This code will allow you to read a file extremely fast and grab its MD5. On a Pentium D 3.6 ghz it can read Explorer.exe and hash it 50 times in under a second. Please try it out and submit any comments or questions.
Update (1/1/08) - Cut down the speed by over 100% by not converting the buffer into a string value. Cut down the size of the code by removing unnecessary functions.
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'Windows API/Global Declarations for :Grab file MD5 quickly
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Crypto APIs as well as ReadFile()
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Really good: 50 rounds in 0.86 sec on a P4 3.4 GHz. Next week I'll receive my new 3GHz Dual Core machine; hope for double speed.
Ehm - two things: 1. For performance measurements i propose to use the QueryPerformanceCounter / QueryPerformanceFrequency API. 2. For maximum perf. avoid to use use local variables; they will be "built" on every procedure call on the stack. Instaed use Module level vars.
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Is there a file size limit the code can handle? I got an "Out of memory error" at InputFile = StrConv(uBuffer, GetvbUnicode), with a 237 Meg file. (If this comment was disrespectful, please report it.)
Even with a file size limit this code is really nice and its fast.
I mainly use MD5 for checking anti-viri definition downloads which aren't very big, I've tried all the free MD5 codes, DLLs and Classes I could find for VB6 and they all returned a wrong hash number sooner or later, so far this is working, will post back otherwise. ;)
Thanks for sharing! ***** (If this comment was disrespectful, please report it.)
Don't blame the coder. VB6 is shaky as heck when it comes too files over 200MB and if you think thats bad, try it on a file thats 500MB+ and watch the sparks fly lol
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To resove the "out of memory" issue, you might try splitting the string into chuncks and processing these in sequence. Just a thought... TerriTop (If this comment was disrespectful, please report it.)
i have optimized your function now it`s 2.5 time faster just change the declaration of the "CryptHashData" function and add then function now you can get the MD5 directly from the function by passing the file name
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Dim hFile As Long, uBuffer() As Byte, lFileSize As Long, lBytesRead As Long, uMD5(BUFFER_SIZE) As Byte, lMD5Len As Long, i As Long, hCrypt As Long, hHash As Long
'Get a handle to the file hFile = CreateFile(sFileName, GENERIC_READ, FILE_SHARE_READ Or FILE_SHARE_WRITE, ByVal 0, OPEN_EXISTING, 0, 0)
'Can't open file If hFile = -1 Then Exit Function lFileSize = GetFileSize(hFile, 0)
If lFileSize < 1 Then CloseHandle hFile Exit Function End If
'Prepare the buffer ReDim uBuffer(lFileSize - 1)
'Read the file If ReadFile(hFile, uBuffer(0), lFileSize, lBytesRead, ByVal 0) <> 0 Then If lBytesRead <> lFileSize Then ReDim Preserve uBuffer(lBytesRead)
'Close the handle to the file CloseHandle hFile (If this comment was disrespectful, please report it.)
'Acquire the MD5 hash generator If CryptAcquireContext(hCrypt, vbNullString, MS_ENHANCED_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT) <> 0 Then If CryptCreateHash(hCrypt, HASH_TYPE, 0, 0, hHash) <> 0 Then If CryptHashData(hHash, uBuffer(0), lFileSize, 0) <> 0 Then If CryptGetHashParam(hHash, HP_HASHSIZE, uMD5(0), UBound(uMD5) + 1, 0) <> 0 Then lMD5Len = uMD5(0)
If CryptGetHashParam(hHash, HP_HASHVAL, uMD5(0), UBound(uMD5) + 1, 0) <> 0 Then For i = 0 To lMD5Len - 1 GetMD5 = GetMD5 & (Right$("0" & Hex$(uMD5(i)), 2)) Next i End If
End If End If End If End If
'Destroy the MD5 hash generator CryptDestroyHash hHash CryptReleaseContext hCrypt, 0 End Function (If this comment was disrespectful, please report it.)
Well, that doesn't seem very fast considering my code is less than a 1/3 the size and hashed explorer.exe 10000 - (YES, Ten Thousand) times in 0.6 (YES, point six) seconds. (If this comment was disrespectful, please report it.)
Very nice code. Great find. (If this comment was disrespectful, please report it.)
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8/4/2007 1:27:23 AM: 
