_m@sddlZddlZddlZddlZejddkZerbddlmZeZ n e Ze Z ej ej fZddZeedeZdS)N)izipcCs}t|t|k}|r-d}|}n d}|}x7tt|t|D]\}}|||AO}qUW|dkS)aReturn ``True`` if the two strings are equal, ``False`` otherwise. The time taken is independent of the number of characters that match. Do not use this function for anything else than comparision with known length targets. This is should be implemented in C in order to get it completely right. This is an alias of :func:`hmac.compare_digest` on Python>=2.7,3.3. r)lenr bytearray)Zval1Zval2Zlen_eqresultleftxyr s