Computes a modular sum at tff.SERVER of a value from tff.CLIENTS.

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 for more information.

Not all executors support tff.federated_secure_modular_sum(); 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 modulus argument is the modulus under which the client values are added. The result of this function will be equivalent to SUM(value) % modulus. Lower values may allow for improved communication efficiency.


value = tff.federated_value(5, tff.CLIENTS)
result = tff.federated_secure_modular_sum(value, 3)
# `result == (5 * num_clients % 3)@SERVER`

value = tff.federated_value((3, 9), tff.CLIENTS)
result = tff.federated_secure_modular_sum(value, (100, 200))
# `result == (3 * num_clients % 100, 9 * num_clients % 100)@SERVER`

value An integer or nested structure of integers placed at tff.CLIENTS. Values outside of the range [0, modulus-1] will be considered equivalent to mod(value, modulus), i.e. they will be projected into the range [0, modulus-1] as part of the modular summation.
modulus A Python integer or nested structure of integers matching the structure of value. If integer modulus is used with a nested value, the same integer is used for each tensor in value.

A representation of the modular sum of the member constituents of value placed on the tff.SERVER. The resulting modular sum will be on the range [0, modulus-1].

TypeError If the argument is not a federated TFF value placed at tff.CLIENTS.