1. Insecure network V Zaurus V R (1) Naive Encryption Scheme (2) Selective Encryption Scheme Video Encoding (H.263) Selective Encryption (DES) P-frame P-frame I-frame P-frame P-frame I-frame • EnergyNaive=eDES*STotal Intra-block Video Encoding (H.263) Naive Encryption (DES) • EnergySelective = eDES*SIB • eDES - energy to encrypt one byte by DES • STotal - size of the whole video data • SIBl - size of Intra-blocks in video data P-frame P-frame I-frame P-frame P-frame I-frame Experimental Setup System Architecture Secure Video Application (Encoder / Decoder) DES H.263 Codec Device Driver 5 V OpenSSL Library Operating System (Linux) R = 22 ohm Mobile Handheld Hardware (Sharp Zaurus) • DAQ board with BNC Connector • Windows XP • 1,000 samples/sec • 400 MHz Intel XScale • 64 MB flash & 32 MB SDRAM VR PZaurus = * VZaurus Power Measurement System R 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 onbattery-operated mobile devices Video Encoder Video Decoder Motion Estimation DCT Quantization Entropy Encoding Entropy Decoding Inverse Quantization IDCT Motion Compensation 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 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 % (4) Video Encryption Algorithm (VEA) (3) Zig-Zag Permutation Scheme 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) VEA (XOR &DES) Video Encoding (H.263) 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 • Naïve encryption scheme consumes twice the energy of Selective encryption scheme • eoverhead - energy to shuffle coefficients • eXOR - energy for XOR Experimental Study on Tradeoffs between Security and Energy Consumption 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 75.78 74.77 80 74.11 72.87 72.26 High (Quant = 1) High (Full) 128.2 13 % 60 70 Huge Difference (98%) (2.4%) (1.7%) 60 50 Low (Partial) 111.0 Measured Energy (Joules) Encoding without Encryption 50 Measured Energy (Joules) 40 Mid-High (Quant = 4) High (Full) 92.05 9 % Encoding with Encryption (Selective) 40 30 Encoding with Encryption (Naïve) Low (Partial) 83.56 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 0 0 Application FOREMAN.qcif NEWS.qcif Low (Quant = 31) High (Full) 70.44 1 % H.263 Encoder H.263 Decoder DES Crypto Video Clips • 11 MB with 300 frames • 1:10(IP ratio),10(Quant),full search 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