tehran — Banned from using popular Western apps, Iranians have been left with little choice but to take up state-backed alternatives, as the authorities tighten internet restrictions for security reasons following months of protests.Iranians are accustomed to using virtual private networks, or VPNs, to evade restrictions and access prohibited websites or apps, including the U.S.-based Facebook, Twitter and YouTube.The authorities went as far as imposing total internet blackouts during the protests that erupted after the September death of 22-year-old Mahsa Amini,…