Public Function MD5(ByVal str As String) As String
        Dim ASCIIenc As New ASCIIEncoding
        Dim strReturn
        Dim ByteSource() As Byte = ASCIIenc.GetBytes(str)
        Dim Md5Hash As New MD5CryptoServiceProvider
        Dim ByteHash() As Byte = Md5Hash.ComputeHash(ByteSource)
        For Each b As Byte In ByteHash
            strReturn &= b.ToString("x2")
        Next
        Return strReturn
    End Function

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VB.NET md5 Hash

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VB.NET