php集成动态口令认证

大多数系统目前均使用的静态密码进行身份认证登录，但由于静态密码容易被窃取，其安全性无法满足安全要求。

动态口令采用一次一密、用过密码作废的方式防止了密码被窃取带来的安全问题。
动态口令分为hotp（基于事件计数的动态口令，rfc4226）、totp（基于时间计数的动态口令,rfc6238）、ocra（挑战应答式动态口令,rfc6287）等方式。

本文介绍了集成totp方式的动态口令认证的方案，php框架采用thinkphp3.2.3，动态口令生成器使用的是google authtication。

1、为thinkphp框架添加oath算法类

oath算法封装类oath.php代码如下：

<?php
/**
 * this program is free software: you can redistribute it and/or modify
 * it under the terms of the gnu general public license as published by
 * the free software foundation, either version 3 of the license, or
 * (at your option) any later version.
 *
 * this program is distributed in the hope that it will be useful,
 * but without any warranty; without even the implied warranty of
 * merchantability or fitness for a particular purpose. see the
 * gnu general public license for more details.
 *
 * you should have received a copy of the gnu general public license
 * along with this program. if not, see <http://www.gnu.org/licenses/>.
 *
 * php google two-factor authentication module.
 *
 * see http://www.idontplaydarts.com/2011/07/google-totp-two-factor-authentication-for-php/
 * for more details
 *
 * @author phil
 **/

class google2fa {

 const keyregeneration  = 30; // interval between key regeneration
 const otplength  = 6; // length of the token generated

 private static $lut = array( // lookup needed for base32 encoding
  "a" => 0, "b" => 1,
  "c" => 2, "d" => 3,
  "e" => 4, "f" => 5,
  "g" => 6, "h" => 7,
  "i" => 8, "j" => 9,
  "k" => 10, "l" => 11,
  "m" => 12, "n" => 13,
  "o" => 14, "p" => 15,
  "q" => 16, "r" => 17,
  "s" => 18, "t" => 19,
  "u" => 20, "v" => 21,
  "w" => 22, "x" => 23,
  "y" => 24, "z" => 25,
  "2" => 26, "3" => 27,
  "4" => 28, "5" => 29,
  "6" => 30, "7" => 31
 );

 /**
  * generates a 16 digit secret key in base32 format
  * @return string
  **/
 public static function generate_secret_key($length = 16) {
  $b32  = "234567qwertyuiopasdfghjklzxcvbnm";
  $s  = "";

  for ($i = 0; $i < $length; $i++)
   $s .= $b32[rand(0,31)];

  return $s;
 }

 /**
  * returns the current unix timestamp devided by the keyregeneration
  * period.
  * @return integer
  **/
 public static function get_timestamp() {
  return floor(microtime(true)/self::keyregeneration);
 }

 /**
  * decodes a base32 string into a binary string.
  **/
 public static function base32_decode($b32) {

  $b32  = strtoupper($b32);

  if (!preg_match('/^[abcdefghijklmnopqrstuvwxyz234567]+$/', $b32, $match))
   throw new exception('invalid characters in the base32 string.');

  $l  = strlen($b32);
  $n = 0;
  $j = 0;
  $binary = "";

  for ($i = 0; $i < $l; $i++) {

   $n = $n << 5;     // move buffer left by 5 to make room
   $n = $n + self::$lut[$b32[$i]];  // add value into buffer
   $j = $j + 5;    // keep track of number of bits in buffer

   if ($j >= 8) {
    $j = $j - 8;
    $binary .= chr(($n & (0xff << $j)) >> $j);
   }
  }

  return $binary;
 }
 /*by tang*/  
 public static function base32_encode($data, $length){
  $basestr = "abcdefghijklmnopqrstuvwxyz234567";
  $count = 0;
  if ($length > 0) {
   $buffer = $data[0];
   $next = 1;
   $bitsleft = 8;

   while (($bitsleft > 0 || $next < $length)) {
    if ($bitsleft < 5) {
    if ($next < $length) {
     $buffer <<= 8;
     $buffer |= $data[$next++] & 0xff;
     $bitsleft += 8;
    } else {
     $pad = 5 - $bitsleft;
     $buffer <<= $pad;
     $bitsleft += $pad;
    }
    }
    $index = 0x1f & ($buffer >> ($bitsleft - 5));
    $bitsleft -= 5;
    $result .= $basestr[$index];
    $count++;
   }
   }
   return $result;  
 }
 /**
  * takes the secret key and the timestamp and returns the one time
  * password.
  *
  * @param binary $key - secret key in binary form.
  * @param integer $counter - timestamp as returned by get_timestamp.
  * @return string
  **/
 public static function oath_hotp($key, $counter)
 {
  if (strlen($key) < 8)
  throw new exception('secret key is too short. must be at least 16 base 32 characters');

