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'Option Explicit
' Rijndael.asp
' Copyright 2001 Phil Fresle 
' phil@frez.co.uk 
' http://www.frez.co.uk
' Implementation of the AES Rijndael Block Cipher. Inspired by Mike Scott's
' implementation in C. Permission for free direct or derivative use is granted
' subject to compliance with any conditions that the originators of the
' algorithm place on its exploitation.
' 3-Apr-2001: Functions added to the bottom for encrypting/decrypting large
' arrays of data. The entire length of the array is inserted as the first four
' bytes onto the front of the first block of the resultant byte array before
' encryption.
' 19-Apr-2001: Thanks to Paolo Migliaccio for finding a bug with 256 bit 
' key. Problem was in the gkey function. Now properly matches NIST values.

Private m_lOnBits(30)
Private m_l2Power(30)
Private m_bytOnBits(7)
Private m_byt2Power(7)

Private m_InCo(3)

Private m_fbsub(255)
Private m_rbsub(255)
Private m_ptab(255)
Private m_ltab(255)
Private m_ftable(255)
Private m_rtable(255)
Private m_rco(29)

Private m_Nk
Private m_Nb
Private m_Nr
Private m_fi(23)
Private m_ri(23)
Private m_fkey(119)
Private m_rkey(119)

m_InCo(0) = &HB
m_InCo(1) = &HD
m_InCo(2) = &H9
m_InCo(3) = &HE
    
m_bytOnBits(0) = 1
m_bytOnBits(1) = 3
m_bytOnBits(2) = 7
m_bytOnBits(3) = 15
m_bytOnBits(4) = 31
m_bytOnBits(5) = 63
m_bytOnBits(6) = 127
m_bytOnBits(7) = 255
    
m_byt2Power(0) = 1
m_byt2Power(1) = 2
m_byt2Power(2) = 4
m_byt2Power(3) = 8
m_byt2Power(4) = 16
m_byt2Power(5) = 32
m_byt2Power(6) = 64
m_byt2Power(7) = 128
    
m_lOnBits(0) = 1
m_lOnBits(1) = 3
m_lOnBits(2) = 7
m_lOnBits(3) = 15
m_lOnBits(4) = 31
m_lOnBits(5) = 63
m_lOnBits(6) = 127
m_lOnBits(7) = 255
m_lOnBits(8) = 511
m_lOnBits(9) = 1023
m_lOnBits(10) = 2047
m_lOnBits(11) = 4095
m_lOnBits(12) = 8191
m_lOnBits(13) = 16383
m_lOnBits(14) = 32767
m_lOnBits(15) = 65535
m_lOnBits(16) = 131071
m_lOnBits(17) = 262143
m_lOnBits(18) = 524287
m_lOnBits(19) = 1048575
m_lOnBits(20) = 2097151
m_lOnBits(21) = 4194303
m_lOnBits(22) = 8388607
m_lOnBits(23) = 16777215
m_lOnBits(24) = 33554431
m_lOnBits(25) = 67108863
m_lOnBits(26) = 134217727
m_lOnBits(27) = 268435455
m_lOnBits(28) = 536870911
m_lOnBits(29) = 1073741823
m_lOnBits(30) = 2147483647
    
m_l2Power(0) = 1
m_l2Power(1) = 2
m_l2Power(2) = 4
m_l2Power(3) = 8
m_l2Power(4) = 16
m_l2Power(5) = 32
m_l2Power(6) = 64
m_l2Power(7) = 128
m_l2Power(8) = 256
m_l2Power(9) = 512
m_l2Power(10) = 1024
m_l2Power(11) = 2048
m_l2Power(12) = 4096
m_l2Power(13) = 8192
m_l2Power(14) = 16384
m_l2Power(15) = 32768
m_l2Power(16) = 65536
m_l2Power(17) = 131072
m_l2Power(18) = 262144
m_l2Power(19) = 524288
m_l2Power(20) = 1048576
m_l2Power(21) = 2097152
m_l2Power(22) = 4194304
m_l2Power(23) = 8388608
m_l2Power(24) = 16777216
m_l2Power(25) = 33554432
m_l2Power(26) = 67108864
m_l2Power(27) = 134217728
m_l2Power(28) = 268435456
m_l2Power(29) = 536870912
m_l2Power(30) = 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 LShiftByte(bytValue, bytShiftBits)
    If bytShiftBits = 0 Then
        LShiftByte = bytValue
        Exit Function
    ElseIf bytShiftBits = 7 Then
        If bytValue And 1 Then
            LShiftByte = &H80
        Else
            LShiftByte = 0
        End If
        Exit Function
    ElseIf bytShiftBits < 0 Or bytShiftBits > 7 Then
        Err.Raise 6
    End If
    
    LShiftByte = ((bytValue And m_bytOnBits(7 - bytShiftBits)) * m_byt2Power(bytShiftBits))
End Function

