What are the legal provisions under which the NPR is being created?

The Citizenship Act 1955 was amended in 2004 by inserting Section 14A which provides for the following:-
(1) The Central Government may compulsorily register every citizen of India and issue National Identity Card.
(2) The Central Government may maintain a National Register of Indian Citizens and for that purpose establish a National Registration Authority.
(3) On and from the date of commencement of the Citizenship (Amendment) Act, 2003, the Registrar General, India, appointed under sub-section
    (1) of section 3 of the Registration of Births and Deaths Act, 1969 (18 of 1969) shall act as the National Registration Authority and he shall function as the Registrar General of Citizen Registration.
(4) The Central Government may appoint such other officers and staff as may be required to assist the Registrar General of Citizen Registration in discharging his functions and responsibilities.
(5) The procedure to be followed in compulsory registration of the citizens of India shall be such as may be prescribed.