(dev/core#2258) PhpseclibCipherSuite - Add default crypto provider

diff --git a/Civi/Core/Container.php b/Civi/Core/Container.php
index 404405adadb94f489dbc2d6df85646bcc3224c17..6c8ac4ffbc25c772036fee9105170a12c5a736d3 100644 (file)
--- a/Civi/Core/Container.php
+++ b/Civi/Core/Container.php
@@ -511,6 +511,7 @@ class Container {
    */
   public static function createCryptoRegistry() {
     $crypto = new \Civi\Crypto\CryptoRegistry();
+    $crypto->addCipherSuite(new \Civi\Crypto\PhpseclibCipherSuite());
 
     $crypto->addPlainText(['tags' => ['CRED']]);
     if (defined('CIVICRM_CRED_KEYS')) {

diff --git a/Civi/Crypto/PhpseclibCipherSuite.php b/Civi/Crypto/PhpseclibCipherSuite.php
new file mode 100644 (file)
index 0000000..6168330
--- /dev/null
+++ b/Civi/Crypto/PhpseclibCipherSuite.php
@@ -0,0 +1,213 @@
+<?php
+
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+namespace Civi\Crypto;
+
+use Civi\Crypto\Exception\CryptoException;
+
+/**
+ * This is an implementation of CipherSuiteInterface based on phpseclib 1.x/2.x.
+ *
+ * It supports multiple ciphers:
+ *
+ * - aes-cbc: AES-256 w/CBC, no authentication
+ * - aes-ctr: AES-256 w/CTR, no authentication
+ * - aes-cbc-hs: AES-256 w/CBC, HMAC-SHA256 authentication. Enc+auth use derived keys.
+ * - aes-ctr-hs: AES-256 w/CTR, HMAC-SHA256 authentication. Enc+auth use derived keys.
+ *
+ * @package CRM
+ * @copyright CiviCRM LLC https://civicrm.org/licensing
+ */
+class PhpseclibCipherSuite implements CipherSuiteInterface {
+
+  /**
+   * List of phpseclib "Cipher" objects. These are template objects
+   * which may be cloned for use with specific keys.
+   *
+   * @var array|null
+   */
+  protected $ciphers = NULL;
+
+  public function __construct() {
+    $this->ciphers = [];
+    if (class_exists('\phpseclib\Crypt\AES')) {
+      // phpseclib v2
+      $this->ciphers['aes-cbc'] = new \phpseclib\Crypt\AES(\phpseclib\Crypt\AES::MODE_CBC);
+      $this->ciphers['aes-cbc']->setKeyLength(256);
+      $this->ciphers['aes-ctr'] = new \phpseclib\Crypt\AES(\phpseclib\Crypt\AES::MODE_CTR);
+      $this->ciphers['aes-ctr']->setKeyLength(256);
+    }
+    elseif (class_exists('Crypt_AES')) {
+      // phpseclib v1
+      $this->ciphers['aes-cbc'] = new \Crypt_AES(\Crypt_AES::MODE_CBC);
+      $this->ciphers['aes-cbc']->setKeyLength(256);
+      $this->ciphers['aes-ctr'] = new \Crypt_AES(\Crypt_AES::MODE_CTR);
+      $this->ciphers['aes-ctr']->setKeyLength(256);
+    }
+    else {
+      throw new CryptoException("Failed to find phpseclib");
+    }
+  }
+
+  /**
+   * @inheritdoc
+   */
+  public function getSuites(): array {
+    return ['aes-cbc', 'aes-ctr', 'aes-cbc-hs', 'aes-ctr-hs'];
+  }
+
+  /**
+   * @inheritdoc
+   */
+  public function encrypt(string $plainText, array $key): string {
+    switch ($key['suite']) {
+      case 'aes-cbc-hs':
+      case 'aes-ctr-hs':
+        return $this->encryptThenSign($plainText, substr($key['suite'], 0, -3), 'sha256', $key['key']);
+
+      case 'aes-cbc':
+      case 'aes-ctr':
+        return $this->encryptOnly($plainText, $key['suite'], $key['key']);
+    }
+  }
+
+  /**
+   * @inheritdoc
+   */
+  public function decrypt(string $cipherText, array $key): string {
+    switch ($key['suite']) {
+      case 'aes-cbc-hs':
+      case 'aes-ctr-hs':
+        return $this->authenticateThenDecrypt($cipherText, substr($key['suite'], 0, -3), 'sha256', $key['key']);
+
+      case 'aes-cbc':
+      case 'aes-ctr':
+        return $this->decryptOnly($cipherText, $key['suite'], $key['key']);
+    }
+  }
+
+  /**
+   * Given an master key, derive a pair of encryption+authentication keys.
+   *
+   * @param string $masterKey
+   * @return array
+   */
