• https://www.technologyuk.net/science/measurement-and-units/luminous-intensity-and-photometry.shtml
• https://www.dcmsistemes.com/en/technical-data/additional-information/2/light-measurements/
• https://www.bipm.org/en/si-base-units/candela

Side-Channel Attack

In computer security, a side-channel attack is any attack based on extra information that can be gathered because of the fundamental way a computer protocol or algorithm is implemented, rather than flaws in the design of the protocol or algorithm itself (e.g. flaws found in a cryptanalysis of a cryptographic algorithm) or minor, but potentially devastating, mistakes or oversights in the implementation. (Cryptanalysis also includes searching for side-channel attacks.) Timing information, power consumption, electromagnetic leaks, and sound are examples of extra information which could be exploited to facilitate side-channel attacks.

Source: Wikipedia

TEMPEST Certification Program

TEMPEST is a U.S. National Security Agency specification and a NATO certification referring to spying on information systems through leaking emanations, including unintentional radio or electrical signals, sounds, and vibrations. TEMPEST covers both methods to spy upon others and how to shield equipment against such spying. The protection efforts are also known as emission security (EMSEC), which is a subset of communications security (COMSEC).

Source: Wikipedia

The TEMPEST Certification Program (TCP) consists of three closely related NSA programs: the Certified TEMPEST Products Program, the Certified TEMPEST Test Services Program, and the Zoned Equipment Program. Each of these programs involves partnerships with industrial companies.

Source: NSA

References

• Side-channel attack
• Tempest (codename)
• TEMPEST
• Packets of crisps and plant leaves may be spying on you

Signal, as a waveform, is the carrier of data. By alternating amplitude, frequency, phase, or any combination of them, the modulation process synthesizes the signal (as the carrier wave) and the data (as an input wave) and generates the modulated result. Modulation can be analog or digital.

Digital Modulation

There are many types of digital modulation techniques, for example:

• ASK – Amplitude Shift Keying
• FSK – Frequency Shift Keying
• PSK – Phase Shift Keying

Tutorialspoint.com has more.

References

• HOW DOES MODULATION WORK?
• Carrier wave
• Data vs Signal | Difference between Data and Signal
• Carrier-sense multiple access
• Carrier-sense multiple access with collision avoidance
• Carrier-sense multiple access with collision detection
• Digital Modulation Techniques