OATH_OCRAParser

Complexity

Total Complexity

46

Size/Duplication

Total Lines	234
Duplicated Lines	0 %

Test Coverage

Coverage

54.31%

Importance

Changes

0

4 Methods

Rating	Name	Duplication	Size	Complexity
A	generateChallenge()	0	26	4
A	__construct()	0	2	1
A	constEqual()	0	12	3
D	parseOCRASuite()	0	133	38

<?php

class OATH_OCRAParser {

	private $OCRASuite = NULL;

	private $OCRAVersion = NULL;

	private $CryptoFunctionType = NULL;
	private $CryptoFunctionHash = NULL;
	private $CryptoFunctionHashLength = NULL;
	private $CryptoFunctionTruncation = NULL;

	private $C = FALSE;
	private $Q = FALSE;
	private $QType = 'N';
	private $QLength = 8;

	private $P = FALSE;
	private $PType = 'SHA1';
	private $PLength = 20;

	private $S = FALSE;
	private $SLength = 64;

	private $T = FALSE;
	private $TLength = 60; // 1M
	private $TPeriods = array('H' => 3600, 'M' => 60, 'S' => 1);

	private $supportedHashFunctions = array('SHA1' => 20, 'SHA256' => 32, 'SHA512' => 64);


    /**
     * @param String $ocraSuite The RFC 6287 OCRA suite to parse. E.g. "OCRA-1:HOTP-SHA1-6:QH10-S"
     * @throws Exception
     */
    public function __construct(String $ocraSuite) {
		$this->parseOCRASuite($ocraSuite);
	}

	/**
	 * Inspired by https://github.com/bdauvergne/python-oath
     *
     * @throws Exception
	 */
	private function parseOCRASuite($ocraSuite) {
		if (!is_string($ocraSuite)) {
			throw new Exception('OCRASuite not in string format: ' . var_export($ocraSuite, TRUE));
		}

		$ocraSuite = strtoupper($ocraSuite);
		$this->OCRASuite = $ocraSuite;

		$s = explode(':', $ocraSuite);
		if (count($s) != 3) {
			throw new Exception('Invalid OCRASuite format: ' . var_export($ocraSuite, TRUE));
		}

		$algo = explode('-', $s[0]);
		if (count($algo) != 2) {
			throw new Exception('Invalid OCRA version: ' . var_export($s[0], TRUE));
		}

		if ($algo[0] !== 'OCRA') {
			throw new Exception('Unsupported OCRA algorithm: ' . var_export($algo[0], TRUE));
		}

		if ($algo[1] !== '1') {
			throw new Exception('Unsupported OCRA version: ' . var_export($algo[1], TRUE));
		}
		$this->OCRAVersion = $algo[1];

		$cf = explode('-', $s[1]);
		if (count($cf) != 3) {
			throw new Exception('Invalid OCRA suite crypto function: ' . var_export($s[1], TRUE));
		}

		if ($cf[0] !== 'HOTP') {
			throw new Exception('Unsupported OCRA suite crypto function: ' . var_export($cf[0], TRUE));
		}
		$this->CryptoFunctionType = $cf[0];

		if (!array_key_exists($cf[1], $this->supportedHashFunctions)) {
			throw new Exception('Unsupported hash function in OCRA suite crypto function: ' . var_export($cf[1], TRUE));
		}
		$this->CryptoFunctionHash = $cf[1];
		$this->CryptoFunctionHashLength = $this->supportedHashFunctions[$cf[1]];

		if (!preg_match('/^\d+$/', $cf[2]) || (($cf[2] < 4 || $cf[2] > 10) && $cf[2] != 0)) {
			throw new Exception('Invalid OCRA suite crypto function truncation length: ' . var_export($cf[2], TRUE));
		}
		$this->CryptoFunctionTruncation = intval($cf[2]);

		$di = explode('-', $s[2]);
		if (count($cf) == 0) {
			throw new Exception('Invalid OCRA suite data input: ' . var_export($s[2], TRUE));
		}

