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
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,$window = 5,$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：
?>
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
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PHP3.2.3整合PHPqrcode生成带logo的二维码》 。 生成密钥二维码代码如下：
$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);
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。
从数据库读取auth_type,seed,last_otp字段。
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编程之家。
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