I'm running a code breaker, but he used a good one.
Given his limited education, he probably did not even know enough mathematics to understand the code breakers' work.
But that was probably "unknown at the time" to the British code breakers, the report says.
Then he noticed something else, significant to the practiced eyes of a former professional code breaker.
He decided to let the code breakers know about the error because "they weren't getting the whole story," he said.
When you take each letter in the alphabet and put it with its numerical order number, use this as the third code breaker.
This is surprising given the success of the British Room 40 code breakers in the previous world war.
These people are cryptanalysts, also known as code breakers.
Electronic eavesdroppers and code breakers have to listen in on conversations.
Indeed they did, and British code breakers had a back door into deciphering the undecipherable.