US Social Security Number (SSN) — PII context Regex for PHP
/^(?!(?:000|666|9[0-9]{2})-|[0-9]{3}-(?:00|[0-9]{3}-0{4}))(?:[0-9]{3})-(?:[0-9]{2})-(?:[0-9]{4})$/What this pattern does
This page provides a comprehensive, battle-tested regular expression for matching us social security number (ssn) — pii context, ported and verified for PHP. Identity and credential patterns need both correctness and safety, since they're frequent targets for adversarial input. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.
Php Implementation
<?php
// US Social Security Number (SSN) — PII context
// ReDoS-safe | RegexVault — Identity & PII > Financial PII
define('US_SOCIAL_SECURITY_NUMBER_SSN_PII_CONTEXT_PATTERN', '/^(?!(?:000|666|9[0-9]{2})-|[0-9]{3}-(?:00|[0-9]{3}-0{4}))(?:[0-9]{3})-(?:[0-9]{2})-(?:[0-9]{4})$/');
function validate_us_social_security_number_ssn_pii_context(string $input): bool {
return (bool) preg_match(US_SOCIAL_SECURITY_NUMBER_SSN_PII_CONTEXT_PATTERN, $input);
}
// Example
var_dump(validate_us_social_security_number_ssn_pii_context("123-45-6789")); // bool(true)Test Cases
Matches (Valid) | Rejects (Invalid) |
|---|---|
123-45-6789 | 000-12-3456 |
001-23-4567 | 666-12-3456 |
123-45-0000 | 900-12-3456 |
| — | 123-00-3456 |
When to use this pattern
This pattern is drawn from the Identity & PII > Financial PII category and carries a ReDoS-safe certification. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.
Common Pitfalls
Never store SSN in application logs or error messages. Required by law to use SSN masking in UI (show only last 4 digits: XXX-XX-6789). Federal law (Privacy Act) restricts collection without stated purpose.
Technical Notes
Intentionally included in Identity & PII batch in addition to Finance batch (fin-tax-01) to ensure Aurora surfaces the appropriate data handling warnings in both contexts. SSN is the most sensitive financial PII in the US — its exposure enables identity theft.
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