Просто попробуйте в оболочке:
>>> h = hashlib.new('ripemd161')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.7/hashlib.py", line 124, in __hash_new
return __get_builtin_constructor(name)(string)
File "/usr/lib/python2.7/hashlib.py", line 91, in __get_builtin_constructor
raise ValueError('unsupported hash type %s' % name)
ValueError: unsupported hash type ripemd161