Add version macros, pkg-config and document build policies

CMakeLists.txt

@@ -4,6 +4,11 @@ project(hmac_cpp VERSION 0.3.0 LANGUAGES CXX)
 option(HMACCPP_BUILD_EXAMPLES "Build the example program" OFF)
 option(HMACCPP_BUILD_TESTS "Build the test suite" OFF)
 option(HMACCPP_BUILD_BENCH "Build benchmarks" OFF)
+option(HMACCPP_BUILD_SHARED "Build hmac_cpp as a shared library" OFF)
+
+if(HMACCPP_BUILD_SHARED)
+    set(BUILD_SHARED_LIBS ON)
+endif()
 
 set(HMAC_SOURCES
     src/sha1.cpp
@@ -23,6 +28,7 @@ set(HMAC_HEADERS
     include/hmac_cpp/sha512.hpp
     include/hmac_cpp/secure_buffer.hpp
     include/hmac_cpp/encoding.hpp
+    include/hmac_cpp/version.hpp
 )
 
 add_library(hmac_cpp ${HMAC_SOURCES})
@@ -91,6 +97,9 @@ install(FILES
     DESTINATION lib/cmake/hmac_cpp
 )
 
+configure_file(cmake/hmac_cpp.pc.in "${CMAKE_CURRENT_BINARY_DIR}/hmac_cpp.pc" @ONLY)
+install(FILES "${CMAKE_CURRENT_BINARY_DIR}/hmac_cpp.pc" DESTINATION lib/pkgconfig)
+
 if(HMACCPP_BUILD_TESTS)
     enable_testing()
     include(FetchContent)

README.md

@@ -32,6 +32,20 @@ CI covers Linux/Windows/macOS. Tested with GCC, Clang, and MSVC; requires C++11.
 
 ---
 
+## 📈 Versioning / SemVer policy
+
+* Follows [Semantic Versioning](https://semver.org).
+* MAJOR: breaking changes to headers or exported symbols.
+* MINOR: backward-compatible additions.
+* PATCH: bug fixes and internal changes.
+
+Version macros live in `<hmac_cpp/version.hpp>`:
+`HMAC_CPP_VERSION_MAJOR`, `HMAC_CPP_VERSION_MINOR`,
+`HMAC_CPP_VERSION_PATCH`, and `HMAC_CPP_VERSION`.
+See [CHANGELOG.md](CHANGELOG.md) for history.
+
+---
+
 ## 🔧 Build & Installation
 
 Examples, tests, and benchmarks are OFF by default. Enable via:
@@ -40,6 +54,10 @@ Examples, tests, and benchmarks are OFF by default. Enable via:
 * `HMACCPP_BUILD_TESTS`
 * `HMACCPP_BUILD_BENCH`
 
+The library builds **static** by default. Use `-DHMACCPP_BUILD_SHARED=ON`
+to produce a shared library. The `HMAC_CPP_API` macro is empty for static
+builds and controls symbol export/import for shared builds.
+
 ### Build
 
 ```bash
@@ -51,23 +69,21 @@ cmake --build build
 
 ```bash
 cmake --install build --prefix _install
+# MSVC
+cmake --install build --config Release --prefix _install
 ```
 
 Install layout:
 
 ```
 _install/
-├─ include/hmac_cpp/
-│  ├─ hmac.hpp
-│  ├─ hmac_utils.hpp
-│  ├─ sha1.hpp
-│  ├─ sha256.hpp
-│  ├─ sha512.hpp
-│  └─ secure_buffer.hpp    # if included in your build
-└─ lib/
-   └─ libhmac_cpp.a
+├── include/hmac_cpp/...
+└── lib/
+    └── libhmac_cpp.a
 ```
 
+A `hmac_cpp.pc` file is installed for `pkg-config`.
+
 ### Consume with CMake
 
 ```cmake
@@ -80,6 +96,10 @@ target_link_libraries(my_app PRIVATE hmac_cpp::hmac_cpp)
 ```bash
 # adjust paths to your prefix
 g++ example.cpp -std=c++11 -I_install/include -L_install/lib -lhmac_cpp
+# MSVC
+cl /EHsc example.cpp /I _install\include /link /LIBPATH:_install\lib hmac_cpp.lib
+# pkg-config
+c++ example.cpp $(pkg-config --cflags --libs hmac_cpp)
 ```
 
 Predefined MinGW build scripts are available: `build_*.bat`.
@@ -154,6 +174,8 @@ auto key  = hmac::pbkdf2_hmac_sha256(password, salt, iters, 32); // 32 = AES-256
 * **Iterations**: tune for \~100–250 ms on target hardware (e.g., desktop ≈ 600k, laptop ≈ 300k, mobile ≈ 150k; adjust).
 * **Derived key length**: 32 bytes; **PRF**: HMAC-SHA256.
 
