Chooses the shift value

Encrypts the message \( m \):

Enter a message (a sentence containing only whitespace and the letters A-Z) that Alice wants to send encrypted to Bob:

Use the following shift between -26 and 26 (Caesar used the shift \( 3 \)):

Hit **enter** to generate the parameters and use the
**left** and **right** arrow keys to navigate.

Hit **enter** to generate the parameters and use the
**left** and **right** arrow keys to navigate.

Alice chooses the shift value \( s \) and sends it through a secure channel to Bob.

Before Alice can encrypt the message \( m \) she needs the index in the English alphabet of each letter in the message \( m \) with the letter \( a \) starting at index \( 0 \).

Alice then use the shift value \( s \) to encrypt the message \( m \).

Before Bob can decrypt the ciphertext \( c \) he needs the index in the English alphabet of each letter in the ciphertext \( c \) with the letter \( a \) starting at index \( 0 \).

Decryption is almost identical to encryption: Instead of adding the two numbers we subtract them.

Receives the shift value \( s \)

Receives the ciphertext \( c \)

Decrypts the ciphertext \( c \):