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Image cryptography
- 1. Dr.P.Muneeshwari Assistant Professor, Dept. of CSE SRM Institute of Science and Technology,Ramapuram Campus Chennai IMAGE CRYPTOGRAPHY
- 2. Outline ⚫ Introduction ⚫ Need ⚫ Image Security ⚫ Methodology ⚫ Example ⚫ Attacks ⚫ Analyses ⚫ Conclusion
- 3. Plaintext Decryption Ciphertext Cryptography ⚫ Means secret writing ⚫ To protect our data against unauthorized access ⚫ Encrypt data into an illegible format that only the intended recipients can decrypt and read Readable Unreadable Readable ⚫ Privacy, trust, access control and authentication ⚫ Remote access, certificate based authentication, online orders and payments, email, messaging Encryption Plaintext
- 4. Digital Images ⚫ Arrangement of pixels ⚫ Information intelligible due to the correlation of pixels ⚫ Binary, Gray, Colour Red Webinar:Dept.of IT,Excel Engg.College, Komarapalayam - 637303 Blue Green 24-04-2020
- 5. Need ⚫ Growth in the arena of multimedia technology ⚫ Digital image has become an important medium of communication ⚫ Over dissemination and use
- 7. Why Not? ⚫ Traditional text cryptosystems to encrypt images ⚫ Image characteristics ⚫ Bulk data capacity ⚫ High data redundancy ⚫ Correlation among adjacent pixels ⚫ Uncorrelate the adjacent pixels
- 8. Effectiveness of Protection ⚫ Kerckhoffs’s doctrine “A cryptosystem should be secure even if everything about the system, except the key, is public knowledge” ⚫ Encryption algorithm ⚫ Quality of key
- 9. Algorithms ⚫ Domain ⚫ Spatial ⚫ Frequency ⚫ Categories ⚫ Lossy ⚫ Lossless ⚫ Transformation ⚫ Block-based ⚫ Image-based
- 10. Key Generation ⚫ Image ⚫ Chaotic sequence ⚫ Other means ⚫ Hybrid
- 11. Confusion n times m times Confusion Key DiffusionKey Diffusion Confusion Cryptosystem ⚫ Shannon’s Principle ⚫ Diffusion ⚫ Confusion ⚫ Scrambling/Shuffling ⚫ Encryption Plaintext Ciphertextt
- 12. Example Original Image Scrambled Image Encrypted Image Decrypted Image ⚫ Scrambling: Bogdanov Map ⚫ No. of iterations: 15 ⚫ Encryption: ⚫ Key Generation: Shobu-Ose-Mori Map
- 13. Attacks ⚫ Known plainimage attack ⚫ Cipherimage-only attack ⚫ Brute-force attack ⚫ Statistical attack ⚫ Differential attack
- 14. Analyses ⚫ Subjective ⚫ Objective ⚫ Correlation Coefficients ⚫ Correlation Distribution ⚫ HistogramAnalysis ⚫ Entropy ⚫ PSNR ⚫ Key SensitivityTest ⚫ NPCR ⚫ UACI
- 15. Conclusion ⚫ Image cryptography plays an important role in digital image transmission ⚫ Each cryptosystem is unique in its own way ⚫ Everyday new techniques are evolving ⚫ Extensive research is still a dynamic process in this field