| Outline |
Indent Level
| |
| Color | Curly Brackets (indicating CPC extensions to IPC) | |
CPC | COOPERATIVE PATENT CLASSIFICATION | ||
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![]() | Apparatus or methods whereby a given sequence of signs, e.g. an intelligible text, is transformed into an unintelligible sequence of signs by transposing the signs or groups of signs or by replacing them by others according to a pre-determined system (cryptographic typewriters G09C 3/00) |
G09C 1/02 | . | by using a ciphering code in chart form |
G09C 1/04 | . | with sign carriers or indicators moved relative to one another to positions determined by a permutation code, or key, so as to indicate the appropriate corresponding clear or ciphered text |
![]() | Typewriters for ciphering or deciphering cryptographic text (marking record carriers G06K) |
G09C 3/02 | . | with auxiliary keys or keyboards acting on the original key or keyboards |
![]() | G09C 3/04 | . | wherein the operative connections between the keys and the type-bars are automatically and continuously permuted, during operation, by a coding or key member |
G09C 5/00 | Ciphering apparatus or methods not provided for in the preceding groups, e.g. involving the concealment or deformation of graphic data such as designs, written or printed messages |