Romania Validate CNP - PHP

sample.php

<?php

// The goal is to prevent human error, not cheating the system.

class Sample {

  private static $_cnpValidationConstant = "279146358279";

  public static function isValidCNP( $cnp ) {
    $cnp = intval( $cnp );

    if( strlen( '' . $cnp ) !== ( strlen( self::$_cnpValidationConstant ) + 1 ) || !is_numeric( $cnp ) )
      return false;

    $security = $cnp % 10;
    $checksum = 0;
    $numberNavigation = floor( $cnp / 10 );

    for( $currentDigit = $numberNavigation % 10, $currentPosition = strlen( self::$_cnpValidationConstant ) - 1;
         $currentPosition >= 0;
         $numberNavigation /= 10, $currentDigit = $numberNavigation % 10, $currentPosition-- )
      $checksum += $currentDigit * self::$_cnpValidationConstant[ $currentPosition ];

    $checksum = $checksum % 11;

    return $checksum === 10 ? ( $security === 1 ) : $security === $checksum;
  }
}