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Private Const BITS_TO_A_BYTE=8
Private Const BYTES_TO_A_WORD=4
Private Const BITS_TO_A_WORD=32
Private m_lOnBits(30)
Private m_l2Power(30)
m_lOnBits(0)=CLng(1)
m_lOnBits(1)=CLng(3)
m_lOnBits(2)=CLng(7)
m_lOnBits(3)=CLng(15)
m_lOnBits(4)=CLng(31)
m_lOnBits(5)=CLng(63)
m_lOnBits(6)=CLng(127)
m_lOnBits(7)=CLng(255)
m_lOnBits(8)=CLng(511)
m_lOnBits(9)=CLng(1023)
m_lOnBits(10)=CLng(2047)
m_lOnBits(11)=CLng(4095)
m_lOnBits(12)=CLng(8191)
m_lOnBits(13)=CLng(16383)
m_lOnBits(14)=CLng(32767)
m_lOnBits(15)=CLng(65535)
m_lOnBits(16)=CLng(131071)
m_lOnBits(17)=CLng(262143)
m_lOnBits(18)=CLng(524287)
m_lOnBits(19)=CLng(1048575)
m_lOnBits(20)=CLng(2097151)
m_lOnBits(21)=CLng(4194303)
m_lOnBits(22)=CLng(8388607)
m_lOnBits(23)=CLng(16777215)
m_lOnBits(24)=CLng(33554431)
m_lOnBits(25)=CLng(67108863)
m_lOnBits(26)=CLng(134217727)
m_lOnBits(27)=CLng(268435455)
m_lOnBits(28)=CLng(536870911)
m_lOnBits(29)=CLng(1073741823)
m_lOnBits(30)=CLng(2147483647)

m_l2Power(0)=CLng(1)
m_l2Power(1)=CLng(2)
m_l2Power(2)=CLng(4)
m_l2Power(3)=CLng(8)
m_l2Power(4)=CLng(16)
m_l2Power(5)=CLng(32)
m_l2Power(6)=CLng(64)
m_l2Power(7)=CLng(128)
m_l2Power(8)=CLng(256)
m_l2Power(9)=CLng(512)
m_l2Power(10)=CLng(1024)
m_l2Power(11)=CLng(2048)
m_l2Power(12)=CLng(4096)
m_l2Power(13)=CLng(8192)
m_l2Power(14)=CLng(16384)
m_l2Power(15)=CLng(32768)
m_l2Power(16)=CLng(65536)
m_l2Power(17)=CLng(131072)
m_l2Power(18)=CLng(262144)
m_l2Power(19)=CLng(524288)
m_l2Power(20)=CLng(1048576)
m_l2Power(21)=CLng(2097152)
m_l2Power(22)=CLng(4194304)
m_l2Power(23)=CLng(8388608)
m_l2Power(24)=CLng(16777216)
m_l2Power(25)=CLng(33554432)
m_l2Power(26)=CLng(67108864)
m_l2Power(27)=CLng(134217728)
m_l2Power(28)=CLng(268435456)
m_l2Power(29)=CLng(536870912)
m_l2Power(30)=CLng(1073741824)

Private Function LShift(lValue,iShiftBits)
  If iShiftBits=0 Then
    LShift=lValue
    Exit Function
  ElseIf iShiftBits=31 Then
    If lValue And 1 Then
      LShift=&H80000000
    Else
      LShift=0
    End If
    Exit Function
  ElseIf iShiftBits<0 Or iShiftBits>31 Then
    Err.Raise 6
  End If

  If (lValue And m_l2Power(31-iShiftBits)) Then
    LShift=((lValue And m_lOnBits(31-(iShiftBits+1)))*m_l2Power(iShiftBits)) Or &H80000000
  Else
    LShift=((lValue And m_lOnBits(31-iShiftBits))*m_l2Power(iShiftBits))
  End If
End Function

Private Function RShift(lValue,iShiftBits)
  If iShiftBits=0 Then
    RShift=lValue
    Exit Function
  ElseIf iShiftBits=31 Then
    If lValue And &H80000000 Then
      RShift=1
    Else
      RShift=0
    End If
    Exit Function
  ElseIf iShiftBits<0 Or iShiftBits>31 Then
    Err.Raise 6
  End If
  
  RShift=(lValue And &H7FFFFFFE)\m_l2Power(iShiftBits)

  If (lValue And &H80000000) Then
    RShift=(RShift Or (&H40000000\m_l2Power(iShiftBits-1)))
  End If
End Function

Private Function RotateLeft(lValue,iShiftBits)
  RotateLeft=LShift(lValue,iShiftBits) Or RShift(lValue,(32-iShiftBits))
End Function

Private Function AddUnsigned(lX,lY)
  Dim lX4
  Dim lY4
  Dim lX8
  Dim lY8
  Dim lResult

  lX8=lX And &H80000000
  lY8=lY And &H80000000
  lX4=lX And &H40000000
  lY4=lY And &H40000000

  lResult=(lX And &H3FFFFFFF)+(lY And &H3FFFFFFF)

