10 BTC 4 U 2 STEAL - Protected by a weak 5-letter password - crack & it's yours!

[Vorksholk]

Got so excited. False positive lol

[thirdchance57]

i wish i could crack it but i'm just a noob.

awesome work creating the bank note generator

[casascius]

K... I think there may be a weakness!!!!, if I understand the code correctly...

HC

If you find one, please share!

[HotDiggityDawg]

I thought I cracked it, and then I realized I hit the "Generate" key on accident lmao.

I'm a total noob with no hope of getting this but it's been fun trying! And obviously I'll continue trying Thanks casascius.

[TTBit]

My 6 character private keys seem secure enough

[finkleshnorts]

hmm, where do I go to write the loops? This is my first application of programming outside school.

[Elxiliath]

You'll need to make the loop conditional on the input of the text field. But you will have to incorporate the checking functions and have the value change after a negative test and adjust the text field there after.

Try Form1.cs

[finkleshnorts]

I give up

[bitfreak!]

Well assuming the password is a word in the dictionary, there are something like 10,000 words which are 5 letters long (that's a very rough guess based on the fact most dictionaries have around 200,000 words).

Some brief testing with the address utility software indicates that it takes about 3.5 seconds to decrypt the private key using my Phenom II X4 810 (also a very rough estimate using only the GUI).

Assuming my calculations so far are remotely correct, to test 10,000 pass phrases when each test takes about 3.5 seconds, will take at least 9 hours. Of course the pass should be found before trying all 10,000.

If the password is a 5 letter English word, it would probably be possible to crack the key using a list of the 5,000 most common 5 letter words or even less. However, the words should be tested in all caps also, so we're back to 10,000.

[Nolo]

I'd like to give it a shot, but have no experience brute forcing a key.  Is there any particular program I could download to try, or is it something I would have to write myself?

[Phinnaeus Gage]

I not going to do this myself, but I will submit one password guess. The first person to try it and it works, please split the bounty with me. Here is my guess: Bruno.

~Bruno K~

[Nolo]

I not going to do this myself, but I will submit one password guess. The first person to try it and it works, please split the bounty with me. Here is my guess: Bruno.

~Bruno K~

Sorry no dice.   

[Elxiliath]

lol, nice.  This is getting more interesting the more I drink.  Haha.  I'm sitting here trying to code in a virtual machine I installed just for this.  I don't think I will guess this or get it, but it's fun and would be nice.

[adamstgBit]

well, i wasted some time on the problem

can't find a C++ version of the SCrypt, so i gave up  

BTW the password is not  "MikeC" 

[Elxiliath]

The coding process is pretty straight forward, it should be easy to compile your own app with both the code or decode process and attempt it. 

[kokojie]

hmm, where do I go to write the loops? This is my first application of programming outside school.

There's no point in writing the loop in C#, as someone already pointed out, using C#, it would take 36 years to crack. You have to rewrite the entire decryption algorithm, in another language, that has a fast scrypt implementation. But if you want to try, the loop should be written in btnPrivWIFToHex_Click method, which is in Form1.cs

[bitfreak!]

Here are some good 5-letter word lists for those who want to take the dictionary approach.

8938 5-letter words:
http://www.poslarchive.com/math/scrabble/lists/common-5.html

5757 5-letter words:
http://homepage.cs.uiowa.edu/~sriram/21/fall07/words.dat

[hardcore-fs]

K... I think there may be a weakness!!!!, if I understand the code correctly...

HC

If you find one, please share!

Well I'd started and my F***** RAID just crashed.

So I may as well share it.... if I understand it correctly.......

It seems that it may have a similar weakness to the zip format.. if I'm not mistaken.


public override bool DecryptWithPassphrase(string passphrase){
.....}


If we look down we see:

byte[] checksum = sha256.ComputeHash(utf8.GetBytes(passphrase + "?"));

            if (hex[2] != 0x80) {
                if ((checksum[0] & 0x7f) != hex[2] || (checksum[1] & 0x7e) != (hex[3] & 0x7e)) {
                    return false;
                }
            }

It seems we can recover a partial solution, because if it is NOT a partial solution the above will fail.

By getting the products up-to this stage, popping them over the serial port to an fpga...... and since Bitcoin is DOUBLE sh256
We can get two engines cycling thrugh the Sha256 keys for the range AAAAA-zzzzz ( actually by splitting the space over two devices we can half the searchtime with a brute it becomes 190102016

Each time we get a 'hit' from the above, we pop it back to the computer to drop it into the code that follows the above code in  "DecryptWithPassphrase"

so even with a XUPV5 I can get over 500MHS through the key address space

52*52*52*52*52=380204032

0.76 seconds  Unless my maths have broken down.

Like I say my development env. crashed so I've nothing to test with.

[adamstgBit]

hmm, where do I go to write the loops? This is my first application of programming outside school.

There's no point in writing the loop in C#, as someone already pointed out, using C#, it would take 36 years to crack. You have to rewrite the entire decryption algorithm, in another language, that has a fast scrypt implementation. But if you want to try, the loop should be written in btnPrivWIFToHex_Click method, which is in Form1.cs

I have a funny feeling scrypt will be slow no matter what the language

The algorithm was specifically designed to make it costly to perform large scale custom hardware attacks by requiring large amounts of memory

good luck

[bitfreak!]

I just read this:

On modern hardware and with default parameters, the cost of cracking the password on a file encrypted by scrypt enc is approximately 100 billion times more than the cost of cracking the same password on a file encrypted by openssl enc; this means that a five-character password using scrypt is stronger than a ten-character password using openssl.

https://www.tarsnap.com/scrypt.html

There's no way anyone is going to crack this via simple brute force. A dictionary attack is the only plausible option. If the password is a random jumble of lowercase and uppercase characters, I doubt anyone will crack it.