| 摘要 |
The method involves encrypting bit by bit, a part of compressed data flow e.g. video flow, by block encryption algorithm. The bits of the compressed data flow, to be encrypted are stored in a buffer having a preset size. A timing mark is inserted in the compressed data flow only after the number of encrypted bits has reached or exceeded the number of bits of encryption block, or only after the buffer has filled. - Independent claims are also included for the following: - (a) a compressed and encrypted data flow obtained by a method of inserting a timing mark in the compressed and encrypted data flow - (b) a coder or decoder of formatted and compressed audio or video data - (c) a computer readable medium on which a program code implementing operations of a method of inserting a timing mark on a compressed and encrypted data flow, is recorded to permit the computer to broadcast the compressed and encrypted data flow.
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