Security::decryptElement() - Code Metrics - Inspection of "Restore some utilities that are still required by..." - simplesamlphp/xml-security - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Push — master ( 82e8be...64e54a )

by Tim

created 2021-07-25 09:37 UTC

Security::decryptElement() A

↳ Parent: Security

Complexity

Conditions	2
Paths	2

Size

Total Lines	14
Code Lines	4

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	2
eloc	4
c	1
b	0
f	0
nc	2
nop	3
dl	0
loc	14
rs	10

<?php

declare(strict_types=1);

namespace SimpleSAML\XMLSecurity\Utils;

use DOMElement;
use Exception;
use RuntimeException;
use SimpleSAML\Assert\Assert;
use SimpleSAML\XML\DOMDocumentFactory;
use SimpleSAML\XMLSecurity\Constants;
use SimpleSAML\XMLSecurity\Exception\InvalidArgumentException;
use SimpleSAML\XMLSecurity\XMLSecEnc;
use SimpleSAML\XMLSecurity\XMLSecurityKey;

use function count;
use function hash_equals;
use function in_array;
use function openssl_pkey_get_details;
use function serialize;
use function sha1;
use function str_pad;
use function str_replace;
use function strlen;
use function strval;
use function substr;
use function trim;
use function var_export;

/**
 * A collection of security-related functions.
 *
 * @package simplesamlphp/xml-security
 */
class Security
{
    /**
     * Compare two strings in constant time.
     *
     * This function allows us to compare two given strings without any timing side channels
     * leaking information about them.
     *
     * @param string $known The reference string.
     * @param string $user The user-provided string to test.
     *
     * @return bool True if both strings are equal, false otherwise.
     */
    public static function compareStrings(string $known, string $user): bool
    {
        return hash_equals($known, $user);
    }


    /**
     * Compute the hash for some data with a given algorithm.
     *
     * @param string $alg The identifier of the algorithm to use.
     * @param string $data The data to digest.
     * @param bool $encode Whether to bas64-encode the result or not. Defaults to true.
     *
     * @return string The (binary or base64-encoded) digest corresponding to the given data.
     *
     * @throws \SimpleSAML\XMLSecurity\Exception\InvalidArgumentException If $alg is not a valid
     *   identifier of a supported digest algorithm.
     */
    public static function hash(string $alg, string $data, bool $encode = true): string
    {
        if (!array_key_exists($alg, Constants::$DIGEST_ALGORITHMS)) {
            throw new InvalidArgumentException('Unsupported digest method "' . $alg . '"');
        }

        $digest = hash(Constants::$DIGEST_ALGORITHMS[$alg], $data, true);
        if ($encode) {
            $digest = base64_encode($digest);
        }
        return $digest;
    }


    /**
     * Helper function to convert a XMLSecurityKey to the correct algorithm.
     *
     * @param \SimpleSAML\XMLSecurity\XMLSecurityKey $key The key.
     * @param string $algorithm The desired algorithm.
     * @param string $type Public or private key, defaults to public.
     * @return \SimpleSAML\XMLSecurity\XMLSecurityKey The new key.
     *
     * @throws \SimpleSAML\Assert\AssertionFailedException if assertions are false
     */
    public static function castKey(XMLSecurityKey $key, string $algorithm, string $type = null): XMLSecurityKey
    {
        $type = $type ?: 'public';
        Assert::oneOf($type, ["private", "public"]);

        // do nothing if algorithm is already the type of the key
        if ($key->type === $algorithm) {
            return $key;
        }

        if (
            !in_array(
                $algorithm,
                [
                    XMLSecurityKey::RSA_1_5,
                    XMLSecurityKey::RSA_SHA1,
                    XMLSecurityKey::RSA_SHA256,
                    XMLSecurityKey::RSA_SHA384,
                    XMLSecurityKey::RSA_SHA512
                ],
                true
            )
        ) {
            throw new Exception('Unsupported signing algorithm.');
        }

