Research And Implementation Of White Box Cipher Technology For Intelligent Terminals

With the development of Internet of Things,smart home,Internet of Vehicles and wearable devices are gradually entering into everyone's daily life.T-Box terminal of Internet of Vehicles and Android smart phones are often exposed in white-box attack environment.They are vulnerable to attack from malicious attackers using reverse tracking,setting breakpoints,dynamic analysis and debugging.So,it is necessary to protect private information,especially key information in these terminals.In recent years,the State Cryptography Administration has issued various national secret algorithms,and some software vendors have also begun to use them as their data encryption algorithm.Therefore,whether traditional AES or DES block ciphers or national ciphers are used as the data encryption algorithms in intelligent terminals,it is vital to solve the problem about secure storage of keys.After studying the issue of secure storage of keys in mobile smart terminals,the thesis proposes a White-box implementation of the AES cryptographic algorithm and the SM4 cipher algorithm.Compared with traditional cryptographic algorithms,secret key information is defused and confused so that it will not be exposed in the algorithm in plaintext.The work in the thesis mainly includes the following points:1.Learn AES cryptography algorithm and related mathematics such as finite fields,study and implement white-box AES cryptography algorithm based on lookup tables.Use docker containers to complete the generation and distribution of T-Box lookup tables,adopt NDK-based development,complete the implementation and application of the white-box AES cryptography algorithm for Android mobile phone,test the correctness and performance of its encryption and decryption,analyze its security.2.Design and implementation of client-server white-box SM4 cryptographic algorithm architecture,including the secure module come up with the lookup table generation module,affine transformation matrix generation module and code module etc.the functional module includes SM4 encryption and decryption module,white-box SM4 encryption and decryption etc.3.Analyze the common operation modes,plaintext grouping and filling modes in encryption process of the block cipher algorithm,applying them into white-box AES and white-box SM4 cryptography algorithms.4.Learn related knowledge of software obfuscation and combine code obfuscation with white-box AES algorithm,implementing white-box AES algorithm based on self-modifying state machine.