Enigma@Home - The First Decrypted Message and the Story of Nazi U-Boat U-264

The Enigma@Home project was first brought to life in 2006 as a wrapper to the M4 project by Stefan Krah, which attempted to break 3 Kriegsmarine messages, enciphered on the notorious four-rotor Enigma M4. Plain text was successfully achieved in 2006 for all three messages using a combination of brute force and hill climbing algorithms. Without going into detail on the mathematics, hill climbing algorithms are used to run through all the possible Enigma settings except the plug board, which eliminated a colossal proportion of the total key space to be covered. The algorithm then identifies the correct plug board settings based on the partially decrypted results.

It took thousand of volunteers only two weeks to break the first message, thanks to the power afforded to the project by distributed computing. In light of the Enigma@Home project recently coming back online to solve another message set, I would like to look back at this first message to try and encourage you to participate in the next deciphering effort.

The original message was intercepted by the British Destroyer HMS Hurricane as it was on patrol in the Atlantic near the end of 1942. This time period is of special significance to Allied intelligence, as it was in the middle of the 10 month blackout after German introduction of the 4 rotor Enigma machine. For this period, the 7000 mathematicians at Bletchley Park were unable to decipher the messages intercepted by their naval forces.

The intercepted message read as follows:

NCZW VUSX PNYM INHZ XMQX SFWX WLKJ AHSH NMCO CCAK UQPM KCSM HKSE INJU SBLK IOSX CKUB HMLL XCSJ USRR DVKO HULX WCCB GVLI YXEO AHXR HKKF VDRE WEZL XOBA FGYU JQUK GRTV UKAM EURB VEKS UHHV OYHA BCJW MAKL FKLM YFVN RIZR VVRT KOFD ANJM OLBG FFLE OPRG TFLV RHOW OPBE KVWM UQFM PWPA RMFH AGKX IIBG

Two weeks of volunteer compute turned up the setting of the Enigma machine that encoded this message over 70 years ago:

Enigma model: Kriegsmarine M4
Reflector: B
Rotors: Beta - II - IV - I
Stecker: AT BL DF GJ HM NW OP QY RZ VX
Ringsettings: A-A-A-V
Rotor startposition: V-J-N-A

If you would like, you can decipher the message yourself using an Enigma Simulator. Even with the setting listed, this will take you a fair amount of time! For those less patient, the plain text that results from the above two pieces of information is:

Von Looks: Funktelegramm 1132/19
Inhalt:
Bei Angriff unter Wasser gedrueckt, Wasserbomben.
Letzter Gegnerstandort 08:30 Uhr,
Marine Quadrat AJ 9863, 220 Grad, 8 Seemeilen, stosse nach.
14 Millibar faellt, NNO 4, Sicht 10.

Which translates to:

From Looks: Radio signal 1132/19
Contents:
Forced to submerge during attack, depth charges.
Last enemy location 08:30h,
Naval Grid AJ 9863, 220 degrees, 8 nautical miles, (I am) following (the enemy).
(Barometer) 1014 Millibar (tendency) falling, North North East 4, visibility 10.

Nothing groundbreaking, and certainly not the coordinates to the missing Nazi gold train we may have hoped for. But, this transmission does raise some questions and some digging reveals a very interesting history as to the circumstances of this message. The history 'books' of the internet revealed the story of U-264:

Between November 1942 and February 1944 U-264 sailed out on six patrols. U-264 operated from the U-boat harbor in St-Nazaire, France. On its first patrol, U-264 sank the Greek 'Mount Taurus' in convoy ONS-144. On its second and third patrol the U-boat came under attack from aircraft fire several times without any damage. On the third patrol U-264 sank the British 'Harperley' and the American 'West Maximus', both in convoy ONS-5.

On February 5, 1944, U-264 left St-Nazaire for its seventh and fatal patrol. U-264 was one of 20 U-boats ordered to sweep area 48°30'N-21°30'W in search of a reported convoy. U-264 arrived at the location in the North Atlantic on February 18th. U-boat command ordered it to submerge during daytime and surface after 18.00h to search for the convoy. At 09.00h, propeller noise was heard and ASDIC sonar located the U-boat. Depth charges were dropped but U-264 only took very little damage. The attacking boat left to the south-west. U-264 surfaced as ordered at 18.00h and mounted the FLAK anti aircraft gun. Ten minutes later, a Sunderland aircraft was spotted and U-264 returned fire with the FLAK gun. The first burst of fire was fatal and another U-boat reported that the aircraft crashed into the ocean.

The next morning, February 19th at 02.00h, U-264 spotted two enemy destroyers and reported this by radio with a short signal message. U-264, still surfaced, was detected by the destroyers radar and received artillery fire. U-264 managed to get away at high speed. At 04.00h they received a message that the convoy was located and U-264 sailed at high speed to the presumed location. At 05.30h, still very dark, a destroyer headed at high speed towards U-264. At 2000 meters U-264 fired a torpedo, missing the destroyer, and sped away from the enemy. At that moment, U-264 spotted the convoy and reported this with a short signal message. At 800 meters the destroyer opened fire at the U-boat and hit the U-boat's diving tanks. The U-boat's hull was not damaged and the order was given to dive immediately. The destroyer dropped several depth charges and stayed on the spot until 06.00h, when she was joined by five other ships that protected convoy ON-224. The five Sloops were HMS Woodpecker, HMS Starling, HMS Kite, HMS Wren and HMS Wild Goose, all specialized in destroying U-boats.

U-264 took many series of a new type of depth charges, the Mine-Depth-Charges, which detonated at 300 meters instead of the usual 120 meters, hitting the U-boat bottom with devastating shockwaves from beneath. U-264 sustained heavy damage. At 13.00h, the destroyers lost track of U-264, but found her again at 18.00h because of a wide oil trace, left behind by U-264 on the surface. 24 more depth charges were dropped on U-264. Since early that morning, 250 depth charges were dropped near the U-264!

Meanwhile at U-264, all electronics were lost and many water leaks were reported. The main pumps could not keep up with the raising water and a bent port side propeller axle caused the port side electric motor to overheat and caught fire. The starboard propeller was jammed completely. U-264 was out of control and sank to a depth of 230 meter. Kapitänleutnant Hartwig Looks gave the order to blow the air tanks and surface.

As they surfaced, the five sloops were in a circle of 3000 meter and immediately opened fire .U-264 could not return fire or use any torpedo since the torpedo hatches were jammed. Kapitänleutnant Looks gave the order to leave the boat. With the port side engine still rotating the U-boat, still under artillery fire, put more and more distance between itself and the men in the water. U-264 sank in the early evening of February 19th at position 48°31'N-22°05'W. Looks and all crew members, 52 men in total, were picked up by HMS Woodpecker. There were no casualties and only two sailors had minor injuries.

The crew of U-264 survived their incredible nightmare of depth charges and spent the rest of the war as prisoners, unlike many other U-boats crews. An estimated 700 German U-boats and 30,000 crew men were lost at sea.

I am currently the top contributor to the attempt at breaking the remaining Enigma messages, and I would love for more people to join me! You can get involved by installing the distributed compute platform BOINC, and joining Enigma@Home. If you so chose, you can also be compensated for your efforts decoding the message in the form of the cryptocurrency GRC.

---

Content Credit:

• All CC