Re: Complex Theoretical One Way Hash Question

none wrote:
Matthew Harrison wrote:
Actually, the two problems are very similar.

Actually - way less similar.

With the text, there is 2^n ways of writing the value of the hash in the string - for a given hash (upper/lower case for each letter).

With the image, if we imagine a realistic list of variables

Size : 6 sizes
Font : 16
Colour : 65000
Case : upper/lower

So each character has around 10 million ways of being drawn.

So there is (10^7)^n ways of drawing the MD5 hash

Assuming n = 32 (for a 128 bit hash) .... that's 2^32 combinations for text and (10^7)^32 for images

To compare ... 10^7 is around 2^22.

So the 2^128 leaves around 2^96 combinations for text, but for image - 2^700 for images leaves so much room to move that it's not funny.


Consider the following algorithm:
for i= 1 to 2^128
put i in the image (or in the string that I mentioned)
do the MD5 thing
if MD5_result=i then we have success
next i

I'll make this a competition... if anyone finds a value of n for which md5(the md5 hash of this string is n) = n, I will buy them a beer. Seeing as MD5 is broken(ish), this may even happen. If anyone does it with SHA, I will buy them a whisky chaser as well.


--
Pinging self [127.0.0.1] with 32 bites of banana cake:

Ping statistics for 127.0.0.1:
Slices: Sent = 4, Received = 0, Lost = 4 (100% loss),
.

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