}

	// Anonymous request return early.
	if accessKey == "" || secretKey == "" {
		return req, nil
	}

	if signer == signerV2 {
		err = signRequestV2(req, accessKey, secretKey)
		req.Header.Del("x-amz-content-sha256")
	} else {
		req.Header.Set("x-amz-content-sha256", "92b165232fbd011da355eca0b033db22b934ba9af0145a437a832d27310b89f9")
		err = signRequestV4(req, accessKey, secretKey)
	}