A method for providing digital signatures to a video stream encoded in layers k = 0, ... , K - 1, wherein each of the K layers is composed of encoded image frames , wherein the method is performed by a transmitter (no), wherein the transmitter (no) has access to a private-public key pair, and wherein the method comprises: providing (S102) a digital signature for a base layer 0 by: - generating signing data for the base layer 0 by hashing the encoded image frames of the base layer 0; and - generating the digital signature for the base layer 0 by encrypting the signing data , or a hash thereof, for the base layer 0 with a private key of the private-public key pair; providing (S104) a respective digital signature for each enhancement layer k = 1, ... , K - 1 by, for each enhancement layer k = 1, ... , K - 1 characterised by : - generating signing data for the enhancement layer k by hashing the encoded image frames of the enhancement layer k and a link to the base layer 0 or any other previous layer 1 to k - 1 on which the enhancement layer k is dependent, wherein the link is the digital signature of said base layer 0 or said any other previous layer 1 to k - 1; and - generating the digital signature for the enhancement layer k by encrypting the signing data , or a hash thereof, for the enhancement layer k with the private key of the private-public key pair; and providing (S106) the respective digital signature for each layer k = 0, ..., K - 1 to its own layer k = 0,..., K - 1 in the video stream . providing (S102) a digital signature for a base layer 0 by: - generating signing data for the base layer 0 by hashing the encoded image frames of the base layer 0; and - generating the digital signature for the base layer 0 by encrypting the signing data , or a hash thereof, for the base layer 0 with a private key of the private-public key pair; - generating signing data for the base layer 0 by hashing the encoded image frames of the base layer 0; and - generating the digital signature for the base layer 0 by encrypting the signing data , or a hash thereof, for the base layer 0 with a private key of the private-public key pair; providing (S104) a respective digital signature for each enhancement layer k = 1, ... , K - 1 by, for each enhancement layer k = 1, ... , K - 1 characterised by : - generating signing data for the enhancement layer k by hashing the encoded image frames of the enhancement layer k and a link to the base layer 0 or any other previous layer 1 to k - 1 on which the enhancement layer k is dependent, wherein the link is the digital signature of said base layer 0 or said any other previous layer 1 to k - 1; and - generating the digital signature for the enhancement layer k by encrypting the signing data , or a hash thereof, for the enhancement layer k with the private key of the private-public key pair; and - generating signing data for the enhancement layer k by hashing the encoded image frames of the enhancement layer k and a link to the base layer 0 or any other previous layer 1 to k - 1 on which the enhancement layer k is dependent, wherein the link is the digital signature of said base layer 0 or said any other previous layer 1 to k - 1; and - generating the digital signature for the enhancement layer k by encrypting the signing data , or a hash thereof, for the enhancement layer k with the private key of the private-public key pair; and providing (S106) the respective digital signature for each layer k = 0, ..., K - 1 to its own layer k = 0,..., K - 1 in the video stream . <EOS>