'Decrypts a response body.
:param resp: application response
:param body_key: decryption key for the response body
:param crypto_meta: crypto_meta for the response body
:param offset: offset into object content at which response body starts
:return: generator for decrypted response body'

def response_iter(self, resp, body_key, crypto_meta, offset):

    decrypt_ctxt = self.crypto.create_decryption_ctxt(body_key, crypto_meta['iv'], offset)
    with closing_if_possible(resp):
        for chunk in resp:
            (yield decrypt_ctxt.update(chunk))
