Codes and Ciphers :: Frequency Analysis

Frequency Analysis is a cryptanalysis technique of studying the frequency that letters occur in the encrypted ciphertext. In English, certain letters are more commonly used than others. This fact can be used to take educated guesses at deciphering a Monoalphabetic Substitution Cipher.

Here is the alphabet in order of the frequency that each letter is used.

E, T, A, O, I, N, S, R, H, L, D, C, U, M, F, P, G, W, Y, B, V, K, X, J, Q, Z

• Monoalphabetic Cipher
• Caesar Cipher
• Atbash Cipher
• Keyword Cipher
• Pigpen / Masonic Cipher
• Polybius Square
• Polyalphabetic Cipher
• Vigenère Cipher
• Beaufort Cipher
• Autokey Cipher
• Running Key Cipher

• Transposition Ciphers
• Rail Fence
• Route Cipher
• Columnar Transposition
• Polygraphic Substitution
• Playfair Cipher
• Bifid Cipher
• Trifid Cipher
• Four-square cipher

• Other Ciphers and Codes
• Book Cipher
• Beale Cipher
• Morse Code
• Tap Code
• One-time Pad
• Scytale
• Semaphore
• ASCII
• Steganography
• Techniques
• Frequency Analysis