1README for Mbed TLS 2=================== 3 4Mbed TLS is a C library that implements cryptographic primitives, X.509 certificate manipulation and the SSL/TLS and DTLS protocols. Its small code footprint makes it suitable for embedded systems. 5 6Mbed TLS includes a reference implementation of the [PSA Cryptography API](#psa-cryptography-api). This is currently a preview for evaluation purposes only. 7 8Configuration 9------------- 10 11Mbed TLS should build out of the box on most systems. Some platform specific options are available in the fully documented configuration file `include/mbedtls/mbedtls_config.h`, which is also the place where features can be selected. This file can be edited manually, or in a more programmatic way using the Python 3 script `scripts/config.py` (use `--help` for usage instructions). 12 13Compiler options can be set using conventional environment variables such as `CC` and `CFLAGS` when using the Make and CMake build system (see below). 14 15We provide some non-standard configurations focused on specific use cases in the `configs/` directory. You can read more about those in `configs/README.txt` 16 17Documentation 18------------- 19 20Documentation for the Mbed TLS interfaces in the default library configuration is available as part of the [Mbed TLS documentation](https://tls.mbed.org/api/). 21 22To generate a local copy of the library documentation in HTML format, tailored to your compile-time configuration: 23 241. Make sure that [Doxygen](http://www.doxygen.nl/) is installed. 251. Run `make apidoc`. 261. Browse `apidoc/index.html` or `apidoc/modules.html`. 27 28For other sources of documentation, see the [SUPPORT](SUPPORT.md) document. 29 30Compiling 31--------- 32 33There are currently three active build systems used within Mbed TLS releases: 34 35- GNU Make 36- CMake 37- Microsoft Visual Studio 38 39The main systems used for development are CMake and GNU Make. Those systems are always complete and up-to-date. The others should reflect all changes present in the CMake and Make build system, although features may not be ported there automatically. 40 41The Make and CMake build systems create three libraries: libmbedcrypto, libmbedx509, and libmbedtls. Note that libmbedtls depends on libmbedx509 and libmbedcrypto, and libmbedx509 depends on libmbedcrypto. As a result, some linkers will expect flags to be in a specific order, for example the GNU linker wants `-lmbedtls -lmbedx509 -lmbedcrypto`. 42 43### Tool versions 44 45You need the following tools to build the library with the provided makefiles: 46 47* GNU Make 3.82 or a build tool that CMake supports. 48* A C99 toolchain (compiler, linker, archiver). We actively test with GCC 5.4, Clang 3.8, IAR 8 and Visual Studio 2013. More recent versions should work. Slightly older versions may work. 49* Python 3.6 to generate the test code, and to generate sample programs in the development branch. 50* Perl to run the tests, and to generate some source files in the development branch. 51* CMake 3.10.2 or later (if using CMake). 52* Microsoft Visual Studio 2013 or later (if using Visual Studio). 53* Doxygen 1.8.11 or later (if building the documentation; slightly older versions should work). 54 55### Generated source files in the development branch 56 57The source code of Mbed TLS includes some files that are automatically generated by scripts and whose content depends only on the Mbed TLS source, not on the platform or on the library configuration. These files are not included in the development branch of Mbed TLS, but the generated files are included in official releases. This section explains how to generate the missing files in the development branch. 58 59The following tools are required: 60 61* Perl, for some library source files and for Visual Studio build files. 62* Python 3, for some sample programs and test data. 63* A C compiler for the host platform, for some test data. 64 65If you are cross-compiling, you must set the `CC` environment variable to a C compiler for the host platform when generating the configuration-independent files. 66 67Any of the following methods are available to generate the configuration-independent files: 68 69* If not cross-compiling, running `make` with any target, or just `make`, will automatically generate required files. 70* On non-Windows systems, when not cross-compiling, CMake will generate the required files automatically. 71* Run `make generated_files` to generate all the configuration-independent files. 72* On Unix/POSIX systems, run `tests/scripts/check-generated-files.sh -u` to generate all the configuration-independent files. 73* On Windows, run `scripts\make_generated_files.bat` to generate all the configuration-independent files. 74 75### Make 76 77We require GNU Make. To build the library and the sample programs, GNU Make and a C compiler are sufficient. Some of the more advanced build targets require some Unix/Linux tools. 