wolfSSL · LinuxJedi · Jul 17, 2026
diff --git a/.gitignore b/.gitignore
@@ -494,8 +494,9 @@ wrapper/Ada/obj/
 wolfssl/debug-trace-error-codes.h
 wolfssl/debug-untrace-error-codes.h
 
-AGENTS.md
-CLAUDE.md
+# Local (untracked) agent instruction files
+AGENTS.local.md
+CLAUDE.local.md
 
 # Code navigation files
 compile_commands.json

diff --git a/AGENTS.md b/AGENTS.md
@@ -0,0 +1,238 @@
+# wolfSSL Integration Guide for Agents
+
+wolfSSL is a lightweight ANSI C (C90) TLS/DTLS library (up to TLS 1.3 and DTLS 1.3)
+built on the wolfCrypt cryptography engine. It targets everything from bare-metal
+microcontrollers and RTOSes to desktop/server systems. Dual licensed: GPLv3
+(GPLv2 may be elected only for specific exception projects) or a commercial
+license from wolfSSL Inc. (see `LICENSING`).
+
+This file is for agents helping users *integrate wolfSSL into their own projects*.
+If `AGENTS.local.md` or `CLAUDE.local.md` exists in the repository root, read
+it before starting work. Those files are gitignored, carry maintainer- and
+machine-specific instructions, and take precedence over this file.
+
+## Choose an integration path
+
+| Situation | Path |
+|---|---|
+| Unix-like host or cross-compile with a toolchain | Autotools (canonical, most tested) |
+| CMake-based project (find_package, add_subdirectory, FetchContent) | CMake |
+| IDE, RTOS, or bare-metal build with no configure step | `user_settings.h` + `-DWOLFSSL_USER_SETTINGS` |
+| Zephyr | `zephyr/` (module.yml, Kconfig) |
+| ESP-IDF | `IDE/Espressif/ESP-IDF/` (also published as a managed component) |
+| Arduino / PlatformIO | `IDE/ARDUINO/`, `IDE/PlatformIO/` |
+| Visual Studio | `wolfssl64.sln`, `wolfssl-VS2022.vcxproj`, `IDE/WIN*/` |
+| Linux/BSD kernel module | `linuxkm/`, `bsdkm/` |
+| Python / Rust / C# / Ada bindings | `wrapper/` |
+| Other IDEs/platforms (Keil, IAR, STM32Cube, Renesas, Xcode, QNX, ...) | `IDE/` (~60 subdirectories, each with a README) |
+
+## The one rule that prevents most integration bugs
+
+The application must be compiled with the **same feature defines** as the library.
+Feature macros change struct layouts and API availability; a mismatch compiles fine
+and corrupts memory at runtime.
+
+- Autotools/CMake builds generate `wolfssl/options.h` recording every define.
+  Include `<wolfssl/options.h>` before any other wolfSSL header, or build the app
+  with `-DWOLFSSL_USE_OPTIONS_H` so headers pull it in automatically.
+- `user_settings.h` builds: define `WOLFSSL_USER_SETTINGS` for **both** the library
+  and the application, and keep one shared `user_settings.h` on the include path.
+- Never commit a generated `wolfssl/options.h` (it is per-configure output).
+
+## Autotools build (primary)
+
+```sh
+./autogen.sh          # git checkouts only; needs autoconf/automake/libtool.
+                      # Release tarballs from wolfssl.com ship a prebuilt configure.
+./configure [options]
+make -j
+make check            # optional but recommended
+sudo make install     # installs lib, headers, wolfssl.pc, cmake package files
+```
+
+- `./configure --help` lists all options (~374 `--enable-*`, ~29 `--with-*`).
+  `configure.ac` is the source of truth for what each option defines.
+- Extra defines: `./configure CFLAGS="-DWOLFSSL_DTLS_NO_HVR_ON_RESUME"` or
+  `EXTRA_CFLAGS`. (`C_EXTRA_FLAGS` is deprecated but still works.)
