An Idea: Fiber Optics Eavesdropping

The “mirror” consolidates and reflects the signal through the magnification lens and into the pirating fiber to the fiber optics eavesdropping attacker.


This idea is just that, an idea bout tapping fiber optics to conduct fiber optics eavesdropping. It is not being developed, has not been developed, and there are no know projects that are testing or assessing the viability of this idea. This idea is solely for the purpose of proposing a creative idea that can be leveraged for thought exploration. Attempting to operationalize this idea is not recommended, supported, or aligned with the posting of this idea, this website, or the author of this idea. Any harm, activity, legal consequence, or other repercussions for any entity that attempts to pursue, operationalize, weaponize, or use this idea is done so without consent, without knowledge, without cooperation, and without approval of this website or the author of this content. This is an idea that is infeasible to all but the most sophisticated (well funded) entities and even those entities most likely would not spend the money to adopt this idea so don’t freak out, don’t try to mitigate this idea, and do not start pulling your fiber cables out of your systems.

Preamble Ramble

I has long been stated that using fiber optic cables is reasonably secure from eavesdropping, but is it? I have taken a few minutes to ponder this belief and try to determine how accurate it actually may be and the conclusions I have come to believe to be true are startling.

The Basic Idea

It seems, at least in theory, that tapping a fiber cable may actually be possible. Not only may it be possible, it may be fairly simple, maybe. Here is the idea that I would like to place in the universe. The creation of a small box that can be clamped onto a fiber-optics line that will splice the line in such a way that will permit the un-spliced path to continue to exist uninterrupted while diverting the signal to a second line controlled by the entity that applied the clamp. Of course, there will need to be a unique block for every discrete type of fiber optic cabling.

Fiber Optics Eavesdropping Box Outer Sections

The box would consist of three sections, the two outside sections that will house the pirated fiber optic line and the central chamber that holds the eavesdropping mechanisms. Visualize three small hand-held sized travel trunks connected end to end. The outside sections are fairly simplistic, they open on a hinge laterally aligned with the longest side of the central chamber. Once opened you can see very sharp razor blade vertically inset into the central mechanism by 0.1 millimeters. Below the razor is the exposed end of a fiber cable that matches the cable to be abused. The base of the inside of the side chamber are crafted to uniquely glide and hold the abused fiber into the correct position and alignment. The inside of the “top” of the side chambers is designed to add pressure to the fiber cable to “clamp” it in the correct position. When fully constructed and in use the device may look like a “T” with a small device attached to the three-way intersection.

Fiber Optics Eavesdropping Box Central Chamber

The central chamber has a few, extremely specific and finely tuned, pieces of equipment. The first is the piece of fiber cable that is used to actually abuse the victim fiber. It is a matching fiber cable but has a 3mm section of shielding removed in the middle. On one side of that 3mm section is a concave, highly polished, piece of mirrored precious metal. On the other side is a 3mm in diameter magnification lens that is placed flush against the pirated line and the line used to carry the pirated signal to the abuser.

How Fiber Optics Eavesdropping May Work

As the signal is transmitted by the sender it travels to the recipient, all good. To install this device an attacker may take a fiber line, ensure it is fairly (extremely) clean and free from debris, soil, dust, and oils. Open the end compartments of the device and lay the victim cable on the device. Close the two end compartments and lock them shut. As the end compartments are closed the razor will slice the fiber as the contours glide the fiber into alignment with the internal components of the device. Additionally, as the compartments close the “lid” of the compartment adds a reasonable amount of pressure to the spliced fibers to force them into flush contact with the internal pirating fiber. As the sender transmits fiber data it enters the device, passes the exposed portion of line and continues onto the recipient with a small amount of degradation. While passing through the device the exposed portion of fiber permits the signal to “escape” towards the pirating wire and the “mirror”. The “mirror” consolidates and reflects the signal through the magnification lens and into the pirating fiber to the attacker.

The Upgraded Option

An optional deviation from this design would be to replace the “mirror” and “lens” with a sensor and laser. As the victim signal passes through the device the sensor “reads” and interprets the signal then sends the interpreted data to the laser. The laser then reproduces the signal on the attacker’s fiber line. This option would require a power source commensurate with the amount of data wishing to be pirated. For instance, a small battery (AAA) may produce a few minutes of data whereas a mobile solar panel might enable long-term theft. Additionally, this option could permit the victim line to be completely spliced with the inclusion of repeater technology that repeats the data on both the legitimate victim and the attacker’s fiber lines.


Most likely not possible but just a creative thought exercise that may be worth exploring in a couple years as technology more readily permits the creation of micro lenses and other advanced micro components.