Ktav Ashuri (Hebrew: כְּתָב אַשּׁוּרִי, k'tav ashurí, lit. "Assyrian Writing") also (Ktav) Ashurit, is the traditional Hebrew language name of the Hebrew alphabet, used to write both Hebrew and Jewish Babylonian Aramaic. It is often referred to as (the) Square script. The names "Ashuri" (Assyrian) or "square script" are used to distinguish it from the Paleo-Hebrew script.
According to Halakha (Jewish religious law), tefillin (phylacteries) and mezuzot (door-post scripts) can only be written in Ashurit.[1]