+- Cross-compile with the usual `--host=<triple>` plus `CC=...`.
+- Consumption after install: `pkg-config --cflags --libs wolfssl`, or CMake
+  `find_package(wolfssl)` (autotools installs the CMake package files too;
+  disable with `--disable-cmake-install`).
+
+### Commonly used configure options
+
+Defaults already on: TLS 1.2/1.3, ECC, RSA, AES(+GCM), SHA-2, ChaCha20-Poly1305,
+Curve25519/Ed25519, hardening (`--enable-harden`: timing resistance + blinding),
+SP math. Most work is *adding* protocols/features or *shrinking* the build.
+
+| Group | Options |
+|---|---|
+| Bundles | `--enable-all`, `--enable-all-crypto`, `--enable-distro`, `--enable-cryptonly` (wolfCrypt only, no TLS) |
+| Small builds | `--enable-leanpsk`, `--enable-leantls`, `--enable-lowresource`, `--enable-tinytls13`, `--enable-smallstack`, `--enable-staticmemory`, `--disable-errorstrings` |
+| Protocols | `--enable-dtls`, `--enable-dtls13`, `--enable-quic`, `--enable-sctp`, `--enable-srtp`, `--enable-oldtls` (TLS 1.0/1.1), `--disable-tls13` |
+| TLS features | `--enable-sni`, `--enable-alpn`, `--enable-session-ticket`, `--enable-earlydata`, `--enable-secure-renegotiation`, `--enable-maxfragment`, `--enable-ocsp`, `--enable-ocspstapling`, `--enable-crl`, `--enable-hrrcookie` |
+| Extra crypto | `--enable-aesccm`, `--enable-aesctr`, `--enable-aesxts`, `--enable-curve448`, `--enable-ed448`, `--enable-sha3`, `--enable-rsapss`, `--enable-cmac`, `--enable-sm2 --enable-sm3 --enable-sm4-gcm` (ShangMi) |
+| Post-quantum | `--enable-mlkem` (alias `--enable-kyber`), `--enable-mldsa` (alias `--enable-dilithium`), `--enable-falcon`, `--enable-lms`, `--enable-xmss` |
+| Performance | `--enable-sp --enable-sp-asm` (default on x86_64/aarch64), `--enable-aesni`, `--enable-intelasm`, `--enable-armasm`, `--enable-riscv-asm`, `--enable-fastmath` |
+| OpenSSL compat | `--enable-opensslextra` (common subset), `--enable-opensslall` (maximum), `--enable-opensslcoexist` (link both libraries) |
+| App recipes | `--enable-curl`, `--enable-nginx`, `--enable-openssh`, `--enable-openvpn`, `--enable-haproxy`, `--enable-stunnel`, `--enable-wpas`, ... (each sets exactly the flags that project needs) |
+| Platform | `--enable-singlethreaded`, `--disable-filesystem`, `--enable-usersettings` (read root `user_settings.h` instead of option defines) |
+| Hardware/secure elements | `--enable-pkcs11`, `--enable-psa`, `--with-cryptoauthlib`, `--with-se050`, `--enable-caam`, `--enable-devcrypto`, `--enable-kcapi`, ... |
+| Debug | `--enable-debug` (defines `DEBUG_WOLFSSL`, enables logging), `--enable-debug-trace-errcodes`, `--enable-valgrind` |
+| FIPS | `--enable-fips=<ver>` (v2, v5, v6, ready, dev, ...). Certified versions need a licensed FIPS source bundle from wolfSSL Inc.; `ready`/`dev` build with the free FIPS Ready bundle from wolfssl.com. None configure from a plain git tree |
+
+Option-to-macro mapping: nearly every `--enable-foo` maps 1:1 to a CMake
+`-DWOLFSSL_FOO=yes` and to one or more C macros usable in `user_settings.h`.
