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：
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<?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 tokenecho("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：
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<?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 <chris.riesen@gmail.com> * @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：
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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：
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从数据库读取temp_seedvendor('oath.oath');$object = new \google2fa();if($object->verify_key($temp_seed, $otp)){ 验证成功，将数据库更新seed为temp_seed，auth_type为1，last_otp为otp} |
2）、动态口令登录
用户动态口令登录验证的代码：
从数据库读取auth_type,seed,last_otp字段。
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if($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服务器之家。
