ATTENTION ALL INTERCEPT OPERATORS!

Crypto Transmission from KPH,

Saturday August 30, 2025 @ 2000 GMT!

The year is 1939. War looms over Europe like a gathering storm. And deep within the quiet halls of a remote country estate, a small, secretive group of the Allies’ brightest minds works tirelessly to pierce the veil of the German military’s most complex encryption device - the Enigma machine. In just two weeks, a critical radio transmission is expected to be sent in Morse code: a stream of meaningless five-letter groups, indecipherable to ordinary listeners but believed to contain plans of the highest importance. Intelligence believes the message may detail the movement of German forces in a way that could change the course of the war before it has even truly begun.

In a daring operation that cost brave agents and precious resources, a codebook has been wrestled from enemy hands. It is stained, scarred by fire…and perhaps incomplete, but it is the best chance we have. You are now part of the small team entrusted with this task. The clock is ticking; every day that passes brings the transmission closer, and once it arrives, you must work with speed and precision to decode its secrets. The fate of ships at sea, soldiers in the field, and perhaps the fate of nations rests in your hands.

 Time is of the essence - crack the code before it’s too late!

The Enigma Transmission

The MRHS in cooperation with our crypto experts at the Cipher History Museum have arranged to transmit the Enigma message via the facilities of coast station KPH on Saturday August 30, 2025 at 2000 GMT. 

KPH listeners, intercept operators and code-breakers everywhere are invited to try their hand at receiving the transmission and decrypting the message.

Certificates will be awarded for proof of successful decode, first to decode and use of original or replica hardware.

You say your Enigma hardware is a bit rusty? Perhaps your Bombe is not fully operational? No problem, MRHS has you covered! Software simulations exist for the Enigma code machine. Click Here for an easy-to-use Enigma simulator. It is web-based, no download necessary. 

For additional information on the Enigma please see Ralph Simpsons' Cipher Museum History site.

Crypto broadcast date, time and formats

The Enigma broadcast will commence at 2000 GMT (1300 Pacific) on 30 August 2025 on all KPH CW frequencies. The CW frequencies are (in kc):

426.0

6477.5

8642.0

12808.5

17016.8

22477.5

Upon completion of the CW transmissions, the broadcast will be repeated on the KPH RTTY frequencies at 2015 GMT. The RTTY transmission will be 170cps shift Baudot, 45 baud. The RTTY frequencies are (in kc):

6324.5

8427.0

12585.5.

Code Sheet

Use this captured code sheet to decode the message. It is in poor condition, but it’s the best we have. Use your knowledge of what a complete Enigma code sheet looks like - it should be enough!

(Editor's Note: You might find it helpful to print the codebook page for easier reading.)

Enigma Code Machine Key Settings - IMPORTANT! 

As a member of an elite team of Allied code-breakers, you already know this, but for you junior members, SIGINT in London reminds them: decoding an Enigma message requires the use of two keys: a Daily Key (valid for a particular day), and a Message Key (unique to each individual message sent that day).

The Daily Key

Prior to decoding a message, the daily key must be set into your Enigma code machine. The daily key settings were specified in secret codebooks and distributed monthly. Consult the codebook (depicted above) to find the daily key setting for the GMT date in the message header plaintext (NOTE: not the date of the broadcast!).

The Message Key

The message key is sent with the message. It consists of two groups of three letters randomly chosen by the Enigma machine operator. The operator encodes each message using the message key. The first group of three letters is used to encode the second group of three. Then the first group (in plaintext) and the second group (now encoded) are sent in the message header, along with the date and letter count, as explained in the above link. The recipient then uses the message key to decode the message. For more information see the following video on Enigma decoding procedures.

Click HERE to watch a video on Enigma decoding procedures..

Enigma Simulators

Several on-line software simulations exist for the Enigma code machine.

 Click Here for an Enigma simulator. It is web-based, no download necessary. 

Certificates

Upon proof of successful decode, the following certificates will be awarded:

  - First to decode the Enigma message

  - Successful decode using original hardware (i.e., an actual Enigma machine)

  - Successful decode using replica hardware 

  - All successful decodes of the message 

Rules for Certificates

1. 48 hour time Limit: Enigma messages are time-sensitive! Your decoded message must be received at the email address below within 48 hours of the start of the broadcast, ie. before 2000 GMT (1300 Pacific) on 01 September 2025.
2. Group Efforts: While MRHS encourages group efforts, only one certificate will be awarded per group. 
3. The Enigma message is top-secret! Please do not share the ciphertext or the decrypted message before the time-limit. 
4. Only apply for a certificate if you or your team have actually received the message over the air (or on a web-based SDR) and personally decrypted the message using an Enigma simulator or Enigma hardware.

To apply for a certificate, send email to crypto@radiomarine.org with the subject line 'Decoded Enigma Message'. Please include the following:

• The decoded message in plaintext, properly re-formatted into words.
• The frequency and location where the coded message was intercepted. Signal reports are encouraged!
• The name you wish to have on the certificate.

The First to Decode award will be based on the timestamp of the first email demonstrating a successful decode. For the Enigma Original Hardware or Replica Hardware certificates, send the decoded message *plus* a photo of your Enigma machine showing the daily key setting. Printed certificates will be mailed for ‘First-to-Decode’, ‘Use of Original Hardware’ and ‘Use of Replica Hardware’ awards. Certificates for ‘Successful Decode’ will be emailed in digital form suitable for printing at home.

Questions and Comments

Questions and comments about the KPH cipher broadcast can be sent to crypto@radiomarine.org.

Questions and comments about the KPH cipher broadcast can be sent to : crypto@radiomarine.org.