Bull, DR

Redmill, DW

Thomas, NM

English

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A novel H.264 SVC encryption scheme for secure bit-rate transcoding

This paper presents a novel architecture for the secure delivery of encrypted H.264 SVC bitstreams. It relies on a block cipher and stream cipher used in a novel way that would allow an intermediary transcoder to truncate the bitstream to the appropriate bit-rate without decrypting the data. The system, called SVC-sec, is compared to other architectures presented in the literature and it is shown that SVC-sec offers many benefits, particularly when used with FGS streams.This paper presents a novel architecture for the secure delivery of encrypted H.264 SVC bitstreams. It relies on a block cipher and stream cipher used in a novel way that would allow an intermediary transcoder to truncate the bitstream to the appropriate bit-rate without decrypting the data. The system, called SVC-sec, is compared to other architectures presented in the literature and it is shown that SVC-sec offers many benefits, particularly when used with FGS stream

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                          Thomas, N. M., Bull, D. R., & Redmill, D. W. (2009). A novel H.264 SVCencryption scheme for secure bit-rate transcoding. In Picture CodingSymposium, 2009 (PCS 2009), Chicago, USA. (pp. 1 - 4). Institute ofElectrical and Electronics Engineers (IEEE). 10.1109/PCS.2009.5167429Link to published version (if available):10.1109/PCS.2009.5167429Link to publication record in Explore Bristol ResearchPDF-documentUniversity of Bristol - Explore Bristol ResearchGeneral rightsThis document is made available in accordance with publisher policies. Please cite only the publishedversion using the reference above. Full terms of use are available:http://www.bristol.ac.uk/pure/about/ebr-terms.htmlTake down policyExplore Bristol Research is a digital archive and the intention is that deposited content should not beremoved. However, if you believe that this version of the work breaches copyright law please contactopen-access@bristol.ac.uk and include the following information in your message:• Your contact details• Bibliographic details for the item, including a URL• An outline of the nature of the complaintOn receipt of your message the Open Access Team will immediately investigate your claim, make aninitial judgement of the validity of the claim and, where appropriate, withdraw the item in questionfrom public view.A NOVEL H.264 SVC ENCRYPTION SCHEME FOR SECURE BIT-RATE TRANSCODINGNithin Thomas, David Bull, David RedmillUniversity of Bristol, UK1 234ABSTRACTRESULTSSVE ARCHITECTURECONCLUSIONSFeatures:• No Decryption required prior to scaling• Any standard cipher can be used• Supports all types of scalabilityError in decryptionD D DIVSection removed by transcodingMotivation:• Traditional encryption causes errors if transcoding is carried out• ECB mode encryption not secure• Adding additional data to preserve synchronization increases bitrate Benefits:• End to end security preserved• Highest level of security using well studied ciphers• No bitrate overhead• Compatible with standard scaling transcodersCipher Block Tree (CBT):• Novel mode of operation• Allows several CBC chains to be connected in a tree structure• Only one key and IV required to support a tree• IV for a chain created using a function, f, on output of block from parent chainD D DIVf D D DSVE:• Derived from CBT for use with SVC• Support for potential future support of FGS• Uses Residual Block Termination (RBT) to avoid bitrate expansion due to paddingResidual Block Termination (RBT):• Standard technique used in block ciphers• Used to encrypt last block if size of plaintext is not multiple of block size   • Avoids bitrate expansion caused by paddingD DIVEBase Layer FGS MGS CGSSecurity:• High level of security• No weaknesses from IV reuse• No weaknesses from use of ECB• NAL headers unencrypted so some information leakedTranscoder Latency:• No latency added by encryption• Packets can be transcodedindependently despite encryptionTranscoding Flexibility:• All forms of bitrate scaling supported• Bit level transcoding using FGS is possible• No effect on the quality of output due to encryptionBitrate Overhead:• Does not add any significant overhead• Only one key and IV need to be transmitted• Padding avoided by use of RBT• An encryption scheme optimised for use with SVC• Can be modified for use with other scalable media• Can support FGS scalability• Encryption transparent to transcoder• High levels of security possible• Benefits of scalable coding preserved• No compromise on codec performance

https://research-information.bris.ac.uk/files/3017190/thomas_IEEE_PCS_2009.pdf

A novel H.264 SVC encryption scheme for secure bit-rate transcoding

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