protected function TfaRandomTrait::randomCharacters in Two-factor Authentication (TFA) 8

Generate random characters of the given length and allowable characters.

Parameters

int $length: The desired length of the returned string.

string $allowable_characters: Characters that are allowed to be return in the generated string.

Return value

string Random string of given length and allowed characters.

Throws

\Exception

3 calls to TfaRandomTrait::randomCharacters()

TfaRandomTrait::randomInteger in src/TfaRandomTrait.php

Generate a random integer of the given character length.

TfaRandomTrait::randomString in src/TfaRandomTrait.php

Generate a random string of the given character length.

TfaRecoveryCode::generateCodes in src/Plugin/TfaValidation/TfaRecoveryCode.php

Generate an array of secure recovery codes.

File

src/TfaRandomTrait.php, line 75

Class

TfaRandomTrait

Trait TfaRandomTrait for generating cryptographically secure random data.

Namespace

Drupal\tfa

Code

protected function randomCharacters($length, $allowable_characters) {

  // Zero-based count of characters in the allowable list:
  $len = strlen($allowable_characters) - 1;

  // Start with a blank string.
  $characters = '';

  // Loop the number of times specified by $length.
  for ($i = 0; $i < $length; $i++) {
    do {

      // Find a secure random number within the range needed.
      $index = ord(random_bytes(1));
    } while ($index > $len);

    // Each iteration, pick a random character from the
    // allowable string and append it to the string we're building.
    $characters .= $allowable_characters[$index];
  }
  return $characters;
}