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refactor hash_equals usage in the EncryptService decrypt method

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Signed-off-by: binsky <timo@binsky.org>
This commit is contained in:
binsky 2022-05-04 01:41:18 +02:00
parent ccb884f5ac
commit f48fd19979
1 changed files with 6 additions and 26 deletions
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28
lib/Service/EncryptService.php
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@ -152,16 +152,16 @@ class EncryptService {
list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key); list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);
if (!$this->hash_equals(hash_hmac('sha512', $enc, $macKey, true), $mac)) { if (hash_equals(hash_hmac('sha512', $enc, $macKey, true), $mac)) {
return false;
}
$dec = openssl_decrypt($enc, $this->cipher, $cipherKey, true, $iv); $dec = openssl_decrypt($enc, $this->cipher, $cipherKey, true, $iv);
$data = $this->unpad($dec); $data = $this->unpad($dec);
return $data; return $data;
} }
return false;
}
/** /**
* Encrypt the supplied data using the supplied key * Encrypt the supplied data using the supplied key
* *
@ -206,26 +206,6 @@ class EncryptService {
return array($cipherKey, $macKey, $iv); return array($cipherKey, $macKey, $iv);
} }
/**
* Use Double HMAC Comparison with a random key to truly blind the comparison operation.
* It is not strictly required by using hash_equals (https://www.php.net/manual/en/function.hash-equals.php),
* but it is a second layer of security to prevent timing attacks.
*
* @param string $a
* @param string $b
*
* @return bool
* @throws \Exception
*/
protected function hash_equals($a, $b) {
if (function_exists('random_bytes')) {
$key = random_bytes(128);
} else {
$key = openssl_random_pseudo_bytes(128);
}
return hash_equals(hash_hmac('sha512', $a, $key), hash_hmac('sha512', $b, $key));
}
/** /**
* Stretch the key using the PBKDF2 algorithm * Stretch the key using the PBKDF2 algorithm
* *