Luftwaffe deciphering of Allied air force codes.

[tcolvin]

Since 1972, when Winterbotham revealed what had gone on in BP, historians of WWII have had to take Ultra into account.

But British ciphers were also compromised for much of the war. Vast losses occurred at sea in 1943 because the RN was lax about following up information from the Americans and BP that B-Dienst were reading RN codes, and introduced the unbroken Typex only late in 1943.

B-Dienst would also have broken RAF codes for much of the war, and possibly USAAF ciphers as well.

I would be interested if anyone knows, or has speculated, about the operational consequences in the air war of Allied cipher insecurity, and what practical benefits the Luftwaffe obtained from it.

Tony

[Nick Beale]

Originally Posted by tcolvin

B-Dienst would also have broken RAF codes for much of the war ...

But didn't, apparently, and I doubt they could have overcome the machine ciphers (TypeX) that the RAF was using, not least because they believed their own machine ciphers were inviolable.

I can't remember if they were breaking the Royal Navy's codes as well as the Convoy Codes (based on code books) used by the Merchant Navy.

[SMF144]

Nick,

I haven't read all of the volumes but I am wondering if British Intelligence in the Second World War by Hinsley et al covers this?

Stephen

[tcolvin]

Originally Posted by Nick Beale

But didn't, apparently, and I doubt they could have overcome the machine ciphers (TypeX) that the RAF was using, not least because they believed their own machine ciphers were inviolable.

I can't remember if they were breaking the Royal Navy's codes as well as the Convoy Codes (based on code books) used by the Merchant Navy.

Thank you for the information that the RAF used TypeX which, you are correct to say, the Germans never even tried to crack as it was based on their 'unbreakable' Enigma.

The problem therefore was only naval. I thought it was systemic. The RN did not adopt CCM (the machine that allowed TypeX to communicate with the US ECM II) until June 1943.

Until then they used Navy Cipher Number 3, which the Germans called 'Convoy Code', and could decipher. BP knew the Germans were reading it and warned the RN, who ignored the warning and continued with near-catastrophic results.

It's explained here: http://www.independent.co.uk/news/uk...es-648269.html

Tony