complex substitution cipher
nounA secret code that swaps each letter for another letter in a tricky way.
The spy used a complex substitution cipher to hide the message from enemies.
OTHER MEANINGS
2. A cipher where one plaintext letter can map to several different ciphertext letters depending on its position.
The Vigenère cipher is a famous complex substitution cipher that changes its mapping for each letter.
3. A coding method that combines multiple substitution rules to make patterns harder to spot.
Breaking the complex substitution cipher required analyzing letter frequencies across several alphabets.
4. Any substitution scheme whose key or rule set is too intricate for simple frequency analysis.
Modern puzzle makers often design a complex substitution cipher to challenge experienced solvers.