Ciphers are used to produce messages which can be understood only by the sender and authorized

receivers, so ciphers can be used for secret correspondence in situations where the message may fall

into the wrong hands. The process of converting a readable message (the plaintext) to an unreadable

form (the ciphertext) is called “encryption” converting ciphertext to plaintext is called “decryption”.

The Vigenere cipher was developed by Biaise de Vigenere around 1586, for French diplomatic and

military communications. The Vigenere cipher uses a keyword and a 26-by-26 matrix of letters to

substitute plaintext letters with ciphertext letters, and vice versa. The message sender and receiver

must both use the same matrix and keyword.-Ciphers are used to produce messages which can be understood only by the sender and authorized

receivers, so ciphers can be used for secret correspondence in situations where the message may fall

into the wrong hands. The process of converting a readable message (the plaintext) to an unreadable

form (the ciphertext) is called “encryption”　converting ciphertext to plaintext is called “decryption”.

The Vigenere cipher was developed by Biaise de Vigenere around 1586, for French diplomatic and

military communications. The Vigenere cipher uses a keyword and a 26-by-26 matrix of letters to

substitute plaintext letters with ciphertext letters, and vice versa. The message sender and receiver

must both use the same matrix and keyword.