NEWS.md
In openfhe.R: R Interface to the 'OpenFHE' Fully Homomorphic Encryption Library

openfhe.R 1.6.1

The vendored library is OpenFHE 1.6.1. Every class, method and enum that the Python package openfhe 1.6.1.0 exposes has an R counterpart. Its tests and examples are run as tests of this package, except one example that needs a 128-bit build of the library.
Contexts, keys and ciphertexts saved by openfhe.R 1.5.1.2, in the binary or the JSON format, are read by this version.
BinFHEParamSet has the 112 members of OpenFHE 1.6.1. Every member except TOY and MEDIUM has a new integer value, so code must refer to members by name (BinFHEParamSet$STD128), never by number.
OpenFHE 1.6.1 redefines the predefined Binary FHE parameter sets under their old names. BinFHEParamSet$STD128_AP now works only with BinFHEMethod$AP.
bin_fhe_context() builds the context for arbitrary-function evaluation whenever arb_func, log_q, n or time_optimization is supplied, as the C++ library does. Before, supplying arb_func = FALSE alone built the Boolean-gate context, which has different parameters.
serialize_eval_keys() to a file that cannot be opened is an error. Before, the JSON format returned TRUE and wrote nothing.
find_automorphism_index() and find_automorphism_indices() refuse a value outside the 32-bit integer range.
length() of the object share_keys() returns is the number of shares.
Functions that return an encrypted value, a key or another handle no longer go through the 'S7' constructor, which saves about 45 microseconds per call.
bin_bt_key_gen() gains the argument internal32.
The help pages for bin_fhe_context(), bin_bt_key_gen() and bin_clear_bt_keys() have a section on memory. The bootstrapping keys of a context can occupy several gigabytes that R's garbage collector does not see; bin_clear_bt_keys() releases them at once.
bin_encrypt() defaults to output = BinFHEOutput$BOOTSTRAPPED, and get_bootstrap_depth() to SecretKeyDist$UNIFORM_TERNARY, as in OpenFHE 1.6.1.
eval_add(), eval_sub() and eval_mult(), with their _in_place and _mutable forms, accept every operand order and type the C++ library declares: a plaintext or a number as the first operand, and complex numbers for a CKKS context with complex data. eval_sub(2, ct) now calls the library's own scalar-first subtraction.
eval_poly(), eval_chebyshev() and their _linear and _ps forms accept integer and complex coefficient vectors as well as doubles. An integer vector is now evaluated with integer arithmetic; it was converted to double before. At OpenFHE 1.6.1 the Paterson-Stockmeyer Chebyshev evaluator returns wrong values for integer coefficients, so pass whole-number Chebyshev coefficients as doubles.
eval_bin_gate() gains extended. eval_floor() and compress() take the library defaults roundbits = 0 and towers_left = 1. level_reduce() and level_reduce_in_place() accept NULL for the evaluation key. get_bootstrap_depth() gains approx_mod_depth. multiparty_key_gen() accepts a list of secret keys. get_length() works on an LWECiphertext.
New set_* functions change one parameter of a BFVParams, BGVParams or CKKSParams object after it has been constructed (set_multiplicative_depth(), set_ring_dim() and 30 others; see ?ccparams_setters), so a parameter object can be built step by step as the OpenFHE examples do. format() and print() of a parameter object show every field.
New gen_crypto_context() builds a context from a parameter object and enables no feature, as OpenFHE's GenCryptoContext() does. fhe_context() is unchanged.
make_ckks_packed_plaintext() accepts params with complex values.
New evaluation functions: eval_add_many(), eval_add_many_in_place(), eval_mult_many(), eval_merge(), eval_linear_wsum(), eval_linear_wsum_mutable(), eval_inner_product(), eval_sum_rows(), eval_sum_cols() with eval_sum_rows_key_gen() and eval_sum_cols_key_gen(), eval_at_index(), composed_eval_mult() and eval_mult_keys_gen().
New in-place forms eval_square_in_place(), rescale_in_place(), relinearize_in_place(), eval_add_mutable_in_place(), eval_sub_mutable_in_place() and eval_mult_mutable_in_place(), and the unchecked forms eval_add_in_place_no_check(), eval_mult_no_check() and eval_mult_no_relin_no_check().
Proxy re-encryption: re_key_gen() and re_encrypt().
make_string_plaintext() encodes a character string.
New accessors. On a context: get_modulus(), get_modulus_ckks(), get_root_of_unity(), get_scheme(), set_scheme_id(), serialized_object_name(), serialized_version(), clear_all_ckks_caches(), clear_bootstrap_precom(), clear_scheme_switch_precom(), get_plaintext_for_decrypt(), the automorphism key index queries get_existing_eval_automorphism_key_indices(), get_eval_automorphism_no_key_indices() and get_unique_values(), and set_multiplicative_depth(), set_eval_add_count(), set_key_switch_count(), set_pre_num_hops() and set_noise_estimate() on a live context. On a ciphertext: clone(), clone_empty(), number_ciphertext_elements(), get_elements(), set_elements(), remove_element(), get_hop_level(), set_hop_level() and set_encoding_type(). On a plaintext: encode(), decode(), get_element_modulus(), get_encoding_params() and set_format().
get_modulus(), ring_dimension() and get_cyclotomic_order() work on an ElementParams object; get_batch_size(), get_plaintext_modulus() and the new get_plaintext_generator() on an EncodingParams object; get_key_tag() and set_key_tag() on an EvalKey; get_crypto_context() on a public or secret key.
