Tool to decode/encode by ROT1. The ROT1 code for Rotation 1 is 1-letter shift cipher in the alphabet, similar to the Caesar code.
ROT1 Cipher - dCode
Tag(s) : Substitution Cipher
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ROT1 Cipher
ROT1 Cipher Decoder
ROT-1 Encoder
Answers to Questions (FAQ)
What is ROT1? (Definition)
The ROT1 cipher is a substitution cipher based on a shift of one (1) letter in the alphabet. Each letter is therefore replaced by the next (A becomes B, B becomes C, etc.).
This shift is the basis of the Caesar code and its variants, sometimes the shift of 1 is called the Augustan code.
How to encrypt using Rot cipher?
All letters in the plaintext are replaced by those immediately following in the alphabet (A becomes B, B becomes C, etc. and for the last letter Z, the alphabet is considered a loop and the letter following Z is therefore A, the first letter)
| Initial alphabet | ABCDEFGHIJKLMNOPQRSTUVWXYZ |
| Alphabet shifted by ROT1 | BCDEFGHIJKLMNOPQRSTUVWXYZA |
Example: The message ROTATION is coded SPUBUJPO
ROT1 code only supports letters of the standard Latin alphabet (A-Z, a-z). Special characters and punctuation are ignored. Optionally, digits can also be shifted by 1.
How to decrypt Rot1 cipher?
Rot1 decryption is similar to encryption but uses the opposite shift by replacing each letter with the one immediately before in the alphabet (and the letter before A is the letter Z as if the alphabet was a loop).
| Alphabet shifted by ROT1 | ABCDEFGHIJKLMNOPQRSTUVWXYZ |
| Plain alphabet | ZABCDEFGHIJKLMNOPQRSTUVWXY |
Example: The message BMQIBCFU is decoded ALPHABET
How to program Rot1 functions?
The algorithm for encryption and decryption of ROT1 is: // Pseudo-code
Function encrypt(text) {
alphabet = {A:B, B:C, .., Y:Z, Z:A}
ciphertext = ''
for each character c in text {
ciphertext += alphabet[c]
}
return ciphertext
}
Function decrypt(text) {
alphabet = {A:Z, B:A, C:B, .., Z:Y}
plaintext = ''
for each character c in text {
plaintext += alphabet[c]
}
return plaintext
}
// Python
def rot1(text):
return ''.join(chr(ord(c) + 1) if A <= c <= Y else (A if c == Z else a) for c in text)
Source code
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