  If lX4 And lY4 Then
    lResult=lResult Xor &H80000000 Xor lX8 Xor lY8
  ElseIf lX4 Or lY4 Then
    If lResult And &H40000000 Then
      lResult=lResult Xor &HC0000000 Xor lX8 Xor lY8
    Else
      lResult=lResult Xor &H40000000 Xor lX8 Xor lY8
    End If
  Else
    lResult=lResult Xor lX8 Xor lY8
  End If

  AddUnsigned=lResult
End Function

Private Function F(x,y,z)
  F=(x And y) Or ((Not x) And z)
End Function

Private Function G(x,y,z)
  G=(x And z) Or (y And (Not z))
End Function

Private Function H(x,y,z)
  H=(x Xor y Xor z)
End Function

Private Function I(x,y,z)
  I=(y Xor (x Or (Not z)))
End Function

Private Sub FF(a,b,c,d,x,s,ac)
  a=AddUnsigned(a,AddUnsigned(AddUnsigned(F(b,c,d),x),ac))
  a=RotateLeft(a,s)
  a=AddUnsigned(a,b)
End Sub

Private Sub GG(a,b,c,d,x,s,ac)
  a=AddUnsigned(a,AddUnsigned(AddUnsigned(G(b,c,d),x),ac))
  a=RotateLeft(a,s)
  a=AddUnsigned(a,b)
End Sub

Private Sub HH(a,b,c,d,x,s,ac)
  a=AddUnsigned(a,AddUnsigned(AddUnsigned(H(b,c,d),x),ac))
  a=RotateLeft(a,s)
  a=AddUnsigned(a,b)
End Sub

Private Sub II(a,b,c,d,x,s,ac)
  a=AddUnsigned(a,AddUnsigned(AddUnsigned(I(b,c,d),x),ac))
  a=RotateLeft(a,s)
  a=AddUnsigned(a,b)
End Sub

Private Function ConvertToWordArray(sMessage)
  Dim lMessageLength
  Dim lNumberOfWords
  Dim lWordArray()
  Dim lBytePosition
  Dim lByteCount
  Dim lWordCount
  Dim lByteValue    ' need these variables to handle byte value and input argument type
  Dim lMessageType

  Const MODULUS_BITS=512
  Const CONGRUENT_BITS=448
  
  lMessageType=Vartype(sMessage)
  Select Case lMessageType    ' strings or Variant Byte Arrays: nothing else!
    Case 8    : lMessageLength=Len(sMessage)
    Case 8209 : lMessageLength=LenB(sMessage)
    Case Else Err.Raise -1,"MD5","Unknown Type passed to MD5 function"
  End Select
  
  lNumberOfWords=(((lMessageLength+((MODULUS_BITS-CONGRUENT_BITS)\BITS_TO_A_BYTE))\(MODULUS_BITS\BITS_TO_A_BYTE))+1)*(MODULUS_BITS\BITS_TO_A_WORD)
  ReDim lWordArray(lNumberOfWords-1)
  
  lBytePosition=0
  lByteCount=0
  Do Until lByteCount >=lMessageLength
    lWordCount=lByteCount\BYTES_TO_A_WORD
    lBytePosition=(lByteCount Mod BYTES_TO_A_WORD)*BITS_TO_A_BYTE
    Select Case lMessageType    ' get the next byte value
      Case 8    : lByteValue = Asc (Mid (sMessage,lByteCount+1,1))
      Case 8209 : lByteValue = AscB(MidB(sMessage,lByteCount+1,1))
    End Select
    lWordArray(lWordCount)=lWordArray(lWordCount) Or LShift(lByteValue,lBytePosition)
    lByteCount=lByteCount+1
  Loop

  lWordCount=lByteCount\BYTES_TO_A_WORD
  lBytePosition=(lByteCount Mod BYTES_TO_A_WORD)*BITS_TO_A_BYTE

  lWordArray(lWordCount)=lWordArray(lWordCount) Or LShift(&H80,lBytePosition)

  lWordArray(lNumberOfWords-2)=LShift(lMessageLength,3)
  lWordArray(lNumberOfWords-1)=RShift(lMessageLength,29)
  
  ConvertToWordArray=lWordArray
End Function

Private Function WordToHex(lValue)
  Dim lByte
  Dim lCount
  
  For lCount=0 To 3
    lByte=RShift(lValue,lCount*BITS_TO_A_BYTE) And m_lOnBits(BITS_TO_A_BYTE-1)
    WordToHex=WordToHex & Right("0" & Hex(lByte),2)
  Next
End Function

Public Function MD5(sMessage)
  Dim x
  Dim k
  Dim AA
  Dim BB
  Dim CC
  Dim DD
  Dim a
  Dim b
  Dim c
  Dim d
  