New classes DCRTPoly and SchemeBase (opaque handles) and enum Format.
Key switching: key_switch_gen(), key_switch(), key_switch_in_place(), key_switch_ext() and key_switch_down_first_element(). multi_mult_eval_key() completes the threshold multiplication-key protocol. sparse_key_gen() is bound as the C++ library declares it.
clear_eval_sum_keys(), get_all_contexts(), and enable_precompute_crt_tables_after_deserializaton() with its disable_ counterpart.
eval_chebyshev_function_ptxt() evaluates a Chebyshev approximation in the clear, and get_multiplicative_depth_by_coeff_vector() gives the depth a polynomial evaluation consumes.
eval_powers() and eval_cheby_polys() compute the powers, or the Chebyshev polynomials, of a ciphertext once, as an object of the new class SeriesPowers; eval_poly_with_precomp() and eval_chebyshev_series_with_precomp() then evaluate any number of series of the same degree from it.
eval_bootstrap_precompute() computes the plaintexts of CKKS bootstrapping after a setup with precompute = FALSE, and eval_bootstrap_stc_first() runs the slots-encoding variant of bootstrapping.
CKKS functional bootstrapping, which refreshes a ciphertext and applies a function to it in one step. For a look-up table on integers: eval_fbt_setup(), eval_fbt(), eval_fbt_no_decoding() and eval_hom_decoding(); for several tables on one input, eval_mvb_precompute(), eval_mvb() and eval_mvb_no_decoding(); with get_hermite_trig_coefficients(), get_fbt_depth() and eval_hermite_trig_series(). For a Fourier series on real values: eval_fe_func_bootstrap_setup(), eval_fe_func_bootstrap(), eval_fe_func_bootstrap_precompute(), eval_fe_func_bootstrap_with_precomp() and get_fefbt_depth().
The RLWE schemelet that functional bootstrapping takes its input from: schemelet_get_element_params(), schemelet_encrypt_coeff(), schemelet_decrypt_coeff(), schemelet_mod_switch(), schemelet_convert_rlwe_to_ckks(), schemelet_convert_ckks_to_rlwe() and schemelet_get_q_prime(), with the new class PolyVector (length(), clone(), -, switch_modulus()).
Scheme switching between CKKS and FHEW. From CKKS to FHEW: eval_ckks_to_fhew_setup(), eval_ckks_to_fhew_key_gen(), eval_ckks_to_fhew_precompute() and eval_ckks_to_fhew(). From FHEW to CKKS: eval_fhew_to_ckks_setup(), eval_fhew_to_ckks_key_gen() and eval_fhew_to_ckks(). Both ways: eval_scheme_switching_setup(), eval_scheme_switching_key_gen(), eval_compare_switch_precompute(), eval_compare_scheme_switching(), eval_min_scheme_switching(), eval_max_scheme_switching() and their _alt forms. The parameters are an object of the new class SchSwchParams, with a set_ and a get_ function per field (see ?SchSwchParams). Also get_bin_cc_for_scheme_switch(), set_bin_cc_for_scheme_switch(), get_swk_fc(), set_swk_fc() and set_params_from_ckks_cryptocontext().
New classes SchemeSwitchingDataSerializer and SchemeSwitchingDataDeserializer write and read everything a scheme-switching computation needs in another session, with set_data_directory(), serialize_scheme_switching_data(), deserialize_scheme_switching_data() and get_raw_ciphertext(). Unlike the C++ classes they have no default directory.
Binary FHE, public-key encryption: bin_key_gen_pair(), bin_pub_key_gen(), bin_key_gen_n(), bin_key_switch_gen() and switch_ct_to_qn(), with the new classes LWEPublicKey, LWEKeyPair and LWESwitchingKey. bin_encrypt() accepts an LWEPublicKey in place of the secret key.
Binary FHE, bootstrapping keys as objects: get_bt_key(), get_bt_key_map(), bin_bt_key_load(), bin_bt_key_map_load_single_element(), bin_clear_bt_keys(), get_switch_key(), get_public_key(), has_internal32_refresh_key() and has_internal32_switch_key(), with the new class RingGSWBTKey.
fhe_serialize() and fhe_deserialize() handle the Binary FHE classes BinFHEContext, LWECiphertext, LWEPrivateKey, LWEPublicKey and RingGSWBTKey, so a Boolean circuit can be set up in one session and evaluated in another.
Binary FHE, other additions: bin_bootstrap(), eval_constant(), eval_decomp(); the parameter accessors get_n(), get_big_n(), get_q(), get_big_q() and get_beta(); get_pt_modulus(), set_modulus() and set_pt_modulus() on an LWECiphertext; get_modulus() and get_length() on LWE ciphertexts and keys, which also compare with == and !=; serialized_object_name() and serialized_version() on a BinFHEContext.
Serialization in memory. fhe_serialize() with no file name returns the serialized object, a raw vector for the binary format and a character string for JSON, and the new fhe_deserialize_string() reads it back. serialize_eval_keys() with no file name does the same for the key registries, with the new deserialize_eval_keys_string().
fhe_serialize() and fhe_deserialize() handle EvalKey and EvalKeyMap objects, and fhe_serialize() a list of EvalKey objects (in memory).
serialize_eval_keys() gains cc, to serialize the keys of one context.
New serialize_eval_bootstrap_key() and deserialize_eval_bootstrap_key() write and read the automorphism keys that CKKS bootstrapping uses.
Integers that can exceed 53 bits are exchanged as strings of decimal digits, because an R number cannot hold them exactly. get_scaling_factor_int() now returns such a string, and set_scaling_factor_int() accepts one. Arguments of this kind also accept a whole number of at most 2^53.
The plaintext_modulus argument of BFVParams() and BGVParams() accepts any 64-bit value; values above 2^31 were previously turned into NA. get_plaintext_modulus() returns a string of decimal digits when the modulus is above 2^53.

