Opampsteg

Opampsteg is a niche concept in steganography that refers to techniques for hiding information within the behavior of operational amplifier (op-amp) circuits. Unlike digital steganography, which conceals data in file formats or protocols, opampsteg exploits subtle variations in analog signals produced by circuits that use op-amps, such as audio or sensor signals. The carrier signal is kept within normal operating parameters so that the hidden data remains unnoticed by standard monitoring.

In broad terms, opampsteg encodes bits by modulating aspects of the op-amp’s response without visibly altering the host signal. Potential techniques involve tiny amplitude adjustments, phase shifts, or controlled exploitation of the op-amp’s nonlinearities, saturation behavior, or bias conditions. The goal is to produce changes that are perceptible only to a receiver equipped with the appropriate detector and timing information, while remaining benign to ordinary functionality.

Detection and extraction typically require synchronization between sender and receiver. A demodulator may use envelope detection, correlation, or differential measurements to separate the covert signal from the host. Successful recovery depends on stable operating conditions, since temperature drift, component tolerances, and aging can affect the encoded representation.

Opampsteg is not widely standardized or extensively documented in peer-reviewed literature; references are mostly experimental, theoretical, or discussed in hobbyist and security-focused forums. It is primarily viewed as a concept for study and demonstration of covert channels in analog hardware, rather than a practical mainstream technique. See also steganography, covert channels, and analog signal processing.