Did the Axis have any significant success breaking Allied codes?

We often hear of how the Allied intelligence services put a great amount of time and manpower into breaking the Axis encrypted communications, especially the Enigma code (I hear they made a fairly successful movie about that), and lately in the weekly episodes we’ve got American intelligence breaking Japanese Naval codes and getting almost everything right, except for the name of the light carrier.

We don’t often hear about Axis attempts or successes in breaking Allied codes, were there any? Did they not invest as much man power into code breaking, or were the Allied codes better, or did the Allies have better opsec, and so on and so on.


They did. And it appears that in some cases the Allies were far too trusting to their own ciphers to react - believing intelligence leaks being caused by actual spies rather than by signals intelligence.

For example (plenty to read there) searching with term ‘finnish’:

Ironically enough after the end of the Continuation War Finnish head of signals intelligence (at the time due to the Operation Stella Polaris located in Stockholm) gave clear warning to that the US State Departments’ STRIP cipher (M-138-A) had been compromised. To the extent that:

His general confidence in their ability to decode any of our messages anytime they wanted to, suggests very strongly that they do just that.