Baudot Code

Encryption with the Baudot code uses a 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.

Encryption consists in transcribing the characters of the message by their code. To switch between character sets, there are two keys: ⇩ and ⇧.

Example: Consider the message to be encoded IA2 BAUDOT, with a machine using the international telegraphic alphabet no. 2 (the most widespread).

Example:

Example: the coded message is then 00110 00011 11011 10011 11111 11001 00011 00111 01001 11000 10000.

Decryption with the Baudot code requires knowing the machine and / or the alphabet used. The decoding consists simply 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: Consider the encrypted message 01001 01110 11011 10110 11111 01001 11011 00001

Example: The plain message is DC0D3.

The message is a binary code, usually 0 and 1.

The code consists of a number of bits multiple of 5.

When coding the binary message, usually one write the value 3 as 00011, with the most significant bit first (the least significant bit the right). One can write also 11000, with, this time, the least significant bit first, on the left.

IA2 is the Baudot variant the most used, here are the codes and their characters:

On some machines, there was a WRU key (for who are you) which allowed you to request the identification of communicating people.

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.

End of the XIXe century (>1870)