Help me with ASM

This is an implementation of a relatively trivial hash function. It doesn't look like a particularly good one, but I doubt you can just "make the opposite function" by virtue of the nature of hashes.

Also, this smells like a reverse engineering/cracking/keygen attempt, in which case, may I say: shame upon you. (Unless I'm wrong, of course.)

I really need to translate this to c++ code and make the opposite function.

The opposite function how?

A hash by definition is one way.

You can make hamburger out of a cow, but you can't make a cow out of hamburger.

Similarly with a hash, you can compute a hash from a message, but you can't compute the message from its hash.

This is a ida pro dump (CODE XREF: gives it away) - so why not use hexrays to give you pseudo c

[quote name='sasho648' timestamp='1339437120' post='4948227']
I really need to translate this to c++ code and make the opposite function.

The opposite function how?

A hash by definition is one way.

You can make hamburger out of a cow, but you can't make a cow out of hamburger.

Similarly with a hash, you can compute a hash from a message, but you can't compute the message from its hash.
[/quote]

You can make new animals though, turn those into hamburgers and see which of those hamburgers best match the original hamburger. (If the hamburger is identical to the original hamburger and the animal you made seems to be a cow then odds are fairly good that your cow is identical to the cow that made the original hamburger)

[s]...If this is password cracking, I suggest banning.[/s]

Post probably isn't necessary. Moderators can do their jobs without comments from the peanut gallery.

This is a ida pro dump (CODE XREF: gives it away) - so why not use hexrays to give you pseudo c

IDA has a free version now, but it doesn't include the decompiler.

To OP: That code is RIDICULOUSLY short and simple. Just do it by hand. It won't take any time at all.

Thanks for the posts . This by the way isn't an "

[background=rgb(250, 251, 252)]reverse engineering/cracking/keygen attempt" [/background]

[background=rgb(250, 251, 252)] I just try to find the real names in a game file archive with hashes which I think is fully legally. Anyway can somebody tell me what the [/background]

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[background=rgb(250, 251, 252)]"[/background]

[/font]repne scasb" call do?

First hit on Google:
http://www.int80h.org/strlen/

In assembly language finding the length of a C-style string is a snap. The x86 family of microprocessors come with with the scasb instruction which searches for the first occurence of a byte whose value is equal to that of the AL register. The address of the start of the string itself has to be in the EDI register. Technically, it is supposed to be in the extra segment, but we do not need to worry about that in the flat 32-bit memory mode anymore. When used along with the repne prefix, the scasb instruction goes up (or down, depending on the direction flag) the memory, looking for the match.
[/quote]

This is also good:
http://www.csc.depauw.edu/~bhoward/asmtut/asmtut7.html

Many thanks for the info (it's shame that I thought this call is a loop ).

EDiT: AnY way I still wait if someone translate this to c.

Can somebody translate this please??

I doubt you will find anyone to do your work for you here.

Also, it will not help you, you will not be able to extract the strings from the hashes.
unless you use it to do a brute force search as SimonForsman suggests, but thats not very practical for anything but very short strings.

Oh anyway the Ida pro do my work and i found the source. I improve it too. Here is it if somebody is curious:





signed int __cdecl STRING_GetHashValue(char* String)
{
signed int StrLen = strlen(String);
signed int Hash = StrLen;

for (int Indx(0); Indx<StrLen; ++Indx)
Hash ^= (Hash >> 2) + 32 * Hash + String[Indx];

return Hash;
}