+To find the macro behind an option, grep `configure.ac` for the option name
+and look at the `AM_CFLAGS="$AM_CFLAGS -D..."` lines, or grep `cmake/options.h.in`.
+
+## CMake build
+
+```sh
+cmake -B build -DWOLFSSL_TLS13=yes -DWOLFSSL_DTLS=yes   # in-source builds are rejected
+cmake --build build
+ctest --test-dir build --output-on-failure
+cmake --install build
+```
+
+- Minimum CMake 3.16. Option rule: `--enable-foo` == `-DWOLFSSL_FOO=yes`,
+  `--disable-foo` == `-DWOLFSSL_FOO=no`. Plus standard `-DBUILD_SHARED_LIBS=ON/OFF`,
+  `-DCMAKE_BUILD_TYPE=Debug|Release`, `-DWOLFSSL_EXAMPLES=no`, `-DWOLFSSL_CRYPT_TESTS=no`.
+- CMake generates its own `<build>/wolfssl/options.h` (template: `cmake/options.h.in`).
+- Consume installed package: `find_package(wolfssl CONFIG REQUIRED)` and link
+  `wolfssl::wolfssl`. Working example: `cmake/consumer/`.
+- Embedding the source tree with `add_subdirectory()`/`FetchContent` also works;
+  link the `wolfssl` target.
+- `-DWOLFSSL_USER_SETTINGS=yes` drops all option defines in favor of your
+  `user_settings.h`.
+
+## user_settings.h build (IDE / RTOS / bare-metal)
+
+1. Pick a template from `examples/configs/` (26 of them, documented in its README):
+   - `user_settings_template.h` -- modular starting point
+   - `user_settings_all.h` (== `--enable-all`), `user_settings_tls12.h`,
+     `user_settings_tls13.h`, `user_settings_tinytls13.h`, `user_settings_dtls13.h`
+   - `user_settings_baremetal.h` (no filesystem, static memory),
+     `user_settings_min_ecc.h`, `user_settings_rsa_only.h`
+   - `user_settings_pq.h` (ML-KEM + ML-DSA), `user_settings_openssl_compat.h`
+   - platform ones: `user_settings_stm32.h`, `user_settings_espressif.h`,
+     `user_settings_arduino.h`, `user_settings_platformio.h`
+   - `user_settings_fipsv2.h`, `user_settings_fipsv5.h`
+2. Copy it into your project as `user_settings.h`, put its directory on the include
+   path, and add `-DWOLFSSL_USER_SETTINGS` to all compilations (library and app).
+3. Add sources to your build: `src/*.c` and `wolfcrypt/src/*.c`, **except** files
+   that are `#include`d into others rather than compiled standalone:
+   `src/ssl_*.c` (inlined into `src/ssl.c`), `wolfcrypt/src/evp.c` and
+   `wolfcrypt/src/misc.c` (inlined unless `NO_INLINE` is defined). Add files from
+   `wolfcrypt/src/port/<vendor>/` only for your hardware.
+4. Include `<wolfssl/wolfcrypt/settings.h>` (or any wolfSSL header, which pulls it
+   in) -- it reads `user_settings.h` first.
+
+Sanity-check a config against this repo: copy it to the repo root as
+`user_settings.h`, then `./configure --enable-usersettings --disable-examples && make`.
+
+`wolfssl/wolfcrypt/settings.h` is the platform switchboard: it reacts to target
+macros (`WOLFSSL_ESPIDF`, `FREERTOS`, `WOLFSSL_ZEPHYR`, `WOLFSSL_STM32F4`,
+`MICROCHIP_PIC32`, `THREADX`, `MICRIUM`, `WOLFSSL_VXWORKS`, `EBSNET`, ...) and sets
+up threading, memory, time, and filesystem primitives. Never edit `settings.h`;
+set the macros in `user_settings.h` or your build flags.
