Patent ID: 8345870

Claim:
A method for encrypting an encoded audio signal, the encoded audio signal comprising base layer and at least one enhancement layer, wherein the base layer has audio data packed in frames, wherein a frame comprises header, main audio data, additional information used for decoding and error check data relating at least to the additional information, the method comprising the steps of separating the base layer temporally into a first section and at least one second section; encrypting the additional information within frames of the second section of the base layer, wherein the first section of the base layer and the main audio data of the second section of the base layer are not encrypted; and encrypting at least a part of the data of the enhancement layer, wherein the encrypted section of the base layer and the encrypted enhancement layer require different decryption keys for decryption, wherein the enhancement layer header contains information that specifies one or more temporal regions of the enhancement layer that are encrypted, and wherein a part of said information is encrypted.