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 (220a, 220b, 220c), 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 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 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 (220b, 220c) 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 the respective digital signature for each layer k = 0,..., K - 1 to its own layer k = 0,..., K - 1 in the video stream. providing 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 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 (220b, 220c) 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 (220b, 220c) 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 the respective digital signature for each layer k = 0,..., K - 1 to its own layer k = 0,..., K - 1 in the video stream.