The OMI cryptograph was a seven-rotor machine produced by Italian firm Ottico Meccanica Italiana.

The OMI cryptograph was a rotor cipher machine produced and sold by Italian firm Ottico Meccanica Italiana (OMI) in Rome.

The machine had seven rotors, including a reflecting rotor. The rotors stepped regularly. Each rotor could be assembled from two sections with different wiring: one section consisted of a "frame" containing ratchet notches, as well as some wiring, while the other section consisted of a "slug" with a separate wiring. The slug section fitted into the frame section, and different slugs and frames could be interchanged with each other. As a consequence, there were many permutations for the rotor selection.

The machine was offered for sale during the 1960s.^[1]

References

^ "Relatives of the Enigma". quadibloc.com.

Cipher A. Deavours and Louis Kruh, "Machine Cryptography and Modern Cryptanalysis", Artech House, 1985, pp. 146–147
F. L. Bauer, Decrypted Secrets, 2nd edition, Springer-Verlag, 2000, ISBN 3-540-66871-3, pp. 112,136.

v t e Cipher machines
Rotor machines	CCM Enigma M-125 Fialka Hebern HX-63 KL-7 Lacida M-325 Mercury NEMA OMI RED SG-39 SG-41 SIGABA SIGCUM Singlet Typex
Mechanical	Bazeries cylinder C-36 C-52 CD-57 Cipher disk HC-9 Kryha Jefferson disk M-94 M-209 Reihenschieber Scytale
Teleprinter	5-UCO BID 770 DUDEK KW-26 KW-37 Lorenz SZ 40/42 Siemens and Halske T52 SIGTOT
Secure voice	BID 150 FASCINATOR KY-3 KY-58 KY-68 NESTOR OMNI SCIP Sectéra Secure Module SIGSALY STE STU-II STU-III VINSON
Other	JADE KG-84 KL-43 KL-51 Noreen Red Purple Pinwheel Rockex
In Computer Hardware	AES instruction set Intel SHA extensions IBM 4758 IBM 4764

v t e Cryptography
General	History of cryptography Outline of cryptography Cryptographic protocol Authentication protocol Cryptographic primitive Cryptanalysis Cryptocurrency Cryptosystem Cryptographic nonce Cryptovirology Hash function Cryptographic hash function Key derivation function Digital signature Kleptography Key (cryptography) Key exchange Key generator Key schedule Key stretching Keygen Cryptojacking malware Ransomware Random number generation Cryptographically secure pseudorandom number generator (CSPRNG) Pseudorandom noise (PRN) Secure channel Insecure channel Subliminal channel Encryption Decryption End-to-end encryption Harvest now, decrypt later Information-theoretic security Plaintext Codetext Ciphertext Shared secret Trapdoor function Trusted timestamping Key-based routing Onion routing Garlic routing Kademlia Mix network
Mathematics	Cryptographic hash function Block cipher Stream cipher Symmetric-key algorithm Authenticated encryption Public-key cryptography Quantum key distribution Quantum cryptography Post-quantum cryptography Message authentication code Random numbers Steganography
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