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Cryptology Academy · Lesson

AES Key Expansion & Key Sizes

Explore 128, 192, and 256-bit keys and the key schedule process.

Welcome

AES expands a short key into multiple round keys through the Key Schedule. Understanding this is essential for grasping how the key permeates every round.

Why Key Expansion?

AES-128 has 10 rounds plus an initial AddRoundKey. That requires 11 round keys × 16 bytes = 176 bytes total. The key schedule expands a 16-byte master key into this full key material.

All lessons in this course

  1. Symmetric Encryption Concepts
  2. AES Structure: Rounds & State Matrix
  3. AES Key Expansion & Key Sizes
  4. Encrypting Files with AES in Practice
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