AbstractSymmetric ciphers are widely used to provide secure communications and data storage. The ubiquitous nature of the symmetric cipher, indicates that its underlying structure is worth study. Block ciphers are the most common form of symmetric cipher. Within all block ciphers will be exclusive or operations and transpositions, but these operations do not provide non-linearity for the cipher. S-box’s (substitution boxes) provide the core non-linearity of block ciphers. An s-box must exhibit certain properties in order to support the overall security of a given block cipher. AES is one of the most widely used symmetric algorithms. With growing awareness of cryptographic backdoors, some organizations have expressed an interest in modifying their AES implementations in order to provide a private version of AES for use only within their own organization. This lecture briefly summarizes s-box structure and implementation, as well as the criteria for an acceptable s-box. Then three different methodologies for effectively altering the AES s-box are explored.
About this LectureNumber of Slides: 25
Duration: 60 minutes
Languages Available: English
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