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<?php |
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declare(strict_types=1); |
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namespace SimpleSAML\XMLSecurity\Utils; |
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use SimpleSAML\XMLSecurity\Constants; |
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use SimpleSAML\XMLSecurity\Exception\InvalidArgumentException; |
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use SimpleSAML\XMLSecurity\XMLSecEnc; |
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use SimpleSAML\XMLSecurity\XMLSecurityKey; |
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use function count; |
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use function hash_equals; |
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use function in_array; |
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use function openssl_pkey_get_details; |
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use function serialize; |
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use function sha1; |
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use function str_pad; |
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use function str_replace; |
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use function strlen; |
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use function strval; |
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use function substr; |
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use function trim; |
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use function var_export; |
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/** |
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* A collection of security-related functions. |
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* |
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* @package simplesamlphp/xml-security |
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*/ |
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class Security |
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{ |
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/** |
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* Compare two strings in constant time. |
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* |
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* This function allows us to compare two given strings without any timing side channels |
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* leaking information about them. |
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* |
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* @param string $known The reference string. |
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* @param string $user The user-provided string to test. |
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* |
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* @return bool True if both strings are equal, false otherwise. |
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*/ |
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public static function compareStrings(string $known, string $user): bool |
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{ |
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return hash_equals($known, $user); |
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} |
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/** |
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* Compute the hash for some data with a given algorithm. |
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* |
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* @param string $alg The identifier of the algorithm to use. |
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* @param string $data The data to digest. |
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* @param bool $encode Whether to bas64-encode the result or not. Defaults to true. |
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* |
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* @return string The (binary or base64-encoded) digest corresponding to the given data. |
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* |
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* @throws \SimpleSAML\XMLSecurity\Exception\InvalidArgumentException If $alg is not a valid |
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* identifier of a supported digest algorithm. |
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*/ |
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public static function hash(string $alg, string $data, bool $encode = true): string |
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{ |
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if (!array_key_exists($alg, Constants::$DIGEST_ALGORITHMS)) { |
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throw new InvalidArgumentException('Unsupported digest method "' . $alg . '"'); |
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} |
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$digest = hash(Constants::$DIGEST_ALGORITHMS[$alg], $data, true); |
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if ($encode) { |
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$digest = base64_encode($digest); |
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} |
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return $digest; |
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} |
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/** |
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* Helper function to convert a XMLSecurityKey to the correct algorithm. |
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* |
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* @param \SimpleSAML\XMLSecurity\XMLSecurityKey $key The key. |
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* @param string $algorithm The desired algorithm. |
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* @param string $type Public or private key, defaults to public. |
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* @return \SimpleSAML\XMLSecurity\XMLSecurityKey The new key. |
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* |
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* @throws \SimpleSAML\Assert\AssertionFailedException if assertions are false |
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*/ |
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public static function castKey(XMLSecurityKey $key, string $algorithm, string $type = null): XMLSecurityKey |
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{ |
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$type = $type ?: 'public'; |
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Assert::oneOf($type, ["private", "public"]); |
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// do nothing if algorithm is already the type of the key |
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if ($key->type === $algorithm) { |
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return $key; |
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} |
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if ( |
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!in_array( |
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$algorithm, |
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[ |
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XMLSecurityKey::RSA_1_5, |
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XMLSecurityKey::RSA_SHA1, |
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XMLSecurityKey::RSA_SHA256, |
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XMLSecurityKey::RSA_SHA384, |
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XMLSecurityKey::RSA_SHA512 |
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], |
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true |
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) |
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) { |
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throw new Exception('Unsupported signing algorithm.'); |
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} |
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/** @psalm-suppress PossiblyNullArgument */ |
