A team of researchers has demonstrated a technique that can detect whether a smartphone has been tampered with — without ever touching the device, and from distances of over a mile. The method, which relies on analyzing the unique radio frequency emissions of a phone’s hardware, represents a significant advance in the ongoing battle against supply chain attacks and firmware-level compromises that have bedeviled governments and enterprises for years. The research, conducted by a group at Ohio State University, focuses on what is known as radio frequency (RF) fingerprinting. Every electronic component in a smartphone — from its processor to its memory chips — emits faint, unintentional electromagnetic signals when operating. These emissions are as unique as a human fingerprint, shaped by microscopic variations introduced during the manufacturing process.…