  Const S11=7
  Const S12=12
  Const S13=17
  Const S14=22
  Const S21=5
  Const S22=9
  Const S23=14
  Const S24=20
  Const S31=4
  Const S32=11
  Const S33=16
  Const S34=23
  Const S41=6
  Const S42=10
  Const S43=15
  Const S44=21

  x=ConvertToWordArray(sMessage)
  
  a=&H67452301
  b=&HEFCDAB89
  c=&H98BADCFE
  d=&H10325476

  For k=0 To UBound(x) Step 16
    AA=a
    BB=b
    CC=c
    DD=d

    FF a,b,c,d,x(k+0),S11,&HD76AA478
    FF d,a,b,c,x(k+1),S12,&HE8C7B756
    FF c,d,a,b,x(k+2),S13,&H242070DB
    FF b,c,d,a,x(k+3),S14,&HC1BDCEEE
    FF a,b,c,d,x(k+4),S11,&HF57C0FAF
    FF d,a,b,c,x(k+5),S12,&H4787C62A
    FF c,d,a,b,x(k+6),S13,&HA8304613
    FF b,c,d,a,x(k+7),S14,&HFD469501
    FF a,b,c,d,x(k+8),S11,&H698098D8
    FF d,a,b,c,x(k+9),S12,&H8B44F7AF
    FF c,d,a,b,x(k+10),S13,&HFFFF5BB1
    FF b,c,d,a,x(k+11),S14,&H895CD7BE
    FF a,b,c,d,x(k+12),S11,&H6B901122
    FF d,a,b,c,x(k+13),S12,&HFD987193
    FF c,d,a,b,x(k+14),S13,&HA679438E
    FF b,c,d,a,x(k+15),S14,&H49B40821

    GG a,b,c,d,x(k+1),S21,&HF61E2562
    GG d,a,b,c,x(k+6),S22,&HC040B340
    GG c,d,a,b,x(k+11),S23,&H265E5A51
    GG b,c,d,a,x(k+0),S24,&HE9B6C7AA
    GG a,b,c,d,x(k+5),S21,&HD62F105D
    GG d,a,b,c,x(k+10),S22,&H2441453
    GG c,d,a,b,x(k+15),S23,&HD8A1E681
    GG b,c,d,a,x(k+4),S24,&HE7D3FBC8
    GG a,b,c,d,x(k+9),S21,&H21E1CDE6
    GG d,a,b,c,x(k+14),S22,&HC33707D6
    GG c,d,a,b,x(k+3),S23,&HF4D50D87
    GG b,c,d,a,x(k+8),S24,&H455A14ED
    GG a,b,c,d,x(k+13),S21,&HA9E3E905
    GG d,a,b,c,x(k+2),S22,&HFCEFA3F8
    GG c,d,a,b,x(k+7),S23,&H676F02D9
    GG b,c,d,a,x(k+12),S24,&H8D2A4C8A
        
    HH a,b,c,d,x(k+5),S31,&HFFFA3942
    HH d,a,b,c,x(k+8),S32,&H8771F681
    HH c,d,a,b,x(k+11),S33,&H6D9D6122
    HH b,c,d,a,x(k+14),S34,&HFDE5380C
    HH a,b,c,d,x(k+1),S31,&HA4BEEA44
    HH d,a,b,c,x(k+4),S32,&H4BDECFA9
    HH c,d,a,b,x(k+7),S33,&HF6BB4B60
    HH b,c,d,a,x(k+10),S34,&HBEBFBC70
    HH a,b,c,d,x(k+13),S31,&H289B7EC6
    HH d,a,b,c,x(k+0),S32,&HEAA127FA
    HH c,d,a,b,x(k+3),S33,&HD4EF3085
    HH b,c,d,a,x(k+6),S34,&H4881D05
    HH a,b,c,d,x(k+9),S31,&HD9D4D039
    HH d,a,b,c,x(k+12),S32,&HE6DB99E5
    HH c,d,a,b,x(k+15),S33,&H1FA27CF8
    HH b,c,d,a,x(k+2),S34,&HC4AC5665

    II a,b,c,d,x(k+0),S41,&HF4292244
    II d,a,b,c,x(k+7),S42,&H432AFF97
    II c,d,a,b,x(k+14),S43,&HAB9423A7
    II b,c,d,a,x(k+5),S44,&HFC93A039
    II a,b,c,d,x(k+12),S41,&H655B59C3
    II d,a,b,c,x(k+3),S42,&H8F0CCC92
    II c,d,a,b,x(k+10),S43,&HFFEFF47D
    II b,c,d,a,x(k+1),S44,&H85845DD1
    II a,b,c,d,x(k+8),S41,&H6FA87E4F
    II d,a,b,c,x(k+15),S42,&HFE2CE6E0
    II c,d,a,b,x(k+6),S43,&HA3014314
    II b,c,d,a,x(k+13),S44,&H4E0811A1
    II a,b,c,d,x(k+4),S41,&HF7537E82
    II d,a,b,c,x(k+11),S42,&HBD3AF235
    II c,d,a,b,x(k+2),S43,&H2AD7D2BB
    II b,c,d,a,x(k+9),S44,&HEB86D391

    a=AddUnsigned(a,AA)
    b=AddUnsigned(b,BB)
    c=AddUnsigned(c,CC)
    d=AddUnsigned(d,DD)
  Next
  
  MD5=LCase(WordToHex(a) & WordToHex(b) & WordToHex(c) & WordToHex(d))
End Function
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