  $bin_counter = pack('n*', 0) . pack('n*', $counter);  // counter must be 64-bit int
  $hash  = hash_hmac ('sha1', $bin_counter, $key, true);

  return str_pad(self::oath_truncate($hash), self::otplength, '0', str_pad_left);
 }

 /**
  * verifys a user inputted key against the current timestamp. checks $window
  * keys either side of the timestamp.
  *
  * @param string $b32seed
  * @param string $key - user specified key
  * @param integer $window
  * @param boolean $usetimestamp
  * @return boolean
  **/
 public static function verify_key($b32seed, $key, $window = 5, $usetimestamp = true) {

  $timestamp = self::get_timestamp();

  if ($usetimestamp !== true) $timestamp = (int)$usetimestamp;

  $binaryseed = self::base32_decode($b32seed);

  for ($ts = $timestamp - $window; $ts <= $timestamp + $window; $ts++)
   if (self::oath_hotp($binaryseed, $ts) == $key)
    return true;

  return false;

 }

 /**
  * extracts the otp from the sha1 hash.
  * @param binary $hash
  * @return integer
  **/
 public static function oath_truncate($hash)
 {
  $offset = ord($hash[19]) & 0xf;

  return (
   ((ord($hash[$offset+0]) & 0x7f) << 24 ) |
   ((ord($hash[$offset+1]) & 0xff) << 16 ) |
   ((ord($hash[$offset+2]) & 0xff) << 8 ) |
   (ord($hash[$offset+3]) & 0xff)
  ) % pow(10, self::otplength);
 }


}
/*
$initalizationkey = "lflfmu2sgvcuiuczkbmekrkliq";     // set the inital key

$timestamp  = google2fa::get_timestamp();
$secretkey  = google2fa::base32_decode($initalizationkey); // decode it into binary
$otp    = google2fa::oath_hotp($secretkey, $timestamp); // get current token

echo("init key: $initalizationkey\n");
echo("timestamp: $timestamp\n");
echo("one time password: $otp\n");

// use this to verify a key as it allows for some time drift.

$result = google2fa::verify_key($initalizationkey, "123456");

var_dump($result);
*/
?>

由于google的动态口令算法中种子密钥使用了base32编码，因此需要base32算法，base32.php内容如下：

<?php
//namespace base32;
/**
 * base32 encoder and decoder
 *
 * last update: 2012-06-20
 *
 * rfc 4648 compliant
 * @link http://www.ietf.org/rfc/rfc4648.txt
 *
 * some groundwork based on this class
 * https://github.com/nticompass/php-base32
 *
 * @author christian riesen <[e-mail]>
 * @link http://christianriesen.com
 * @license mit license see license file
 */
class base32
{
 /**
  * alphabet for encoding and decoding base32
  *
  * @var array
  */
 private static $alphabet = 'abcdefghijklmnopqrstuvwxyz234567=';
 /**
  * creates an array from a binary string into a given chunk size
  *
  * @param string $binarystring string to chunk
  * @param integer $bits number of bits per chunk
  * @return array
  */
 private static function chunk($binarystring, $bits)
 {
  $binarystring = chunk_split($binarystring, $bits, ' ');
  if (substr($binarystring, (strlen($binarystring)) - 1) == ' ') {
   $binarystring = substr($binarystring, 0, strlen($binarystring)-1);
  }
  return explode(' ', $binarystring);
 }
 /**
  * encodes into base32
  *
  * @param string $string clear text string
  * @return string base32 encoded string
  */
 public static function encode($string)
 {
  if (strlen($string) == 0) {
   // gives an empty string
   return '';
  }
  // convert string to binary
  $binarystring = '';
  foreach (str_split($string) as $s) {
   // return each character as an 8-bit binary string
   $binarystring .= sprintf('%08b', ord($s));
  }
  // break into 5-bit chunks, then break that into an array
  $binaryarray = self::chunk($binarystring, 5);
  // pad array to be divisible by 8
  while (count($binaryarray) % 8 !== 0) {
   $binaryarray[] = null;
  }
  $base32string = '';
  // encode in base32
  foreach ($binaryarray as $bin) {
   $char = 32;
   if (!is_null($bin)) {
    // pad the binary strings
    $bin = str_pad($bin, 5, 0, str_pad_right);
    $char = bindec($bin);
   }
   // base32 character
   $base32string .= self::$alphabet[$char];
  }
  return $base32string;
 }
 /**
  * decodes base32
  *
  * @param string $base32string base32 encoded string
  * @return string clear text string
  */
 public static function decode($base32string)
 {
  // only work in upper cases
  $base32string = strtoupper($base32string);
  // remove anything that is not base32 alphabet
  $pattern = '/[^a-z2-7]/';
  $base32string = preg_replace($pattern, '', $base32string);
  if (strlen($base32string) == 0) {
   // gives an empty string
   return '';
  }
  $base32array = str_split($base32string);
  $string = '';
  foreach ($base32array as $str) {
   $char = strpos(self::$alphabet, $str);
   // ignore the padding character
   if ($char !== 32) {
    $string .= sprintf('%05b', $char);
   }
  }
  while (strlen($string) %8 !== 0) {
   $string = substr($string, 0, strlen($string)-1);
  }
  $binaryarray = self::chunk($string, 8);
  $realstring = '';
  foreach ($binaryarray as $bin) {
   // pad each value to 8 bits
   $bin = str_pad($bin, 8, 0, str_pad_right);
   // convert binary strings to ascii
   $realstring .= chr(bindec($bin));
  }
  return $realstring;
 }
}

