Thursday, April 24, 2008

KSM Encryption/ Decryption Exercise 4/26 and 5/3

KSM, a licensed commercial station using vintage equipment and antennas at historic KPH on Pt. Reyes, CA, will be doing a very interesting broadcast in World War II M-209 encryption. It's at 1900 and 2100 UTC on April 26 (also International Marconi Day) and a week later on May 3. The key will be broadcast, and listeners are invited to attempt decryption of the message with readily available freeware.

M-209, for those of us who weren't born yet, is a US military mechanical code machine slightly resembling a 6-rotor, patch board-less version of the better known German ENIGMA.

Here's the full release from Richard Dillman of MRHS:

KSM will broadcast messages encrypted with the military M-209 crypto machine via RTTY on 26 April and 3 May.

The idea for the broadcast came up in conversations between myself and Dave Ross as a way for the MRHS to support the Military Radio Collectors Group meet taking place in San Luis Obispo, CA on 2-3 May. We thought it would be fun to give the attendees something to copy on their vintage military RTTY gear and then exercise their M-209 skills by decoding the message. But we thought other listeners may enjoy trying their hand at decoding the message as well, thus this announcement (see below for information about a M-209 emulator in case you don't have access to the genuine article).

MRHS transmitter engineer Steve Hawes, who manages our RTTY broadcasts, was keen for the idea and Dave provided the text so all the pieces are in place. Here are the details:

Dates: 26 April and 3 May

Times: Approximately 1200pdt and 1400pdt

Modes: RTTY and FEC. Baudot transmissions are at 170cps shift, 45 baud. FEC transmissions are at 170cps shift, 100 baud

Frequencies: 8433.0kc, 12631.0kc

Text: Dave's text will start with a plaintext preamble and will include the settings for the M-209 as well as the key. That will be followed by the encrypted text in five letter groups.

Additional information:


M-209 emulator for those who wish to participate but don't have a M-209 -