QR Code Based Data Transmission in Mobile Devices Using AES Encryption

QR codes have played a significant role in mobile applications due to their beneficial properties, including small tag, large data capacity, reliability, and high-speed scanning. Any information on a cell phone can be transmitted to a second cell phone as QR code displayed on the LCD which is then captured using camera of second phone and can be decoded there. But motion-blur distortions can be introduced in captured image due to relative movements during capture. This can be solved by using orthogonal frequency division multiplexing (OFDM) modulation along with differential phase shift keying (DPSK). In this technique, large number of closely spaced orthogonal sub-carriers carries data on several parallel data streams (channels). The sub-carriers can be modulated with any of the conventional modulation techniques whereas here DPSK modulation is used. In order to make the sub-carriers orthogonal, Inverse Fast Fourier Transform (IFFT) is applied. This modulated message is encoded into QR code is displayed. The original message can be obtained by applying Fast Fourier Transform (FFT) on QR code captured by receiver, followed by demodulation. Since data is stored in phase difference, adjacent elements are less affected by the motion blur distortions. However, the private data of the QR barcode lacks adequate security protection. Due to the visual nature, 2D barcodes are subject to eavesdropping when they are displayed on the Smartphone screens. In order to add security to this data transmission, AES 128 encryption is used.