The C-22 process did not exist at that time, but the one used was a close approximation to it.

The original chromogenic Kodacolor film had no mask whatsoever, and relied on any 'mask' being formed by using either interimage effects, or a wash after the color developer to promote formation of a positive 'fog' image. Some unmasked color negative films used this method into the 60s.

The silver mask in Kodacolor, when introduced, was formed much as you say, but none of my texts or records show what kind of developer was used.