MD5 is pretty weak these days, and getting worse. I demonstrated an attack on MD5 recently using the academic research supplied. You can find my original posting from December at the link below. I also include the important parts below... http://seclists.org/fulldisclosure/2007/Dec/0004.html
I know of many commercial security products which still utilize MD5 to prove integrity of the data they distribute to customers. This should no longer be considered appropriate. Now that tools are readily available to exploit newer MD5 collision research, I think it is safe to say that the public should retire its usage for good. Read the most recent research regarding chosen-prefix collisions: http://www.win.tue.nl/hashclash/EC07v2.0.pdf A concrete example for your perusal: khermans_at_khermans-laptop:/tmp$ wget http://www.win.tue.nl/hashclash/SoftIntCodeSign/HelloWorld-colliding.exe --04:36:32-- http://www.win.tue.nl/hashclash/SoftIntCodeSign/HelloWorld-colliding.exe => `HelloWorld-colliding.exe' Resolving www.win.tue.nl... 131.155.70.190 Connecting to www.win.tue.nl|131.155.70.190|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 41,792 (41K) [application/octet-stream] 100%[====================================>] 41,792 109.16K/s 04:36:33 (108.92 KB/s) - `HelloWorld-colliding.exe' saved [41792/41792] khermans_at_khermans-laptop:/tmp$ wget http://www.win.tue.nl/hashclash/SoftIntCodeSign/GoodbyeWorld-colliding.exe --04:36:37-- http://www.win.tue.nl/hashclash/SoftIntCodeSign/GoodbyeWorld-colliding.exe => `GoodbyeWorld-colliding.exe' Resolving www.win.tue.nl... 131.155.70.190 Connecting to www.win.tue.nl|131.155.70.190|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 41,792 (41K) [application/octet-stream] 100%[====================================>] 41,792 127.20K/s 04:36:38 (126.82 KB/s) - `GoodbyeWorld-colliding.exe' saved [41792/41792] khermans_at_khermans-laptop:/tmp$ ls -lsha *.exe 44K -rw-r--r-- 1 khermans khermans 41K 2007-11-23 01:08 GoodbyeWorld-colliding.exe 44K -rw-r--r-- 1 khermans khermans 41K 2007-11-23 01:08 HelloWorld-colliding.exe khermans_at_khermans-laptop:/tmp$ strings HelloWorld-colliding.exe | tail SetFilePointer MultiByteToWideChar LCMapStringA LCMapStringW GetStringTypeA GetStringTypeW SetStdHandle CloseHandle KERNEL32.dll Hello World ;-) khermans_at_khermans-laptop:/tmp$ strings GoodbyeWorld-colliding.exe | tail SetFilePointer MultiByteToWideChar LCMapStringA LCMapStringW GetStringTypeA GetStringTypeW SetStdHandle CloseHandle KERNEL32.dll Goodbye World :-( khermans_at_khermans-laptop:/tmp$ md5sum HelloWorld-colliding.exe | awk '{print $1}' | tee hw 18fcc4334f44fed60718e7dacd82dddf khermans_at_khermans-laptop:/tmp$ md5sum GoodbyeWorld-colliding.exe | awk '{print $1}' | tee gw 18fcc4334f44fed60718e7dacd82dddf khermans_at_khermans-laptop:/tmp$ cmp hw gw khermans_at_khermans-laptop:/tmp$ echo $? 0 There you have it. Surely a GPL'd tool implementing this attack style will be available shortly. And since Chinese researchers have been attacking SHA-1 lately, should SHA-256 be considered the proper replacement? I am unsure :-( -- Kristian Erik Hermansen "Know something about everything and everything about something." -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
