Task of the code converter is to transform 5bit Fs characters (character = Zeichens)
Letters -> Code converter -> Vorchiffreiren (Encryption)-> Decryption -> Code converter -> Letters
The converter used by T-310 is the ITA2, international telegraph alphabet no.2, described below: Sources: [1] [2]
Interestingly, this is also mentioned in the book Breaking Teleprinter Ciphers at Bletchley Park: An edition of I.J. Good, D. Michie and G. Timms: General Report on Tunny with Emphasis on Statistical Methods (1945).
Notes:
Special characters:
WR : oooxo : Carriage return
ZV : oxooo : Line feed
BU : xxxxx : Letters switchover
ZI : xxoxx : Digits switchover
Zwr: ooxoo : Space
-- : ooooo : Blank : aka te
Differences:
The BU, ZI, Zwr have positions changed in the german desc. and the interantional standard description, some care has to be taken to examine if this makes a difference.
As descibed in 1, we the special characters are mapped to two or more characters as decribed below:
No.|Character || Out ||
---|----|--------|-----|----|------------
1 | A | xx.ooo | 1 1 | AA | xxooo xxooo
27 | WR | oo.oxo | 1 5 | AE | xxooo xoooo
28 | ZV | ox.ooo | 1 9 | AI | xxooo oxxoo
29 | Bu | xx.xxx | 1 14| ON | xxooo ooxxo
30 | Zi | xx.oxx | 1 18| AR | xxooo oxoxo
31 | Zwr| oo.xoo | 1 19| AS | xxooo xoxoo
32 | te | oo.ooo | 1 20| AT | xxooo oooox
An implementation can be found at cryptii to convert text to ITA2