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苹果登录服务端JWT算法验证－PHP
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验证参数
可用的验证参数有 userID、authorizationCode、identityToken，需要iOS客户端传过来
验证方式
苹果登录验证可以选择两种验证方式
具体可参考这篇文章 https://juejin.im/post/5e21c212f265da3e0640bf49
我们采用JWT算法校验 identityToken 的方式来验证
JWT算法原理
客户端传过来的userID示例 000327.cd00e3974ea8402dbe3a33e6867f1ee6.1006
identityToken 示例
eyJraWQiOiJlWGF1bm1MIiwiYWxnIjoiUlMyNTYifQ.eyJpc3MiOiJodHRwczovL2FwcGxlaWQuYXBwbGUuY29tIiwiYXVkIjoiY29tLnl3c3kuaW9zLmRlbW8iLCJleHAiOjE1ODY5NDY5NzAsImlhdCI6MTU4Njk0NjM3MCwic3ViIjoiMDAwMzI3LmNkMDBlMzk3NGVhODQwMmRiZTNhMzNlNjg2N2YxZWU2LjEwMDYiLCJjX2hhc2giOiJsQTFkcDlZMnZBVzlFQXlkSWw2MVh3IiwiZW1haWwiOiI5ZXpyMmszaDZzQHByaXZhdGVyZWxheS5hcHBsZWlkLmNvbSIsImVtYWlsX3ZlcmlmaWVkIjoidHJ1ZSIsImlzX3ByaXZhdGVfZW1haWwiOiJ0cnVlIiwiYXV0aF90aW1lIjoxNTg2OTQ2MzcwLCJub25jZV9zdXBwb3J0ZWQiOnRydWV9.GqZFKMQ3KTG42x2-W7r69nnYqqoBHszI4LBI7m7ysyqBRyt1XSGDPy440F153C8x05VgZgkYi0mIZheCIenIMl5R0unOKrXhvHihgwIKtuvPClRQmAyZYxOWct8xGoPvrRpZr4AkJwxauUxaY8NIoV8-UrNduQcjW8-63-wF9B0F-2p61WZuOEmCoULj2aW7fBoRgFylGbQpXAU_8t32fj1JG3OJzErDJsi1P1CJyKaamd-UpVmgwyaCl0nXMnX0CB0ERqb76M67BHY0ji3VBuIp3uZczEEJMzFtgAevOfgoNYRFicVBr25XoyaWYPxZgYnI-AeUQgvnwHaacx4bkg
使用JWT算法做验证，不需要authorizationCode。校验算法是对identityToken做处理的。
把identityToken 用 . 点号分割得到三个部分，前两个部分可以用base64_decode分别得到两串JSON信息。
第一段称为 header，描述了这段消息的加密方式
{"kid":"eXaunmL","alg":"RS256"}
第二段称为 payload，是消息的具体内容
{
"iss":"https://appleid.apple.com",
"aud":"com.ywsy.ios.demo",
"exp":1586946970,
"iat":1586946370,
"sub":"000327.cd00e3974ea8402dbe3a33e6867f1ee6.1006",
"c_hash":"lA1dp9Y2vAW9EAydIl61Xw",
"email":"9ezr2k3h6s@privaterelay.appleid.com",
"email_verified":"true",
"is_private_email":"true",
"auth_time":1586946370,
"nonce_supported":true
}
校验流程
1、解析出identityToken的第二段信息，即payload；
2、检查userID与payload中的sub字段是否一致；
3、检查payload中的exp字段，有效期时间戳是否已过期；
4、从苹果服务器读取公钥；
5、苹果公钥转为pem格式；
6、使用pem公钥校验identityToken；
其中第4步，从苹果服务器读取公钥 https://appleid.apple.com/auth/keys得到一串JSON
{
"keys": [
{
"kty": "RSA",
"kid": "86D88Kf",
"use": "sig",
"alg": "RS256",
"n": "iGaLqP6y-SJCCBq5Hv6pGDbG_SQ11MNjH7rWHcCFYz4hGwHC4lcSurTlV8u3avoVNM8jXevG1Iu1SY11qInqUvjJur--hghr1b56OPJu6H1iKulSxGjEIyDP6c5BdE1uwprYyr4IO9th8fOwCPygjLFrh44XEGbDIFeImwvBAGOhmMB2AD1n1KviyNsH0bEB7phQtiLk-ILjv1bORSRl8AK677-1T8isGfHKXGZ_ZGtStDe7Lu0Ihp8zoUt59kx2o9uWpROkzF56ypresiIl4WprClRCjz8x6cPZXU2qNWhu71TQvUFwvIvbkE1oYaJMb0jcOTmBRZA2QuYw-zHLwQ",
"e": "AQAB"
},
{
"kty": "RSA",
"kid": "eXaunmL",
"use": "sig",
"alg": "RS256",
"n": "4dGQ7bQK8LgILOdLsYzfZjkEAoQeVC_aqyc8GC6RX7dq_KvRAQAWPvkam8VQv4GK5T4ogklEKEvj5ISBamdDNq1n52TpxQwI2EqxSk7I9fKPKhRt4F8-2yETlYvye-2s6NeWJim0KBtOVrk0gWvEDgd6WOqJl_yt5WBISvILNyVg1qAAM8JeX6dRPosahRVDjA52G2X-Tip84wqwyRpUlq2ybzcLh3zyhCitBOebiRWDQfG26EH9lTlJhll-p_Dg8vAXxJLIJ4SNLcqgFeZe4OfHLgdzMvxXZJnPp_VgmkcpUdRotazKZumj6dBPcXI_XID4Z4Z3OM1KrZPJNdUhxw",
"e": "AQAB"
