M-94 (cipher machine)
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The M-94 was a piece of cryptographic equipment used by the United States Army, consisting of several lettered discs arranged as a cylinder. It was also employed by the US Navy, under the name CSP 488
The M-94 at the National Cryptologic Museum
An M-138-A at the National Cryptologic Museum"
DRYAD
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The DRYAD Numeral Cipher/Authentication System is a simple, paper cryptographic system employed by the U.S. military for authentication and for encryption of short, numerical messages. Each unit with
M-94 (cipher machine)
…the M-94 was still good enough during the early years of World War II for its intended use as a "tactical cipher"; in a similar way to the more modern DRYAD and BATCO. The M-138-A was stronger because slips with new alphabets could be issued periodically, even by radio using more secure systems like SIGABA…
Holder for coding sheets with slide to facilitate use