        /** @psalm-suppress PossiblyNullArgument */
        $keyInfo = openssl_pkey_get_details($key->key);
        if ($keyInfo === false) {
            throw new Exception('Unable to get key details from XMLSecurityKey.');
        }
        if (!isset($keyInfo['key'])) {
            throw new Exception('Missing key in public key details.');
        }

        $newKey = new XMLSecurityKey($algorithm, ['type' => $type]);
        $newKey->loadKey($keyInfo['key']);

        return $newKey;
    }


    /**
     * Decrypt an encrypted element.
     *
     * This is an internal helper function.
     *
     * @param \DOMElement $encryptedData The encrypted data.
     * @param \SimpleSAML\XMLSecurity\XMLSecurityKey $inputKey The decryption key.
     * @param array &$blacklist Blacklisted decryption algorithms.
     * @throws \Exception
     * @return \DOMElement The decrypted element.
     */
    private static function doDecryptElement(
        DOMElement $encryptedData,
        XMLSecurityKey $inputKey,
        array &$blacklist
    ): DOMElement {
        $enc = new XMLSecEnc();

        $enc->setNode($encryptedData);
        $enc->type = $encryptedData->getAttribute("Type");

        $symmetricKey = $enc->locateKey($encryptedData);
        if (!$symmetricKey) {
            throw new Exception('Could not locate key algorithm in encrypted data.');
        }

        $symmetricKeyInfo = $enc->locateKeyInfo($symmetricKey);
        if (!$symmetricKeyInfo) {
            throw new Exception('Could not locate <dsig:KeyInfo> for the encrypted key.');
        }

        $inputKeyAlgo = $inputKey->getAlgorithm();
        if ($symmetricKeyInfo->isEncrypted) {
            $symKeyInfoAlgo = $symmetricKeyInfo->getAlgorithm();

            if (in_array($symKeyInfoAlgo, $blacklist, true)) {
                throw new Exception('Algorithm disabled: ' . var_export($symKeyInfoAlgo, true));
            }

            if ($symKeyInfoAlgo === XMLSecurityKey::RSA_OAEP_MGF1P && $inputKeyAlgo === XMLSecurityKey::RSA_1_5) {
                /*
                 * The RSA key formats are equal, so loading an RSA_1_5 key
                 * into an RSA_OAEP_MGF1P key can be done without problems.
                 * We therefore pretend that the input key is an
                 * RSA_OAEP_MGF1P key.
                 */
                $inputKeyAlgo = XMLSecurityKey::RSA_OAEP_MGF1P;
            }

            /* Make sure that the input key format is the same as the one used to encrypt the key. */
            if ($inputKeyAlgo !== $symKeyInfoAlgo) {
                throw new Exception(
                    'Algorithm mismatch between input key and key used to encrypt ' .
                    ' the symmetric key for the message. Key was: ' .
                    var_export($inputKeyAlgo, true) . '; message was: ' .
                    var_export($symKeyInfoAlgo, true)
                );
            }

            /** @var XMLSecEnc $encKey */
            $encKey = $symmetricKeyInfo->encryptedCtx;
            $symmetricKeyInfo->key = $inputKey->key;

            $keySize = $symmetricKey->getSymmetricKeySize();
            if ($keySize === null) {
                /* To protect against "key oracle" attacks, we need to be able to create a
                 * symmetric key, and for that we need to know the key size.
                 */
                throw new Exception(
                    'Unknown key size for encryption algorithm: ' . var_export($symmetricKey->type, true)
                );
            }

            try {
                /**
                 * @var string $key
                 * @psalm-suppress UndefinedClass
                 */
                $key = $encKey->decryptKey($symmetricKeyInfo);
                if (strlen($key) !== $keySize) {
                    throw new Exception(
                        'Unexpected key size (' . strval(strlen($key) * 8) . 'bits) for encryption algorithm: ' .
                        var_export($symmetricKey->type, true)
                    );
                }
            } catch (Exception $e) {
                /* We failed to decrypt this key. Log it, and substitute a "random" key. */
//                Utils::getContainer()->getLogger()->error('Failed to decrypt symmetric key: ' . $e->getMessage());
                /* Create a replacement key, so that it looks like we fail in the same way as if the key was correctly
                 * padded. */

