[usrusr]

By the time statistical evidence could have grown strong enough to shine through the careful layers of deception, they were far to busy not noticing that they were losing the war to notice that they lost the encryption battle. In a world of believers, only traitors quantify bad news.

[WalterBright]

Oh, they noticed all right. From "U-Boat Ace" by Jordan Vause pg. 103:

"retrieved a working Enigma machine along with the documents and code keys for three months. Not surprisingly, U-Bootwaffe fortunes declined in the following months, and from that point on Doenitz remained in doubt about the Enigma cyphers his boats were using. But the experts reassured him over and over again that they were sound, and so he retained them until the end of the war."

[lostlogin]

I haven't found anything on the subject, but he would have been alive when Enigma become public. It would be great to know his thoughts (and those of people like Speer).