}
]
}
关键步骤要做的就是把 “kid”:"eXaunmL" 的这部分JSON拿出来，用其n值和e值构造出苹果pem格式的公钥。
JWT算法函数，涉及密码数学知识，不详解
<?php
static function createPemFromModulusAndExponent($n, $e)
static function urlsafeB64Decode($input)
static function encodeLength($length)
核心代码
<?php
class Common_Apple{ protected static $supported_algs = array(
'HS256' => array('hash_hmac', 'SHA256'),
'HS512' => array('hash_hmac', 'SHA512'),
'HS384' => array('hash_hmac', 'SHA384'),
'RS256' => array('openssl', 'SHA256'),
'RS384' => array('openssl', 'SHA384'),
'RS512' => array('openssl', 'SHA512'),
); function __construct($game_id){} function get_login_info($userID, $authorizationCode, $identityToken){
/*{{{*/
$token = explode('.', $identityToken);
$jwt_header = json_decode( base64_decode($token[0]), TRUE);
$jwt_data = json_decode( base64_decode($token[1]), TRUE);
$jwt_sign = $token[2];
// var_dump($jwt_header);
// var_dump($jwt_data);
// var_dump($jwt_sign);
if( $userID !== $jwt_data['sub']){
return fail('用户ID与token不对应');
}
if( PRODUCTION_ENV && $jwt_data['exp'] < time() ){
return fail('token已过期，请重新登录');
} $applekeys = Common_Http::get_https_content('https://appleid.apple.com/auth/keys');
$applekeys = json_decode($applekeys, TRUE);
// var_dump($applekeys);
if( !$applekeys ){
return fail('请求苹果服务器失败');
} $the_apple_key = [];
foreach($applekeys['keys'] as $key){
if($key['kid'] == $jwt_header['kid'] ){
$the_apple_key = $key;
}
}unset($key);
// var_dump($the_apple_key); $pem = self::createPemFromModulusAndExponent($the_apple_key['n'], $the_apple_key['e']);
$pKey = openssl_pkey_get_public($pem);
// var_dump($pKey);
if( $pKey === FALSE ){
return fail('生成苹果pem失败');
}
$publicKeyDetails = openssl_pkey_get_details($pKey);
// var_dump($publicKeyDetails); $pub_key = $publicKeyDetails['key'];
$alg = $jwt_header['alg']; $ok = self::verify("$token[0].$token[1]", static::urlsafeB64Decode($jwt_sign), $pub_key, $alg);
// var_dump($ok);
if( !$ok ){
return fail('苹果登录签名校验失败');
} return success([]);
/*}}}*/
} /**
*
* Create a public key represented in PEM format from RSA modulus and exponent information
*
* @param string $n the RSA modulus encoded in Base64
* @param string $e the RSA exponent encoded in Base64
* @return string the RSA public key represented in PEM format
*/
protected static function createPemFromModulusAndExponent($n, $e)
{
$modulus = static::urlsafeB64Decode($n);
$publicExponent = static::urlsafeB64Decode($e); $components = array(
'modulus' => pack('Ca*a*', 2, self::encodeLength(strlen($modulus)), $modulus),
'publicExponent' => pack('Ca*a*', 2, self::encodeLength(strlen($publicExponent)), $publicExponent)
); $RSAPublicKey = pack(
'Ca*a*a*',
48,
self::encodeLength(strlen($components['modulus']) + strlen($components['publicExponent'])),
$components['modulus'],
$components['publicExponent']
); // sequence(oid(1.2.840.113549.1.1.1), null)) = rsaEncryption.
