1 / 13

main(int ac, char** av){ int i; for(i=1; i<ac; i++) printf(av[i]); }

main(int ac, char** av){ int i; for(i=1; i&lt;ac; i++) printf(av[i]); }. main(int ac, char** av){ int i; for(i=1; i&lt;ac; i++) printf(strlen(av[i])); }. #define MAX 100 main(){ int i; char t[200]; for(i=1; i&lt;=MAX; i++){ scanf(“%s<br>”, t); printf(t); } }.

anson
Download Presentation

main(int ac, char** av){ int i; for(i=1; i&lt;ac; i++) printf(av[i]); }

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. main(int ac, char** av){ int i; for(i=1; i<ac; i++) printf(av[i]); }

  2. main(int ac, char** av){ int i; for(i=1; i<ac; i++) printf(strlen(av[i])); }

  3. #define MAX 100 main(){ int i; char t[200]; for(i=1; i<=MAX; i++){ scanf(“%s\n”, t); printf(t); } }

  4. #include <stdio.h> #include <string.h> #include <stdlib.h> main(int ac, char** av){ char key[]="HelloWorld"; int i; char ct[200]; for(i=0;i<strlen(av[1]);i++) ct[i] = av[1][i] ^ key[i%strlen(key)]; printf(ct); }

  5. Eve ALICE BOB

  6. Challenge response(the lab door protocol) Eve Challenge: n Id, {Id+n}Kid ALICE OK

  7. What can go wrong? • One sided authentication • But isn’t the visual authentication of the door enough!? • n is not really random • n is not really unrepeatable • PDA compromise / copy • PDA loss • Key compromise or theft • Brute force attacks • Algorithm weaknesses

  8. IFF (Identify-Friend-or-Foe) Systems

  9. MIG in the middle(not true but interesting)http://www.cl.cam.ac.uk/~rja14/errata.html MIG In The Middle Attack south african air defense = SAAD south african bomber = SAB Angolan air defense = AAD Angolan MIG = MIG SAAD --> MIG: N MIG --> AAD: N AAD --> SAB: N SAB --> AAD: KT{SAB, N} AAD --> MIG: KT{SAB, N} MIG --> SAAD: KT{SAB, N}

  10. Good protocol wrong problem! • Aircraft verification vs. detection

  11. Microsoft has proposed the so-called passport protocol for authenticating users on the web. The protocol works as follows: (a) Initially users connect to the passport web site and create profiles for themselves (each profile includes a user name and password); (b)When the user wants to login to a secure site (e.g., secure.com) he/she direct their browser to site; (c) The secure site then redirects the user to the passport web site; (d)The user then enters his/her username and password; (e) If logging in is successful the passport site sets a special cookie in the user’s browser and redirects him/her back to the original site (secure.com, in this case); (f) The cookies contain information about the user’s identity and are encrypted and signed so that they cannot be forged; (g)Secure.com collects the cookie from the user and decrypts it to verify the user’s identity and the authenticity of the cookie; and (h)If all is well the user is allowed access to the site.

  12. http://avirubin.com/passport.html

  13. http://avirubin.com/passport.html

More Related