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Cryptography
Reuel Ramos Ribeiro
Agenda
● Modern life and confidential information
● Understanding cryptography
● First methods ( and the key distribution ...
Two problems for you
“Caesar is Canadian (x10)”
Data over the Internet
Am I safe?
Let’s talk about online security...
Let’s talk about online security...
Let’s talk about online security...
What is cryptography?
Purpose
"Always be yourself, express
yourself, have faith in yourself, do
not go out and look for a successful
personality...
Algorithm
Key
Cryptography’s basis
First methods…
Transposition and Substitution
Spartan Scytale (500 B.C.E)
Polybius’ Checkerboard (205 B.C.E)
“Meet me at the park”
becomes
32151544 3215 1144
442315 35114225
Symmetric Key
Public-Key Cryptography
A mathematical approach
Mathematical functions
RSA algorithm (MIT - 1977)
Symmetric Key
Asymmetric Key
Asymmetric Key
Related
Asymmetric Key
Related
887 * 983871921
prime * prime
(private key)
semiprime
(public key)
Prime number (617 digits)
251959084756578934940271832400483985714292821262040320277771378360436620
20707595556264018525880...
Why is that safe?
1.There are infinite prime numbers
2.There is no general mathematical formula
to get ALL prime numbers
3...
Conclusion
Web browsers
Example
Bibliography
Invitation to Cryptology
Author: Thomas H. Barr
Date: 2002
Publisher: Prentice Hall
The Code Book: How to Make It, Break It, Hack It, Crack It
Author: Simon Singh
Date: 2001
Publisher: Delacorte Press
Code Breaking: A history and exploration
Author: Rudolf Kippenhahn
Date: 1999
Publisher: Overlook Press
Questions
I’ll be glad to answer them (really)
Bibliography
Baar, T. H. (2002). Invitation to Cryptology. New Jersey: Prentice Hall.
Kippenhahn, R. (1999). Code Breaking...
Cryptography
Cryptography
Cryptography
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Cryptography

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Cryptography

  1. 1. Dszquphsbqiz Sfvfm Sbnpt Sjcfjsp
  2. 2. Cryptography Reuel Ramos Ribeiro
  3. 3. Agenda ● Modern life and confidential information ● Understanding cryptography ● First methods ( and the key distribution problem ) ● Actual methods ( public-key distribution ) ● Conclusion
  4. 4. Two problems for you “Caesar is Canadian (x10)”
  5. 5. Data over the Internet Am I safe?
  6. 6. Let’s talk about online security...
  7. 7. Let’s talk about online security...
  8. 8. Let’s talk about online security...
  9. 9. What is cryptography?
  10. 10. Purpose "Always be yourself, express yourself, have faith in yourself, do not go out and look for a successful personality and duplicate it." Bruce Lee. ylGgbjwpVnrN4Mx4kTDG4LD8blwtFU G2X7MQt5olmuWRw7HPIY6/U8Fplmz EdVWWX+/0ivQ5pRMjUzhSmxXuZG09 HqLiWWrV7Fr4pCG7bTeEEq0LDr0Lze /rYgLy1faxhYZb9M0ADol1XmaFS5iTK gjv/PWTQbV8v7eTBaxKL/xQUvAUjQ b1ZeZWd7pyzhf8 ORIGINAL CIPHERED
  11. 11. Algorithm Key Cryptography’s basis
  12. 12. First methods… Transposition and Substitution
  13. 13. Spartan Scytale (500 B.C.E)
  14. 14. Polybius’ Checkerboard (205 B.C.E) “Meet me at the park” becomes 32151544 3215 1144 442315 35114225
  15. 15. Symmetric Key
  16. 16. Public-Key Cryptography A mathematical approach
  17. 17. Mathematical functions
  18. 18. RSA algorithm (MIT - 1977)
  19. 19. Symmetric Key
  20. 20. Asymmetric Key
  21. 21. Asymmetric Key Related
  22. 22. Asymmetric Key Related 887 * 983871921 prime * prime (private key) semiprime (public key)
  23. 23. Prime number (617 digits) 251959084756578934940271832400483985714292821262040320277771378360436620 207075955562640185258807844069182906412495150821892985591491761845028084 891200728449926873928072877767359714183472702618963750149718246911650776 133798590957000973304597488084284017974291006424586918171951187461215151 726546322822168699875491824224336372590851418654620435767984233871847744 479207399342365848238242811981638150106748104516603773060562016196762561 338441436038339044149526344321901146575444541784240209246165157233507787 077498171257724679629263863563732899121548314381678998850404453640235273 81951378636564391212010397122822120720357
  24. 24. Why is that safe? 1.There are infinite prime numbers 2.There is no general mathematical formula to get ALL prime numbers 3.There is no efficient algorithm to factorize numbers
  25. 25. Conclusion
  26. 26. Web browsers
  27. 27. Example
  28. 28. Bibliography
  29. 29. Invitation to Cryptology Author: Thomas H. Barr Date: 2002 Publisher: Prentice Hall
  30. 30. The Code Book: How to Make It, Break It, Hack It, Crack It Author: Simon Singh Date: 2001 Publisher: Delacorte Press
  31. 31. Code Breaking: A history and exploration Author: Rudolf Kippenhahn Date: 1999 Publisher: Overlook Press
  32. 32. Questions I’ll be glad to answer them (really)
  33. 33. Bibliography Baar, T. H. (2002). Invitation to Cryptology. New Jersey: Prentice Hall. Kippenhahn, R. (1999). Code Breaking: A history and exploration . New York: Overlook Press. Singh, S. (2001). The Code Book: How to Make It, Break It, Hack It, Crack It. New York: Delacorte Press.

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