Security with Context.Items

Hi there!

 I'm wondering how much secure is this to restrict a page acess: 

 

PageA.aspx.vb 

Context.Items.Add("SecureIt", "654thtrerty345y")

 

 PageB.aspx.vb

        If Context.Items("SecureIt") = "654thtrerty345y" Then
            Context.Items.Clear()
        Else
            Server.Transfer("outside.aspx")
        End If


Many thanks people!
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