Only three variants of the Kryha machine appear to have entered series production: an early clockwork-driven desktop model (the Kryha Standard); a later and more flexible clockwork-driven desktop model introduced around 1934 (also called the Kryha Standard); and a pocket-watch-sized clockwork model (called the Liliput) that was interoperable with the later version of the Standard. The machine evaluated in 1930 by Parker Hitt was an electrically operated version interoperable with the early version of the Standard; it is not clear if this was a one-off prototype or a production model. Kryha's designs were protected by numerous patent filings, for both actual and projectedmodels.
More or less identical early
patents were filed in several countries, describing a simple model that
would have been very weak cryptographically. The diagrams show an
8-segment control wheel with a peg and rod regulating mechanism, rather
than the fixed gear wheel with varying groups of teeth that was used in
the later, production machines.
Kryha claimed that the electrically operated model of the machine was much faster in operation than the mechanical version. It would have been much more expensive to manufacture than the clockwork models since it consisted of two electric typewriters interconnected via a central enciphering unit that was by itself more complex than the clockwork model. The patent diagrams show numerous adjustment points that would have needed careful setup for reliable operation. In his evaluation, Parker Hitt reported that the electrical version made numerous enciphering errors.
The diagrams of the two French patents do not correspond, but the diagrams of the later French patent (682338) correspond with those of the British patent application (345218). The British application was not accepted and became void.
Kryha marketing literature describes a model intended for diplomatic use (Typ Diplomat)
as having two separate control wheel driven by two separate clockwork
motors (the Standard model had just one of each). The following
patent appears to correspond to this description even though it does
not mention the name "Diplomat".
The following patent
corresponds most closely to the early version of the Kryha Standard, of
which numerous examples still exist. Both the early and late
versions of the Standard were clockwork-driven, desktop machines.
They differ in that the control wheel of the early model was fixed
(though different fixed wheels could be interchanged), while the later
model was equipped with a control wheel that could be adjusted by
raising or lowering embedded grub screws. The later model was
more flexible and somewhat more secure.