Private Function RShiftByte(bytValue, bytShiftBits)
    If bytShiftBits = 0 Then
        RShiftByte = bytValue
        Exit Function
    ElseIf bytShiftBits = 7 Then
        If bytValue And &H80 Then
            RShiftByte = 1
        Else
            RShiftByte = 0
        End If
        Exit Function
    ElseIf bytShiftBits < 0 Or bytShiftBits > 7 Then
        Err.Raise 6
    End If
    
    RShiftByte = bytValue \ m_byt2Power(bytShiftBits)
End Function

Private Function RotateLeft(lValue, iShiftBits)
    RotateLeft = LShift(lValue, iShiftBits) Or RShift(lValue, (32 - iShiftBits))
End Function

Private Function RotateLeftByte(bytValue, bytShiftBits)
    RotateLeftByte = LShiftByte(bytValue, bytShiftBits) Or RShiftByte(bytValue, (8 - bytShiftBits))
End Function

Private Function Pack(b())
    Dim lCount
    Dim lTemp
    
    For lCount = 0 To 3
        lTemp = b(lCount)
        Pack = Pack Or LShift(lTemp, (lCount * 8))
    Next
End Function

Private Function PackFrom(b(), k)
    Dim lCount
    Dim lTemp
    
    For lCount = 0 To 3
        lTemp = b(lCount + k)
        PackFrom = PackFrom Or LShift(lTemp, (lCount * 8))
    Next
End Function

Private Sub Unpack(a, b())
    b(0) = a And m_lOnBits(7)
    b(1) = RShift(a, 8) And m_lOnBits(7)
    b(2) = RShift(a, 16) And m_lOnBits(7)
    b(3) = RShift(a, 24) And m_lOnBits(7)
End Sub

Private Sub UnpackFrom(a, b(), k)
    b(0 + k) = a And m_lOnBits(7)
    b(1 + k) = RShift(a, 8) And m_lOnBits(7)
    b(2 + k) = RShift(a, 16) And m_lOnBits(7)
    b(3 + k) = RShift(a, 24) And m_lOnBits(7)
End Sub

Private Function xtime(a)
    Dim b
    
    If (a And &H80) Then
        b = &H1B
    Else
        b = 0
    End If
    
    xtime = LShiftByte(a, 1)
    xtime = xtime Xor b
End Function

Private Function bmul(x, y)
    If x <> 0 And y <> 0 Then
        bmul = m_ptab((CLng(m_ltab(x)) + CLng(m_ltab(y))) Mod 255)
    Else
        bmul = 0
    End If
End Function

Private Function SubByte(a)
    Dim b(3)
    
    Unpack a, b
    b(0) = m_fbsub(b(0))
    b(1) = m_fbsub(b(1))
    b(2) = m_fbsub(b(2))
    b(3) = m_fbsub(b(3))
    
    SubByte = Pack(b)
End Function

Private Function product(x, y)
    Dim xb(3)
    Dim yb(3)
    
    Unpack x, xb
    Unpack y, yb
    product = bmul(xb(0), yb(0)) Xor bmul(xb(1), yb(1)) Xor bmul(xb(2), yb(2)) Xor bmul(xb(3), yb(3))
End Function

Private Function InvMixCol(x)
    Dim y
    Dim m
    Dim b(3)
    
    m = Pack(m_InCo)
    b(3) = product(m, x)
    m = RotateLeft(m, 24)
    b(2) = product(m, x)
    m = RotateLeft(m, 24)
    b(1) = product(m, x)
    m = RotateLeft(m, 24)
    b(0) = product(m, x)
    y = Pack(b)
    
    InvMixCol = y
End Function

Private Function ByteSub(x)
    Dim y
    Dim z
    
    z = x
    y = m_ptab(255 - m_ltab(z))
    z = y
    z = RotateLeftByte(z, 1)
    y = y Xor z
    z = RotateLeftByte(z, 1)
    y = y Xor z
    z = RotateLeftByte(z, 1)
    y = y Xor z
    z = RotateLeftByte(z, 1)
    y = y Xor z
    y = y Xor &H63
    
    ByteSub = y
End Function

Public Sub gentables()
    Dim i
    Dim y
    Dim b(3)
    Dim ib
    
    m_ltab(0) = 0
    m_ptab(0) = 1
    m_ltab(1) = 0
    m_ptab(1) = 3
    m_ltab(3) = 1
    
    For i = 2 To 255
        m_ptab(i) = m_ptab(i - 1) Xor xtime(m_ptab(i - 1))
        m_ltab(m_ptab(i)) = i
    Next
    
    m_fbsub(0) = &H63
    m_rbsub(&H63) = 0
    
    For i = 1 To 255
        ib = i
        y = ByteSub(ib)
        m_fbsub(i) = y
        m_rbsub(y) = i
    Next