# SYMMETRIC CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2.

## Presentation on theme: "SYMMETRIC CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2."— Presentation transcript:

SYMMETRIC CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2

Block Ciphers Symmetric Cryptosystems 6/05/2014 | pag. 3

Block Ciphers: Modes of Use Cryptography 6/05/2014 | pag. 4 ECB: Electronic Codebook CBC: Cipherblock Chaining CFB: Cipher Feedback OFB: Output Feedback

Block Ciphers: Classical examples Symmetric Cryptosystems 6/05/2014 | pag. 5 Affine Cipher Affine Linear and Linear Cipher Vigenère Hill We first need some linear algebra!

Intermezzo: Greatest Common Divisor Symmetric Cryptosystems 6/05/2014 | pag. 6

Intermezzo: Greatest Common Divisor Symmetric Cryptosystems 6/05/2014 | pag. 7

Intermezzo: Greatest Common Divisor Symmetric Cryptosystems 6/05/2014 | pag. 8

Intermezzo: Greatest Common Divisor Symmetric Cryptosystems 6/05/2014 | pag. 9

Intermezzo: Greatest Common Divisor Cryptography 6/05/2014 | pag. 10

Intermezzo: Euclidean Algorithm Cryptography 6/05/2014 | pag. 11

Intermezzo: Euclidean Algorithm Cryptography 6/05/2014 | pag. 12

Intermezzo: Euclidean Algorithm Cryptography 6/05/2014 | pag. 13

Intermezzo: Extended Euclidean Algorithm Cryptography 6/05/2014 | pag. 14

Intermezzo: Extended Euclidean Algorithm Cryptography 6/05/2014 | pag. 15

Intermezzo: Extended Euclidean Algorithm Cryptography 6/05/2014 | pag. 16

Intermezzo: Invertible Elements in a Residue Class Ring Cryptography 6/05/2014 | pag. 17

Intermezzo: Invertible Elements in a Residue Class Ring Cryptography 6/05/2014 | pag. 18

Affine Cipher Symmetric Cryptosystems 6/05/2014 | pag. 19

Example: Affine Cipher Symmetric Cryptosystems 6/05/2014 | pag. 20

Example: Cryptanalysis of the Affine Cipher Symmetric Cryptosystems 6/05/2014 | pag. 21

Example: Cryptanalysis of the Affine Cipher Symmetric Cryptosystems 6/05/2014 | pag. 22

Intermezzo: Matrices over Rings Cryptography 6/05/2014 | pag. 23

Intermezzo: Invertible Matrices Cryptography 6/05/2014 | pag. 24

Intermezzo: Invertible Matrices Cryptography 6/05/2014 | pag. 25

Intermezzo: Invertible Matrices Cryptography 6/05/2014 | pag. 26

Intermezzo: Invertible Matrices Cryptography 6/05/2014 | pag. 27

Intermezzo: Affine Linear Functions Cryptography 6/05/2014 | pag. 28

Intermezzo: Affine Linear Functions Cryptography 6/05/2014 | pag. 29

Affine Linear Cipher Cryptography 6/05/2014 | pag. 30

Affine Linear Cipher Cryptography 6/05/2014 | pag. 31

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