bits. cryptography