rijndael.asp

The enclosed VB project includes a VB class that implements the Rijndael AES block encryption algori

    y = 1
    For i = 0 To 29
        m_rco(i) = y
        y = xtime(y)
    Next
    
    For i = 0 To 255
        y = m_fbsub(i)
        b(3) = y Xor xtime(y)
        b(2) = y
        b(1) = y
        b(0) = xtime(y)
        m_ftable(i) = Pack(b)
        
        y = m_rbsub(i)
        b(3) = bmul(m_InCo(0), y)
        b(2) = bmul(m_InCo(1), y)
        b(1) = bmul(m_InCo(2), y)
        b(0) = bmul(m_InCo(3), y)
        m_rtable(i) = Pack(b)
    Next
End Sub

Public Sub gkey(nb, nk, key())                
    Dim i
    Dim j
    Dim k
    Dim m
    Dim N
    Dim C1
    Dim C2
    Dim C3
    Dim CipherKey(7)
    
    m_Nb = nb
    m_Nk = nk
    
    If m_Nb >= m_Nk Then
        m_Nr = 6 + m_Nb
    Else
        m_Nr = 6 + m_Nk
    End If
    
    C1 = 1
    If m_Nb < 8 Then
        C2 = 2
        C3 = 3
    Else
        C2 = 3
        C3 = 4
    End If
    
    For j = 0 To nb - 1
        m = j * 3
        
        m_fi(m) = (j + C1) Mod nb
        m_fi(m + 1) = (j + C2) Mod nb
        m_fi(m + 2) = (j + C3) Mod nb
        m_ri(m) = (nb + j - C1) Mod nb
        m_ri(m + 1) = (nb + j - C2) Mod nb
        m_ri(m + 2) = (nb + j - C3) Mod nb
    Next
    
    N = m_Nb * (m_Nr + 1)
    
    For i = 0 To m_Nk - 1
        j = i * 4
        CipherKey(i) = PackFrom(key, j)
    Next
    
    For i = 0 To m_Nk - 1
        m_fkey(i) = CipherKey(i)
    Next
    
    j = m_Nk
    k = 0
    Do While j < N
        m_fkey(j) = m_fkey(j - m_Nk) Xor _
            SubByte(RotateLeft(m_fkey(j - 1), 24)) Xor m_rco(k)
        If m_Nk <= 6 Then
            i = 1
            Do While i < m_Nk And (i + j) < N
                m_fkey(i + j) = m_fkey(i + j - m_Nk) Xor _
                    m_fkey(i + j - 1)
                i = i + 1
            Loop
        Else
            i = 1
            Do While i < 4 And (i + j) < N
                m_fkey(i + j) = m_fkey(i + j - m_Nk) Xor _
                    m_fkey(i + j - 1)
                i = i + 1
            Loop
            If j + 4 < N Then
                m_fkey(j + 4) = m_fkey(j + 4 - m_Nk) Xor _
                    SubByte(m_fkey(j + 3))
            End If
            i = 5
            Do While i < m_Nk And (i + j) < N
                m_fkey(i + j) = m_fkey(i + j - m_Nk) Xor _
                    m_fkey(i + j - 1)
                i = i + 1
            Loop
        End If
        
        j = j + m_Nk
        k = k + 1
    Loop
    
    For j = 0 To m_Nb - 1
        m_rkey(j + N - nb) = m_fkey(j)
    Next
    
    i = m_Nb
    Do While i < N - m_Nb
        k = N - m_Nb - i
        For j = 0 To m_Nb - 1
            m_rkey(k + j) = InvMixCol(m_fkey(i + j))
        Next
        i = i + m_Nb
    Loop
    
    j = N - m_Nb
    Do While j < N
        m_rkey(j - N + m_Nb) = m_fkey(j)
        j = j + 1
    Loop
End Sub

Public Sub encrypt(buff())
    Dim i
    Dim j
    Dim k
    Dim m
    Dim a(7)
    Dim b(7)
    Dim x
    Dim y
    Dim t
    
    For i = 0 To m_Nb - 1
        j = i * 4
        
        a(i) = PackFrom(buff, j)
        a(i) = a(i) Xor m_fkey(i)
    Next
    
    k = m_Nb
    x = a
    y = b
    
    For i = 1 To m_Nr - 1
        For j = 0 To m_Nb - 1
            m = j * 3
            y(j) = m_fkey(k) Xor m_ftable(x(j) And m_lOnBits(7)) Xor _
                RotateLeft(m_ftable(RShift(x(m_fi(m)), 8) And m_lOnBits(7)), 8) Xor _
                RotateLeft(m_ftable(RShift(x(m_fi(m + 1)), 16) And m_lOnBits(7)), 16) Xor _
                RotateLeft(m_ftable(RShift(x(m_fi(m + 2)), 24) And m_lOnBits(7)), 24)
            k = k + 1
        Next
        t = x
        x = y
        y = t
    Next
    
    For j = 0 To m_Nb - 1
        m = j * 3
        y(j) = m_fkey(k) Xor m_fbsub(x(j) And m_lOnBits(7)) Xor _
            RotateLeft(m_fbsub(RShift(x(m_fi(m)), 8) And m_lOnBits(7)), 8) Xor _
            RotateLeft(m_fbsub(RShift(x(m_fi(m + 1)), 16) And m_lOnBits(7)), 16) Xor _
            RotateLeft(m_fbsub(RShift(x(m_fi(m + 2)), 24) And m_lOnBits(7)), 24)
        k = k + 1
    Next
    
