cryptography
DESCRIPTION
Cryptography. Contact Information. Introduction. Cryptology. A form of communication which is primarily concerned with the secure transmission (through encryption ) of a secret message over an insecure channel. Cryptography. +. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/1.jpg)
![Page 2: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/2.jpg)
Contact Information
Cryptography 22/04/23 | pag. 2
Professor
Assistant
Office
Webpage
Course Text
Adriaan [email protected]
Pleinlaan 9, 2.29
http://homepages.vub.ac.be/~andooms (Education)
• Johanes A. Buchmann. Introduction to Cryptography, Springer, 2000.• Richard Mollin, Codes: The Guide to Secrecy From Ancient to Modern Times, Chapman & Hall, 2005. • Alfred J. Menezes, Paul C. van Oorschot and Scott A. Vanstone Handbook of Applied Cryptography, CRC Press, 1996.
![Page 3: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/3.jpg)
Introduction
Introduction22/04/23 | pag. 3
![Page 4: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/4.jpg)
Cryptology
Introduction22/04/23 | pag. 4
Cryptology
+
A form of communication which is primarily concerned with the secure transmission (through encryption) of a secret message over an insecure channel.
Deals with attacks on encrypted intercepted messages to recover the secret message.
=
Cryptography
Cryptanalysis
![Page 5: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/5.jpg)
Cryptosystem
Introduction22/04/23 | pag. 5
![Page 6: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/6.jpg)
Example: Ceasar Cipher
Cryptography 22/04/23 | pag. 6
![Page 7: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/7.jpg)
Example: Ceasar Cipher
Introduction22/04/23 | pag. 7
Hence the number of keys should be large!
![Page 8: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/8.jpg)
Basic Concepts
Introduction22/04/23 | pag. 8
![Page 9: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/9.jpg)
Symmetric vs AsymmetricCryptosystems
Introduction22/04/23 | pag. 9
![Page 10: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/10.jpg)
Cryptanalysis
Introduction22/04/23 | pag. 10
Kerckhoff’s principle
![Page 11: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/11.jpg)
Attacks
Introduction22/04/23 | pag. 11
![Page 12: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/12.jpg)
Example: Attacks
Introduction22/04/23 | pag. 12
![Page 13: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/13.jpg)
Alphabet
Introduction22/04/23 | pag. 13
![Page 14: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/14.jpg)
Alphabet
Introduction22/04/23 | pag. 14
![Page 15: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/15.jpg)
Words
Introduction22/04/23 | pag. 15
![Page 16: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/16.jpg)
Permutations
Introduction22/04/23 | pag. 16
![Page 17: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/17.jpg)
Permutations
Cryptography 22/04/23 | pag. 17
![Page 18: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/18.jpg)
Symmetric Cryptosystems
Symmetric Cryptosystems22/04/23 | pag. 18
![Page 19: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/19.jpg)
Block Ciphers
Symmetric Cryptosystems22/04/23 | pag. 19
![Page 20: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/20.jpg)
Block Ciphers
Symmetric Cryptosystems22/04/23 | pag. 20
![Page 21: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/21.jpg)
Block Ciphers:Permutation Cipher
Symmetric Cryptosystems22/04/23 | pag. 21
![Page 22: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/22.jpg)
Block Ciphers:Multiple Encryption
Symmetric Cryptosystems22/04/23 | pag. 22
![Page 23: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/23.jpg)
Block Ciphers:Modes of Use
Cryptography 22/04/23 | pag. 23
• ECB: Electronic Codebook
• CBC: Cipherblock Chaining
• CFB: Cipher Feedback
• OFB: Output Feedback
![Page 24: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/24.jpg)
Block Ciphers – ECB:Electronic Codebook Mode
Cryptography 22/04/23 | pag. 24
![Page 25: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/25.jpg)
Block Ciphers – ECB:Electronic Codebook Mode
Cryptography 22/04/23 | pag. 25
![Page 26: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/26.jpg)
Block Ciphers – ECB:Electronic Codebook Mode
Cryptography 22/04/23 | pag. 26
![Page 27: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/27.jpg)
Example:Block Ciphers – ECB
Cryptography 22/04/23 | pag. 27
![Page 28: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/28.jpg)
Drawback:Block Ciphers – ECB
Cryptography 22/04/23 | pag. 28
![Page 29: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/29.jpg)
Example:Block Ciphers – ECB
Cryptography 22/04/23 | pag. 29
![Page 30: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/30.jpg)
Block Ciphers – CBC:Cipherblock Chaining Mode
Cryptography 22/04/23 | pag. 30
![Page 31: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/31.jpg)
Block Ciphers – CBC:XOR
Cryptography 22/04/23 | pag. 31
![Page 32: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/32.jpg)
Block Ciphers – CBC:Cipherblock Chaining Mode
Cryptography 22/04/23 | pag. 32
![Page 33: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/33.jpg)
Block Ciphers – CBC:Cipherblock Chaining Mode
Cryptography 22/04/23 | pag. 33
![Page 34: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/34.jpg)
Block Ciphers – CBC:Cipherblock Chaining Mode
Cryptography 22/04/23 | pag. 34
![Page 35: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/35.jpg)
Example:Block Ciphers – CBC
Cryptography 22/04/23 | pag. 35
![Page 36: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/36.jpg)
Block Ciphers – CBC:Cipherblock Chaining Mode
Cryptography 22/04/23 | pag. 36
![Page 37: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/37.jpg)
Example:Block Ciphers – CBC
Cryptography 22/04/23 | pag. 37
![Page 38: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/38.jpg)
Drawback:Block Ciphers – CBC
Cryptography 22/04/23 | pag. 38
![Page 39: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/39.jpg)
Block Ciphers – CFB:Cipher Feedback Mode
Cryptography 22/04/23 | pag. 39
![Page 40: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/40.jpg)
Block Ciphers – CFB:Cipher Feedback Mode
Cryptography 22/04/23 | pag. 40
![Page 41: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/41.jpg)
Block Ciphers – CFB:Cipher Feedback Mode
Cryptography 22/04/23 | pag. 41
![Page 42: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/42.jpg)
Example:Block Ciphers – CFB
Cryptography 22/04/23 | pag. 42
![Page 43: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/43.jpg)
Drawback:Block Ciphers – CFB
Cryptography 22/04/23 | pag. 43
The smaller the block length r, the shorter the ciphertext blocks. This means on the hand that transmission is faster, but on the other hand that the block encryption function must be applied more frequently. The optimal choice of r depends on a tradeoff between transmission and computation speed.
![Page 44: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/44.jpg)
Block Ciphers – OFB:Output Feedback Mode
Cryptography 22/04/23 | pag. 44
![Page 45: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/45.jpg)
Block Ciphers – OFB:Output Feedback Mode
Cryptography 22/04/23 | pag. 45
![Page 46: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/46.jpg)
Block Ciphers – OFB:Output Feedback Mode
Cryptography 22/04/23 | pag. 46
![Page 47: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/47.jpg)
Example:Block Ciphers – OFB
Cryptography 22/04/23 | pag. 47
![Page 48: Cryptography](https://reader036.vdocuments.us/reader036/viewer/2022070418/56815a06550346895dc752dd/html5/thumbnails/48.jpg)
Drawback:Block Ciphers – OFB
Cryptography 22/04/23 | pag. 48