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Symmetric Cryptosystems
Symmetric Cryptosystems10/04/23 | pag. 2
Block Ciphers
Symmetric Cryptosystems10/04/23 | pag. 3
Block Ciphers:Modes of Use
Cryptography 10/04/23 | pag. 4
• ECB: Electronic Codebook
• CBC: Cipherblock Chaining
• CFB: Cipher Feedback
• OFB: Output Feedback
Block Ciphers:Classical examples
Symmetric Cryptosystems10/04/23 | pag. 5
• Affine Cipher
• Affine Linear and Linear Cipher
• Vigenère
• Hill
We first need some linear algebra!
Intermezzo:Greatest Common Divisor
Symmetric Cryptosystems10/04/23 | pag. 6
Intermezzo:Greatest Common Divisor
Symmetric Cryptosystems10/04/23 | pag. 7
Intermezzo:Greatest Common Divisor
Symmetric Cryptosystems10/04/23 | pag. 8
Intermezzo:Greatest Common Divisor
Symmetric Cryptosystems10/04/23 | pag. 9
Intermezzo:Greatest Common Divisor
Cryptography 10/04/23 | pag. 10
Intermezzo:Euclidean Algorithm
Cryptography 10/04/23 | pag. 11
Intermezzo:Euclidean Algorithm
Cryptography 10/04/23 | pag. 12
Intermezzo:Euclidean Algorithm
Cryptography 10/04/23 | pag. 13
Intermezzo:Extended Euclidean Algorithm
Cryptography 10/04/23 | pag. 14
Intermezzo:Extended Euclidean Algorithm
Cryptography 10/04/23 | pag. 15
Intermezzo:Extended Euclidean Algorithm
Cryptography 10/04/23 | pag. 16
Intermezzo:Invertible Elements in a Residue Class Ring
Cryptography 10/04/23 | pag. 17
Intermezzo:Invertible Elements in a Residue Class Ring
Cryptography 10/04/23 | pag. 18
Affine Cipher
Symmetric Cryptosystems10/04/23 | pag. 19
Example:Affine Cipher
Symmetric Cryptosystems10/04/23 | pag. 20
Example: Cryptanalysis of the Affine Cipher
Symmetric Cryptosystems10/04/23 | pag. 21
Example: Cryptanalysis of the Affine Cipher
Symmetric Cryptosystems10/04/23 | pag. 22
Intermezzo:Matrices over Rings
Cryptography 10/04/23 | pag. 23
Intermezzo:Invertible Matrices
Cryptography 10/04/23 | pag. 24
Intermezzo:Invertible Matrices
Cryptography 10/04/23 | pag. 25
Intermezzo:Invertible Matrices
Cryptography 10/04/23 | pag. 26
Intermezzo:Invertible Matrices
Cryptography 10/04/23 | pag. 27
Intermezzo:Affine Linear Functions
Cryptography 10/04/23 | pag. 28
Intermezzo:Affine Linear Functions
Cryptography 10/04/23 | pag. 29
Affine Linear Cipher
Cryptography 10/04/23 | pag. 30
Affine Linear Cipher
Cryptography 10/04/23 | pag. 31
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