I stand corrected.
I had previously read a few articles about VENONA and incorrectly assumed the Russian codes could be broken with extensive use of a computer.
I read the Wikipedia link for one-time pad. You're right. It is virtually impossible to crack. The only stuff we know is because of a lucky break.
Nonetheless, it would be fascinating if we were able to translate the remaining VENONA intercepts. I think we'd be horrified at the depths of Soviet penetration of our government.