                /* We base the symmetric key on the encrypted key and private key, so that we always behave the
                 * same way for a given input key.
                 */
                $encryptedKey = $encKey->getCipherValue();
                if ($encryptedKey === null) {
                    throw new Exception('No CipherValue available in the encrypted element.');
                }

                /** @psalm-suppress PossiblyNullArgument */
                $pkey = openssl_pkey_get_details($symmetricKeyInfo->key);
                $pkey = sha1(serialize($pkey), true);
                $key = sha1($encryptedKey . $pkey, true);

                /* Make sure that the key has the correct length. */
                if (strlen($key) > $keySize) {
                    $key = substr($key, 0, $keySize);
                } elseif (strlen($key) < $keySize) {
                    $key = str_pad($key, $keySize);
                }
            }
            $symmetricKey->loadkey($key);
        } else {
            $symKeyAlgo = $symmetricKey->getAlgorithm();
            /* Make sure that the input key has the correct format. */
            if ($inputKeyAlgo !== $symKeyAlgo) {
                throw new Exception(
                    'Algorithm mismatch between input key and key in message. ' .
                    'Key was: ' . var_export($inputKeyAlgo, true) . '; message was: ' .
                    var_export($symKeyAlgo, true)
                );
            }
            $symmetricKey = $inputKey;
        }

        $algorithm = $symmetricKey->getAlgorithm();
        if (in_array($algorithm, $blacklist, true)) {
            throw new Exception('Algorithm disabled: ' . var_export($algorithm, true));
        }

        /**
         * @var string $decrypted
         * @psalm-suppress UndefinedClass
         */
        $decrypted = $enc->decryptNode($symmetricKey, false);

        /*
         * This is a workaround for the case where only a subset of the XML
         * tree was serialized for encryption. In that case, we may miss the
         * namespaces needed to parse the XML.
         */
        $xml = '<root xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" ' .
                        'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">' .
            $decrypted . '</root>';

        try {
            $newDoc = DOMDocumentFactory::fromString($xml);
        } catch (RuntimeException $e) {
            throw new Exception('Failed to parse decrypted XML. Maybe the wrong sharedkey was used?', 0, $e);
        }

        /** @psalm-suppress PossiblyNullPropertyFetch */
        $decryptedElement = $newDoc->firstChild->firstChild;
        if (!($decryptedElement instanceof DOMElement)) {
            throw new Exception('Missing decrypted element or it was not actually a DOMElement.');
        }

        return $decryptedElement;
    }


    /**
     * Decrypt an encrypted element.
     *
     * @param \DOMElement $encryptedData The encrypted data.
     * @param \SimpleSAML\XMLSecurity\XMLSecurityKey $inputKey The decryption key.
     * @param array $blacklist Blacklisted decryption algorithms.
     * @throws \Exception
     * @return \DOMElement The decrypted element.
     */
    public static function decryptElement(
        DOMElement $encryptedData,
        XMLSecurityKey $inputKey,
        array $blacklist = []
    ): DOMElement {
        try {
            return self::doDecryptElement($encryptedData, $inputKey, $blacklist);
        } catch (Exception $e) {
            /*
             * Something went wrong during decryption, but for security
             * reasons we cannot tell the user what failed.
             */
//            Utils::getContainer()->getLogger()->error('Decryption failed: ' . $e->getMessage());
            throw new Exception('Failed to decrypt XML element.', 0, $e);
        }
    }
}


