SECURE AUDIO STREAM SCRAMBLING SYSTEM

The invention relates to a method of distributing digital audio sequences according to a nominal stream format consisting of a series of frames. Each of said frames comprises a digital block containing a certain number of coefficients corresponding to simple audio elements which are digitally encoded according to a mode identified in the relevant stream and used by all of the audio decoders capable of doing so, such that the stream can be decoded correctly. The invention is characterised in that it comprises: a preparatory step consisting in modifying at least one of the aforementioned coefficients; and a transmission step involving the transmission of (i) a main stream with the nominal format, which is made up of the blocks modified during the preparatory step, and (ii), using a channel separate from said main stream, complementary digital information which enables the original stream to be reconstructed from the calculation on the recipient device according to the main stream and the complementary information. The invention also relates to a system and a piece of equipment which are used to implement the inventive method.