terris
Uploaded by
48 SLIDES
698 VUES
490LIKES

Cryptography

DESCRIPTION

Cryptography is an essential field focused on securing communication through encryption, allowing the transmission of secret messages over insecure channels. It encompasses various concepts, including symmetric and asymmetric cryptosystems. Key techniques involve cryptanalysis and understanding attacks on encrypted messages. This overview explores block ciphers, including different modes of operation such as ECB, CBC, CFB, and OFB, each with unique advantages and drawbacks. By understanding these principles, one can appreciate the complexities and importance of safeguarding information.

1 / 48

Télécharger la présentation

Cryptography

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cryptography

  2. Contact Information

  3. Introduction

  4. Cryptology A form of communication which is primarily concerned with the secure transmission (through encryption) of a secretmessage over an insecure channel. Cryptography + Deals with attacks on encrypted intercepted messages to recover the secret message. Cryptanalysis Cryptology =

  5. Cryptosystem

  6. Example: Ceasar Cipher

  7. Example: Ceasar Cipher Hence the number of keys should be large!

  8. Basic Concepts

  9. Symmetric vs AsymmetricCryptosystems

  10. Cryptanalysis Kerckhoff’s principle

  11. Attacks

  12. Example: Attacks

  13. Alphabet

  14. Alphabet

  15. Words

  16. Permutations

  17. Permutations

  18. Symmetric Cryptosystems

  19. Block Ciphers

  20. Block Ciphers

  21. Block Ciphers:Permutation Cipher

  22. Block Ciphers:Multiple Encryption

  23. Block Ciphers:Modes of Use • ECB: Electronic Codebook • CBC: Cipherblock Chaining • CFB: Cipher Feedback • OFB: Output Feedback

  24. Block Ciphers – ECB:Electronic Codebook Mode

  25. Block Ciphers – ECB:Electronic Codebook Mode

  26. Block Ciphers – ECB:Electronic Codebook Mode

  27. Example:Block Ciphers – ECB

  28. Drawback:Block Ciphers – ECB

  29. Example:Block Ciphers – ECB

  30. Block Ciphers – CBC:Cipherblock Chaining Mode

  31. Block Ciphers – CBC:XOR

  32. Block Ciphers – CBC:Cipherblock Chaining Mode

  33. Block Ciphers – CBC:Cipherblock Chaining Mode

  34. Block Ciphers – CBC:Cipherblock Chaining Mode

  35. Example:Block Ciphers – CBC

  36. Block Ciphers – CBC:Cipherblock Chaining Mode

  37. Example:Block Ciphers – CBC

  38. Drawback:Block Ciphers – CBC

  39. Block Ciphers – CFB:Cipher Feedback Mode

  40. Block Ciphers – CFB:Cipher Feedback Mode

  41. Block Ciphers – CFB:Cipher Feedback Mode

  42. Example:Block Ciphers – CFB

  43. Drawback:Block Ciphers – CFB 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.

  44. Block Ciphers – OFB:Output Feedback Mode

  45. Block Ciphers – OFB:Output Feedback Mode

  46. Block Ciphers – OFB:Output Feedback Mode

  47. Example:Block Ciphers – OFB

  48. Drawback:Block Ciphers – OFB

More Related