Function pow_montgomery_form 

pub const fn pow_montgomery_form<const LIMBS: usize, const RHS_LIMBS: usize>(
    x: &Uint<LIMBS>,
    exponent: &Uint<RHS_LIMBS>,
    exponent_bits: usize,
    modulus: &Uint<LIMBS>,
    r: &Uint<LIMBS>,
    mod_neg_inv: Limb,
) -> Uint<LIMBS>

Performs modular exponentiation using Montgomery’s ladder. exponent_bits represents the number of bits to take into account for the exponent.

NOTE: this value is leaked in the time pattern.