Lea Vohar (2019) QR codes. EngD thesis.
Abstract
In this thesis QR codes are considered. A QR code is a two-dimensional bar code for machine-readable data. Data are first encoded using Reed-Solomon error correction codes to ensure readability even if the QR code is damaged. In the first part of the thesis we first review finite fiels that are needed in the sequel. Next we introduce error correction codes and define Reed-Solomon codes. Reed-Solomon codes attain the Singleton bound which means that they are capable of correcting the maximum possible number of errors with respect to to the number of symbols that are added to the message. We also present algorithms for coding and decoding Reed-Solomon codes, which are used for QR codes. In the second part of the thesis we describe the structure of the QR code symbol in detail. We explain how the message is encoded in the QR code and how a QR code is decoded. We illustrate these procedures with examples. Finally, we discuss the security of QR codes and possibilities of their abuse.
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