Classical Ciphers
Challenge Gallery
Quick Reference
| Cipher/Encoding | How to Identify | How to Decode |
|---|---|---|
| Base64 | Ends with = or ==, uses A-Za-z0-9+/ | base64 -d |
| Hex | All 0-9 and A-F | xxd -r -p |
| Morse | Dots and dashes | CyberChef or lookup table |
| Caesar | Letters only, shifted pattern | Brute force 25 shifts |
| ROT13 | Caesar shift 13 | tr 'A-Za-z' 'N-ZA-Mn-za-m' |
| Vigenere | Letters with keyword | dcode.fr or Python script |
| Rail Fence | Transposition, zigzag pattern | dcode.fr |
Cipher Identification Decision Tree
Is it dots and dashes? → Morse
Is it all hex (0-9, A-F)? → Hex encoding
Does it end with = or ==? → Base64
Is it all letters, same case? → Caesar/ROT13 (try shift)
Letters with a known keyword? → Vigenere
Scrambled letters, no pattern? → Rail Fence or substitution
Large numbers (n, e, c)? → RSA