[vlovich123]

And number theory was critical to breaking enigma. So they were all used within 5 years.

[l33t7332273]

Was it? My understanding was that they didn’t use number theoretic approaches.

[vlovich123]

My bad. You’re right. It was group theory and cryptanalysis. Number theory comes in later in the 1970s for public key cryptography (1976 publicly, early 1970s at GCHQ). So the military work on it really started in the late 1960s.