+> PBKDF2 is CPU-bound; for user passwords prefer memory-hard KDFs such as Argon2 or scrypt if available.
+
 **Serialization example** (binary):
 
 ```
@@ -262,12 +284,14 @@ ctest --test-dir build --output-on-failure
 
 Covered vectors:
 
-* HMAC — **RFC 4231**
-* PBKDF2 — **RFC 6070**
-* HOTP — **RFC 4226** (Appendix D)
-* TOTP — **RFC 6238** (Appendix B)
+| Suite  | RFC |
+| ------ | --- |
+| HMAC   | RFC 4231 |
+| PBKDF2 | RFC 6070 |
+| HOTP   | RFC 4226 (App D) |
+| TOTP   | RFC 6238 (App B) |
 
-CI runs these on Linux/Windows/macOS.
+CI: [GitHub Actions](https://github.com/NewYaroslav/hmac-cpp/actions).
 
 ---
 
@@ -302,15 +326,18 @@ g++ example.cpp -std=c++11 -I_install/include -L_install/lib -lhmac_cpp
 MSVC:
 
 ```bat
-cl /EHsc example.cpp /I _install\include /link /LIBPATH:_install\lib hmach_cpp.lib
+cl /EHsc example.cpp /I _install\include /link /LIBPATH:_install\lib hmac_cpp.lib
 ```
 
 ---
 
 ## ⚠️ Exceptions & Contracts
 
-* Functions may throw `std::invalid_argument` (bad params) and `std::runtime_error` (internal errors).
-* `constant_time_equal` assumes lengths are public; compare sizes first.
+* `pbkdf2`, `hkdf_*`, HOTP/TOTP, and time-token helpers validate parameters and throw
+  `std::invalid_argument`; time-token helpers also throw `std::runtime_error` if the
+  system clock fails.
+* `base64_decode` and `base32_decode` are `noexcept` and return `false` on invalid input.
+* `constant_time_equal` is `noexcept`; compare sizes first.
 * PBKDF2 limits: `dkLen ≤ (2^32−1)·hLen`; iterations ≥ 1; salt length ≥ 16 recommended.
 * HKDF limits: `L ≤ 255·HashLen`.
 * Thread-safety: functions are stateless and thread-safe given separate buffers.

cmake/hmac_cpp.pc.in

@@ -0,0 +1,10 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+exec_prefix=${prefix}
+libdir=${exec_prefix}/lib
+includedir=${prefix}/include
+
+Name: hmac_cpp
+Description: HMAC/PBKDF2/HKDF library
+Version: @PROJECT_VERSION@
+Libs: -L${libdir} -lhmac_cpp
+Cflags: -I${includedir}

include/hmac_cpp/hmac_utils.hpp

@@ -76,6 +76,7 @@ namespace hmac_cpp {
 
     /// PBKDF2 Security Notes:
     /// - Use a random salt of at least 16 bytes and never reuse it.
+    /// - PBKDF2 is CPU-bound; prefer Argon2 or scrypt for user passwords when available.
     /// - Choose iterations so the derivation takes about 200–500 ms on 2025 hardware.
     /// - Store {salt, iterations} with the ciphertext or hash; these values are public.
     /// - Salts and iteration counts must be unique per password.

include/hmac_cpp/version.hpp

@@ -0,0 +1,9 @@
+#ifndef HMAC_CPP_VERSION_HPP
+#define HMAC_CPP_VERSION_HPP
+
+#define HMAC_CPP_VERSION_MAJOR 0
+#define HMAC_CPP_VERSION_MINOR 3
+#define HMAC_CPP_VERSION_PATCH 0
+#define HMAC_CPP_VERSION "0.3.0"
+
+#endif // HMAC_CPP_VERSION_HPP