Tool to decode/encode with Baudot. Baudot code is one of the first telecommunication code in binary from a machine (telegraph), it uses 5 bits per character and 2 character sets.
Baudot Code - dCode
Tag(s) : Telecom, Character Encoding
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Baudot Code
Baudot Decoder
Baudot Encoder
Answers to Questions (FAQ)
What is the Baudot code? (Definition)
The Baudot code is the name given to the alphabet set up to communicate with the telegraph machine. It has known several variations to adapt to different users and languages. The alphabet was later standardized under the name ITA2 (International Telegraph Alphabet No. 2).
How to encrypt using Baudot cipher
Encryption with the Baudot code uses a substitution/coding alphabet on 5 bits and 2 sets of characters (usually one for letters and the other for numbers and punctuation). The coding alphabet depend on the machine (Baudot type) used:
| Baudot | Original Alphabet (French) |
| Baudot UK | Alphabet modified by the British |
| ITA2 | International Telegraph Alphabet No. 2 (most common) |
| ITA1 | International Telegraph Alphabet No. 1 |
| MURRAY | Baudot Alphabet Modified by Murray (CCITT2) |
| USTTY | ITA2 Alphabet Modified for the American Teletypewriter |
| MTK2 | ITA2 Alphabet Modified for Russian |
The encoding binary alphabet can be used in both directions: MSB (most significant bit) or LSB (least significant bit) first.
Encryption consists in transcribing the characters of the message by their code. To switch between character sets, there are two keys: ⇩ (switch to letters) and ⇧ (switch to digits).
Example: Encode the message IA2 BAUDOT with a machine using the international telegraphic alphabet no. 2 (the most widespread).
| Letter | Code | Notes |
|---|---|---|
| I | 00110 | By default the letter character set is used |
| A | 00011 | |
| ⇧ | 11011 | The next character (2) is a number (therefore absent from the letters' character set), type ⇧ (switch to digits) |
| 2 | 10011 | |
| (space) | 00100 | The space code is the same for each character sets (numbers and letters) in the international alphabet 2 |
| ⇩ | 11111 | The next character (B) is a letter (thus absent from the digits' character set), type ⇩ (switch to letters) |
| B | 11001 | |
| A | 00011 | |
| U | 00111 | |
| D | 01001 | |
| O | 11000 | |
| T | 10000 |
Example: the coded message is then 00110 00011 11011 10011 11111 11001 00011 00111 01001 11000 10000.
How to decrypt Baudot cipher
Decryption with the Baudot code requires knowing the machine and / or the alphabet used. The decoding consists of replacing the 5-bit groups (0 and 1) by their corresponding character in the alphabet.
When the code corresponds to ⇩ (digits to letters) or ⇧ (letters to numbers), the character set must be changed.
Example: The encrypted message is 01001 01110 11011 10110 11111 01001 11011 00001
| 01001 | 01110 | 11011 | 10110 | 11111 | 01001 | 11011 | 00001 |
| D | C | ⇧ | 0 | ⇩ | D | ⇧ | 3 |
Example: The plain message is DC0D3.
How to recognize a Baudot ciphertext?
The message is a binary code, usually 0 and 1.
The code consists of a number of bits multiple of 5.
What is the Least/Most significant bit first/last?
For 5-bit binary coding, usually the most significant bit is on the left (least on the right)
Example: The value 3 is written 00011 (5bit, least significant bit on the right).
But it is possible to write with the least significant bit to the left
Example: The value 3 is written 11000 (5bit, least significant bit on the left).
What is the International Alphabet n°2?
IA2 is the Baudot variant the most used, here are the codes and their characters:
| Code | Letters | Digits |
|---|---|---|
| 00000 | null | null |
| 00100 | espace | espace |
| 10111 | Q | 1 |
| 10011 | W | 2 |
| 00001 | E | 3 |
| 01010 | R | 4 |
| 10000 | T | 5 |
| 10101 | Y | 6 |
| 00111 | U | 7 |
| 00110 | I | 8 |
| 11000 | O | 9 |
| 10110 | P | 0 |
| 00011 | A | - |
| 00101 | S | BELL |
| 01001 | D | $ |
| 01101 | F | ! |
| 11010 | G | & |
| 10100 | H | # |
| 01011 | J | ' |
| 01111 | K | ( |
| 10010 | L | ) |
| 10001 | Z | " |
| 11101 | X | / |
| 01110 | C | : |
| 11110 | V | ; |
| 11001 | B | ? |
| 01100 | N | , |
| 11100 | M | . |
| 01000 | Carriage Return CR | Carriage Return CR |
| 00010 | Line Feed LF | Line Feed LF |
| 11011 | Switch to Digits |
What is the WRU code?
On some machines, there was a WRU key (for who are you) which allowed you to request the identification of communicating people.
How to understand the Coldplay album X&Y?
The cover drawing of the album represents colored boxes or blank ones, either in binary 1 or 0, the translation in Baudot code for each line gives X & Y the title of the album.
When was Baudot Code invented?
Émile Baudot described it at the end of the 19th century (about 1877). The electric telegraph had already been invented since 1838.
Source code
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Questions / Comments
- Baudot Decoder
- Baudot Encoder
- What is the Baudot code? (Definition)
- How to encrypt using Baudot cipher
- How to decrypt Baudot cipher
- How to recognize a Baudot ciphertext?
- What is the Least/Most significant bit first/last?
- What is the International Alphabet n°2?
- What is the WRU code?
- How to understand the Coldplay album X&Y?
- When was Baudot Code invented?
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