公开(公告)号：US20240323029A1

公开(公告)日：2024-09-26

申请号：US18437463

申请日：2024-02-09

Applicant: Axis AB

Inventor： Linus LEXFORS ,  Björn VÖLCKER ,  Hannes NILSSON ,  Caroline HOLMSTRÖM

IPC: H04L9/32 ,  G10L19/018 ,  G10L19/02 ,  G10L25/51

CPC classification number: H04L9/3247 ,  G10L19/018 ,  G10L19/0204 ,  G10L25/51

Abstract: A method of providing a signed bitstream, performed in association with a process of capturing an audio signal and encoding it as a bitstream, which includes a sequence of data units representing time segments of the audio signal. The method comprises: assigning a score to each data unit; monitoring an accumulated score of data units back to a reference point; when the accumulated score reaches a threshold, inserting into the bitstream a signature unit including a digital signature of fingerprints of a subsequence of the data units back to the reference point; and resetting the reference point. The score is based on a) a detected content of the time segment of the audio signal corresponding to the data unit, b) contextual information relating the time segment to a history of the audio signal, and/or c) information relating to the conditions of capturing the time segment.

公开(公告)号：US20240203457A1

公开(公告)日：2024-06-20

申请号：US18511001

申请日：2023-11-16

Applicant: Axis AB

Inventor： Stefan LUNDBERG ,  Björn VÖLCKER

IPC: G11B27/036 ,  G06F21/10

CPC classification number: G11B27/036 ,  G06F21/1062

Abstract: A signed video bitstream obtained by prediction coding of a video sequence includes data units and associated signature units, wherein each data unit represents at most one macroblock in a video frame of the video sequence, and each signature unit includes a digital signature of a bitstring derived from fingerprints of exactly one associated data unit each. The bitstream is edited by: receiving a request to substitute a region; determining a first set of macroblocks, in which said region is contained, and a second set of macroblocks referring to macroblocks in the first set; adding an archive object that includes fingerprints of a first and a second set of data units, which represent the first and second set of macroblocks; editing the first set of data units in accordance with the request to substitute; and re-encoding the second set of data units.

公开(公告)号：US20240163112A1

公开(公告)日：2024-05-16

申请号：US18503586

申请日：2023-11-07

Applicant: Axis AB

Inventor： Björn VÖLCKER ,  Stefan Lundberg

IPC: H04L9/32 ,  H04L9/08 ,  H04N19/159 ,  H04N19/177

CPC classification number: H04L9/3247 ,  H04L9/0825 ,  H04L9/3236 ,  H04N19/159 ,  H04N19/177

Abstract: A method of signing prediction-coded video data comprises: obtaining a coded video sequence comprising a set of frames including at least one intra frame having independently decodable image data, and at least one inter frame, containing image data decodable by reference to another frame; generating a group hash of the coded video sequence by hashing the image data of the coded video sequence; generating a plurality of individual hashes of frame subsets including at least one frame by hashing the image data derived from each of the frame subsets, reducing the length of each of the individual hashes to a length shorter than a total length of the group hash, generating a digital signature by encrypting at least the group hash and the individual hashes with reduced lengths; providing the group hash and the reduced length individual hashes together with the digital signature and the coded video sequence.

公开(公告)号：US20230188732A1

公开(公告)日：2023-06-15

申请号：US17980150

申请日：2022-11-03

Applicant: Axis AB

Inventor： Björn VÖLCKER ,  Stefan LUNDBERG

IPC: H04N19/172 ,  G06F21/62 ,  G06F21/64 ,  H04L9/32

CPC classification number: H04N19/172 ,  G06F21/6209 ,  G06F21/64 ,  H04L9/3247

Abstract: A method for verifying a digital signature in a video data segment generated by a video delivery chain comprises: obtaining the video data segment comprising encoded image frames and a plurality of node device datasets associated with respective labels; wherein one or more node device datasets include respective digital signatures; wherein the one or more node device datasets comprises a first node device dataset which includes a first digital signature generated by a first node device based on a first number of node device datasets that have been last added to the video data segment before the first node device dataset; locating the labels; identifying , using the labels, the first number of node device datasets; and verifying the first digital signature. The application also discloses a method of adding a digital signature to a video data segment.