𝐂𝐨𝐝𝐞𝐬 𝐚𝐧𝐝 𝐂𝐢𝐩𝐡𝐞𝐫𝐬

𝐍𝐢𝐡𝐢𝐥𝐢𝐬𝐭 𝐍𝐮𝐦𝐛𝐞𝐫 𝐂𝐨𝐝𝐞

–Nihilist cipher is a manually operated symmetric encryption cipher originally used by Russian Nihilists in the 1880's to organize terrorism against the tsarist regime. The term is sometimes extended to several improved algorithms used much later for communication by the First Chief Directorate with its spies. This code requires a KEYWORD and the Polybius square. And, simple mathematics. Sa mga hindi po nakaka-alam ng Polybius square it looks like this: 
1 2 3 4 5 
1 A B C D E 
2 F G H I/J K 
3 L M N O P 
4 Q R S T U 
5 V W X Y Z 

So, let's make an example. The keyword will be PAGE. And the plaintext (hidden message) will be DETECTIVE CODES. After that, do this (newbie style): 
(Legend: P – Plaintext)
(K – Keyword) 
P — K 
D— P 
E — A 
T — G 
E — E 
C — P 
T — A 
I — G 
V — E 
E — P 
C — A 
O — G 
D — E 
E — P 
S — A 

Use Polybius Square for the Plaintext and also for the Keyword for their equivalents. 
Like this: 
P K D(14)– P(35) 
E(15) – A(11) 
T(44) – G(22) 
E(15) – E(15) 
C(13) – P(35) 
T(44) – A(11) 
I(24) – G(22) 
V(51) – E(15) 
E(15) – P(35) 
C(13) – A(11) 
O(34) – G(22) 
D(14) – E(15) 
E(15) – P(35) 
S(43) – A(11) 

After getting their equivalents using POLYBIUS SQUARE, let's do the simple math: ADDITION. 

So it will look like this: 
D=49 
E=26 
T=66 
E=30 
C=48 
T=55 
I=46 
V=66 
E=50 
C=24 
O=56 
D=29 
E=50 
S=54 

The encrypted form will look like this: 49 26 66 30 48 55 46 66 50 24 56 29 50 54 

You can put symbols for division like hypen (-), or slash (/), or this (>). Also to make it look like a hard code. 

To decrypt Nihilist, you need to look for the keyword. 

For example: 49 is the code and PAGE is the keyword. Look for polybius and the equivalent of P, which is 35 then subtract it to 49. The result will be 14 which is "D" in polybius. Repeat the process until you finish the whole text.

~~~CTTRO