Function verify_known_key_ordered 

pub fn verify_known_key_ordered(key_order: &[u8]) -> Program

Known-key verification core: [S]B + [k](-A) as two fixed-base walks.

Digit slots 0..54 hold S, slots 64..118 hold k = H(R ‖ A ‖ M) mod l, and the key table holds point_table(-A). Outputs projective X, Y, Z (indices 0..3); the controller encodes the point and compares it with R. key_order is the lookup order of the key chain (the base chain uses LOOKUP_ORDER).

The two scalars give two independent chains, so this program does not split each walk into odd and even chains as fixed_base does.