move more common elements to StreamCipher class

phpseclib/Crypt/Common/StreamCipher.php

@@ -24,6 +24,28 @@ namespace phpseclib3\Crypt\Common;
  */
 abstract class StreamCipher extends SymmetricKey
 {
+    /**
+     * Block Length of the cipher
+     *
+     * Stream ciphers do not have a block size
+     *
+     * @see \phpseclib3\Crypt\Common\SymmetricKey::block_size
+     * @var int
+     * @access private
+     */
+    protected $block_size = 0;
+
+    /**
+     * Default Constructor.
+     *
+     * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct()
+     * @return \phpseclib3\Crypt\Common\StreamCipher
+     */
+    public function __construct()
+    {
+        parent::__construct('stream');
+    }
+
     /**
      * Stream ciphers not use an IV
      *

phpseclib/Crypt/RC4.php

@@ -63,18 +63,6 @@ class RC4 extends StreamCipher
     const DECRYPT = 1;
     /**#@-*/
 
-    /**
-     * Block Length of the cipher
-     *
-     * RC4 is a stream cipher
-     * so we the block_size to 0
-     *
-     * @see \phpseclib3\Crypt\Common\SymmetricKey::block_size
-     * @var int
-     * @access private
-     */
-    protected $block_size = 0;
-
     /**
      * Key Length (in bytes)
      *
@@ -111,18 +99,6 @@ class RC4 extends StreamCipher
      */
     private $stream;
 
-    /**
-     * Default Constructor.
-     *
-     * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct()
-     * @return \phpseclib3\Crypt\RC4
-     * @access public
-     */
-    public function __construct()
-    {
-        parent::__construct('stream');
-    }
-
     /**
      * Test for engine validity
      *

phpseclib/Crypt/Salsa20.php

@@ -50,16 +50,6 @@ class Salsa20 extends StreamCipher
      */
     protected $key_length = 32; // = 256 bits
 
-    /**
-     * Block Length of the cipher
-     *
-     * Salsa20 is a stream cipher
-     * so we the block_size to 0
-     *
-     * @var int
-     */
-    protected $block_size = 0;
-
     /**#@+
      * @access private
      * @see \phpseclib3\Crypt\Salsa20::crypt()
@@ -96,17 +86,6 @@ class Salsa20 extends StreamCipher
      */
     protected $usingGeneratedPoly1305Key = false;
 
-    /**
-     * Default Constructor.
-     *
-     * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct()
-     * @return \phpseclib3\Crypt\Salsa20
-     */
-    public function __construct()
-    {
-        parent::__construct('stream');
-    }
-
     /**
      * Salsa20 uses a nonce
      *