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[5.5] Add GCM support to encrypter #21963

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[5.5] Add GCM support to encrypter #21963

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95f2ce5
Add GCM support to encrypter
bukka Nov 5, 2017
14424a9
Improve listing of available ciphers and skip GCM test for 7.0
bukka Nov 5, 2017
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185 changes: 157 additions & 28 deletions src/Illuminate/Encryption/Encrypter.php
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,18 @@

class Encrypter implements EncrypterContract
{
/**
* The supported cipher algorithms and their settings.
*
* @var array
*/
private static $supportedCiphers = [
'aes-128-cbc' => ['size' => 16, 'aead' => false],
'aes-256-cbc' => ['size' => 32, 'aead' => false],
'aes-128-gcm' => ['size' => 16, 'aead' => true, 'since' => '7.1.0'],
'aes-256-gcm' => ['size' => 32, 'aead' => true, 'since' => '7.1.0'],
];

/**
* The encryption key.
*
Expand All @@ -23,6 +35,13 @@ class Encrypter implements EncrypterContract
*/
protected $cipher;

/**
* Whether the cipher is AEAD cipher.
*
* @var bool
*/
protected $aead;

/**
* Create a new encrypter instance.
*
Expand All @@ -35,12 +54,15 @@ class Encrypter implements EncrypterContract
public function __construct($key, $cipher = 'AES-128-CBC')
{
$key = (string) $key;
$cipher = strtolower($cipher);

if (static::supported($key, $cipher)) {
$this->key = $key;
$this->cipher = $cipher;
$this->aead = self::$supportedCiphers[$this->cipher]['aead'];
} else {
throw new RuntimeException('The only supported ciphers are AES-128-CBC and AES-256-CBC with the correct key lengths.');
$ciphers = implode(', ', $this->getAvailableCiphers());
throw new RuntimeException("The only supported ciphers are $ciphers with the correct key lengths.");
}
}

Expand All @@ -53,10 +75,18 @@ public function __construct($key, $cipher = 'AES-128-CBC')
*/
public static function supported($key, $cipher)
{
$length = mb_strlen($key, '8bit');
if (! isset(self::$supportedCiphers[$cipher])) {
return false;
}

$cipherSetting = self::$supportedCiphers[$cipher];
if (isset($cipherSetting['since']) &&
version_compare(PHP_VERSION, $cipherSetting['since'], '<')
) {
return false;
}

return ($cipher === 'AES-128-CBC' && $length === 16) ||
($cipher === 'AES-256-CBC' && $length === 32);
return mb_strlen($key, '8bit') === $cipherSetting['size'];
}

/**
Expand All @@ -67,7 +97,7 @@ public static function supported($key, $cipher)
*/
public static function generateKey($cipher)
{
return random_bytes($cipher == 'AES-128-CBC' ? 16 : 32);
return random_bytes(self::$supportedCiphers[$cipher]['size'] ?? 32);
}

/**
Expand All @@ -83,13 +113,56 @@ public function encrypt($value, $serialize = true)
{
$iv = random_bytes(openssl_cipher_iv_length($this->cipher));

if ($serialize) {
$value = serialize($value);
}
$json = json_encode(
$this->aead ? $this->encryptAead($value, $iv) : $this->encryptMac($value, $iv)
);

if (json_last_error() !== JSON_ERROR_NONE) {
throw new EncryptException('Could not encrypt the data.');
}

return base64_encode($json);
}

/**
* Encrypt value using AEAD cipher.
*
* @param string $value
* @param string $iv
* @return array
*/
protected function encryptAead($value, $iv)
{
// We will encrypt AEAD ciphers which will give us authentication tag.
$value = openssl_encrypt($value, $this->cipher, $this->key, 0, $iv, $tag);

if ($value === false) {
throw new EncryptException('Could not encrypt the data.');
}

return [
'iv' => base64_encode($iv),
'value' => $value,
'tag' => base64_encode($tag),
];
}

/**
* Encrypt value using non AEAD cipher and MAC.
*
* @param string $value
* @param string $iv
* @return array
*/
protected function encryptMac($value, $iv)
{
// First we will encrypt the value using OpenSSL. After this is encrypted we
// will proceed to calculating a MAC for the encrypted value so that this
// value can be verified later as not having been changed by the users.
$value = \openssl_encrypt(
$serialize ? serialize($value) : $value,
$this->cipher, $this->key, 0, $iv
);
$value = openssl_encrypt($value, $this->cipher, $this->key, 0, $iv);

if ($value === false) {
throw new EncryptException('Could not encrypt the data.');
Expand All @@ -100,13 +173,7 @@ public function encrypt($value, $serialize = true)
// its authenticity. Then, we'll JSON the data into the "payload" array.
$mac = $this->hash($iv = base64_encode($iv), $value);

$json = json_encode(compact('iv', 'value', 'mac'));

if (json_last_error() !== JSON_ERROR_NONE) {
throw new EncryptException('Could not encrypt the data.');
}

return base64_encode($json);
return compact('iv', 'value', 'mac');
}

/**
Expand Down Expand Up @@ -134,19 +201,62 @@ public function decrypt($payload, $unserialize = true)
$payload = $this->getJsonPayload($payload);

