Identifier detector
Austrian social insurance number (SVNR): format, validation and detection
Short answer
An Austrian social insurance number (SVNR) has 10 digits. The fourth digit is a check digit: the ten digits weighted 3, 7, 9, 0, 5, 8, 4, 2, 1, 6 must give a sum whose remainder modulo 11 equals that digit.
What it is
The Sozialversicherungsnummer identifies people insured in Austria. Maskflare's Austria pack covers it as a social security number, and the GDPR (EU/EEA) profile includes the pack.
In Maskflare this is the detector at_social_security, labelled "Austria - Social insurance number (SVNR)", category social security number, in the Austria pack.
Format and layout
- 10 digits, printed 1237 010180: a four-digit serial with the check digit in position four, then the birth date as DDMMYY.
- The first digit is not 0.
How the check works
Weight the ten digits 3, 7, 9, 0, 5, 8, 4, 2, 1, 6 (the fourth weight is 0, so the check digit does not count itself), add the products, and take the remainder modulo 11. The remainder must not be 10 and must equal the fourth digit.
Valid and invalid examples
| Example | Result | Why |
|---|---|---|
1237 010180 | Valid | Matches the layout and passes the validator. |
1237 010181 | Invalid | The invalid example changes one character, the last character: 0 becomes 1. |
In running text the valid example reads, for instance, SVNR 1237 010180. The invalid one is left alone: a value that fails the validator is treated as an ordinary string.
Regex and validation caveats
- The check digit sits in the middle of the number rather than at the end, which can surprise people writing their own validator.
- The birth date part is not validated, only the check digit.
- The detector has no context words; the group layout and check digit decide.
Words that confirm it
The formatted shape is masked without a keyword. For a run with no separators, these words count as the detector's own keywords when a word like order, invoice or phone is also close: social insurance, social security, sozialversicherungsnummer, ssn, sv nr, sv-nr, sv-nummer, svnr, versicherungsnummer. The nearer word wins.
How to detect it in LLM traffic
Austrian social insurance number (SVNR) values reach an LLM inside ordinary work rather than as standalone data: a pasted block of HR or payroll rows, a customer-support thread, an onboarding or identity-check form, a spreadsheet someone wants summarised, or an email they want rewritten. The model needs none of the digits for any of those jobs, so the safest place to remove them is before the request leaves the company.
Maskflare reads the whole request body, including the system prompt, earlier messages and tool arguments, so a number buried in the fourth message of a long chat is found as readily as one in the latest message. Each match is replaced with a token such as mf_mask_d7e0 before the request goes out, and with response restoration turned on the real value is put back into the answer for the person who is allowed to see it.
If you build the detection yourself
- Strip spaces, dots and hyphens before running any arithmetic, but remember where they were so the original text can be replaced exactly.
- Match the shape with a pattern anchored on word boundaries, so that a long digit string is not read as several shorter Austrian social insurance number (SVNR) candidates.
- Run the check from the section above. A failing check is almost always a typo or a made-up value; a passing one removes most look-alikes.
- Treat a run with no separators more carefully than a formatted one: reject it when a word such as order, invoice, phone or reference is nearer to it than one of the identifier's own keywords.
- Replace the value before the text is sent anywhere, and keep a mapping if the answer has to be restored afterwards.
How Maskflare handles it
- Protect now, Finance - Protect now, Healthcare and Developer: mask (a reversible token) when Austria is a primary country.
- Monitor first: alert (counted, forwarded unchanged) when Austria is a primary country.
The available actions are mask (reversible token), redact, partial, hash, format-preserving encryption, generalize, alert and block. Masked values are kept encrypted for 30 days so that answers can be restored, then they expire; prompts and responses are not logged. The full list of detectors is in the detector reference.
Compliance profiles that include it
One compliance profile includes the Austria pack, and applying it turns this detector on: GDPR - EU/EEA. For the GDPR (EU/EEA) profile the Austria pack is one of the country packs the administrator can choose from; the profile turns on the ones chosen. A profile is a floor: it never turns anything off or weakens a rule that is already stricter.
Frequently asked questions
Where is the check digit in an Austrian SVNR?
In fourth position, not last. The weights give position four a weight of zero.
Is the birth date validated?
Maskflare's validator does not check the date. It checks length, the first digit and the check digit.
Is the Austrian social insurance number (SVNR) detector on by default?
It depends on the organisation's primary countries. It is part of the Austria pack, which the default Protect now template turns on with the action mask when Austria is a primary country.
Does a valid Austrian social insurance number (SVNR) prove the person exists?
No. A check digit shows the value is well formed. Many valid-looking numbers have never been issued, and Maskflare masks them all the same.
Rules on this page describe what Maskflare's detectors and validators check. They are read from the detection catalogue and are not the specification of the body that issues the identifier. Examples are synthetic.