A cylinder lock includes a side bar assembly comprising a binding bar and a testing bar and code pins, each comprising a key projection, a code hole, and binding features. Partial rotation of the cylinder causes the binding bar to engage the binding features of the code pins to prevent radial movement of the pins. If the code holes of the code pins are aligned with code points of the testing bar, the testing bar is able to move inwardly with the binding bar and out of the slot so as to permit the cylinder to rotate within the bore. If one or more code holes is not aligned with a code point of the testing bar, the code point will contact the body of the code pin and thereby be prevented from moving radially inwardly out of a locking slot, thus blocking rotation of the cylinder.