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$keyInfo = openssl_pkey_get_details($key->key); |
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if ($keyInfo === false) { |
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throw new Exception('Unable to get key details from XMLSecurityKey.'); |
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} |
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if (!isset($keyInfo['key'])) { |
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throw new Exception('Missing key in public key details.'); |
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} |
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$newKey = new XMLSecurityKey($algorithm, ['type' => $type]); |
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$newKey->loadKey($keyInfo['key']); |
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return $newKey; |
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} |
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/** |
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* Decrypt an encrypted element. |
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* |
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* This is an internal helper function. |
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* |
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* @param \DOMElement $encryptedData The encrypted data. |
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* @param \SimpleSAML\XMLSecurity\XMLSecurityKey $inputKey The decryption key. |
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* @param array &$blacklist Blacklisted decryption algorithms. |
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* @throws \Exception |
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* @return \DOMElement The decrypted element. |
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*/ |
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private static function doDecryptElement( |
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DOMElement $encryptedData, |
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XMLSecurityKey $inputKey, |
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array &$blacklist |
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): DOMElement { |
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$enc = new XMLSecEnc(); |
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$enc->setNode($encryptedData); |
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$enc->type = $encryptedData->getAttribute("Type"); |
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$symmetricKey = $enc->locateKey($encryptedData); |
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if (!$symmetricKey) { |
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throw new Exception('Could not locate key algorithm in encrypted data.'); |
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} |
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$symmetricKeyInfo = $enc->locateKeyInfo($symmetricKey); |
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if (!$symmetricKeyInfo) { |
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throw new Exception('Could not locate <dsig:KeyInfo> for the encrypted key.'); |
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} |
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$inputKeyAlgo = $inputKey->getAlgorithm(); |
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if ($symmetricKeyInfo->isEncrypted) { |
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$symKeyInfoAlgo = $symmetricKeyInfo->getAlgorithm(); |
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if (in_array($symKeyInfoAlgo, $blacklist, true)) { |
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throw new Exception('Algorithm disabled: ' . var_export($symKeyInfoAlgo, true)); |
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} |
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if ($symKeyInfoAlgo === XMLSecurityKey::RSA_OAEP_MGF1P && $inputKeyAlgo === XMLSecurityKey::RSA_1_5) { |
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/* |
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* The RSA key formats are equal, so loading an RSA_1_5 key |
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* into an RSA_OAEP_MGF1P key can be done without problems. |
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* We therefore pretend that the input key is an |
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* RSA_OAEP_MGF1P key. |
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*/ |
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$inputKeyAlgo = XMLSecurityKey::RSA_OAEP_MGF1P; |
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} |
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/* Make sure that the input key format is the same as the one used to encrypt the key. */ |
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if ($inputKeyAlgo !== $symKeyInfoAlgo) { |
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throw new Exception( |
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'Algorithm mismatch between input key and key used to encrypt ' . |
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' the symmetric key for the message. Key was: ' . |
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var_export($inputKeyAlgo, true) . '; message was: ' . |
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var_export($symKeyInfoAlgo, true) |
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); |
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} |
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/** @var XMLSecEnc $encKey */ |
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$encKey = $symmetricKeyInfo->encryptedCtx; |
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$symmetricKeyInfo->key = $inputKey->key; |
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$keySize = $symmetricKey->getSymmetricKeySize(); |
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if ($keySize === null) { |
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/* To protect against "key oracle" attacks, we need to be able to create a |
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* symmetric key, and for that we need to know the key size. |
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*/ |
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throw new Exception( |
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'Unknown key size for encryption algorithm: ' . var_export($symmetricKey->type, true) |
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); |
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} |
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try { |
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/** |
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* @var string $key |
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* @psalm-suppress UndefinedClass |
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*/ |
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$key = $encKey->decryptKey($symmetricKeyInfo); |
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if (strlen($key) !== $keySize) { |
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throw new Exception( |
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'Unexpected key size (' . strval(strlen($key) * 8) . 'bits) for encryption algorithm: ' . |
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var_export($symmetricKey->type, true) |
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); |
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} |
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} catch (Exception $e) { |
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/* We failed to decrypt this key. Log it, and substitute a "random" key. */ |
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// Utils::getContainer()->getLogger()->error('Failed to decrypt symmetric key: ' . $e->getMessage()); |
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/* Create a replacement key, so that it looks like we fail in the same way as if the key was correctly |
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* padded. */ |
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/* We base the symmetric key on the encrypted key and private key, so that we always behave the |
