Saturday, February 22, 2014

James Bamford NSA video

Interesting presentation on the history of the NSA by author James Bamford

Wednesday, February 19, 2014

Saturday, February 15, 2014

RAF Strength Far East Command – January 1942

In December 1941 Japan entered WWII on the side of the Axis by attacking the forces of the USA and UK stationed in the Pacific.

The most audacious attack was against the US fleet in Pearl Harbor but in the same period the Japanese invaded the Philippines, Thailand and British controlled Hong Kong and Malaya.
Both the Americans and the British had underestimated Japan’s military and they paid the price. The British also suffered from their ongoing war against Germany and Italy. They had limited military resources and the choice had been made to concentrate these in Europe. Thus their forces in the Far East were equipped with outdated weapons. This is obvious in the case of the RAF, as shown by the following strength reports:


Source: AIR 22 ‘Air Ministry: Periodical Returns, Intelligence Summaries and Bulletins’
The types available were second line aircraft like the Hawker Audax, Westland Wapiti, Westland Lysander, Vickers Vildebeest and a handful of relatively modern Curtiss P-36, Bristol Blenheim, Bristol Beaufort, Lockheed Hudson and Brewster F2A Buffalo.

These forces were not capable of standing up to the modern Japanese planes, especially the Mitsubishi A6M Zero.

Sunday, February 9, 2014

British cryptologic security failures in WWII

Signals intelligence and codebreaking played an important role in WWII. British and American codebreakers solved many important Axis crypto systems, such as the German Enigma machine and the Japanese Navy’s code JN25.

Historians have not only acknowledged these Allied successes but they’ve probably exaggerated their importance in the actual campaigns of the war.
Unfortunately the work of the Axis codebreakers hasn’t received similar attention. As I’ve mentioned in my piece Acknowledging failures of crypto security all the participants suffered setbacks from weak/compromised codes and they all had some successes with enemy systems.

Britain, the Soviet Union and the United States did not have impenetrable codes. In the course of WWII all three suffered setbacks from their compromised communications.
Time to take a look at the British side and their worst failures.

Book cyphers
The basic British cryptosystem for important radio-traffic was the enciphered codebook. These 4-figure codebooks were enciphered with subtractor tables, using the non-carrying system. The military services had their own series of cyphers such as the War Office Cypher for the Army and the RAF cypher for the airforce plus there were diplomatic editions for the Foreign Office and the Interdepartmental Cypher that was used both by the services and the civilian organizations.

The codebook was basically a dictionary that assigned a 4-figure group to each word. For example the word ‘division’ would have the code 5538, ‘attack’ 2090, ‘artillery’ 0231 etc etc
So the cipher clerk would first use the codebook in order to find the code groups corresponding to the words of the message and then he would have to use the subtractor tables in order to encipher them. This means that each codegroup would be subtracted from the key groups (of the subtractor table) without carrying over the numbers.

Sunday, February 2, 2014

State Department’s strip cipher – reuse of alphabet strips and key lists

During WWII the US State Department used several cryptosystems in order to protect its radio communications from the Axis powers. For low level messages the unenciphered Gray and Brown codebooks were used.  For important messages four different codebooks (A1,B1,C1,D1) enciphered with substitution tables were available.

Their most modern and (in theory) secure system was the M-138-A strip cipher. Unfortunately for the Americans this system was compromised and diplomatic messages were read by the Germans, Finns, Japanese, Italians and Hungarians. The strip cipher carried the most important diplomatic traffic of the United States (at least until late 1944) and by reading these messages the Axis powers gained insights into global US policy.
The strip cipher was not a weak system cryptologically, even though it could not offer the security of cipher machines. The success of German and Finnish codebreakers was facilitated in many cases by the poor way that the system was used by the State Department.

Use of the M-138 strip cipher by the State department
Each embassy had 50 ‘circular’ alphabet strips and 50 ‘specials’. The ‘circulars’ were used for communications between embassies and for messages from Washington to all embassies. The ‘specials’ were used for direct communications between Washington and a specific embassy.

The way the system worked was that each day 30 alphabet strips were chosen out of the available 50 (both for the ‘circulars’ and the ‘specials’). The strips used and the order that they were inserted in the metal frame was the ‘daily key’. 

The strip system did not have a separate ‘key’ for each day. Instead there were only 40 different rearrangements for the entire year.
The daily key table indicated which of the 40 keys was valid for the specific day. For example in the following table assuming that the date is April 10 then the numerical key to be used is 30.