- Integrate another note

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@124639 c90b9560-bf6c-de11-be94-00142212c4b1

reference/mcrypt/functions/mcrypt-generic.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.4 $ -->
+<!-- $Revision: 1.5 $ -->
 <!-- splitted from ./en/functions/mcrypt.xml, last change in rev 1.7 -->
   <refentry id="function.mcrypt-generic">
    <refnamediv>
@@ -20,6 +20,24 @@
      of the returned string can in fact be longer then the input,
      due to the padding of the data.
     </para>
+    <para>
+     If you want to store the encrypted data in a database make sure to store
+     the entire string as returned by mcrypt_generic, or the string will not
+     entirely decrypt properly.  If your original string is 10 characters long
+     and the block size is 8 (use
+     <function>mcrypt_enc_get_block_size</function> to determine the
+     blocksize), you would need at least 16 characters in your database field.
+     Note the string returned by <function>mdecrypt_generic</function> will be
+     16 characters as well...use <function>rtrim</function>($str, "\0") to
+     remove the padding.
+    </para>
+    <para>
+     If you are for example storing the data in a MySQL database remember tha
+     varchar fields automatically have trailing spaces removed during
+     insertion. As encrypted data can end in a space (ASCII 32), the data will
+     be damaged by this removal.  Store data in a tinyblob/tinytext (or
+     larger) field instead.
+    </para>
     <para>
      The encryption handle should always be initialized with
      <function>mcrypt_generic_init</function> with a key and an IV before