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Overview

Overview. Basic Communication Scenario for Cryptography Possible Attacks (a) Ciphertext only (b) Known plaintext (c) Chosen plaintext (d) Chosen ciphertext. Basic Communication Scenario for Cryptography. Symmetric vs. Public Key Algorithms. Symmetric key algorithms

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Overview

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  1. Overview • Basic Communication Scenario for Cryptography • Possible Attacks (a) Ciphertext only (b) Known plaintext (c) Chosen plaintext (d) Chosen ciphertext

  2. Basic Communication Scenario for Cryptography

  3. Symmetric vs. Public Key Algorithms • Symmetric key algorithms (a) DES (Data Encryption Standard) (b) AES (Advanced Encryption Standard) • Public key algorithms (a) RSA (Rivest-Shamir-Adleman) (b) Discrete Algorithm (ElGamal) (c) Algorithm based on Error Correcting Code (McEliece)

  4. Key Lengths • 16 bits – 2^16=65536 • 32 bits – 2^32=4,294,967,296 • DES has a 56-bit key • AES might require 192-bit keys • How soon can you factor 78185641 and 3127 into the product of primes by hand? • 53, 59, 1193, 65537

  5. Convert Raw Image to PostScript • C Program http://www.cs.nthu.edu.tw/~cchen/CS4351/raw2ps.c • Description http://www.cs.nthu.eud.tw/~cchen/CS4351/Imageprint.ps • Matlab programs http://www.cs.nthu.eud.tw/~cchen/CS4351/io6.m • Examples for printing 6 images in a single page mandrill.raw, scene.raw, fingerprint.raw, texture.raw, ladyface.raw, array150.raw

  6. Lenna and Koala

  7. Introduction to Matlab • See the Appendix C • Read the reference [2] • http://www.cs.nthu.edu.tw/~cchen/CS3331 • http://www.cs.nthu.edu.tw/~cchen/ISA5305

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