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LinkedIn Learning

Symmetric Cryptography Essential Training

via LinkedIn Learning


Get an overview of symmetric cryptography, an important information security tool for encrypting data.

No matter what your role, if you work with computers, you use cryptography every day. Symmetric cryptography is a common method that uses the same key for encryption and decryption of data. Faster and less resource intensive than asymmetric cryptography, symmetric cryptography is important for all IT professionals—software developers, system architects, and security engineers alike—to understand. This course delivers a practical overview of the technology, with an emphasis on high-level concepts that affect how our data is stored and transmitted. Instructor Jeremy Hansen explains the difference between single key (symmetric) and multiple key (asymmetric) algorithms, and shows how symmetric encryption affects underlying binary data. Learn about the basic ciphers used in symmetric cryptography, including substitution, permutation, and transposition, and influential symmetric-key algorithms such as the Advanced Encryption Standard and its predecessor, the Data Encryption Standard. Finally review modern block cipher modes, such as cipher block chaining (CBC), cipher feedback (CFB), output feedback (OFB), and counter (CTR), which can help authenticate large amounts of data.


  • Cryptography is everywhere
  • Basic terminology
1. Symmetric Cryptography
  • Cryptography's role
  • Kerckhoffs's principle
  • Symmetric keys
  • Block vs. stream ciphers
2. Representing and Manipulating Binary Data
  • Binary representation
  • Characters
  • Integers
  • Floating point numbers
  • Boolean logical operations
  • Padding
3. Fundamental Algorithms and Components
  • Simple substitution ciphers
  • Polyalphabetic substitution ciphers
  • Permutation and transposition ciphers
  • Simple one-time pads with XOR
  • S-Box and P-Box
  • Feistel ciphers
  • Linear-feedback shift registers (LFSRs)
4. Symmetric Algorithms
  • The Data Encryption Standard (DES)
  • The Advanced Encryption Standard (AES)
  • AES and DES in practice
  • The RC4 stream cipher
5. Block Cipher Modes
  • Introduction to block cipher modes
  • Cipher block chaining (CBC)
  • CFB: Cipher feedback
  • OFB: Output feedback
  • CTR: Counter
  • Next steps

Taught by

Jeremy A. Hansen

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