Code 63 : Nihilist Cipher

Nihilist Cipher

Background

The Nihilists were a Russian group who fought against the Tsar regime in the 1880s.¹

Principle

The cipher is based on the Polybius cipher. The message as well as the key are encoded with the Polybius cipher and the results are added.
If the message "GEHEIMNIS" should be encoded and the key would be "KEY", than a Polybious matrix may look like this:

	1	2	3	4	5
1	Q	W	E	R	T
2	Z	U	I/J	O	P
3	A	S	D	F	G
4	H	K	L	Y	X
5	C	V	B	N	M

Encoding the message as well as the key according to this matrix results in:

Row	3	1	4	1	2	5	5	2	3
Column	5	3	1	3	3	5	4	3	2

Message:    "35 13 41 13 23 55 54 23 32"
Key:              "42 13 44 42 13 44 42 13 44"
Ciphertext:  "77 26 85 55 36 99 96 36 76"

Security

The Nihilist cipher can be roughly described as a numeric version of the Vigenère cipher and therefore is vulnerable to similar cracking strategies.

Weblinks

http://en.wikipedia.org/wiki/Nihilist_cipher
http://dic.academic.ru/dic.nsf/enwiki/2011717 

References

¹ Kippenhan, Rudolf: "Verschlüsselte Botschaften", Nikol, 2006,  P. 127