US police use radio encryption to stop iPhone eavesdropping

Anxiety over the public snooping of police radios using smartphones is persuading a growing number of US police forces to take the controversial step of moving their communications to fully-encrypted operation.

The Washington D.C. police department has become the latest to adopt radio encryption after mounting evidence that criminals were listening in to police conversations using cheap applications running on mass-market phones, the Associated Press has reported.

The same adoption is happening in Orange County Florida, Santa Monica California and even small out-of-the-way towns in Kansas, the agency discovered. Although scanning open analogue and digital radio services has been possible for decades using fixed radios, doing so reliably from any location or while moving is extremely difficult - the frequencies vary widely for different services across county and state boundaries.