"Saul" <saul.dobney@dobney.com> writes:

>On 23 Feb, 18:07, Unruh <unruh-s...@physics.ubc.ca> wrote:
>> Uh, you postulate that the user has 10's of thousands of images on his
>> comptuter. You really expect them to leaf through them all to find that one
>> image, even if it is "recognizeable"? Your assumptions contradict each
>> other. So the user labels the image "password" so he can remember which it
>> is.

>Thanks for the thoughts. You've convinced me it's worth trying as the
>objections are mainly: 1. if they had access to the computer and 2. if
>they could sniff the filelength (the file would never be sent in
>cleartext BTW). Otherwise they don't know what file to use - file
>length would be difficult to ascertain if the file is sent securely
>with other data.

>A 'guess' or 'automated' remote attack would be impossible from
>someone without the right file. A remote attack on the users computer
>could compromise the file - but which would be difficult to ascertain
>remotely - and would be no worse than someone compromising the
>computer on which the passwords are held in the MyPasswords folder
>(yes I've seen them too), or stealing another certificate. The image
>can be protected as the certificate can be protected on the users
>machine.

>By the way as someone who has done a lot of professional market
>research work on measuring recall and recognition in different
>situations, I think you are confusing unprompted and prompted recall.
>The benefit of having a recognisable image as the certificate is huge
>compared to spontaneous recall of a semi-random text string, the
>memory includes both image and position recognition which is why we
>want an image prompt.

>I will produce a proof of concept in the next few weeks.


"We"? Now there are a bunch of you. You are now going to use this in a
context where it means something? I shudder.
You are wanting this to be distributed to people who have no idea or
discipline about crypto. You can assume that their comuter is cracked--
that it is owned by nefarious people out there ( What is the figure-- 30%
of computers are broken into and usable by outsiders?). And I would also
still insist that the very conditions you are aducing as security--- many
image files on the computer-- are also what makes the nemonic value of the
image useless. The more usefull it is ( which of these four image files is
the right one) the less security it offers. (This guy only has four image
files. Lets try them all).