Merge pull request #127 from technion/cryptsecure

Cryptsecure

Author: xqus

lib/phpSec/Crypt/Crypto.php

@@ -77,19 +77,24 @@ public function encrypt($data, $key) {
         return false;
       }
     } else {
-      /* No spsecific size is needed. */
+      /* No specific size is needed. */
       if($keySize == 0 || $keySize > mcrypt_enc_get_key_size($td)) {
         throw new \phpSec\Exception\InvalidKeySpecException('Key is out of range. Should be between  1 and ' . mcrypt_enc_get_key_size($td).' bytes.');
         return false;
       }
     }
 
+    /* Using PBKDF with constant salts dedicated to each purpose 
+     * can securely derivce two keys from one */
+    $key1 = $this->pbkdf2($key, "encrypt", 1, $keySize);
+    $key2 = $this->pbkdf2($key, "HMAC", 1, $keySize);
+
     /* Create IV. */
     $rnd = $this->psl['crypt/rand'];
     $iv = $rnd->bytes(mcrypt_enc_get_iv_size($td));
 
     /* Init mcrypt. */
-    mcrypt_generic_init($td, $key, $iv);
+    mcrypt_generic_init($td, $key1, $iv);
 
     /* Prepeare the array with data. */
     $serializedData = serialize($data);
@@ -111,7 +116,7 @@ public function encrypt($data, $key) {
     $encrypted['iv']    = base64_encode($iv);                                  /* Initialization vector, just a bunch of randomness. */
     $encrypted['cdata'] = base64_encode(mcrypt_generic($td, $serializedData)); /* The encrypted data. */
     $encrypted['mac']   = base64_encode(                                       /* The message authentication code. Used to make sure the */
-                            $this->pbkdf2($encrypted['cdata'], $key, 1000, 32)  /* message is valid when decrypted. */
+                            $this->pbkdf2($encrypted['cdata'], $key2, 1, 32)  /* message is valid when decrypted. */
                           );
     return json_encode($encrypted);
   }
@@ -148,14 +153,20 @@ public function decrypt($data, $key) {
     $td = mcrypt_module_open($data['algo'], '', $data['mode'], '');
     $block = mcrypt_enc_get_block_size($td);
 
+    /* Using PBKDF with constant salts dedicated to each purpose 
+     * can securely derivce two keys from one */
+    $keySize = strlen($key);
+    $key1 = $this->pbkdf2($key, "encrypt", 1, $keySize);
+    $key2 = $this->pbkdf2($key, "HMAC", 1, $keySize);
+
     /* Check MAC. */
-    if(base64_decode($data['mac']) != $this->pbkdf2($data['cdata'], $key, 1000, 32)) {
+    if(base64_decode($data['mac']) != $this->pbkdf2($data['cdata'], $key2, 1, 32)) {
       throw new \phpSec\Exception\GeneralSecurityException('Message authentication code invalid');
       return false;
     }
 
     /* Init mcrypt. */
-    mcrypt_generic_init($td, $key, base64_decode($data['iv']));
+    mcrypt_generic_init($td, $key1, base64_decode($data['iv']));
 
     $decrypted = rtrim(mdecrypt_generic($td, base64_decode($this->stripPadding($block, $data['cdata']))));
 

tests/phpSec/Crypt/CryptoTest.php

@@ -7,12 +7,19 @@ public function testCrypto() {
 
     $str = 'foobaz';
     $key = '123abc12123abc12';
+    $badkey = '123abcR77123abc12';
+
 
     $encrypted = $crypto->encrypt($str, $key);
 
     $decrypted = $crypto->decrypt($encrypted, $key);
 
     $this->assertEquals($decrypted, $str);
+    try {
+        $ret = $crypto->decrypt($encrypted, $badkey);
+    }catch(Exception $e){
+       $this->assertEquals("Message authentication code invalid",$e->getMessage());
+    }
 
   }
-}
+}