+  protected function createEncAuthKeys($masterKey) {
+    return [
+      hash_hmac('sha256', 'enc', $masterKey, TRUE),
+      hash_hmac('sha256', 'auth', $masterKey, TRUE),
+    ];
+  }
+
+  protected function encryptOnly($plainText, $suite, $key) {
+    $cipher = $this->createCipher($suite, $key);
+    $blockBytes = $cipher->getBlockLength() >> 3;
+    $iv = random_bytes($blockBytes);
+    $cipher->setIV($iv);
+    return $iv . $cipher->encrypt($plainText);
+  }
+
+  protected function decryptOnly(string $cipherText, $suite, $key) {
+    $cipher = $this->createCipher($suite, $key);
+    $blockBytes = $cipher->getBlockLength() >> 3;
+    $iv = substr($cipherText, 0, $blockBytes);
+    $cipher->setIV($iv);
+    return $cipher->decrypt(substr($cipherText, $blockBytes));
+  }
+
+  /**
+   * @param string $plainText
+   * @param string $suite
+   *   The encryption algorithms
+   *   Ex: aes-cbc, aes-ctr
+   * @param string $digest
+   *   The authentication algorithm
+   *   Ex: sha256
+   * @param string $masterKey
+   *   Binary representation of the key
+   *
+   * @return string
+   *   The concatenation of IV, ciphertext, signature
+   */
+  protected function encryptThenSign($plainText, $suite, $digest, $masterKey) {
+    list ($encKey, $authKey) = $this->createEncAuthKeys($masterKey);
+    $cipher = $this->createCipher($suite, $encKey);
+    $blockBytes = $cipher->getBlockLength() >> 3;
+    $iv = random_bytes($blockBytes);
+    $cipher->setIV($iv);
+    $ivText = $iv . $cipher->encrypt($plainText);
+    $sig = hash_hmac($digest, $ivText, $authKey, TRUE);
+    $this->assertLen($this->getDigestBytes($digest), $sig);
+    return $ivText . $sig;
+  }
+
+  /**
+   * @param string $cipherText
+   *   Combined ciphertext (IV + encrypted text + signature)
+   * @param string $suite
+   *   The encryption algorithms
+   *   Ex: aes-cbc, aes-ctr
+   * @param string $digest
+   *   The authentication algorithm
+   *   Ex: sha256
+   * @param string $masterKey
+   *   Binary representation of the key
+   *
+   * @return string
+   *   Decrypted text
+   * @throws CryptoException
+   *   Throws an exception if authentication fails.
+   */
+  protected function authenticateThenDecrypt($cipherText, $suite, $digest, $masterKey) {
+    list ($encKey, $authKey) = $this->createEncAuthKeys($masterKey);
+    $cipher = $this->createCipher($suite, $encKey);
+    $blockBytes = $cipher->getBlockLength() >> 3;
+    $digestBytes = $this->getDigestBytes($digest);
+    $sigExpect = substr($cipherText, -1 * $digestBytes);
+    $sigActual = hash_hmac($digest, substr($cipherText, 0, -1 * $digestBytes), $authKey, TRUE);
+    if (!hash_equals($sigActual, $sigExpect)) {
+      throw new CryptoException("Failed to decrypt token. Invalid digest.");
+    }
+    $cipher->setIV(substr($cipherText, 0, $blockBytes));
+    return $cipher->decrypt(substr($cipherText, $blockBytes, -1 * $digestBytes));
+  }
+
+  /**
+   * @param $suite
+   * @param $key
+   * @return \phpseclib\Crypt\Base|\Crypt_Base
+   */
+  protected function createCipher($suite, $key) {
+    if (!isset($this->ciphers[$suite])) {
+      throw new \RuntimeException("Cipher suite does not support " . $suite);
+    }
+
+    $cipher = clone $this->ciphers[$suite];
+    $this->assertLen($cipher->getKeyLength() >> 3, $key);
+    $cipher->setKey($key);
+    return $cipher;
+  }
+
+  protected function getDigestBytes($digest) {
+    if ($digest === 'sha256') {
+      return 32;
+    }
+    throw new \RuntimeException('Unrecognized digest');
+  }
+
+  private function assertLen($bytes, $value) {
+    if ($bytes != strlen($value)) {
+      throw new \InvalidArgumentException("Malformed AES key");
+    }
+  }
+
+}