return ErrSignatureDoesNotMatch
	}
	return ErrNone
}

func calculateSignatureV2(stringToSign string, secret string) string {
	hm := hmac.New(sha1.New, []byte(secret))
	hm.Write([]byte(stringToSign))
	return base64.StdEncoding.EncodeToString(hm.Sum(nil))
}

// Return signature-v2 for the presigned request.

      return empty;
    }
    try {
      return fromEntryArrayCheckingBucketOverflow(n, entryArray, throwIfDuplicateKeys);
    } catch (BucketOverflowException e) {
      // probable hash flooding attack, fall back to j.u.HM based implementation and use its
      // implementation of hash flooding protection
      return JdkBackedImmutableMap.create(n, entryArray, throwIfDuplicateKeys);
    }
  }

	stringToSign := getStringToSignV2(req.Method, encodedResource, strings.Join(unescapedQueries, "&"), req.Header, expiresStr)
	hm := hmac.New(sha1.New, []byte(secretAccessKey))
	hm.Write([]byte(stringToSign))

	// Calculate signature.
	signature := base64.StdEncoding.EncodeToString(hm.Sum(nil))

	query := req.URL.Query()
	// Handle specially for Google Cloud Storage.
	query.Set("AWSAccessKeyId", accessKeyID)