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Security Fundamentals & Crypto · Advanced

Grover's Algorithm

Quantum search algorithm offering a quadratic speedup that effectively halves symmetric key and hash security.

Definition

Grover's algorithm reduces brute-force search from 2^n to about 2^(n/2) operations. AES-128 would offer roughly 64-bit quantum security in theory, though practical overheads make the attack much harder. The mitigation is simply using larger keys, such as AES-256 and SHA-384 or larger.

Example

CNSA 2.0 requires AES-256 to retain a large margin against Grover's algorithm.

Exam tip

Double symmetric key length to counter Grover; no new algorithms needed.

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