Abstract
Mobile payments today are dominated by two technologies: NFC and optical barcodes. Although NFC offers stronger security, better usability, and improved accessibility, nearly half of smartphones either lack NFC hardware or keep it disabled in practice. As a result, many users are forced to rely on barcode-based payments, despite their weaker security guarantees and less favorable user experience. In this work, we present MagCode+, a physical side-channel communication mechanism that enables an NFC reader to transmit data directly to a smartphone camera by generating standards-compliant barcodes through benign magnetic interference on the CMOS sensor. Unlike prior approaches that depend on private, non-standard protocol stacks, MagCode+ employs a format-accurate modulation and decoding pipeline that produces barcodes natively compatible with smartphone barcode decoders, while remaining fully consistent with existing payment and retail protocols. We prototype both the NFC-side waveform generation engine and the smartphone-side decoding module, and evaluate the system across 11 devices from major vendors (e.g., Samsung, Huawei, Xiaomi). MagCode+ natively supports six major barcode standards, achieves throughput up to 537bps, and delivers widely used payment barcodes (e.g., Code128) within 0.21s. These results demonstrate that MagCode+ provides an immediately deployable bridge between existing NFC infrastructure and non-NFC smartphones, without requiring any modification to current barcode-based payment ecosystems.
Demo: NFC-Enabled Communication via Commercial Barcodes
Compatibility: Universal Support for Commercial Barcode Standards
Our approach is compatible with nearly all existing commercial barcode standards, ensuring broad applicability across diverse retail and industrial environments.
This work has been accepted for publication in the IEEE Internet of Things Journal. The article is available on IEEE Xplore.