Caesar cipher and ROT variants

Caesar cipher is a shift cipher. See more on Wikipedia

The transformation can be represented by aligning two alphabets; the cipher is the plain alphabet rotated left or right by some number of positions. For instance, here is a Caesar cipher using a left rotation of three places, equivalent to a right shift of 23 (the shift parameter is used as the key):

Type	Alphabet
Plain	ABCDEFGHIJKLMNOPQRSTUVWXYZ
Cipher	XYZABCDEFGHIJKLMNOPQRSTUVW

When encrypting, a person looks up each letter of the message in the “plain” line and writes down the corresponding letter in the “cipher” line.

Type	Data
Plaintext	THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
Ciphertext	QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD

Deciphering is done in reverse, with a right shift of 3.

Other ciphers that use the same shifting technique:

• ROT5:

  • Primarily for numbers with digits 0-9
  • Shifts each digit 5 positions

• ROT13:

  • Like Caesar Cipher
  • Shift each letter 13 positions

• ROT18:

  • Similar to ROT13, but using the 36 alphanumeric characters, A-Z0-9
  • Shift letters using ROT13, and shift numbers using ROT5
  • ROT18 = ROT13 + ROT5

• ROT47:

  • Uses an extended alphabet

    !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
    PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~

• ROT8000:

  • Uses the Unicode character set
  • Shifts by 0x8000 (32,768) positions