An example of ASP implementation of MD5 irreversible encryption algorithm

Encryption | Algorithm this is a foreign reprint function, can convert any character to MD5 16 for character encryption form, and for irreversible change.
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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)

Private Function LShift (LValue, Ishiftbits)
If ishiftbits = 0 Then
LShift = LValue
Exit Function
ElseIf ishiftbits = Then
If LValue and 1 Then
LShift = &h80000000
Else
LShift = 0
End If
Exit Function
ElseIf ishiftbits < 0 Or ishiftbits > Then
Err.Raise 6
End If

If (LValue and M_l2power (31-ishiftbits)) Then
LShift = ((LValue and M_lonbits ()-(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 = Then
If LValue and &h80000000 Then
Rshift = 1
Else
Rshift = 0
End If
Exit Function
ElseIf ishiftbits < 0 Or ishiftbits > 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 &AMP;H3FFFFFFF) + (LY and &AMP;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 md5_f (x, Y, z)
Md5_f = (x and y) Or (not x) and Z)
End Function

Private Function md5_g (x, Y, z)
Md5_g = (x and z) Or (y and not z)
End Function

Private Function md5_h (x, Y, z)
Md5_h = (x xor y xor Z)
End Function

Private Function md5_i (x, Y, z)
Md5_i = (y Xor (x Or not z))
End Function

Private Sub md5_ff (A, B, C, D, X, S, AC)
A = addunsigned (A, addunsigned (addunsigned (Md5_f (b, C, D), x), AC)
A = Rotateleft (A, s)
A = Addunsigned (A, B)
End Sub

Private Sub Md5_gg (A, B, C, D, X, S, AC)
A = addunsigned (A, addunsigned (addunsigned (Md5_g (b, C, D), x), AC)
A = Rotateleft (A, s)
A = Addunsigned (A, B)
End Sub

Private Sub md5_hh (A, B, C, D, X, S, AC)
A = addunsigned (A, addunsigned (addunsigned (Md5_h (b, C, D), x), AC)
A = Rotateleft (A, s)
A = Addunsigned (A, B)
End Sub

Private Sub Md5_ii (A, B, C, D, X, S, AC)
A = addunsigned (A, addunsigned (addunsigned (md5_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

Const modulus_bits = 512
Const congruent_bits = 448

Lmessagelength = Len (smessage)

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
Lwordarray (Lwordcount) = Lwordarray (Lwordcount) Or LShift (ASC (Mid smessage, Lbytecount + 1, 1), 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)