Patent ID: 7308099

Claim:
Apparatus for generating an encrypted data stream from an audio signal, comprising: an encoder encoding the audio signal in order to generate a data stream with a predefined data stream syntax as output signal; an encryptor coupled with the encoder influencing encoder internal data in a uniquely reversible manner based on a key such that the generated encrypted data stream comprises payload information differing from payload information of a data stream that would be generated by the apparatus without the presence of the encryptor and that the generated encrypted data stream comprises the predefined data stream syntax, wherein said encoder is an encoder for audio signals, comprising: an analysis filter bank converting the audio signal from the time domain into a spectral representation in order to obtain spectral values; a quantizer quantizing the spectral values under consideration of a psychoacoustic model; and an entropy encoder arranged to carry out an entropy encoding of the quantized spectral values via a plurality of predefined code tables wherein each code table for the entropy encoding of quantized spectral values is provided in a frequency band and wherein at least one frequency band comprises two or more quantized spectral values, and wherein said encryptor is arranged to resort the two or more quantized spectral values in the frequency band comprising two or more quantized spectral values having an associated code table based on the key.