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* same way for a given input key. |
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*/ |
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$encryptedKey = $encKey->getCipherValue(); |
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if ($encryptedKey === null) { |
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throw new Exception('No CipherValue available in the encrypted element.'); |
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} |
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/** @psalm-suppress PossiblyNullArgument */ |
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$pkey = openssl_pkey_get_details($symmetricKeyInfo->key); |
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$pkey = sha1(serialize($pkey), true); |
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$key = sha1($encryptedKey . $pkey, true); |
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/* Make sure that the key has the correct length. */ |
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if (strlen($key) > $keySize) { |
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$key = substr($key, 0, $keySize); |
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} elseif (strlen($key) < $keySize) { |
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$key = str_pad($key, $keySize); |
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} |
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} |
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$symmetricKey->loadkey($key); |
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} else { |
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$symKeyAlgo = $symmetricKey->getAlgorithm(); |
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/* Make sure that the input key has the correct format. */ |
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if ($inputKeyAlgo !== $symKeyAlgo) { |
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throw new Exception( |
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'Algorithm mismatch between input key and key in message. ' . |
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'Key was: ' . var_export($inputKeyAlgo, true) . '; message was: ' . |
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var_export($symKeyAlgo, true) |
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); |
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} |
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$symmetricKey = $inputKey; |
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} |
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253
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$algorithm = $symmetricKey->getAlgorithm(); |
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if (in_array($algorithm, $blacklist, true)) { |
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throw new Exception('Algorithm disabled: ' . var_export($algorithm, true)); |
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} |
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258
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/** |
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* @var string $decrypted |
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* @psalm-suppress UndefinedClass |
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*/ |
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$decrypted = $enc->decryptNode($symmetricKey, false); |
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264
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/* |
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* This is a workaround for the case where only a subset of the XML |
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* tree was serialized for encryption. In that case, we may miss the |
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* namespaces needed to parse the XML. |
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*/ |
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$xml = '<root xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" ' . |
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'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">' . |
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$decrypted . '</root>'; |
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273
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try { |
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$newDoc = DOMDocumentFactory::fromString($xml); |
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} catch (RuntimeException $e) { |
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throw new Exception('Failed to parse decrypted XML. Maybe the wrong sharedkey was used?', 0, $e); |
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} |
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279
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/** @psalm-suppress PossiblyNullPropertyFetch */ |
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$decryptedElement = $newDoc->firstChild->firstChild; |
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if (!($decryptedElement instanceof DOMElement)) { |
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throw new Exception('Missing decrypted element or it was not actually a DOMElement.'); |
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} |
284
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285
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return $decryptedElement; |
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} |
287
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288
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289
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/** |
290
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* Decrypt an encrypted element. |
291
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* |
292
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* @param \DOMElement $encryptedData The encrypted data. |
293
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* @param \SimpleSAML\XMLSecurity\XMLSecurityKey $inputKey The decryption key. |
294
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* @param array $blacklist Blacklisted decryption algorithms. |
295
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* @throws \Exception |
296
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* @return \DOMElement The decrypted element. |
297
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*/ |
298
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public static function decryptElement( |
299
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DOMElement $encryptedData, |
300
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XMLSecurityKey $inputKey, |
301
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array $blacklist = [] |
302
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): DOMElement { |
303
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try { |
304
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return self::doDecryptElement($encryptedData, $inputKey, $blacklist); |
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} catch (Exception $e) { |
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/* |
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* Something went wrong during decryption, but for security |
308
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* reasons we cannot tell the user what failed. |
309
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*/ |
310
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// Utils::getContainer()->getLogger()->error('Decryption failed: ' . $e->getMessage()); |
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throw new Exception('Failed to decrypt XML element.', 0, $e); |
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} |
313
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} |
314
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} |
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The issue could also be caused by a filter entry in the build configuration. If the path has been excluded in your configuration, e.g.
excluded_paths: ["lib/*"]
, you can move it to the dependency path list as follows:For further information see https://scrutinizer-ci.com/docs/tools/php/php-scrutinizer/#list-dependency-paths