Battle.net Server Signature

[rabbit]

OMG I SOLVED IT!!!!
log(10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000)

I win.

[Joe]

wtf? Anyhow, heres an (almost) port to VB of the checking function. Theres one line thats (cleary) still in Java, so iago or somebody can fix that, or I will eventually.

Code: [Select]

'---------------------------------------------------------------------------------------
' Module    : modServerSig
' Author    : Joe[x86]
'             www.x86labs.org
' Purpose   : Verification of WAR3/W3XP Battle.net server signatures.
'---------------------------------------------------------------------------------------

Option Explicit

Public Function checkServerSignature(sig As String, ip As String) As Boolean
    Dim I As Integer, Ret As Boolean
    Dim K() As Byte: Let K = Array(0, 1, 1, 0)
    Dim N() As Byte: Let N = Array(&HD5, &HA3, &HD6, &HAB, &HF, &HD, &HC5, &HF, &HC3, &HFA, &H6E, &H78, &H9D, &HB, &HE3, &H32, &HB0, &HFA, &H20, &HE8, &H42, &H19, &HB4, &HA1, &H3A, &H3B, &HCD, &HE, &H8F, &HB5, &H56, &HB5, &HDC, &HE5, &HC1, &HFC, &H2D, &HBA, &H56, &H35, &H29, &HF, &H48, &HB, &H15, &H5A, &H39, &HFC, &H88, &H7, &H43, &H9E, &HCB, &HF3, &HB8, &H73, &HC9, &HE1, &H77, &HD5, &HA1, &H6, &HA6, &H20, &HD0, &H82, &HC5, &H2D, &H4D, &HD3, &H25, &HF4, &HFD, &H26, &HFC, &HE4, &HC2, &H0, &HDD, &H98, &H2A, &HF4, &H3D, &H5E, &H8, &H8A, &HD3, &H20, &H41, &H84, &H32, &H69, &H8E, &H8A, &H34, &H76, &HEA, &H16, &H8E, &H66, &H40, &HD9, &H32, &HB0, &H2D, &HF5, &HBD, &HE7, &H57, &H51, &H78, &H96, &HC2, &HED, &H40, &H41, &HCC, &H54, &H9D, &HFD, &HB6, &H8D, &HC2, &HBA, &H7F, &H69, &H8D, &HCF)
   
    'Do the calculation
    byte []result = new BigIntegerEx(BigIntegerEx.LITTLE_ENDIAN, sig).modPow(key, mod).toByteArray();
   
    Dim CorrectResult As String: CorrectResult = String(Len(Result), Chr(&HBB))
    CorrectResult = ip & Mid(CorrectResult, 5)
       
    Ret = True
    For I = 0 To Len(Result) Step 1
        If Result(I) <> CorrectResult(I) Then
            Ret = False
        End If
    Next I
End Function
EDIT -
Hrm, got somewhere with porting BigIntegerEx too!

Code: [Select]

Public Const BIG_ENDIAN As Integer = 0
Public Const LITTLE_ENDIAN As Integer = 1
Public Const BIGINT_SIZE = 32

[iago]

    byte []result = new BigIntegerEx(BigIntegerEx.LITTLE_ENDIAN, sig).modPow(key, mod).toByteArray();

That's the most important line, and the one line that I'm pretty sure you can't do in Visual Basic.  First, it creates an arbitrary length integer from the signature, then does the calculation (signature^key % mod) (where % is modular division).  This is the standard formula for encryption/decrypting/creating keys.  a^b%c with arbitrary length integers is cryptographically the most important function. 

[rabbit]

Code: [Select]

function poiuytrewq(a as long, b as long, c as long) as currency
    poiuytrewq = (a ^ b) mod c
end function?

[iago]

Code: [Select]

function poiuytrewq(a as long, b as long, c as long) as currency
    poiuytrewq = (a ^ b) mod c
end function?

I think he's trying to implement modpow with short variables.  A "long" isn't arbitrary length.

[rabbit]

currency is the closest to arbitrary you can get, and long ...eh...whatever I give up.  VB sucks that way.

[iago]

I don't think a currency can do 1024-bit numbers, though, which is what the server signature is.

[Newby]

    byte []result = new BigIntegerEx(BigIntegerEx.LITTLE_ENDIAN, sig).modPow(key, mod).toByteArray();

That's the most important line, and the one line that I'm pretty sure you can't do in Visual Basic.  First, it creates an arbitrary length integer from the signature, then does the calculation (signature^key % mod) (where % is modular division).  This is the standard formula for encryption/decrypting/creating keys.  a^b%c with arbitrary length integers is cryptographically the most important function. 

I'm pretty sure you can do a^b%c.

You just have to use an API call for the a^b

Wait, never mind. If the numbers are 1024-bit, good luck I guess!