1. Overview of Secure Video Applications
Problem and Motivation
Attacks
Battery
-Operated
Devices
Battery
-Operated
Devices
Mobile multimedia applications are vulnerable
to security attacks in wireless networks
Significant computation for video encryption is
expected on battery-operated mobile devices
Video Encoder
Video Decoder
Motion
Estimation
DCT
Quantization
Entropy
Encoding
Entropy
Decoding
Inverse
Quantization
IDCT
Motion
Compensation
Insecure
network
Raw
Video
Compressed
Bit Stream
Compressed
Bit Stream
Decompressed
Bit Stream
Evaluate symmetric video encryption schemes
from the perspective of energy consumption
both analytically and experimentally
Symmetric
Encryption
Technique
Symmetric
Decryption
Technique
Secure Video Encoder
Secure Video Decoder
Encrypted &
Compressed
Bit Stream
Encrypted &
Compressed
Bit Stream
Analytical Study of Video Encryption Schemes with respect to Energy Consumption
Studied Video Encryption Schemes
Analytical Comparison of Video Encryption Schemes
I-frame
P-frame
Naive
Encryption
(DES)
Video
Encoding
(H.263)
EnergyNaive=eDES*STotal
eDES - energy to encrypt one byte by DES
STotal - size of the whole video data
(1) Naive Encryption Scheme
EnergySelective = eDES*SIB
SIBl - size of Intra-blocks in video data
Intra-block
I-frame
P-frame
Selective
Encryption
(DES)
Video
Encoding
(H.263)
(2) Selective Encryption Scheme
Algorithm
Security
Speed
Size
Drawback
Relative
Energy
Naive
Encryption of all frames
High
Slow
No Change
Significant
Computation
100 %
Selective
Partial encryption
(e.g. Intra-blocks)
Moderate
Fast
No Change
Moderate
Security
59 %
(3) Zig-Zag Permutation Scheme
(4) Video Encryption Algorithm (VEA)
Zig-Zag
Shuffling coefficients
from Quantization
Very Low
Very Fast
Big Increase
Breaks efficiency
of Video Encoding
< 1 %
Video Encoding
& Zig-Zag Permutation
(H.263 & Shuffle)
Video
Encoding
(H.263)
VEA
(XOR & DES)
P-frame
P-frame
I-frame
P-frame
P-frame
I-frame
P-frame
P-frame
I-frame
VEA
XORing and Half Encryption
using even byte distribution
High
Fast
No Change
Not applicable
for H.263 without
even distribution
50 %
EnergyZig-Zag = eoverhead
EnergyVEA = ½*(eDES+eXOR)*STotal
eoverhead - energy to shuffle coefficients
eXOR - energy for XOR
Naïve encryption scheme consumes twice the energy of Selective encryption scheme
Experimental Study on Tradeoffs between Security and Energy Consumption
Experimental Setup
5 V V
Zaurus
R = 22 ohm R
Power Measurement System
PZaurus = * VZaurus VR
DAQ board with
BNC Connector
Windows XP
1,000 samples/sec
Secure Video Application
(Encoder / Decoder)
DES
H.263
Codec
Device
Driver
OpenSSL
Library
Operating System
(Linux)
Mobile Handheld Hardware
(Sharp Zaurus)
400 MHz Intel XScale
64 MB flash & 32 MB SDRAM
System Architecture
Energy Consumption for Varying Quality & Security
Experimental Results
Negligible Energy Overhead
Quality
(Quant Scale)
Security
(Full vs. Partial)
Measured
Energy (J)
Energy
Overhead 80
74.77 90
77.62 70 80
74.77
75.78
72.87
74.11
72.26
High
(Quant = 1)
High (Full)
128.2
13 % 60
Huge
Difference
(98%) 70
(2.4%)
(1.7%) 50 60
Low (Partial)
111.0
Measured Energy (Joules)
Encoding without Encryption 40
Measured Energy (Joules) 50
Mid-High
(Quant = 4)
High (Full)
92.05
9 %
Encoding with Encryption (Selective) 40 30
Low (Partial)
83.56
Encoding with Encryption (Naïve) 30 20
11.37 20
Mid-Low
(Quant = 10)
High (Full)
77.62
2 % 10
Appropriate for
mobile video
1.5 10
Low (Partial)
75.78
Application
FOREMAN.qcif
NEWS.qcif
Low
(Quant = 31)
High (Full)
70.44
1 %
H.263 Encoder
H.263 Decoder
DES Crypto
11 MB with 300 frames
1:10(IP ratio),10(Quant),full search
Video Clips
Low (Partial)
69.89
Encryption consumes negligible
energy as compared to encoding
Energy consumption of encryption is
negligible irrespective of video clips
Energy overhead for full video encryption is NEGLIGIBLE