Symmetric Cryptography

Welcome to Symmetric Cryptography! Symmetric cryptography relies on shared secret key to ensure message confidentiality, so that the unauthorized attackers cannot retrieve the message. The course describes substitution and transposition techniques, which were the bases for classical cryptography when the message is encoded in natural language such as English. Then, we build on product ciphers (using both substitution and transposition/permutation) to describe modern block ciphers and review the widely used cipher algorithms in DES, 3-DES, and AES. Lastly, we enable the use of block ciphers to support variable data length by introducing different modes of block cipher operations in ECB, CBC, CFB, OFB, and CTR modes. This course is cross-listed and is a part of the two specializations, the Applied Cryptography specialization and the Introduction to Applied Cryptography specialization

• Build product ciphers using substitution and transposition techniques
• Explain modern block cipher algorithms such as DES, 3-DES, and AES
• Apply different block cipher operation modes to secure variable data lengths

• Basic familiarity with the topic and its common terminology
• Readiness to practice through applied exercises or case-based work