Nihilist Cipher Examples (encoder / decoder)

1. Nihilist Cipher encoder

Text : ABCD efghi
Key : key
Alphabet25 : abcdefghiklmnopqrstuvwxyz
Separator :
Row Heading : 12345
Column Heading : 12345
Coordinates Read Order : Row then Column

Solution:

The Nihilist cipher is a 5x5 grid-based Polybius square cipher, that converts both plaintext and keyword to a series of two digit numbers, then these numbers are added to get ciphertext

Alphabet = abcdefghiklmnopqrstuvwxyz

	1	2	3	4	5
1	a	b	c	d	e
2	f	g	h	i	k
3	l	m	n	o	p
4	q	r	s	t	u
5	v	w	x	y	z

Plaintext	a	b	c	d	e	f	g	h	i
Text Position (2)	11	12	13	14	15	21	22	23	24
Key repeated(key)	k	e	y	k	e	y	k	e	y
Key Position (3)	25	15	54	25	15	54	25	15	54
Cipher Addtion (2) + (3)	36	27	67	39	30	75	47	38	78

Plaintext	: abcdefghi
Key	: key
Ciphertext	: 36 27 67 39 30 75 47 38 78

2. Nihilist Cipher encoder

Text : hello world
Key : key
Alphabet25 : abcdefghiklmnopqrstuvwxyz
Separator :
Row Heading : 12345
Column Heading : 12345
Coordinates Read Order : Row then Column

Solution:

The Nihilist cipher is a 5x5 grid-based Polybius square cipher, that converts both plaintext and keyword to a series of two digit numbers, then these numbers are added to get ciphertext

Alphabet = abcdefghiklmnopqrstuvwxyz

	1	2	3	4	5
1	a	b	c	d	e
2	f	g	h	i	k
3	l	m	n	o	p
4	q	r	s	t	u
5	v	w	x	y	z

Plaintext	h	e	l	l	o	w	o	r	l	d
Text Position (2)	23	15	31	31	34	52	34	42	31	14
Key repeated(key)	k	e	y	k	e	y	k	e	y	k
Key Position (3)	25	15	54	25	15	54	25	15	54	25
Cipher Addtion (2) + (3)	48	30	85	56	49	106	59	57	85	39

Plaintext	: helloworld
Key	: key
Ciphertext	: 48 30 85 56 49 106 59 57 85 39

This material is intended as a summary. Use your textbook for detail explanation.
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1. Examples