Two Square Cipher
Description
A two square tables are prepared. The squares are filled with the letters
of the alphabet, at least one of them with a mixed
alphabet. For example, the key word KEY applied to a 25 letter
alphabet gives the following table:
| 1st plain text
2nd cipher text |
|
2nd plain text
1st cipher text |
| A |
B |
C |
D |
E |
|
K |
E |
Y |
A |
B |
| F |
G |
H |
I |
K |
|
C |
D |
F |
G |
H |
| L |
M |
N |
O |
P |
|
I |
L |
M |
N |
O |
| Q |
R |
S |
T |
U |
|
P |
Q |
R |
S |
T |
| V |
W |
X |
Y |
Z |
|
U |
V |
W |
X |
Y |
To encipher the text, is is split into groups of two letters. If the number
of the letters in the text is odd, a random letter must be appended (CipherClerk's Applet
appends the first letter of the message): MESSAGE becomes ME
SS AG EM. The two letters are located in the plain text squares
and replaced by the letters found in the same row of the cipher text
squares above or below the other letter: ME is thus replaced
by OO, AG by EB.
CipherClerk's Applet's implementation requires two keyword unless you choose
No Second Key. You may choose from alphabets with 25 and 36 letters.
Finally, you may choose either to have horizontal orientation (the
two squares side by side as shown above) or vertical orientation
(one square below the other).
To proceed, you may