+
+## Where to look
+
+| Path | Contents |
+|---|---|
+| `wolfssl/ssl.h` | Main TLS/DTLS API (`wolfSSL_*`) |
+| `wolfssl/wolfcrypt/*.h` | Crypto APIs (`wc_*`): aes.h, ecc.h, rsa.h, sha256.h, random.h, ... |
+| `wolfssl/openssl/*.h` | OpenSSL compatibility headers (with `--enable-opensslextra`) |
+| `wolfssl/wolfio.h` | Transport I/O callback API |
+| `wolfssl/wolfcrypt/settings.h` | Platform/feature switchboard (read-only) |
+| `wolfssl/certs_test.h` | Test certs/keys as C arrays (for `NO_FILESYSTEM` demos only) |
+| `wolfssl/internal.h` | Internal -- do not use from applications |
+| `src/` | TLS implementation (ssl.c, tls13.c, dtls13.c, internal.c) |
+| `wolfcrypt/src/` | Crypto implementations |
+| `wolfcrypt/src/port/` | ~30 hardware/OS crypto ports: arm, intel, Espressif, Renesas, st, nxp, atmel, silabs, psa, kcapi, caam, liboqs, ... |
+| `examples/client/`, `examples/server/` | Full-featured reference apps; run with `-h` for all flags |
+| `examples/tls13/` | Minimal TLS 1.3 samples, incl. in-memory I/O (no sockets) |
+| `examples/configs/` | The `user_settings_*.h` templates |
+| `certs/` | Test certificates for examples/tests -- never use in production |
+| `IDE/` | Per-IDE/platform project files and READMEs |
+| `zephyr/`, `linuxkm/`, `bsdkm/`, `wrapper/` | Zephyr module, kernel modules, language bindings |
+| `INSTALL` | Platform-by-platform build notes (iOS, Windows, Yocto, MQX, ...) |
+| `doc/` | Pointers to the manual and Doxygen API docs |
+
+## Minimal TLS client flow
+
+```c
+#include <wolfssl/options.h>   /* or user_settings.h scheme; must be first */
+#include <wolfssl/ssl.h>
+
+wolfSSL_Init();
+WOLFSSL_CTX* ctx = wolfSSL_CTX_new(wolfTLSv1_3_client_method());
+wolfSSL_CTX_load_verify_locations(ctx, "ca-cert.pem", NULL);
+WOLFSSL* ssl = wolfSSL_new(ctx);
+wolfSSL_set_fd(ssl, sockfd);            /* connected TCP socket */
+wolfSSL_connect(ssl);                   /* handshake (server: wolfSSL_accept) */
+wolfSSL_write(ssl, msg, msgSz);
+wolfSSL_read(ssl, buf, sizeof(buf));
+wolfSSL_shutdown(ssl);
+wolfSSL_free(ssl); wolfSSL_CTX_free(ctx); wolfSSL_Cleanup();
+```
+
+With `NO_FILESYSTEM`, use the buffer variants: `wolfSSL_CTX_load_verify_buffer()`,
+`wolfSSL_CTX_use_certificate_buffer()`, `wolfSSL_CTX_use_PrivateKey_buffer()`.
+On error, get details with `wolfSSL_get_error(ssl, ret)` and
+`wolfSSL_ERR_error_string()`.
