Frequency analysis is a technique of cryptanalysis that exploits the statistical patterns of letters or symbols in an encrypted message. Frequency analysis assumes that the frequency distribution of the plaintext is preserved in the ciphertext, and that the frequency distribution of the plaintext is known or can be estimated. Knowing the language in which an encrypted message was originally produced might help a cryptanalyst to perform frequency analysis, as different languages have different letter frequencies, digraphs, and word lengths. For example, in English, the letter "e" is the most common, while in French, it is the letter "a". By comparing the frequency distribution of the ciphertext with the expected frequency distribution of the plaintext language, a cryptanalyst can make educated guesses about the encryption key or algorithm23. References:
* Breaking the Vigenere Cipher Flashcards | Quizlet, Section: Terms in this set (6)
* Frequency Analysis: Breaking the Code - Crypto Corner, Section: The Method
* Cipher Identifier (online tool) | Boxentriq, Section: Frequency Analysis