1			<?php
2
3			declare(strict_types=1);
4
5			namespace SimpleSAML\XMLSecurity\Utils;
6
7			use DOMElement;
8			use Exception;
9			use RuntimeException;
10			use SimpleSAML\Assert\Assert;
11			use SimpleSAML\XML\DOMDocumentFactory;
12			use SimpleSAML\XMLSecurity\Constants;
13			use SimpleSAML\XMLSecurity\Exception\InvalidArgumentException;
14			use SimpleSAML\XMLSecurity\XMLSecEnc;
15			use SimpleSAML\XMLSecurity\XMLSecurityKey;
16
17			use function count;
18			use function hash_equals;
19			use function in_array;
20			use function openssl_pkey_get_details;
21			use function serialize;
22			use function sha1;
23			use function str_pad;
24			use function str_replace;
25			use function strlen;
26			use function strval;
27			use function substr;
28			use function trim;
29			use function var_export;
30
31			/**
32			* A collection of security-related functions.
33			*
34			* @package simplesamlphp/xml-security
35			*/
36			class Security
37			{
38			/**
39			* Compare two strings in constant time.
40			*
41			* This function allows us to compare two given strings without any timing side channels
42			* leaking information about them.
43			*
44			* @param string $known The reference string.
45			* @param string $user The user-provided string to test.
46			*
47			* @return bool True if both strings are equal, false otherwise.
48			*/
49			public static function compareStrings(string $known, string $user): bool
50			{
51			return hash_equals($known, $user);
52			}
53
54
55			/**
56			* Compute the hash for some data with a given algorithm.
57			*
58			* @param string $alg The identifier of the algorithm to use.
59			* @param string $data The data to digest.
60			* @param bool $encode Whether to bas64-encode the result or not. Defaults to true.
61			*
62			* @return string The (binary or base64-encoded) digest corresponding to the given data.
63			*
64			* @throws \SimpleSAML\XMLSecurity\Exception\InvalidArgumentException If $alg is not a valid
65			* identifier of a supported digest algorithm.
66			*/
67			public static function hash(string $alg, string $data, bool $encode = true): string
68			{
69			if (!array_key_exists($alg, Constants::$DIGEST_ALGORITHMS)) {
70			throw new InvalidArgumentException('Unsupported digest method "' . $alg . '"');
71			}
72
73			$digest = hash(Constants::$DIGEST_ALGORITHMS[$alg], $data, true);
74			if ($encode) {
75			$digest = base64_encode($digest);
76			}
77			return $digest;
78			}
79
80
81			/**
82			* Helper function to convert a XMLSecurityKey to the correct algorithm.
83			*
84			* @param \SimpleSAML\XMLSecurity\XMLSecurityKey $key The key.
85			* @param string $algorithm The desired algorithm.
86			* @param string $type Public or private key, defaults to public.
87			* @return \SimpleSAML\XMLSecurity\XMLSecurityKey The new key.
88			*
89			* @throws \SimpleSAML\Assert\AssertionFailedException if assertions are false
90			*/
91			public static function castKey(XMLSecurityKey $key, string $algorithm, string $type = null): XMLSecurityKey
92			{
93			$type = $type ?: 'public';
94			Assert::oneOf($type, ["private", "public"]);
95
96			// do nothing if algorithm is already the type of the key
97			if ($key->type === $algorithm) {
98			return $key;
99			}
100
101			if (
102			!in_array(
103			$algorithm,
104			[
105			XMLSecurityKey::RSA_1_5,
106			XMLSecurityKey::RSA_SHA1,
107			XMLSecurityKey::RSA_SHA256,
108			XMLSecurityKey::RSA_SHA384,
109			XMLSecurityKey::RSA_SHA512
110			],
111			true
112			)
113			) {
114			throw new Exception('Unsupported signing algorithm.');
115			}
116
117			/** @psalm-suppress PossiblyNullArgument */
118			$keyInfo = openssl_pkey_get_details($key->key);
119			if ($keyInfo === false) {
