A method of signing an encoded video sequence, comprising: - obtaining an encoded video sequence composed of encoded image frames; - generating a set of one or more frame fingerprints for each encoded image frame, wherein a frame fingerprint is a unique identifier of an encoded image frame, and wherein the frame fingerprint is obtained by: performing a hashing operation or a checksum operation on the encoded image frame or on a subset thereof, or by digitally signing the encoded image frame or a subset thereof, wherein the encoded image frame or the subset thereof is digitally signed by asymmetric cryptography; - generating a document comprising a header of a supplemental information unit, and a representation of the generated sets of one or more frame fingerprints, wherein the document is a data structure, wherein the header of the supplemental information unit comprises an indication of the supplemental information unit, and wherein the representation of the generated sets of one or more frame fingerprints comprises a set of frame fingerprints from all the generated sets of one or more frame fingerprints or from a part of the frame fingerprints from all the generated sets of one or more frame fingerprints, or one or more hashes of the frame fingerprints from all generated sets of one or more frame fingerprints or one or more hashes of parts of the frame fingerprints from all the generated sets of one or more frame fingerprints; - generating a document signature by digitally signing the document, wherein the document signature is a digital signature for the document, and wherein the document signature is generated by asymmetric cryptography; - generating the supplemental information unit which only consists of the document, the document signature and an indication of an end of the supplemental information unit; and - signing the encoded video sequence by associating the generated supplemental information unit with the encoded video sequence. - obtaining an encoded video sequence composed of encoded image frames; - generating a set of one or more frame fingerprints for each encoded image frame, wherein a frame fingerprint is a unique identifier of an encoded image frame, and wherein the frame fingerprint is obtained by: performing a hashing operation or a checksum operation on the encoded image frame or on a subset thereof, or by digitally signing the encoded image frame or a subset thereof, wherein the encoded image frame or the subset thereof is digitally signed by asymmetric cryptography; performing a hashing operation or a checksum operation on the encoded image frame or on a subset thereof, or by digitally signing the encoded image frame or a subset thereof, wherein the encoded image frame or the subset thereof is digitally signed by asymmetric cryptography; - generating a document comprising a header of a supplemental information unit, and a representation of the generated sets of one or more frame fingerprints, wherein the document is a data structure, wherein the header of the supplemental information unit comprises an indication of the supplemental information unit, and wherein the representation of the generated sets of one or more frame fingerprints comprises a set of frame fingerprints from all the generated sets of one or more frame fingerprints or from a part of the frame fingerprints from all the generated sets of one or more frame fingerprints, or one or more hashes of the frame fingerprints from all generated sets of one or more frame fingerprints or one or more hashes of parts of the frame fingerprints from all the generated sets of one or more frame fingerprints; - generating a document signature by digitally signing the document, wherein the document signature is a digital signature for the document, and wherein the document signature is generated by asymmetric cryptography; - generating the supplemental information unit which only consists of the document, the document signature and an indication of an end of the supplemental information unit; and - signing the encoded video sequence by associating the generated supplemental information unit with the encoded video sequence.