On the Subject of the Caesar CM

Convert the letter on screen 1 to a Value via the Value Table. Then modulo it by 25, plus 1. The resulting number will be referred to as the Caesar Offset.

If the Submit Button is white, follow the instructions under Encrypt Instructions. Otherwise follow the instructions under Decrypt Instructions.

Encrypt Instructions

• Subtract the alphabetic position (A1Z26) of the Nth letter of the encrypted word by the Caesar Offset.
• If the resulting number is below 1, add 26 to it.
• Turn the number back into a letter (A1Z26).
• Do this for each letter of the encrypted word to get a decrypted word.

Decrypt Instructions

• Sum the alphabetic position (A1Z26) of the Nth letter of the encrypted word and the Caesar Offset.
• If the resulting number is above 26, subtract 26 from it.
• Turn the number back into a letter (A1Z26).
• Do this for each letter of the encrypted word to get a decrypted word.

Example 1

Encrypted Word: UWJANJB
Caesar Offset: (4 mod 25) + 1 = 5
Using Encrypt Rules

UWJANJB → PREVIEW

Example 2

Encrypted Word: JCYB
Caesar Offset: (1 mod 25) + 1 = 2
Using Decrypt Rules

JCYB → LEAD

Alternative Method

Convert the letter on screen 1 to a Value via the Value Table. Then modulo it by 25, plus 1. The resulting number will be referred to as the Caesar Offset.

If the Boolean Expression on screen B is true, follow the instructions under Encrypt Instructions. Otherwise follow the instructions under Decrypt Instructions.

Encrypt Instructions

• Write 2 alphabets, one on top of the other.
• Shift the bottom alphabet to the right X times where X is the Caesar Offset.
• Find the Nth letter of the encrypted word in the top alphabet.
• Replace it with the letter below it in the bottom alphabet.
• Do this for each letter of the encrypted word to get a decrypted word.

Decrypt Instructions

• Write 2 alphabets, one on top of the other.
• Shift the bottom alphabet to the left X times where X is the Caesar Offset.
• Find the Nth letter of the encrypted word in the top alphabet.
• Replace it with the letter below it in the bottom alphabet.
• Do this for each letter of the encrypted word to get a decrypted word.

Example 1

Encrypted Word: UWJANJB
Caesar Offset: (4 mod 25) + 1 = 5
Using Encrypt Rules

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UWJANJB → PREVIEW

Example 2

Encrypted Word: JCYB
Caesar Offset: (1 mod 25) + 1 = 2
Using Decrypt Rules

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JCYB → LEAD

Table Version

Convert the letter on screen 1 to a Value via the Value Table. Then modulo it by 25, plus 1. The resulting number will be referred to as the Caesar Offset.

If the Boolean Expression on screen B is true, subtract the Caesar Offset from 26. This is your new Caesar Offset.

For each letter of the encrypted word, use the offset as the row and the letter as the column in the table below. The intersection in the table will give you a decrypted letter.

	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z
01	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A
02	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B
03	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C
04	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D
05	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E
06	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F
07	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G
08	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H
09	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I
10	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J
11	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K
12	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L
13	N	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M
14	O	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N
15	P	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O
16	Q	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P
17	R	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q
18	S	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R
19	T	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S
20	U	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T
21	V	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U
22	W	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V
23	X	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W
24	Y	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X
25	Z	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y