?>

将这两个文件放到thinkphp框架的thinkphp\library\vendor\oath目录下，oath目录是自己创建的。

2、添加数据库字段

用户表添加如下字段:
auth_type（0-静态密码，1-动态口令）
seed（种子密钥）
temp_seed（临时种子密钥）
last_logintime（上次登录成功时间）
last_otp（上次使用密码）
其中auth_type是为了标明用户使用的哪种认证方式，seed为用户的种子密钥，temp_seed为用户未开通前临时保存的一个种子密钥，如果用户开通动态口令认证成功，该字段内容会填到seed字段。last_logintime和last_otp为上次认证成功的时间和动态口令，用于避免用户同一个口令重复使用。

3、代码集成

1）、开通动态口令

在原有系统的修改密码页面，加上认证方式的选择，例如：

如果用户选择动态口令方式，则会生成一张二维码显示在页面，用于用户开通动态口令。为了兼容google authtication，其二维码格式与谷歌一样。生成二维码的方法见我的另一篇《thinkphp3.2.3整合phpqrcode生成带logo的二维码》 。
生成密钥二维码代码如下：

public function qrcode()
 { 
  vendor('oath.base32');
  $base32 = new \base32();
  $rand = random(16);//生成随机种子
  $rand = $base32->encode($rand);
  $rand=str_replace('=','',$rand);//去除填充的‘='

  $errorcorrectionlevel =intval(3) ;//容错级别 
  $matrixpointsize = intval(8);//生成图片大小

  //生成二维码图片 
  vendor('phpqrcode.phpqrcode');
  $object = new \qrcode();
  $text = sprintf("otpauth://totp/%s?secret=%s", $user, $rand);
  $object->png($text, false, $errorcorrectionlevel, $matrixpointsize, 2);

  生成的种子$rand保存到数据库的temp_seed字段
 }

random是生成随机字符串函数。$rand=str_replace('=','',$rand)这句代码是因为谷歌手机令牌中base32解码算法并没有填充的‘='号。

验证用户动态口令的代码如下：

从数据库读取temp_seed
vendor('oath.oath');
$object = new \google2fa();
if($object->verify_key($temp_seed, $otp)){
 验证成功，将数据库更新seed为temp_seed，auth_type为1，last_otp为otp
}

2）、动态口令登录

用户动态口令登录验证的代码：

从数据库读取auth_type,seed,last_otp字段。

if($auth_type==1){//动态口令
 //防止重复认证    
 if($lat_otp == $otp) {
  动态口令重复使用返回    
 }
 vendor('oath.oath');
 $object = new \google2fa();
 if(!$object->verify_key($seed, $otp))
 {
  动态口令不正确
 }
 else
 {
  登录成功，将数据库更新last_otp为$otp,last_logintime为time()
 }    
}

4、测试验证

下载google authtication，使用静态密码登录系统，进入修改密码页面。
打开google authtication，扫描二维码，会显示动态口令。

保存内容，开通动态口令成功！
然后你就可以用高大上的动态口令登录系统了!

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。