$rsaOID = pack('H*', '300d06092a864886f70d0101010500'); // hex version of MA0GCSqGSIb3DQEBAQUA
$RSAPublicKey = chr(0) . $RSAPublicKey;
$RSAPublicKey = chr(3) . self::encodeLength(strlen($RSAPublicKey)) . $RSAPublicKey; $RSAPublicKey = pack(
'Ca*a*',
48,
self::encodeLength(strlen($rsaOID . $RSAPublicKey)),
$rsaOID . $RSAPublicKey
); $RSAPublicKey = "-----BEGIN PUBLIC KEY-----\r\n" .
chunk_split(base64_encode($RSAPublicKey), 64) .
'-----END PUBLIC KEY-----'; return $RSAPublicKey;
} /**
* Decode a string with URL-safe Base64.
*
* @param string $input A Base64 encoded string
*
* @return string A decoded string
*/
protected static function urlsafeB64Decode($input)
{
$remainder = strlen($input) % 4;
if ($remainder) {
$padlen = 4 - $remainder;
$input .= str_repeat('=', $padlen);
}
return base64_decode(strtr($input, '-_', '+/'));
} /**
* DER-encode the length
*
* DER supports lengths up to (2**8)**127, however, we'll only support lengths up to (2**8)**4. See
* {@link http://itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf#p=13 X.690 paragraph 8.1.3} for more information.
*
* @access private
* @param int $length
* @return string
*/
protected static function encodeLength($length)
{
if ($length <= 0x7F) {
return chr($length);
} $temp = ltrim(pack('N', $length), chr(0));
return pack('Ca*', 0x80 | strlen($temp), $temp);
} /**
* Get the number of bytes in cryptographic strings.
*
* @param string
*
* @return int
*/
protected static function safeStrlen($str)
{
if (function_exists('mb_strlen')) {
return mb_strlen($str, '8bit');
}
return strlen($str);
} /**
* Verify a signature with the message, key and method. Not all methods
* are symmetric, so we must have a separate verify and sign method.
*
* @param string $msg The original message (header and body)
* @param string $signature The original signature
* @param string|resource $key For HS*, a string key works. for RS*, must be a resource of an openssl public key
* @param string $alg The algorithm
*
* @return bool
*
* @throws DomainException Invalid Algorithm or OpenSSL failure
*/
protected static function verify($msg, $signature, $key, $alg)
{
if (empty(static::$supported_algs[$alg])) {
throw new DomainException('Algorithm not supported');
} list($function, $algorithm) = static::$supported_algs[$alg];
switch($function) {
case 'openssl':
$success = openssl_verify($msg, $signature, $key, $algorithm);
if ($success === 1) {
return true;
} elseif ($success === 0) {
return false;
}
// returns 1 on success, 0 on failure, -1 on error.
throw new DomainException(
'OpenSSL error: ' . openssl_error_string()
);
case 'hash_hmac':
default:
$hash = hash_hmac($algorithm, $msg, $key, true);
if (function_exists('hash_equals')) {
return hash_equals($signature, $hash);
}
$len = min(static::safeStrlen($signature), static::safeStrlen($hash)); $status = 0;
for ($i = 0; $i < $len; $i++) {
$status |= (ord($signature[$i]) ^ ord($hash[$i]));
}
$status |= (static::safeStrlen($signature) ^ static::safeStrlen($hash)); return ($status === 0);
}
} }
