Luftwaffe/Heer Enigma Encoding Procedures

Written: April 1998
Published: Jun 14, 2008
Author: Drew Ballard

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Luftwaffe/Heer Procedures

Encrypting Method: Daily: 1. Set Ringstellung(ring position) according to Tagelschlüssel(daily key). ie. F-T-X (06-20-24) This is done by turning the letter (or sometimes number) ring on the rotor and locking it with a pin. 2. Install wheels according to Tagelschüssel. ie. I-V-III 3. Set 20 plug-pairings according to Tagelschlüssel. ie. UA-PF-RQ-... etc. Called steckering(plugging). For each message: 4. Turn wheels to random 3 character setting. ie. JCM (Indicator Setting) 5. Twice type 3 more random characters. ie. BGZBGZ (Message setting) 6. Record 6 character output. ie. TNUFDQ (Indicator) 7. Set wheels to message setting. BGZ. (Grundtsellung) 8. Type message

A Common Transmission Format: A) Callsign, time of origin, # of characters in text, indicator setting* B) 5 character group. 2 padding letters followed by 3 characters of Kenngruppen. ie. JEU (Discriminant) Indicates diferent types of Enigma traffic. If the discriminant isn't in your codebook, then the message isn't for you. C) 6 character indicator (cyphered message setting) TNUFDQ D) text in groups of 5 characters According to Codebreakers Hinsley & Stripp According to The Hut 6 Story Welchman

Decrypting Method: 9. Set up machine according to Tagelschlüssel. (Same as steps 1-3) 10. Set wheels to indicator setting. JCM 11. Enter message setting. TNUFDQ 12. If the frist 3 characters repeat (BGZ-BGZ) then the machine is setup properly. 13. Set machine to BGZ. (Grundstellung) 14. Enter message. *At first glance, it may not appear too wise to transmit the actual indicator setting. But as long as the letter rings are switched on the rotors on a daily basis, the indicator setting is worthless. The electro-mechanical machines used to discover the wheel settings search every non-conflicting possibility anyway. NOTE: Later in the war, only a 3 character message setting was encyphered, sent and decyphered. Thus, step 12 was skipped. The only confirmation of the machine being set up properly was whether or not the message was garbled.