> For the complete documentation index, see [llms.txt](https://docs.zama.org/tfhe-rs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zama.org/tfhe-rs/tfhe-rs/0.6-3/guides/c_api.md). # High-level API in C This document describes the C bindings to the **TFHE-rs** high-level primitives for creating Fully Homomorphic Encryption (FHE) programs. ## Setting up TFHE-rs C API for C programming. You can build **TFHE-rs** C API on a Unix x86\_64 machine using the following command: ```shell RUSTFLAGS="-C target-cpu=native" cargo +nightly build --release --features=x86_64-unix,high-level-c-api -p tfhe && make symlink_c_libs_without_fingerprint ``` For a Unix aarch64 machine, use the following command: ```shell RUSTFLAGS="-C target-cpu=native" cargo +nightly build --release --features=aarch64-unix,high-level-c-api -p tfhe && make symlink_c_libs_without_fingerprint ``` Locate files in the right path: * In `${REPO\_ROOT}/target/release/`, you can find: * The `tfhe.h` header * The static (.a) and dynamic (.so) `libtfhe` binaries * In `${REPO\_ROOT}/target/release/deps/`, you can find: * The `tfhe-c-api-dynamic-buffer.h` header * The static (.a) and dynamic (.so) libraries Ensure your build system configures the C or C++ program links against **TFHE-rs** C API binaries and the dynamic buffer library. The following is a minimal `CMakeLists.txt` configuration example: ```cmake project(my-project) cmake_minimum_required(VERSION 3.16) set(TFHE_C_API "/path/to/tfhe-rs/target/release") include_directories(${TFHE_C_API}) include_directories(${TFHE_C_API}/deps) add_library(tfhe STATIC IMPORTED) set_target_properties(tfhe PROPERTIES IMPORTED_LOCATION ${TFHE_C_API}/libtfhe.a) add_library(tfheDynamicBuffer STATIC IMPORTED) set_target_properties(tfheDynamicBuffer PROPERTIES IMPORTED_LOCATION ${TFHE_C_API}/deps/libtfhe_c_api_dynamic_buffer.a) if(APPLE) find_library(SECURITY_FRAMEWORK Security) if (NOT SECURITY_FRAMEWORK) message(FATAL_ERROR "Security framework not found") endif() endif() set(EXECUTABLE_NAME my-executable) add_executable(${EXECUTABLE_NAME} main.c) target_include_directories(${EXECUTABLE_NAME} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}) target_link_libraries(${EXECUTABLE_NAME} LINK_PUBLIC tfhe tfheDynamicBuffer m pthread dl) if(APPLE) target_link_libraries(${EXECUTABLE_NAME} LINK_PUBLIC ${SECURITY_FRAMEWORK}) endif() target_compile_options(${EXECUTABLE_NAME} PRIVATE -Werror) ``` ## Commented code of a uint128 subtraction using `TFHE-rs C API`. The following example demonstrates uint128 subtraction using the **TFHE-rs** C API: {% hint style="warning" %} **WARNING**: this example omits proper memory management in the error case to improve code readability. {% endhint %} Ensure the above `CMakeLists.txt` and `main.c` files are in the same directory. Use the following commands to execute the example: ```shell # /!\ Be sure to update CMakeLists.txt to give the absolute path to the compiled tfhe library $ ls CMakeLists.txt main.c $ mkdir build && cd build $ cmake .. -DCMAKE_BUILD_TYPE=RELEASE ... $ make ... $ ./my-executable FHE computation successful! $ ``` ```c #include #include #include int main(void) { int ok = 0; // Prepare the config builder for the high level API and choose which types to enable ConfigBuilder *builder; Config *config; // Put the builder in a default state without any types enabled config_builder_default(&builder); // Use the small LWE key for encryption config_builder_default_with_small_encryption(&builder); // Populate the config config_builder_build(builder, &config); ClientKey *client_key = NULL; ServerKey *server_key = NULL; // Generate the keys using the config generate_keys(config, &client_key, &server_key); // Set the server key for the current thread set_server_key(server_key); FheUint128 *lhs = NULL; FheUint128 *rhs = NULL; FheUint128 *result = NULL; // A 128-bit unsigned integer containing value: 20 << 64 | 10 U128 clear_lhs = { .w0 = 10, .w1 = 20 }; // A 128-bit unsigned integer containing value: 2 << 64 | 1 U128 clear_rhs = { .w0 = 1, .w1 = 2 }; ok = fhe_uint128_try_encrypt_with_client_key_u128(clear_lhs, client_key, &lhs); assert(ok == 0); ok = fhe_uint128_try_encrypt_with_client_key_u128(clear_rhs, client_key, &rhs); assert(ok == 0); // Compute the subtraction ok = fhe_uint128_sub(lhs, rhs, &result); assert(ok == 0); U128 clear_result; // Decrypt ok = fhe_uint128_decrypt(result, client_key, &clear_result); assert(ok == 0); // Here the subtraction allows us to compare each word assert(clear_result.w0 == 9); assert(clear_result.w1 == 18); // Destroy the ciphertexts fhe_uint128_destroy(lhs); fhe_uint128_destroy(rhs); fhe_uint128_destroy(result); // Destroy the keys client_key_destroy(client_key); server_key_destroy(server_key); printf("FHE computation successful!\n"); return EXIT_SUCCESS; } ``` --- # Agent Instructions This documentation is published with GitBook. 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