78 79We intentionally only use a minimum of functionality in the makefiles in order to keep them as simple and independent of different toolchains as possible, to allow users to more easily move between different platforms. Users who need more features are recommended to use CMake. 80 81In order to build from the source code using GNU Make, just enter at the command line: 82 83 make 84 85In order to run the tests, enter: 86 87 make check 88 89The tests need Python to be built and Perl to be run. If you don't have one of them installed, you can skip building the tests with: 90 91 make no_test 92 93You'll still be able to run a much smaller set of tests with: 94 95 programs/test/selftest 96 97In order to build for a Windows platform, you should use `WINDOWS_BUILD=1` if the target is Windows but the build environment is Unix-like (for instance when cross-compiling, or compiling from an MSYS shell), and `WINDOWS=1` if the build environment is a Windows shell (for instance using mingw32-make) (in that case some targets will not be available). 98 99Setting the variable `SHARED` in your environment will build shared libraries in addition to the static libraries. Setting `DEBUG` gives you a debug build. You can override `CFLAGS` and `LDFLAGS` by setting them in your environment or on the make command line; compiler warning options may be overridden separately using `WARNING_CFLAGS`. Some directory-specific options (for example, `-I` directives) are still preserved. 100 101Please note that setting `CFLAGS` overrides its default value of `-O2` and setting `WARNING_CFLAGS` overrides its default value (starting with `-Wall -Wextra`), so if you just want to add some warning options to the default ones, you can do so by setting `CFLAGS=-O2 -Werror` for example. Setting `WARNING_CFLAGS` is useful when you want to get rid of its default content (for example because your compiler doesn't accept `-Wall` as an option). Directory-specific options cannot be overridden from the command line. 102 103Depending on your platform, you might run into some issues. Please check the Makefiles in `library/`, `programs/` and `tests/` for options to manually add or remove for specific platforms. You can also check [the Mbed TLS Knowledge Base](https://tls.mbed.org/kb) for articles on your platform or issue. 104 105In case you find that you need to do something else as well, please let us know what, so we can add it to the [Mbed TLS Knowledge Base](https://tls.mbed.org/kb). 106 107### CMake 108 109In order to build the source using CMake in a separate directory (recommended), just enter at the command line: 110 111 mkdir /path/to/build_dir && cd /path/to/build_dir 112 cmake /path/to/mbedtls_source 113 cmake --build . 114 115In order to run the tests, enter: 116 117 ctest 118 119The test suites need Python to be built and Perl to be executed. If you don't have one of these installed, you'll want to disable the test suites with: 120 121 cmake -DENABLE_TESTING=Off /path/to/mbedtls_source 122 123If you disabled the test suites, but kept the programs enabled, you can still run a much smaller set of tests with: 124 125 programs/test/selftest 126 127To configure CMake for building shared libraries, use: 128 129 cmake -DUSE_SHARED_MBEDTLS_LIBRARY=On /path/to/mbedtls_source 130 131There are many different build modes available within the CMake buildsystem. Most of them are available for gcc and clang, though some are compiler-specific: 132 133- `Release`. This generates the default code without any unnecessary information in the binary files. 134- `Debug`. This generates debug information and disables optimization of the code. 135- `Coverage`. This generates code coverage information in addition to debug information. 136- `ASan`. This instruments the code with AddressSanitizer to check for memory errors. (This includes LeakSanitizer, with recent version of gcc and clang.) (With recent version of clang, this mode also instruments the code with UndefinedSanitizer to check for undefined behaviour.) 137- `ASanDbg`. Same as ASan but slower, with debug information and better stack traces. 138- `MemSan`. This instruments the code with MemorySanitizer to check for uninitialised memory reads. Experimental, needs recent clang on Linux/x86\_64. 139- `MemSanDbg`. Same as MemSan but slower, with debug information, better stack traces and origin tracking. 140- `Check`. This activates the compiler warnings that depend on optimization and treats all warnings as errors. 141 142Switching build modes in CMake is simple. For debug mode, enter at the command line: 143 144 cmake -D CMAKE_BUILD_TYPE=Debug /path/to/mbedtls_source 145 146To list other available CMake options, use: 147 148 cmake -LH 149 150Note that, with CMake, you can't adjust the compiler or its flags after the 151initial invocation of cmake. This means that `CC=your_cc make` and `make 152CC=your_cc` will *not* work (similarly with `CFLAGS` and other variables). 