Frequency Analysis & Cryptanalysis Basics
Break classical ciphers using letter frequency statistics.
Welcome
Frequency analysis is the art of using statistical patterns in language to break substitution ciphers. It was discovered in 850 CE and is still relevant today.
English Letter Frequencies
The most frequent English letters (approx): E(12.7%), T(9.1%), A(8.2%), O(7.5%), I(7.0%), N(6.7%). If you see 'X' appearing 12% of the time in ciphertext, X likely represents E.
All lessons in this course
- Caesar Cipher Mechanics
- Atbash & Affine Ciphers
- Vigenère & Polyalphabetic Ciphers
- Frequency Analysis & Cryptanalysis Basics