stegoProeasy
Новогодний смех (New Year Laughter)
bug-makers
Task: 73-second stereo WAV of New Year bells and laughter hiding a flag in the ultrasonic band. Solution: a faint ~20 kHz carrier near Nyquist is on/off-keyed; isolate it with a bandpass filter, extract the amplitude envelope, threshold to ON/OFF, and decode short/long pulses as binary OOK bits into ASCII.
$ ls tags/ techniques/
ultrasonic_carrier_stegoon_off_keying_demodulationamplitude_envelope_extractionbinary_pulse_decoding
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