Function secured_cipher::permutation::core::quarter_round

pub fn quarter_round(a: usize, b: usize, c: usize, d: usize, state: &mut Block)

Performs the quarter round operation on the state.

This operation modifies four words in the state as per the ChaCha20 algorithm’s quarter round rules. It involves a series of addition, XOR, and rotation operations to mix the input words.

Arguments

• a, b, c, d - Indices of the state words to be modified.
• state - A mutable reference to the 512-bit state array.