$iv = base64_decode($payload['iv']);
$decrypted = $this->aead
? $this->decryptAead($payload, $iv)
: $this->decryptMac($payload, $iv);

return $unserialize ? unserialize($decrypted) : $decrypted;
}

/**
* Decrypt value using AEAD cipher.
*
* @param array $payload
* @param string $iv
* @return string
*/
protected function decryptAead($payload, $iv)
{
// Here we will decrypt the value. If we are able to successfully decrypt it
// we will then unserialize it and return it out to the caller. If we are
// unable to decrypt this value we will throw out an exception message.
$decrypted = \openssl_decrypt(
// we will return it. If we are nable to decrypt this value, it means that the tag
// is invalid and we will throw out an exception message.
$decrypted = openssl_decrypt(
$payload['value'], $this->cipher, $this->key, 0, $iv, base64_decode($payload['tag'])
);

if ($decrypted === false) {
throw new DecryptException('The authentication tag is invalid.');
}

return $decrypted;
}

/**
* Decrypt value using non AEAD cipher and MAC.
*
* @param array $payload
* @param string $iv
* @return string
*/
protected function decryptMac($payload, $iv)
{
// First we will check if the MAC is valid
if (! $this->validMac($payload)) {
throw new DecryptException('The MAC is invalid.');
}

// Here we will decrypt the value. If we are able to successfully decrypt it
// we will return it. If we are unable to decrypt this value we will throw out
// an exception message (this should however never happen for AES CBC mode).
$decrypted = openssl_decrypt(
$payload['value'], $this->cipher, $this->key, 0, $iv
);

if ($decrypted === false) {
throw new DecryptException('Could not decrypt the data.');
}

return $unserialize ? unserialize($decrypted) : $decrypted;
return $decrypted;
}

/**
Expand Down Expand Up @@ -186,15 +296,11 @@ protected function getJsonPayload($payload)

// If the payload is not valid JSON or does not have the proper keys set we will
// assume it is invalid and bail out of the routine since we will not be able
// to decrypt the given value. We'll also check the MAC for this encryption.
// to decrypt the given value.
if (! $this->validPayload($payload)) {
throw new DecryptException('The payload is invalid.');
}

if (! $this->validMac($payload)) {
throw new DecryptException('The MAC is invalid.');
}

return $payload;
}

Expand All @@ -206,9 +312,13 @@ protected function getJsonPayload($payload)
*/
protected function validPayload($payload)
{
return is_array($payload) && isset(
$payload['iv'], $payload['value'], $payload['mac']
);
if (! is_array($payload)) {
return false;
}

return $this->aead
? isset($payload['iv'], $payload['value'], $payload['tag'])
: isset($payload['iv'], $payload['value'], $payload['mac']);
}

/**
Expand Down Expand Up @@ -240,6 +350,25 @@ protected function calculateMac($payload, $bytes)
);
}

/**
* Get available ciphers.
*
* @return array
*/
private function getAvailableCiphers()
{
$availableCiphers = [];
foreach (self::$supportedCiphers as $cipherName => $setting) {
if (! isset($setting['since']) ||
version_compare(PHP_VERSION, $setting['since'], '>=')
) {
$availableCiphers[] = strtoupper($cipherName);
}
}

return $availableCiphers;
}

/**
* Get the encryption key.
*
Expand Down
28 changes: 24 additions & 4 deletions tests/Encryption/EncrypterTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -44,9 +44,19 @@ public function testWithCustomCipher()
$this->assertEquals('foo', $e->decrypt($encrypted));
}

public function testAeadCipher()
{
$this->onlyForAead();
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Just use the @requires PHP 7.1 annotation.

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And drop the extra method. :)


$e = new Encrypter(str_repeat('b', 32), 'AES-256-GCM');
$encrypted = $e->encrypt('bar');
$this->assertNotEquals('bar', $encrypted);
$this->assertEquals('bar', $e->decrypt($encrypted));
}

/**
* @expectedException \RuntimeException
* @expectedExceptionMessage The only supported ciphers are AES-128-CBC and AES-256-CBC with the correct key lengths.
* @expectedExceptionMessageRegExp /The only supported ciphers are (AES-\d{3}-[A-Z]{3}(, )?)+ with the correct key lengths./
*/
public function testDoNoAllowLongerKey()
{
Expand All @@ -55,7 +65,7 @@ public function testDoNoAllowLongerKey()

/**
* @expectedException \RuntimeException
* @expectedExceptionMessage The only supported ciphers are AES-128-CBC and AES-256-CBC with the correct key lengths.
* @expectedExceptionMessageRegExp /The only supported ciphers are (AES-\d{3}-[A-Z]{3}(, )?)+ with the correct key lengths./
*/
public function testWithBadKeyLength()
{
Expand All @@ -64,7 +74,7 @@ public function testWithBadKeyLength()

/**
* @expectedException \RuntimeException
* @expectedExceptionMessage The only supported ciphers are AES-128-CBC and AES-256-CBC with the correct key lengths.
* @expectedExceptionMessageRegExp /The only supported ciphers are (AES-\d{3}-[A-Z]{3}(, )?)+ with the correct key lengths./
*/
public function testWithBadKeyLengthAlternativeCipher()
{
Expand All @@ -73,7 +83,7 @@ public function testWithBadKeyLengthAlternativeCipher()

/**
* @expectedException \RuntimeException
* @expectedExceptionMessage The only supported ciphers are AES-128-CBC and AES-256-CBC with the correct key lengths.
* @expectedExceptionMessageRegExp /The only supported ciphers are (AES-\d{3}-[A-Z]{3}(, )?)+ with the correct key lengths./
*/
public function testWithUnsupportedCipher()
{
Expand Down Expand Up @@ -102,4 +112,14 @@ public function testExceptionThrownWithDifferentKey()
$b = new Encrypter(str_repeat('b', 16));
$b->decrypt($a->encrypt('baz'));
}

/**
* Run test only for AEAD.
*/
private function onlyForAead()
{
if (version_compare(PHP_VERSION, '7.1', '<')) {
$this->markTestSkipped('The AEAD is not supported in PHP 7.0');
}
}
}