    For i = 0 To m_Nb - 1
        j = i * 4
        UnpackFrom y(i), buff, j
        x(i) = 0
        y(i) = 0
    Next
End Sub

Public Sub decrypt(buff())
    Dim i
    Dim j
    Dim k
    Dim m
    Dim a(7)
    Dim b(7)
    Dim x
    Dim y
    Dim t
    
    For i = 0 To m_Nb - 1
        j = i * 4
        a(i) = PackFrom(buff, j)
        a(i) = a(i) Xor m_rkey(i)
    Next
    
    k = m_Nb
    x = a
    y = b
    
    For i = 1 To m_Nr - 1
        For j = 0 To m_Nb - 1
            m = j * 3
            y(j) = m_rkey(k) Xor m_rtable(x(j) And m_lOnBits(7)) Xor _
                RotateLeft(m_rtable(RShift(x(m_ri(m)), 8) And m_lOnBits(7)), 8) Xor _
                RotateLeft(m_rtable(RShift(x(m_ri(m + 1)), 16) And m_lOnBits(7)), 16) Xor _
                RotateLeft(m_rtable(RShift(x(m_ri(m + 2)), 24) And m_lOnBits(7)), 24)
            k = k + 1
        Next
        t = x
        x = y
        y = t
    Next
    
    For j = 0 To m_Nb - 1
        m = j * 3
        
        y(j) = m_rkey(k) Xor m_rbsub(x(j) And m_lOnBits(7)) Xor _
            RotateLeft(m_rbsub(RShift(x(m_ri(m)), 8) And m_lOnBits(7)), 8) Xor _
            RotateLeft(m_rbsub(RShift(x(m_ri(m + 1)), 16) And m_lOnBits(7)), 16) Xor _
            RotateLeft(m_rbsub(RShift(x(m_ri(m + 2)), 24) And m_lOnBits(7)), 24)
        k = k + 1
    Next
    
    For i = 0 To m_Nb - 1
        j = i * 4
        
        UnpackFrom y(i), buff, j
        x(i) = 0
        y(i) = 0
    Next
End Sub

Private Function IsInitialized(vArray)
    On Error Resume Next
    
    IsInitialized = IsNumeric(UBound(vArray))
End Function

Private Sub CopyBytesASP(bytDest, lDestStart, bytSource(), lSourceStart, lLength)
    Dim lCount
    
    lCount = 0
    Do
        bytDest(lDestStart + lCount) = bytSource(lSourceStart + lCount)
        lCount = lCount + 1
    Loop Until lCount = lLength
End Sub

Public Function EncryptData(bytMessage, bytPassword)
    Dim bytKey(31)
    Dim bytIn()
    Dim bytOut()
    Dim bytTemp(31)
    Dim lCount
    Dim lLength
    Dim lEncodedLength
    Dim bytLen(3)
    Dim lPosition
    
    If Not IsInitialized(bytMessage) Then
        Exit Function
    End If
    If Not IsInitialized(bytPassword) Then
        Exit Function
    End If
    
    For lCount = 0 To UBound(bytPassword)
        bytKey(lCount) = bytPassword(lCount)
        If lCount = 31 Then
            Exit For
        End If
    Next
    
    gentables
    gkey 8, 8, bytKey
    
    lLength = UBound(bytMessage) + 1
    lEncodedLength = lLength + 4
    
    If lEncodedLength Mod 32 <> 0 Then
        lEncodedLength = lEncodedLength + 32 - (lEncodedLength Mod 32)
    End If
    ReDim bytIn(lEncodedLength - 1)
    ReDim bytOut(lEncodedLength - 1)
    
    Unpack lLength, bytIn
    CopyBytesASP bytIn, 4, bytMessage, 0, lLength

    For lCount = 0 To lEncodedLength - 1 Step 32
        CopyBytesASP bytTemp, 0, bytIn, lCount, 32
        Encrypt bytTemp
        CopyBytesASP bytOut, lCount, bytTemp, 0, 32
    Next
    
    EncryptData = bytOut
End Function

Public Function DecryptData(bytIn, bytPassword)
    Dim bytMessage()
    Dim bytKey(31)
    Dim bytOut()
    Dim bytTemp(31)
    Dim lCount
    Dim lLength
    Dim lEncodedLength
    Dim bytLen(3)
    Dim lPosition
    
    If Not IsInitialized(bytIn) Then
        Exit Function
    End If
    If Not IsInitialized(bytPassword) Then
        Exit Function
    End If
    
    lEncodedLength = UBound(bytIn) + 1
    
    If lEncodedLength Mod 32 <> 0 Then
        Exit Function
    End If
    
    For lCount = 0 To UBound(bytPassword)
        bytKey(lCount) = bytPassword(lCount)
        If lCount = 31 Then
            Exit For
        End If
    Next
    
    gentables
    gkey 8, 8, bytKey

    ReDim bytOut(lEncodedLength - 1)
    
    For lCount = 0 To lEncodedLength - 1 Step 32
        CopyBytesASP bytTemp, 0, bytIn, lCount, 32
        Decrypt bytTemp
        CopyBytesASP bytOut, lCount, bytTemp, 0, 32
    Next

    lLength = Pack(bytOut)
    
    If lLength > lEncodedLength - 4 Then
        Exit Function
    End If
    
    ReDim bytMessage(lLength - 1)
    CopyBytesASP bytMessage, 0, bytOut, 4, lLength
    
    DecryptData = bytMessage
End Function
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