get_bt_key: The bootstrapping keys of a BinFHE context
In openfhe.R: R Interface to the 'OpenFHE' Fully Homomorphic Encryption Library

get_bt_key

R Documentation

The bootstrapping keys of a BinFHE context

Description

get_bt_key() returns the keys bin_bt_key_gen() generated, as one RingGSWBTKey; bin_bt_key_load() puts such an object into a context, and bin_clear_bt_keys() removes the keys of a context. Together with fhe_serialize() and fhe_deserialize() they move bootstrapping keys between sessions.

Usage

get_bt_key(ctx)

get_bt_key_map(ctx)

bin_bt_key_load(ctx, key, internal32 = TRUE)

bin_bt_key_map_load_single_element(ctx, base_g, key)

bin_clear_bt_keys(ctx)

get_switch_key(ctx)

has_internal32_refresh_key(ctx)

has_internal32_switch_key(ctx)

Arguments

`ctx`	A `BinFHEContext`.
`key`	A RingGSWBTKey.
`internal32`	Logical; if `TRUE` (default) keys whose moduli fit are converted to the 32-bit internal form on loading.
`base_g`	Integer; the gadget base the key is for.

Details

A context for large-precision evaluation keeps one key per gadget base. get_bt_key_map() returns them, and bin_bt_key_map_load_single_element() loads one.

get_switch_key() returns the switching key among the bootstrapping keys, and get_public_key() the public key.

has_internal32_refresh_key() and has_internal32_switch_key() say whether the refreshing and the switching key are held in the library's 32-bit internal form.

Value

get_bt_key(): a RingGSWBTKey. get_bt_key_map(): a list of them, named by gadget base. get_switch_key(): an LWESwitchingKey, or NULL if the context holds none in the 64-bit form. The has_ functions: a logical. The others: ctx, invisibly.

Memory

The bootstrapping keys of a context can occupy several gigabytes (about 5.8 GB for STD128 with arb_func = TRUE and log_q = 12). R's garbage collector does not see this memory, so removing a context with rm() does not release it until a collection happens to run.

Build one context and reuse it. The keys depend only on the parameters and the secret key.
When a context is no longer needed, call bin_clear_bt_keys(). The keys are released at once.
To release the rest of the context, remove it and call gc().