		$data_input = array();
		foreach($di as $elem) {
			$letter = $elem[0];
			if (array_key_exists($letter, $data_input)) {
				throw new Exception('Duplicate field in OCRA suite data input: ' . var_export($elem, TRUE));
			}
			$data_input[$letter] = 1;

			if ($letter === 'C' && strlen($elem) == 1) {
				$this->C = TRUE;
			} elseif ($letter === 'Q') {
				if (strlen($elem) == 1) {
					$this->Q = TRUE;
				} elseif (preg_match('/^Q([AHN])(\d+)$/', $elem, $match)) {
					$q_len = intval($match[2]);
					if ($q_len < 4 || $q_len > 64) {
						throw new Exception('Invalid OCRA suite data input question length: ' . var_export($q_len, TRUE));
					}
					$this->Q = TRUE;
					$this->QType = $match[1];
					$this->QLength = $q_len;
				} else {
					throw new Exception('Invalid OCRA suite data input question: ' . var_export($elem, TRUE));
				}
			} elseif ($letter === 'P') {
				if (strlen($elem) == 1) {
					$this->P = TRUE;
				} else {
					$p_algo = substr($elem, 1);
					if (!array_key_exists($p_algo, $this->supportedHashFunctions)) {
						throw new Exception('Unsupported OCRA suite PIN hash function: ' . var_export($elem, TRUE));
					}
					$this->P = TRUE;
					$this->PType = $p_algo;
					$this->PLength = $this->supportedHashFunctions[$p_algo];
				}
			} elseif ($letter === 'S') {
				if (strlen($elem) == 1) {
					$this->S = TRUE;
				} elseif (preg_match('/^S(\d+)$/', $elem, $match)) {
					$s_len = intval($match[1]);
					if ($s_len <= 0 || $s_len > 512) {
						throw new Exception('Invalid OCRA suite data input session information length: ' . var_export($s_len, TRUE));
					}

					$this->S = TRUE;
					$this->SLength = $s_len;
				} else {
					throw new Exception('Invalid OCRA suite data input session information length: ' . var_export($elem, TRUE));
				}
			} elseif ($letter === 'T') {
				if (strlen($elem) == 1) {
					$this->T = TRUE;
				} elseif (preg_match('/^T(\d+[HMS])+$/', $elem)) {
					preg_match_all('/(\d+)([HMS])/', $elem, $match);

					if (count($match[1]) !== count(array_unique($match[2]))) {
						throw new Exception('Duplicate definitions in OCRA suite data input timestamp: ' . var_export($elem, TRUE));
					}

					$length = 0;
					for ($i = 0; $i < count($match[1]); $i++) {

It seems like you are calling the size function count() as part of the test condition. You might want to compute the size beforehand, and not on each iteration.

						$length += intval($match[1][$i]) * $this->TPeriods[$match[2][$i]];
					}
					if ($length <= 0) {
						throw new Exception('Invalid OCRA suite data input timestamp: ' . var_export($elem, TRUE));
					}

					$this->T = TRUE;
					$this->TLength = $length;
				} else {
					throw new Exception('Invalid OCRA suite data input timestamp: ' . var_export($elem, TRUE));
				}
			} else {
				throw new Exception('Unsupported OCRA suite data input field: ' . var_export($elem, TRUE));
			}
		}

		if (!$this->Q) {
			throw new Exception('OCRA suite data input question not defined: ' . var_export($s[2], TRUE));
		}
	}

    /** Generate an OCRA challenge question according to the ocra suite specified in the constructor
     * @return String: The randomly generated OCRA question
     * @throws Exception
     *
     * The required format and length of the challenge question are specified in the "Q" part OCRA suite:
     * OCRA-1:...:QH10-... means 10 hex digits
     * OCRA-1:...:QN08-... means 8 decimal digits
     * OCRA-1:...:QA06-... means 6 ASCII digits
     * Note that the question string is the exact question string a specified in the OCRA strandard (RFC 6287)
     * The challenge is not yet hex encoded as expected by OCRA::generateOCRA()
     */
	public function generateChallenge() : String {
		$q_length = $this->QLength;
		$q_type = $this->QType;

        $bytes = Tiqr_Random::randomBytes($q_length);

		switch($q_type) {
			case 'A':
				$challenge = base64_encode($bytes);
				$tr = implode("", unpack('H*', $bytes));
				$challenge = rtrim(strtr($challenge, '+/', $tr), '=');
				break;
			case 'H':
				$challenge = implode("", unpack('H*', $bytes));
				break;
			case 'N':
				$challenge = implode("", unpack('N*', $bytes));
				break;
			default:
				throw new Exception('Unsupported OCRASuite challenge type: ' . var_export($q_type, TRUE));
				break;
		}

		$challenge = substr($challenge, 0, $q_length);

		return $challenge;
	}


	/**
	 * Constant time string comparison, see http://codahale.com/a-lesson-in-timing-attacks/
	 */
	public static function constEqual(string $s1, string $s2): bool {
		if (strlen($s1) != strlen($s2)) {
			return FALSE;
		}

		$result = TRUE;
		$length = strlen($s1);
		for ($i = 0; $i < $length; $i++) {
			$result &= ($s1[$i] == $s2[$i]);
		}

		return (boolean)$result;
	}

}