120			throw new Exception('Unable to get key details from XMLSecurityKey.');
121			}
122			if (!isset($keyInfo['key'])) {
123			throw new Exception('Missing key in public key details.');
124			}
125
126			$newKey = new XMLSecurityKey($algorithm, ['type' => $type]);
127			$newKey->loadKey($keyInfo['key']);
128
129			return $newKey;
130			}
131
132
133			/**
134			* Decrypt an encrypted element.
135			*
136			* This is an internal helper function.
137			*
138			* @param \DOMElement $encryptedData The encrypted data.
139			* @param \SimpleSAML\XMLSecurity\XMLSecurityKey $inputKey The decryption key.
140			* @param array &$blacklist Blacklisted decryption algorithms.
141			* @throws \Exception
142			* @return \DOMElement The decrypted element.
143			*/
144			private static function doDecryptElement(
145			DOMElement $encryptedData,
146			XMLSecurityKey $inputKey,
147			array &$blacklist
148			): DOMElement {
149			$enc = new XMLSecEnc();
150
151			$enc->setNode($encryptedData);
152			$enc->type = $encryptedData->getAttribute("Type");
153
154			$symmetricKey = $enc->locateKey($encryptedData);
155			if (!$symmetricKey) {
156			throw new Exception('Could not locate key algorithm in encrypted data.');
157			}
158
159			$symmetricKeyInfo = $enc->locateKeyInfo($symmetricKey);
160			if (!$symmetricKeyInfo) {
161			throw new Exception('Could not locate <dsig:KeyInfo> for the encrypted key.');
162			}
163
164			$inputKeyAlgo = $inputKey->getAlgorithm();
165			if ($symmetricKeyInfo->isEncrypted) {
166			$symKeyInfoAlgo = $symmetricKeyInfo->getAlgorithm();
167
168			if (in_array($symKeyInfoAlgo, $blacklist, true)) {
169			throw new Exception('Algorithm disabled: ' . var_export($symKeyInfoAlgo, true));
170			}
171
172			if ($symKeyInfoAlgo === XMLSecurityKey::RSA_OAEP_MGF1P && $inputKeyAlgo === XMLSecurityKey::RSA_1_5) {
173			/*
174			* The RSA key formats are equal, so loading an RSA_1_5 key
175			* into an RSA_OAEP_MGF1P key can be done without problems.
176			* We therefore pretend that the input key is an
177			* RSA_OAEP_MGF1P key.
178			*/
179			$inputKeyAlgo = XMLSecurityKey::RSA_OAEP_MGF1P;
180			}
181
182			/* Make sure that the input key format is the same as the one used to encrypt the key. */
183			if ($inputKeyAlgo !== $symKeyInfoAlgo) {
184			throw new Exception(
185			'Algorithm mismatch between input key and key used to encrypt ' .
186			' the symmetric key for the message. Key was: ' .
187			var_export($inputKeyAlgo, true) . '; message was: ' .
188			var_export($symKeyInfoAlgo, true)
189			);
190			}
191
192			/** @var XMLSecEnc $encKey */
193			$encKey = $symmetricKeyInfo->encryptedCtx;
194			$symmetricKeyInfo->key = $inputKey->key;
195
196			$keySize = $symmetricKey->getSymmetricKeySize();
197			if ($keySize === null) {
198			/* To protect against "key oracle" attacks, we need to be able to create a
199			* symmetric key, and for that we need to know the key size.
200			*/
201			throw new Exception(
202			'Unknown key size for encryption algorithm: ' . var_export($symmetricKey->type, true)
203			);
204			}
205
206			try {
207			/**
208			* @var string $key
209			* @psalm-suppress UndefinedClass
210			*/
211			$key = $encKey->decryptKey($symmetricKeyInfo);
212			if (strlen($key) !== $keySize) {
213			throw new Exception(
214			'Unexpected key size (' . strval(strlen($key) * 8) . 'bits) for encryption algorithm: ' .
215			var_export($symmetricKey->type, true)
216			);
217			}
218			} catch (Exception $e) {
219			/* We failed to decrypt this key. Log it, and substitute a "random" key. */
220			// Utils::getContainer()->getLogger()->error('Failed to decrypt symmetric key: ' . $e->getMessage());
221			/* Create a replacement key, so that it looks like we fail in the same way as if the key was correctly
