AlphaEta™ Encryption FAQ's

Frequently Asked Questions:

How does your encryption system differ from other encryption methods?

Like other encryption methods, such as the Advanced Encryption Standard (AES), we use advanced cryptographic algorithms. However, unlike typical data encryption methods which flip the transmitted data bit parity from a zero to a one or from a one to a zero in a complex way, we actually change the data modulation format. This technique forces excess optical noise into an attacker’s measurement. This takes standard encryption technology and makes it even stronger.

Is this similar to spread spectrum techniques in the RF domain?

Typically AlphaEta modulation does not change the spectrum of the signal. This is in part because we want the signal to be compatible with traditional dense wavelength division multiplexers (DWDM) filters. You could look at the technique as a "spread signal" technology, however unlike in the RF domain the quantum noise encountered in optics can not be circumvented with technology. In other words, the amount of noise an attacker has to deal with is precisely quantifiable and does not depend on the quality of the eavesdropper’s equipment or his knowledge of the other channels in the network.

What is "physical layer" encryption?

This is encryption that works at the so-called physical layer, which is the direct interface to the transmission medium, for instance fiber optics. Encryption can and usually should be performed at higher layers too, such as in software on a personal computer. Do not confuse physical layer encryption, which can be done using standard methods such as advanced encryption standard (AES), with physics based encryption such as AlphaEta™. Although AlphaEta™ does encrypt at the physical layer, it also takes advantage of inherent optical noise in the transmitted signal. Thus, it is a physics based physical layer encryption system.

Will you be compatible with my optical equipment?

An encrypted communication system needs to use complementary protocols at the transmitter and receiver. If you put an AlphaEta™ transceiver between your usual optical equipment and the optical link, the system can function with no additional changes over all-optical networks. Our current AlphaEta™ system is not compatible with electronic switching equipment, so the signals must be decrypted before they are processed electronically.

How far can these signals propagate over optical fiber?

As in any optical system, this depends on the optical infrastructure that is being used. However, simulations of AlphaEta™ signals propagating through optical fibers show that ~5,000km reach is possible, with well over 1,000km being met in an un-optimized dense wavelength division multiplexers (DWDM) system. Experiments in excess of 800km in installed in-ground (DWDM) systems have also demonstrated the robustness of the technology.

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