class Aws::Sigv4::Signer

def signature(secret_access_key, date, string_to_sign) 

def signature(secret_access_key, date, string_to_sign)
  k_date = hmac("AWS4" + secret_access_key, date)
  k_region = hmac(k_date, @region)
  k_service = hmac(k_region, @service)
  k_credentials = hmac(k_service, 'aws4_request')
  hexhmac(k_credentials, string_to_sign)
end