222			* padded. */
223
224			/* We base the symmetric key on the encrypted key and private key, so that we always behave the
225			* same way for a given input key.
226			*/
227			$encryptedKey = $encKey->getCipherValue();
228			if ($encryptedKey === null) {
229			throw new Exception('No CipherValue available in the encrypted element.');
230			}
231
232			/** @psalm-suppress PossiblyNullArgument */
233			$pkey = openssl_pkey_get_details($symmetricKeyInfo->key);
234			$pkey = sha1(serialize($pkey), true);
235			$key = sha1($encryptedKey . $pkey, true);
236
237			/* Make sure that the key has the correct length. */
238			if (strlen($key) > $keySize) {
239			$key = substr($key, 0, $keySize);
240			} elseif (strlen($key) < $keySize) {
241			$key = str_pad($key, $keySize);
242			}
243			}
244			$symmetricKey->loadkey($key);
245			} else {
246			$symKeyAlgo = $symmetricKey->getAlgorithm();
247			/* Make sure that the input key has the correct format. */
248			if ($inputKeyAlgo !== $symKeyAlgo) {
249			throw new Exception(
250			'Algorithm mismatch between input key and key in message. ' .
251			'Key was: ' . var_export($inputKeyAlgo, true) . '; message was: ' .
252			var_export($symKeyAlgo, true)
253			);
254			}
255			$symmetricKey = $inputKey;
256			}
257
258			$algorithm = $symmetricKey->getAlgorithm();
259			if (in_array($algorithm, $blacklist, true)) {
260			throw new Exception('Algorithm disabled: ' . var_export($algorithm, true));
261			}
262
263			/**
264			* @var string $decrypted
265			* @psalm-suppress UndefinedClass
266			*/
267			$decrypted = $enc->decryptNode($symmetricKey, false);
268
269			/*
270			* This is a workaround for the case where only a subset of the XML
271			* tree was serialized for encryption. In that case, we may miss the
272			* namespaces needed to parse the XML.
273			*/
274			$xml = '<root xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" ' .
275			'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">' .
276			$decrypted . '</root>';
277
278			try {
279			$newDoc = DOMDocumentFactory::fromString($xml);
280			} catch (RuntimeException $e) {
281			throw new Exception('Failed to parse decrypted XML. Maybe the wrong sharedkey was used?', 0, $e);
282			}
283
284			/** @psalm-suppress PossiblyNullPropertyFetch */
285			$decryptedElement = $newDoc->firstChild->firstChild;
286			if (!($decryptedElement instanceof DOMElement)) {
287			throw new Exception('Missing decrypted element or it was not actually a DOMElement.');
288			}
289
290			return $decryptedElement;
291			}
292
293
294			/**
295			* Decrypt an encrypted element.
296			*
297			* @param \DOMElement $encryptedData The encrypted data.
298			* @param \SimpleSAML\XMLSecurity\XMLSecurityKey $inputKey The decryption key.
299			* @param array $blacklist Blacklisted decryption algorithms.
300			* @throws \Exception
301			* @return \DOMElement The decrypted element.
302			*/
303			public static function decryptElement(
304			DOMElement $encryptedData,
305			XMLSecurityKey $inputKey,
306			array $blacklist = []
307			): DOMElement {
308			try {
309			return self::doDecryptElement($encryptedData, $inputKey, $blacklist);
310			} catch (Exception $e) {
311			/*
312			* Something went wrong during decryption, but for security
313			* reasons we cannot tell the user what failed.
314			*/
315			// Utils::getContainer()->getLogger()->error('Decryption failed: ' . $e->getMessage());
316			throw new Exception('Failed to decrypt XML element.', 0, $e);
317			}
318			}
319			}
320

simplesamlphp / xml-security

Push — master ( 82e8be...64e54a )

Security::decryptElement() A

Complexity

Size

Duplication

Importance

Duplication Side-by-Side

Filter issues like