G09C - CPC Classification

• G09C1/00 » 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 1,2K
• G09C3/00 » Typewriters for ciphering or deciphering cryptographic text 1
• G09C5/00 » 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 468