preg match for repeating or incremental characters

Question

I am using preg match to validate password as:

(preg_match("/^.*(?=.{5,}).*$/", $password)

which accept special characters too.

but for some reason, i need to modify it which should accept

• only alphanumeric
• minimum 5 characters long
• and very important that it must not have any repeating or incremental characters like: aaaa or 12345 or abc123 etc

.

Answer 1

if (preg_match(
    '%^           # Start of string
    (?!.*(.)\1)   # Assert no repeated characters
                  # Assert no sequential digits/characters
    (?!.*(?:01|12|23|34|45|56|67|78|89|90|
            ab|bc|cd|de|ef|fg|gh|hi|ij|jk|
            kl|lm|mn|no|op|pq|qr|rs|st|tu|
            uv|vw|wx|xy|yz))
    [a-z0-9]{5,}  # Match at least five alnum characters
    $             # End of string%ix', 
    $password)) {
    # Successful match
    }

Answer 2

expanding on @TimPietzcker and he should take all credit. So be sure to upvote his answer. But I needed this:

no triple repeated characters

no triple incremental characters / digits

because double incremental characters is odd, you won't even notice you did it.

E.g. test4x3x6 should work right? wrong, st is an incremental character. This will just drive your users crazy.

So I used this:

function is_password_strong($password){
  $preg_res = preg_match(
      '%^           # Start of string
    (?!.*(.)\1{2})   # Assert no triple repeated characters
                  # Assert no sequential digits/characters
    (?!.*(?:012|123|234|345|456|567|678|789|890|
            abc|bcd|cde|def|efg|fgh|ghi|hij|ijk|jkl|
            klm|lmn|mno|nop|opq|pqr|qrs|rst|stu|tuv|
            uvw|vwx|wxy|xyz))
    .{8,}  # Match at least 8 characters
    $             # End of string%ix',
      $password);

  if ($preg_res) {

    return true;
  }else{
    return false;
  }
}