Rodné číslo

Purpose

Use the rodne_cislo detector for Czech birth numbers (rodné číslo).

This detector is designed for structured personal identifiers and has reported accuracy above 95%.

It validates the encoded date, handles both 9-digit and 10-digit variants, and exposes metadata that is useful for downstream policy decisions.

Detector Name

rodne_cislo

Supported Formats

• YYMMDD/XXXX
• YYMMDDXXXX
• 9-digit pre-1954 form: YYMMDD/XXX or YYMMDDXXX

FastPII strips / and spaces before validation.

For women, the encoded month typically uses +50.

Example: 53 means March for a female record.

Pre-1954 records use the 9-digit format and follow different year handling rules.

Validation Logic

The detector performs validation in this order:

1. Remove / and spaces.
2. Require 9 or 10 digits.
3. Parse the embedded date.
4. For 10-digit values, run the MOD 11 checksum check.

Date Rules

• 10-digit values use year mapping 00-53 -> 2000-2053, 54-99 -> 1900-1999.
• 9-digit values use year mapping 00-53 -> 1900-1953, 54-99 -> 1800-1899.
• The detector normalizes encoded month values before constructing a real date.

Checksum Algorithm

For 10-digit values:

1. Take the first 9 digits.
2. Compute first_9_digits % 11.
3. If the remainder is 10, the expected checksum digit becomes 0.
4. Otherwise, the expected checksum digit is the remainder.
5. Compare that result with the last digit.

9-digit records do not use checksum validation in FastPII.

Python Examples

Validate a birth number

from fastpii import PrivacyGuard

guard = PrivacyGuard(regions=["cz"])
result = guard.validate("8001011238", "rodne_cislo")

print(result.is_valid)
print(result.metadata)

Detect in free text

from fastpii import PrivacyGuard

guard = PrivacyGuard(regions=["cz"])
result = guard.detect("RČ: 800101/1238", detector_names=["rodne_cislo"])

for finding in result.findings:
    print(finding.type, finding.value, finding.metadata)

Expected Metadata

When validation or detection succeeds, this detector can return:

• gender: male or female
• birth_date: normalized ISO date string
• article_9: True
• checksum_valid: present for 10-digit values

Example Output

{
    "gender": "male",
    "birth_date": "1980-01-01",
    "article_9": True,
    "checksum_valid": True,
}

Limitations

• 9-digit records validate by format and date only, not checksum.
• Metadata depends on successful date parsing.
• The detector is Czech-specific and should not be used for generic national ID formats.
• Birth numbers are highly sensitive personal data; FastPII marks them with article_9 = True.

Notes

If you need a quick single-value check, this is the exact validation call verified in the codebase:

guard.validate("8001011238", "rodne_cislo")