Encryption & decryption apparatus

摘要

In an encryption apparatus comprising; (a) a transmission-data-format-transformer (4) which transforms transmission data into synchronous transmission data having a data format of a transmitting line, (b) an encrypting device (3) which produces an encrypted synchronous transmission data by encrypting the synchronous transmission data with a transmission key for transmitting, (c) a transmission command processor (1) which processes a transmission control signal, (d) a transmission admission device (2) which outputs control information received from the transmission admission device as asynchronous data, and also admits the data to be transmitted, (e) a multiplexing device (6) which multiplexes the encrypted synchronous data as well as asynchronous transmission data to output, a data encryption device for encrypting transmission data is provided by using a transmission key for data in order that the transmission admission device produces a transmission key for data responsive to the data content to be encrypted by the data encryption device. A decryption apparatus for decrypting the encrypted signal, and an encryption & decryption apparatus which combines the above encryption apparatus and the decryption apparatus are also available. Independent of encrypting a transmitting line, various depths of an encryption strength can be applied to data responsive to a data content arbitrary. As a result, a depth of encryption strength can be changeable according to a type and a content of transmission/reception data, and thus, an encryption method can be flexibly changeable depending on a type of video, or a compression method of video data.