A monthly Enigma code breaking tournament
SCHEDULE: New challenge deploys every 3rd day of the month at 00:00 hours UTC
INTERCEPTED TRANSMISSION:
INTELLIGENCE BRIEF: Reflector = B, plugboard has 6 pairs, ring settings unknown.
[All submissions timestamped] Our response time: 48 hours // Description of approach from winner always appreciated
INTELLIGENCE: The keyword was a weather term.
STATUS: BROKEN
| RANK | CALL SIGN | BREAKTHROUGH TIME |
|---|---|---|
| 1 | KMS-ULM | 2025-07-01 02:37 UTC |
| 2 | UBOAT-317 | 2025-07-01 03:14 UTC |
| 3 | SIGINT-DELTA | 2025-07-01 06:52 UTC |
| 4 | KMS-BREMEN | 2025-07-01 08:09 UTC |
INTELLIGENCE: The plugboard was very simple.
STATUS: BROKEN
| RANK | CALL SIGN | BREAKTHROUGH TIME |
|---|---|---|
| 1 | SIGINT-DELTA | 2025-05-03 01:15 UTC |
| 2 | KMS-BREMEN | 2025-05-03 01:52 UTC |
| 3 | DECODE-ALPHA | 2025-05-03 03:28 UTC |
| 4 | BASE-CIPHER | 2025-05-03 04:41 UTC |
📚 See reading links below for more details.
Operating your Enigma replica with historical accuracy adds both authenticity and challenge. These protocols simulate real Wehrmacht and Kriegsmarine operational procedures:
Use daily key sheets (codebooks) with rotor order, ring settings, and plugboard pairs.
Start each message with a randomly chosen message key, encrypted using the daily key, following original Enigma protocol.
For multi-part transmissions, re-use the same message key, not the daily key.
The M4 Enigma requires a fourth rotor: choose between Greek rotors Beta, Gamma, etc., and set reflector B Thin or C Thin accordingly.
Use five-letter groups for ciphertext to simulate military formatting standards.
Use daily key sheets (codebooks) with rotor order, ring settings, and plugboard pairs.
Start each message with a randomly chosen message key, encrypted using the daily key, following original Enigma protocol.
For multi-part transmissions, re-use the same message key, not the daily key.
The M4 Enigma requires a fourth rotor: choose between Greek rotors Beta, Gamma, etc., and set reflector B Thin or C Thin accordingly.
Use five-letter groups for ciphertext to simulate military formatting standards.
[NOTE] The German Navy used the Enigma M4 with more complex procedures than Army/Air Force units with the M3. M4 messages should consider using 8-10 plugboard pairs and regular rotor turnover changes.
Send out Enigma messages to a friend who knows your settings, or to the world as a code breaking challenge. Supply hints if you wish, or make the world realise that Enigma ciphers are still pretty effective without hints :-)
[CLASSIFIED] User-submitted encrypted messages awaiting decryption
INTELLIGENCE: ROTOR ORDER I-II-III, NO PLUGBOARD
INTELLIGENCE: CONTAINS COORDINATES – REFLECTOR C THIN
[SOLUTION] M4 III-V-I-GAMMA, C THIN, RING Q-G-D-R, PB AN EZ KO
INTELLIGENCE: RINGS A-A-A-A – KNOWN WORD "COMMAND"
INTELLIGENCE: 5 PAIR PLUGBOARD – NO 4TH ROTOR
[SOLUTION] I-II-III, REFLECTOR B, RING D-M-A, PB FH GI JN LP QT
INTELLIGENCE: PLAINTEXT LIKELY REPEATS
INTELLIGENCE: STARTS WITH CALL SIGN
[SOLUTION] IV-I-II-GAMMA, B THIN, RING A-D-F-B, PB CE PR ST
INTELLIGENCE: PLUGBOARD (AB CD EF GH IJ KL)
INTELLIGENCE: COMMON PHRASE – BOMBE ATTACK MAY HELP
[SOLUTION] BETA-I-V-III, C THIN, RING J-K-G-X, PB DL MX