Generate a signature for a request

gen-sig.py

def do_signature(self, secret_key):

    keys = sorted(self.params.keys())
    args = '&'.join('%s=%s' % (key, quote(unicode(self.params[key]).encode('utf-8'),safe='~')) for key in keys)

    msg = 'GET'
    msg += '\necs.amazonaws.com'
    msg += '\n/onca/xml'
    msg += '\n' + args

    signature = base64.encodestring(hmac.new(self.secret_key, msg, hashlib.sha256).digest())

    url = 'http://%s/onca/xml?%s&Signature=%s' % ('ecs.amazonaws.com', args, signature.replace('/','%2F').replace('+','%2B').replace('=','%3D'))
    return url