Hair Color (AAMVA Standardized) Regex for PHP

What this pattern does

This page provides a well-structured, multi-part regular expression for matching hair color (aamva standardized), 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
// Hair Color (AAMVA Standardized)
// ReDoS-safe | RegexVault — Identity & PII > Biometric & Physical

define('HAIR_COLOR_AAMVA_STANDARDIZED_PATTERN', '/^(?:BAL|BLK|BLN|BRO|GRY|RED|SDY|WHI|UNK)$/');

function validate_hair_color_aamva_standardized(string $input): bool {
    return (bool) preg_match(HAIR_COLOR_AAMVA_STANDARDIZED_PATTERN, $input);
}

// Example
var_dump(validate_hair_color_aamva_standardized("BAL")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Biometric & Physical 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

Technical Notes

AAMVA codes: BAL=bald, BLK=black, BLN=blond/strawberry, BRO=brown, GRY=gray, RED=red/auburn, SDY=sandy, WHI=white, UNK=unknown. Used on US/Canadian driver's licences. Part of physical description data.