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The CTF Recipes
  • Introduction
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    • Introduction
    • General knowledge
      • Encoding
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      • Maths
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          • Greatest Common Divisor
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          • Modular binomial
      • Padding
        • PKCS#7
    • Misc
      • XOR
    • Mono-alphabetic substitution
      • Index of coincidence
      • frequency analysis
      • Well known algorithms
        • 🔴Scytale
        • 🔴ROT
        • 🔴Polybe
        • 🔴Vigenere
        • 🔴Pigpen cipher
        • 🔴Affine cipher
    • Symmetric Cryptography
      • AES
        • Block Encryption procedure
          • Byte Substitution
          • Shift Row
          • Mix Column
          • Add Key
          • Key Expansion / Key Schedule
        • Mode of Operation
          • ECB
            • Block shuffling
              • Challenge example
            • ECB Oracle
              • Challenge example
          • CBC
            • Bit flipping
              • Challenge example
            • Padding oracle
              • Challenge example
          • OFB
            • Key stream reconstruction
            • Encrypt to Uncrypt
  • 🛠️Pwn
    • General knowledge
      • STACK
        • Variables storage
        • Stack frame
      • PLT and GOT
      • HEAP
        • HEAP operations
        • Chunk
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      • Syscall
    • Architectures
      • aarch32
        • Registers
        • Instruction set
        • Calling convention
      • aarch64
        • Registers
        • Instruction set
        • Calling convention
      • mips32
        • Registers
        • Instruction set
        • Calling convention
      • mips64
        • Registers
        • Instruction set
        • Calling convention
      • x86 / x64
        • Registers
        • Instruction set
        • Calling convention
    • Stack exploitation
      • Stack Buffer Overflow
        • Dangerous functions
          • gets
          • memcpy
          • sprintf
          • strcat
          • strcpy
        • Basics
          • Challenge example
        • Instruction pointer Overwrite
          • Challenge example
        • De Bruijn Sequences
        • Stack reading
          • Challenge example
      • Format string
        • Dangerous functions
          • printf
          • fprintf
        • Placeholder
        • Data Leak
          • Challenge example
        • Data modification
          • Challenge example
      • Arbitrary code execution
        • Shellcode
        • ret2reg
        • Code reuse attack
          • Ret2plt
          • Ret2dlresolve
          • GOT Overwrite
          • Ret2LibC
          • Leaking LibC
          • Ret2csu
          • Return Oriented Programming - ROP
          • Sigreturn Oriented Programming - SROP
          • Blind Return Oriented Programming - BROP
            • Challenge example
          • 🔴Call Oriented Programming - COP
          • 🔴Jump Oriented Programming - JOP
          • One gadget
        • Stack pivoting
    • 🛠️Heap exploitation
      • Heap overflow
        • Challenge example
      • Use after free
        • Challenge example
      • 🛠️Double free
      • 🔴Unlink exploit
    • Protections
      • Stack Canaries
      • No eXecute
      • PIE
      • ASLR
      • RELRO
    • Integer overflow
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  1. Cryptography
  2. Symmetric Cryptography
  3. AES

Block Encryption procedure

PreviousAESNextByte Substitution

Last updated 2 years ago

To encrypt, AES applies 4 distinct functions to the Plain Text in a specific and repetitive order, each of which is reversible (in order to be able to decrypt later)

Every rounds made these four operations except the last one where the Mix Column is skipped

Resources

https://www.angelfire.com/biz7/atleast/mix_columns.pdf
https://engineering.purdue.edu/kak/compsec/NewLectures/Lecture8.pdf
AES demonstration tool
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githublog/rolling-your-own-crypto-aes.md at main · francisrstokes/githublogGitHub
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