# tff.federated_secure_sum_bitwidth

<br />

|---|
| [![](https://www.tensorflow.org/images/GitHub-Mark-32px.png) View source on GitHub](https://github.com/tensorflow/federated/blob/v0.87.0 Version 2.0, January 2004 Licensed under the Apache License, Version 2.0 (the) |

Computes a sum at [`tff.SERVER`](https://www.tensorflow.org/federated/api_docs/python/tff#SERVER) of a `value` placed on the [`tff.CLIENTS`](https://www.tensorflow.org/federated/api_docs/python/tff#CLIENTS).

    tff.federated_secure_sum_bitwidth(
        value, bitwidth
    )

This function computes a sum such that it should not be possible for the
server to learn any clients individual value. The specific algorithm and
mechanism used to compute the secure sum may vary depending on the target
runtime environment the computation is compiled for or executed on. See
<https://research.google/pubs/pub47246/> for more information.

Not all executors support [`tff.federated_secure_sum_bitwidth()`](https://www.tensorflow.org/federated/api_docs/python/tff/federated_secure_sum_bitwidth); consult the
documentation for the specific executor or executor stack you plan on using
for the specific of how it's handled by that executor.

The `bitwidth` argument represents the bitwidth of the aggregand, that is the
bitwidth of the input `value`. The federated secure sum bitwidth (i.e., the
bitwidth of the *sum* of the input `value`s over all clients) will be a
function of this bitwidth and the number of participating clients.

#### Example:

    value = tff.federated_value(1, tff.CLIENTS)
    result = tff.federated_secure_sum_bitwidth(value, 2)

    value = tff.federated_value([1, 1], tff.CLIENTS)
    result = tff.federated_secure_sum_bitwidth(value, [2, 4])

    value = tff.federated_value([1, [1, 1]], tff.CLIENTS)
    result = tff.federated_secure_sum_bitwidth(value, [2, [4, 8]])

> [!NOTE]
> **Note:** To sum non-integer values or to sum integers with fewer constraints and weaker privacy properties, consider using `federated_sum`.

<br />

<br />

<br />

| ## Args ||
|---|---|
| `value` | An integer value of a TFF federated type placed at the [`tff.CLIENTS`](https://www.tensorflow.org/federated/api_docs/python/tff#CLIENTS), in the range \[0, 2\^bitwidth - 1\]. |
| `bitwidth` | An integer or nested structure of integers matching the structure of `value`. If integer `bitwidth` is used with a nested `value`, the same integer is used for each tensor in `value`. |

<br />

<br />

<br />

<br />

| ## Returns ||
|---|---|
| A representation of the sum of the member constituents of `value` placed on the [`tff.SERVER`](https://www.tensorflow.org/federated/api_docs/python/tff#SERVER). ||

<br />

<br />

<br />

<br />

| ## Raises ||
|---|---|
| `TypeError` | If the argument is not a federated TFF value placed at [`tff.CLIENTS`](https://www.tensorflow.org/federated/api_docs/python/tff#CLIENTS). |

<br />