| With the development of the computer and communication technology, the users'requirements for the information's safety storage, safety process and safety transmission are getting more and more exigent. As the core technology of supporting and achieving information security, cryptology has been attached great importance all over the world. Because of the properties of the high-speed, easy-standardization, easy-implementation by the software and hardware, and so on, block cipher has become the core scheme of the data encryption, digital signature, authorization, key management in information and network safety. In January 2001, Europe started New European Schemes for Signatures, Integrity and Encryption, hoping to issue a series of strong security cipher standards, including not only block cipher, but also stream cipher, Hash function, message authentication code, digital signature and public key cipher are included. Due to the excellent performance in various platforms and its ability to stand various attack tests, SHACAL-2 was chosen as European block cipher standard in February 2003.In this dissertation, using related-key impossible differential cryptanalysis to research the security of SHACAL-2, some achievements were obtained as follows:Using the key schedule algorithm of SHACAL-2, an 18-round distinguisher of related-key impossible differential was constructed.On the basis of 18-round SHACAL-2, 21-round SHACAL-2 was analysed.Guessing some parts of sub-keys, 31-round related-key impossible differential of SHACAL-2 was concluded. The conclusion of 31 reduced-round SHACAL-2 was not immune to this attack was found. Where this attack required 938 chosen plaintexts and had time complexity of about 2469.75. |
