AES.sboxCompute

private ubyte sboxCompute(uint input) pure nothrow @nogc @safe

Computes the AES S-box in constant time.

This implementation scans all 256 table entries, using masking to select the correct value without data-dependent branching. While slower than a direct table lookup, this prevents cache-timing attacks.

Constant-Time Guarantee: All 256 table entries are accessed

regardless of the input value, ensuring uniform timing.