+
+## Porting hooks
+
+| Need | Hook | Where |
+|---|---|---|
+| Custom transport (no BSD sockets) | `wolfSSL_CTX_SetIORecv()` / `wolfSSL_CTX_SetIOSend()` + `wolfSSL_SetIOReadCtx()` / `wolfSSL_SetIOWriteCtx()` | `wolfssl/wolfio.h` |
+| Custom allocator | `XMALLOC_USER` (your xmalloc/xfree/xrealloc), or `wolfSSL_SetAllocators()`, or `WOLFSSL_STATIC_MEMORY` (no heap) | `wolfssl/wolfcrypt/types.h`, `memory.h` |
+| Entropy source | implement `wc_GenerateSeed()`, or define `CUSTOM_RAND_GENERATE_SEED` / `CUSTOM_RAND_GENERATE_BLOCK`, or `WC_RNG_SEED_CB` | `wolfssl/wolfcrypt/random.h`, `wolfcrypt/src/random.c` |
+| Time source | `XTIME`/`XGMTIME` overrides, `NO_ASN_TIME` (`wc_port.h`); `USER_TICKS` low-res timer (`settings.h`) | `wolfssl/wolfcrypt/wc_port.h` |
+| No RTOS / one thread | define `SINGLE_THREADED` (drops mutex deps) | `wolfssl/wolfcrypt/wc_port.h` |
+| No filesystem | define `NO_FILESYSTEM`, use `*_buffer()` APIs | `wolfssl/wolfcrypt/wc_port.h` |
+| Logging | build with `DEBUG_WOLFSSL` (`--enable-debug`), then `wolfSSL_Debugging_ON()`; redirect with `wolfSSL_SetLoggingCb()` (e.g. to a UART) | `wolfssl/wolfcrypt/logging.h` |
+| Crypto offload / secure element | PKCS#11 (`--enable-pkcs11`), crypto callbacks (`wc_CryptoCb_RegisterDevice`, `WOLF_CRYPTO_CB`), or a `wolfcrypt/src/port/` driver | `wolfssl/wolfcrypt/cryptocb.h` |
+
+## Verifying an integration
+
+- `./wolfcrypt/test/testwolfcrypt` -- crypto self-test; `wolfcrypt/test/test.c` is
+  portable and commonly compiled into embedded targets as a smoke test
+  (call `wolfcrypt_test()`).
+- `./wolfcrypt/benchmark/benchmark` -- crypto benchmark (also portable).
+- `./examples/server/server` + `./examples/client/client` -- loopback TLS smoke
+  test using `certs/`.
+- Full suite in-repo: `make check` (autotools) or `ctest` (CMake).
+
+## Gotchas
+
+- Feature-define mismatch between lib and app is the #1 integration bug (see
+  "The one rule" above). Symptoms: crashes or corruption inside otherwise-correct
+  calls.
+- `wolfSSL_Debugging_ON()` is a silent no-op unless the build defined
+  `DEBUG_WOLFSSL`.
+- Certificate loading fails (`ASN_NO_SIGNER_E`, error -188) when the CA is not
+  loaded: wolfSSL verifies peers by default; load the CA chain or (dev only!)
+  `wolfSSL_CTX_set_verify(ctx, WOLFSSL_VERIFY_NONE, NULL)`.
+- `certs/` and `wolfssl/certs_test.h` are shared test credentials -- never ship
+  them.
+- Hardening (timing resistance/blinding) is on by default; `--disable-harden` is
+  a security decision, not a build convenience.
+- No `--enable-fips` variant builds from the plain git tree: configure errors out
+  while `wolfcrypt/src/fips.c` is the empty stub. Certified FIPS (v2/v5/v6)
+  requires a licensed source bundle from wolfSSL Inc.; `--enable-fips=ready` or
+  `=dev` works with the free FIPS Ready download from wolfssl.com, running the
+  full module machinery (integrity check, self-tests) but without a FIPS
+  certificate.
+- OpenSSL compat is source-level, not ABI-level: recompile the app against
+  `wolfssl/openssl/*.h`; you cannot swap shared libraries under an
+  OpenSSL-linked binary.
+
+## Further documentation
+
+- wolfSSL manual: https://www.wolfssl.com/documentation/manuals/wolfssl/
+- API reference (wolfSSL + wolfCrypt Doxygen): `doc/dox_comments` directory
+- Standalone example projects: https://github.com/wolfSSL/wolfssl-examples
+- Support / commercial licensing: support@wolfssl.com
diff --git a/CLAUDE.md b/CLAUDE.md
@@ -0,0 +1 @@
+@AGENTS.md