openfhe.R 1.5.1.2

Under R CMD check the package caps OpenFHE at two threads.
set_num_threads() now sets the cap through OpenFHE's own thread controls rather than the OpenMP runtime, and returns the cap in effect (invisibly).
The package now installs on musl-based Linux (Alpine).
rlang is declared in Imports.
Every handle the package passes between R and C++ now carries its type, and every binding checks that type before using the pointer.
bin_fhe_context() returns an object of the new BinFHEContext class instead of the base OpenFHEObject. The boolean-circuit context and the CryptoContext used by BFV, BGV, and CKKS are therefore distinct classes, and passing one where the other belongs is an error rather than a silent misuse.
OpenFHEObject, the base class, is now abstract. It was never useful to construct directly, and every handle now belongs to a concrete class.
decrypt() accepts its arguments in either order, matching the C++ library, which declares both. decrypt(private_key, ciphertext) is now equivalent to decrypt(ciphertext, private_key).

openfhe.R 1.5.1.1

Fixed undefined behavior in the vendored OpenFHE library reported by CRAN's UBSAN check platforms. RingGSWAccumulator::SignedDigitDecompose sign-extended a balanced digit by shifting a signed value into and past the sign bit, which is undefined in C++17. The vendored library now carries the upstream fix (OpenFHE PR #1238), which computes the same digits without signed shifts. Results are unchanged.
The eval_sign() example in the BinFHE vignette and its corresponding test are skipped on CRAN, where their bootstrapping-key generation dominated the check time. Both still run on CI and locally.

openfhe.R 1.5.1

Initial release. An R interface to the OpenFHE C++ library for fully homomorphic encryption, with a binding surface that mirrors openfhe-python.

Supports the BFV, BGV, and CKKS schemes for computation on encrypted integers and approximate reals, plus BinFHE (FHEW/TFHE) for Boolean circuits over encrypted bits.
Provides threshold (multiparty) FHE, including interactive bootstrapping, for computations shared across several key-holders.
Built on S7 classes and cpp11 bindings; the OpenFHE C++ library is vendored and built from source, so the package version tracks the library version.
Ships an API tour vignette plus worked examples of CKKS bootstrapping and BinFHE Boolean circuits.