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<?php
class nextpage{
public function __construct($scraper){
$this->scraper = $scraper;
}
public function store($payload, $page){
$page = $page[0];
$password = random_bytes(256); // 2048 bit
$salt = random_bytes(16);
$key = hash_pbkdf2("sha512", $password, $salt, 20000, 32, true);
$iv =
random_bytes(
openssl_cipher_iv_length("aes-256-gcm")
);
$tag = "";
$out = openssl_encrypt($payload, "aes-256-gcm", $key, OPENSSL_RAW_DATA, $iv, $tag, "", 16);
$key = apcu_inc("key", 1);
apcu_store(
$page . "." .
$this->scraper .
(string)($key),
gzdeflate($salt.$iv.$out.$tag),
420 // cache information for 7 minutes blaze it
);
return
$this->scraper . $key . "." .
rtrim(strtr(base64_encode($password), '+/', '-_'), '=');
}
public function get($npt, $page){
$page = $page[0];
$explode = explode(".", $npt, 2);
if(count($explode) !== 2){
throw new Exception("Malformed nextPageToken!");
}
$apcu = $page . "." . $explode[0];
$key = $explode[1];
$payload = apcu_fetch($apcu);
if($payload === false){
throw new Exception("The nextPageToken is invalid or has expired!");
}
$key =
base64_decode(
str_pad(
strtr($key, '-_', '+/'),
strlen($key) % 4,
'=',
STR_PAD_RIGHT
)
);
$payload = gzinflate($payload);
$key =
hash_pbkdf2(
"sha512",
$key,
substr($payload, 0, 16), // salt
20000,
32,
true
);
$ivlen = openssl_cipher_iv_length("aes-256-gcm");
$payload =
openssl_decrypt(
substr(
$payload,
16 + $ivlen,
-16
),
"aes-256-gcm",
$key,
OPENSSL_RAW_DATA,
substr($payload, 16, $ivlen),
substr($payload, -16)
);
if($payload === false){
throw new Exception("The nextPageToken is invalid or has expired!");
}
// remove the key after using
apcu_delete($apcu);
return $payload;
}
}
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