If radio waves are just non-visible light waves that are picked up by a vibrating rod, how does a radio wave get “encrypted” so that it can’t be picked up unless it’s unencrypted?
Edit: Everyone keeps commenting that the content of the message is what’s encrypted, not the radio waves itself, but that’s not what I mean. Someone answered that digital signals themselves can be modulated or disguised, which is what I meant when I asked
In: Technology
*Signals* can be encrypted, not necessarily the medium carrying them.
Many radio transmissions are now digital, rather than the analog methods used since its inception. Instead of converting sound pressure directly to varying voltage, a series of pulses are transmitted that correspond to bits.
Most everything we call “wireless” today is digital, such as 4G, Wi-Fi, and Bluetooth. Those data streams can be obscured with encryption, even if the transmissions themselves are still visible to other parties. Converted directly to an audio signal without decoding, all you would hear is a series of beeps, or noise if the signal is too dense. Digital encoding is itself a form of encryption if eavesdroppers do not know what encoding scheme is used, or do not possess the proper decoding equipment.
Even with analog means, the transmitted messages can still be encrypted as described in other answers. They can also be made difficult to track or eavesdrop using methods like spread spectrum (use more than one frequency, and divide the signal among these) or frequency hopping (changing the frequency in a pattern). The intended parties decide on the system used in advance.
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