Scalable coding,
Scalable coding is a technology that encodes a multimedia signal
in a scalable manner where various representations can be
extracted from a single codestream to fit a wide range of
applications. current scalable codecs are JPEG2000(image),
MPEG-4 FGS(Video), SVC(Scalable video coding). In this project,
we research protection for scalable coding especially SVC
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Fig. 1.
SVC Adaptation
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As Fig 1 showed, SVC encoded contents adapted by
Extraction procedure. extraction conditions are various. e.g. terminal
conditions, Network bandwidth, user preferences
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Scalable Video Encryption,
Multimedia Encryption different with Data encryption. because of
large data size, multimedia
contents encrypt selectively. encryption regions are multimedia
dependent manner (e.g.
video contents use I-frame, I-block or Motion Vector). moreover
scalable contents provide scalability after encryption. In this
project, We research SVC suitable encryption scheme
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The goal of this project is the followings
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1. Encryption for
SVC bitstream
Encryption for SVC
Extraction procedure
SVC format compliance encryption
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2. Conditional
access control
Access to certain
spatial-temporal-quality layers
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Fig. 2. SVC
encryption and decyption
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Fig 2 Shows flow of SVC bitstream. the bitstream flows
Encoding, Encryption, Extraction, Decryption, Decoding. in this
procedure encryption provide secure extraction. because
extractions are possibly not trust, and encryption provide
decoding
without decryption. and
Encryption Region (Data encryption)
: Naive algorithm, selective algorithm, scrambling
Encryption Region (Multimedia
encryption) : I-Frame, I-block, Motion vector,
Coefficient
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Requirement for
Selective Encryption
Visual leakage
Security
Encoder Complexity
Compression overhead
Format compliance
Scalability
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NAL structure in the SVC bitstream
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Fig. 3. SVC NAL
structure and enhancement procedure
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Fig. 3. shows NAL structure in the SVC Bitstream.
SVC bitstream consist of Spatial-temporal-quality base layer and
enhancing layer these layers decided encoding step. each NAL means
each enhancing layer, and extraction performs NAL unit. therefore
NAL units are fundamental encryption unit. moreover NAL unit
encryptions are good for conditional access control
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Conditional access control
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Fig. 4. NAL unit
encryption for conditional access control
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Fig. 4. shows typical SVC bitstreams providing 2
spatial layer, 2 temporal layer, 2 quality layer. if these NAL
encrypt different keys then contents provider can controls access
certain spatial, temporal, quality layer using combination of keys
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Spatial
Quality
15 fps (0)
30 fps (1)
QCIF(0)
Base(0)
{k(0,0,0)}
Not exist
FGS(1)
{key(0,0,0),key(0,0,1)}
Not exist
CIF(1)
Base(0)
{key(0,0,0),key(0,0,1)
key (1,0,0) }
{key(0,0,0),key(0,0,1)
Key(1,0,0),key(1,1,0)}
FGS(1)
{key (0,0,0),k(0,0,1)
key (1,0,0),key(1,0,1)}
{key(0,0,0),key(0,0,1)
key(1,0,0),key(1,0,1)
key(1,1,1),key(1,1,0)}
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Table.
1. Keys for access certain layer
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Table 1. shows access key for certain layer in Fig 4
case. if client don't have enough keys then access denied