A US Navy WWII Encryption Device

[Puster Bill]

Originally Posted by Rockin Robbins

Whew! Not exactly Enigma, is it? I wonder how many of those "secret" messages were read.

For the M-94/CSP-488, probably quite a number of them. The system isn't really that secure, and it was only used for low level tactical communications. Although, quite frankly, Japanese signals intelligence left a *LOT* to be desired, so maybe not.

Certainly, today, the M-94/CSP-488 isn't secure.

Now, the M-138-A/CSP-845 is a different story. With 100 strips, only 25 or 30 of which would be used at once, it probably gives about as much security as a 4 rotor Naval Enigma. It's telling, though, that it was considered only "medium" security.

I settled on an M-94 variant because the wheel alphabets are published, and there are fewer strips to cut out, which is the most tedious part of making this.

I'm thinking about building a wheel version. I'm going to check around at the local hardware stores and see what I can use as the wheels. If I manage to build a decent one, I'll post pictures and a how-to.