1 / 55

Cryptography

Cryptography. Presented by: Noushin Ranjkesh Olinka Bedroya Sharif University of Technology-1391 Department of Physics, Tehran, Iran. Chapter 4 The Language Barrier. The impenetrability of unknown languages, the Navajo code talkers of World War II and the decipherment of

kaseem-richard
Download Presentation

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 Presented by: Noushin Ranjkesh Olinka Bedroya Sharif University of Technology-1391 Department of Physics, Tehran, Iran

  2. Chapter 4The Language Barrier The impenetrability of unknown languages, the Navajo code talkers of World War II and the decipherment of Egyptian hieroglyphs

  3. Purple Code , Battle of Midway 1 /47

  4. 2 / 47

  5. بیهودگی بنیادی ماشین های رمزنگاری، سرعت پایین انتقال اطلاعات در نبردهای مناطق محدود، به ویژه جنگ های اقیانوس آرام، در نهایت موجب استفاده از کد گوهای ناواجو گردید. 3 / 47

  6. 4 / 47

  7. کاستی های استفاده از زبان ناواجو برای رمزگذاری اطلاعات در جنگ جهانی دوم • نبودن واژه های معادل در زبان ناواجو،برای واژه های نظامی معادل سازی واژه های کاربردی در جنگ با نام حیوانات و واژهای اصیل در زبان ناواجو • نام مکان ها و افراد که در هر زبانی، به صورت مشابه ادا می شود تهیه ی واژه نامه ای از واژه های دارای معادل،در زبان ناواجو برای هر حرف الفبا 5 / 47

  8. 6 / 47

  9. The Navajo terms fighter plane amphibious vehicle Submarine owl (Da-he-tih-hi) frog (Chal) iron fish (Besh-lo) The military terms 7 / 47

  10. Pacific • Pig • Ant • Cat • Ice • Fox • Ice • Cat • Bi-sodih • Wol-la-chee • Moasi • Tkin • Ma-e • Tkin • Moasi 8 / 47

  11. Deciphering Lost Language And Ancient Scripts 9 /47

  12. Hieroglyph 10 / 47

  13. Hieroglyph • زبان مصریان باستا ن از حدود سه هزار سال پیش از میلاد • یک زبان بسیار زینتی و کاربردی برای معابد به دلیل سختی نوشتار این زبان کم کم به زبان هیراتیک و سپس دموتیک که برای استفاده در روزمره مناسب تر است، تبدیل شده اند. در حدود چهار قرن پس از میلاد مسیح،با گسترش مسیحیت و افزایش قدرت نفوذ کلیسا،زبان یونانی غالب شد و الفبای جدیدی از ترکیب 24 حرف از زبان یونانی و 6 نشانه از زبان دموتیک ساخته شد و زبان قبطی شکل گرفت. 11 / 47

  14. Hieratic 12 / 47

  15. 13 /47

  16. 14 /47

  17. Demotic 15 /47

  18. Coptic 16 /47

  19. The Rosetta Stone 17 /47

  20. سنگ روزتا • توسط گروه باستان شناس اعزامی اسکندر در شهر روزتا کشف شد. • در موزه ی بریتانیا نگه داری می شود. • شامل یک متن ثابت به سه زبان یونانی، دموتیک و هیروگلیف است. 18 / 47

  21. 19 /47

  22. Thomas Young 20 /47

  23. Karnak Temple 21 /47

  24. Jean-François Champollion 22 /47

  25. 23 /47

  26. 24 /47

  27. 25 /47

  28. Berenika 26 /47

  29. 27 /47

  30. Ptolemaios Cleopatra 28 /47

  31. 29 /47

  32. RA (درقبطی به خورشید گفته می شود) RAMSS( رامسس) 30 / 47

  33. Chapter 5Alice and Bob Go Public Modern cryptography,the solution to the so-calledkey-distribution problemand the secret history ofnonsecret encryption

  34. Entering the computer age Break of lorenz cypher: sending a same 4000 characters message twice (slightly different) Bill Tutte A Lorenz cypher machine John Tiltman 31 /47

  35. Entering the computer age Max Newman Thomas H. Flowers ENIAC ,1945 Colossus,delivered 1943 32 /44

  36. Entering the computer age Differences between computer and mechanical encryption: • complexity • speed • Computers deal with binary numbers e.g. computer version of a substitution cipher: Message HELLO Message in ASCII 10010001000101100110010011001001111 Key(DAVID) 10001001000001101011010010011000100 Ciphertext00011000000100001101000001010001011 ASCII table 33 /47

  37. Entering the computer age • 1947, invention of transistor • 1951, Ferranti began to make computers to order. • 1953, IBM launched its first computer • 1957, introduction of Fortran • 1959, invention of the integrated circuit First transistor Ferranti’s computer 34 /47 IBMs first computer

  38. Key Distribution • Vigenère key • Delivering the Enigma monthly code book • 1970s, Banks needed to deliver keys to customers 35 /47

  39. Key Distribution Merkle puzzles Quadratic gap is best possible if we treat cipher as a black box oracle [B. Barak and M. Mahmoody-Ghidary. Merkle Puzzles are Optimal] 36 /47

  40. Key Distribution Whitfield Diffie connections of the world wide web. Colors represent different domains. 37 /47

  41. Key Distribution • Exchanging keys in person • No key sharing - double locked • Asymmetric key… Martin Hellman Ralph Merkle 38 /47

  42. Asymmetric Key What symmetric and asymmetric indicate To build an asymmetric cipher: • Alice publishes a public key • People lookup for Alice’s Public key • They use the public key and encryption method to send Alice messages • Alice uses her private key to decrypt 39 /47

  43. One way functions Mixing colors 40 /47

  44. One way functions Modular Exponentiation Diffie-Hellman • Agree on a public modulus N and a base g • Alice chooses a private key x between 1 and N -1 • She constructs a public key by computing X=g x mod N • Bob chooses a random y and calculate K=X y. • Bob sends Alice the enciphered text and Y=g y • Alice calculates the K=Y x and deciphers the text 41 /47

  45. One way functions 42 /47

  46. RSA Cryptosystem Ronald Rivest, Adi Shamir and Leonard Adleman. 43 /47

  47. RSA Cryptosystem 44 /47

  48. RSA Cryptosystem • N = 114,381,625,757,888,867,669,235,779,976,146,612,010, 218,296,721,242,362,562,561,842,935,706,935,245,733,897, 830,597,123,563,958,705,058,989,075,147,599,290,026,879, 543,541 • q = 3,490,529,510,847,650,949,147,849,619,903,898,133,417, 764,638,493,387,843,990,820,577 • p = 32,769,132,993,266,709,549,961,988,190,834,461,413,177, 642,967,992,942,539,798,288,533 • Thus far, the best way known to invert RSA is to factor N. • The best running time for a fully proved algorithm is Dixon’s Random squares which runs in time • It took 2 years to factor a 232 digit number, using hundreds of machines • P should have 1024 bits 45 /47

  49. The Secret History Of Public Key Cryptography James Ellis, joined GCHQ in 1965 Both new and old GCHQbuildings  Malcolm Williamson , joined GCHQ in 1974 Clifford Cocks , joined GCHQ in 1973 46 /47

  50. Brief review of chapter 5 Birth of computer encryption Key distribution problem Asymmetric encryption Diffie-Hellman cryptosystem RSA crypto system 47 /47

More Related