Cryptanalysis of the Vigenère Cipher: How Kasiski's Test Reveals the Secret 🔍

The Vigenère Cipher was long regarded as a secure encryption method and unbreakable. In 1863, however, the Prussian infantry major Friedrich Wilhelm Kasiski published a method for determining the key length used in the encryption. This made the Vigenère cipher vulnerable. This short shows how Kasiski's test is carried out.

See the full video on how to break the ciphertext after performing the Kasiski examination:
https://youtu.be/Pl6AcJOEFvE