slnic 0.1.0

Parse, validate, convert, and generate Sri Lankan NIC (National Identity Card) numbers

slnic

Parse, validate, convert, and generate Sri Lankan NIC (National Identity Card) numbers in Python.

A Sri Lankan NIC number encodes the holder's birth date and gender. slnic understands both the old 10-character format (853400123V) and the new 12-digit format (198534000123), and gives you a clean, typed API to work with them — zero dependencies.

Installation

pip install slnic

Quick start

import slnic

nic = slnic.parse("853400123V")

nic.birth_date      # datetime.date(1985, 12, 5)
nic.gender          # <Gender.MALE: 'male'>
nic.age()           # 40  (as of today)
nic.format          # <NICFormat.OLD: 'old'>
nic.voter_eligible  # True  ('V' suffix; 'X' → False; None for new format)
nic.serial          # '012'
nic.check_digit     # '3'

str(nic.to_new())   # '198534000123'

Validate

slnic.is_valid("853400123V")    # True
slnic.is_valid("858400123v")    # True  (case-insensitive, female)
slnic.is_valid("859990123V")    # False (invalid day-of-year segment)

# parse() raises InvalidNICError with a helpful message:
slnic.parse("870600012V")
# InvalidNICError: day of year 60 means 29 February, but 1987 is not a leap year

Convert between formats

old = slnic.parse("853400123V")
new = old.to_new()              # NIC('198534000123')

# New → old works when the birth year is 1900-1999 and the serial fits.
# The V/X letter was dropped in the new format, so supply it (default 'V'):
back = new.to_old(voter_eligible=True)   # NIC('853400123V')

Generate test data

from datetime import date
from slnic import generate

nic = generate(date(1992, 7, 14), gender="female", nic_format="new")
str(nic)   # e.g. '199269604823'

Note: the NIC checksum algorithm has never been published, so generated numbers are structurally valid (great for test fixtures and demos) but may not correspond to any real, issued NIC. For the same reason, parse() and is_valid() do not verify the check digit — no library can.

How NIC numbers work

Segment	Old format (853400123V)	New format (198534000123)
Birth year	85 → 1985 (always 19xx)	1985
Day of year	340	340
Serial	012 (3 digits)	0012 (4 digits)
Check digit	3	3
Voter letter	V eligible / X not	(dropped)

• Gender: if the day-of-year segment is greater than 500, the holder is female — subtract 500 to get the actual day (e.g. 840 → day 340).
• February always counts as 29 days in the NIC calendar, regardless of leap year. So 1 March is always day 61, and day 60 (29 Feb) is only valid for leap-year births.
• Old → new conversion: prepend 19 to the year and left-pad the serial with 0.

API

Function / attribute	Description
slnic.parse(s) -> NIC	Parse either format; raises InvalidNICError
slnic.is_valid(s) -> bool	Structural validity check
slnic.generate(birth_date, ...) -> NIC	Build a structurally valid NIC (test data)
NIC.birth_date, .gender, .serial, .check_digit, .voter_eligible, .format, .number	Parsed fields
NIC.birth_year, .day_of_year, .age(on=None)	Derived values
NIC.to_new(), NIC.to_old(voter_eligible=True)	Format conversion (raises ConversionError when impossible)

NIC is a frozen (immutable, hashable) dataclass, and the package ships type hints (py.typed).

Development

git clone https://github.com/RavinduPabasara/slnic
cd slnic
make install-dev
make test

Privacy note

NIC numbers are personal data. This library only decodes what the number format itself encodes; take care when logging or storing NICs in your own applications.

License

MIT — see LICENSE.

Author

Ravindu Pabasara Karunarathna — also the author of sinhaladate.