The Design And Implementation Of A QR Code Encryption Algorithm Based On Ising Model

The bar code is an information technique which integrates data collection,encoding, printing and identification. It can be quickly recognized by machines, andtherefore has extensive applications. Bar codes include one-dimension andtwo-dimension codes, and the latter can carry more information. QR (Quick Response)bar code is the most popular two-dimensional bar code. Because QR code is commonlyadopted in business applications, it is important to protect information encoded in QRboth for practical purpose and for theoretical research. In this thesis, two QR encryptionalgorithms are proposed based on Ising model and QR encoding process.The main work in this thesis can be divided into following parts:First of all, the current situation of the encryption research on QR code is analyzedand the main content of the subject in this paper is described. Then some fundamentalknowledge of cryptology and image encryption techniques is introduced, followed bydetailed introduction about Ising model and QR code.Secondly, a QR code encryption algorithm is proposed, which is incompatible withthe standard format of QR code. There are several rounds of encryption in the executionof the encryption algorithm and the plaintext participates in each round to achieve thepurpose of information diffusion. As a result, the outcome has plaintext sensitivity.Similarly, the output of decryption has ciphertext sensitivity. Analysis of the impacts ofparameters on the encryption demonstrates why the algorithm is incompatible.Extensive experiments show that the cryptographic properties of the proposed algorithmare acceptable.Thirdly, another QR code encryption algorithm is proposed, which is compatiblewith standard format of QR code. There are several rounds of encryption executed togenerate an encryption matrix which is used to encrypt the plaintext. The plaintext onlyparticipates in one encryption cryptographic operation. For this reason, the outcomedoes not have plaintext sensitivity. Similarly, the output of decryption does not haveciphertext sensitivity. Extensive experiments demonstrate that the proposed algorithmpossesses good properties. Compared with the previous algorithm proposed in thisthesis, this one solves the incompatible issue and is more efficient and effective.