CTF Cryptography

Binary#

Binary basics : https://learn.sparkfun.com/tutorials/binary ↗

Base64 basics : https://levelup.gitconnected.com/an-introduction-to-base64-encoding-716cdccc58ce ↗

Historical encoding#

• Semaphore flag signals
  
• Morse Code
  
  https://morsecode.world/international/translator.html ↗
• Braille
  
• Maritime Signal Flags
  https://en.wikipedia.org/wiki/International_maritime_signal_flags ↗
  

Cipher#

Caeser Cipher
Left shift 3

cat cipher.txt | tr "d-za-cD-ZA-C" "a-zA-Z"

The tr command translates text from one set of characters to another, using a mapping. The first parameter to the tr command represents the input set of characters, and the second represents the output set of characters. Hence, if you provide parameters “abcd” and “pqrs”, and the input string to the tr command is “ac”, the output string will be “pr”.

• https://www.dcode.fr/cipher-identifier ↗
• https://www.boxentriq.com/code-breaking/caesar-cipher ↗
• https://www.dummies.com/article/home-auto-hobbies/games/puzzles/cryptograms/cryptography-101-basic-solving-techniques-for-substitution-ciphers-195424/ ↗
• https://www.boxentriq.com/code-breaking/vigenere-cipher ↗
• https://ctf101.org/cryptography/what-is-xor/ ↗