Confusion
Confusion is Shannon’s cipher-design principle that the statistical relationship between key and ciphertext should be as complex as possible, preventing attackers from inferring the key from the ciphertext.
Purpose
It complicates the key’s influence on the ciphertext through nonlinear substitution (S-boxes) and is one of the two guiding principles of block-cipher design.
Mechanism
Nonlinear components such as S-boxes make every ciphertext bit depend on the key through a complex nonlinear function rather than a simple linear relation. The high nonlinearity of the AES S-box directly serves confusion.
Use cases
- Block-cipher design principle
- AES S-box design
- Cryptographic theory