153These variables need to be adjusted when invoking cmake for the first time, 154for example: 155 156 CC=your_cc cmake /path/to/mbedtls_source 157 158If you already invoked cmake and want to change those settings, you need to 159remove the build directory and create it again. 160 161Note that it is possible to build in-place; this will however overwrite the 162provided Makefiles (see `scripts/tmp_ignore_makefiles.sh` if you want to 163prevent `git status` from showing them as modified). In order to do so, from 164the Mbed TLS source directory, use: 165 166 cmake . 167 make 168 169If you want to change `CC` or `CFLAGS` afterwards, you will need to remove the 170CMake cache. This can be done with the following command using GNU find: 171 172 find . -iname '*cmake*' -not -name CMakeLists.txt -exec rm -rf {} + 173 174You can now make the desired change: 175 176 CC=your_cc cmake . 177 make 178 179Regarding variables, also note that if you set CFLAGS when invoking cmake, 180your value of CFLAGS doesn't override the content provided by cmake (depending 181on the build mode as seen above), it's merely prepended to it. 182 183#### Consuming Mbed TLS 184 185Mbed TLS provides a package config file for consumption as a dependency in other 186CMake projects. You can include Mbed TLS's CMake targets yourself with: 187 188 find_package(MbedTLS) 189 190If prompted, set `MbedTLS_DIR` to `${YOUR_MBEDTLS_INSTALL_DIR}/cmake`. This 191creates the following targets: 192 193- `MbedTLS::mbedcrypto` (Crypto library) 194- `MbedTLS::mbedtls` (TLS library) 195- `MbedTLS::mbedx509` (X509 library) 196 197You can then use these directly through `target_link_libraries()`: 198 199 add_executable(xyz) 200 201 target_link_libraries(xyz 202 PUBLIC MbedTLS::mbedtls 203 MbedTLS::mbedcrypto 204 MbedTLS::mbedx509) 205 206This will link the Mbed TLS libraries to your library or application, and add 207its include directories to your target (transitively, in the case of `PUBLIC` or 208`INTERFACE` link libraries). 209 210#### Mbed TLS as a subproject 211 212Mbed TLS supports being built as a CMake subproject. One can 213use `add_subdirectory()` from a parent CMake project to include Mbed TLS as a 214subproject. 215 216### Microsoft Visual Studio 217 218The build files for Microsoft Visual Studio are generated for Visual Studio 2010. 219 220The solution file `mbedTLS.sln` contains all the basic projects needed to build the library and all the programs. The files in tests are not generated and compiled, as these need Python and perl environments as well. However, the selftest program in `programs/test/` is still available. 221 222In the development branch of Mbed TLS, the Visual Studio solution files need to be generated first as described in [“Generated source files in the development branch”](#generated-source-files-in-the-development-branch). 223 224Example programs 225---------------- 226 227We've included example programs for a lot of different features and uses in [`programs/`](programs/README.md). 228Please note that the goal of these sample programs is to demonstrate specific features of the library, and the code may need to be adapted to build a real-world application. 229 230Tests 231----- 232 233Mbed TLS includes an elaborate test suite in `tests/` that initially requires Python to generate the tests files (e.g. `test\_suite\_mpi.c`). These files are generated from a `function file` (e.g. `suites/test\_suite\_mpi.function`) and a `data file` (e.g. `suites/test\_suite\_mpi.data`). The `function file` contains the test functions. The `data file` contains the test cases, specified as parameters that will be passed to the test function. 234 235For machines with a Unix shell and OpenSSL (and optionally GnuTLS) installed, additional test scripts are available: 236 237- `tests/ssl-opt.sh` runs integration tests for various TLS options (renegotiation, resumption, etc.) and tests interoperability of these options with other implementations. 238- `tests/compat.sh` tests interoperability of every ciphersuite with other implementations. 239- `tests/scripts/test-ref-configs.pl` test builds in various reduced configurations. 240- `tests/scripts/key-exchanges.pl` test builds in configurations with a single key exchange enabled 241- `tests/scripts/all.sh` runs a combination of the above tests, plus some more, with various build options (such as ASan, full `mbedtls_config.h`, etc). 242 243Porting Mbed TLS 244---------------- 245 246Mbed TLS can be ported to many different architectures, OS's and platforms. Before starting a port, you may find the following Knowledge Base articles useful: 247 248- [Porting Mbed TLS to a new environment or OS](https://tls.mbed.org/kb/how-to/how-do-i-port-mbed-tls-to-a-new-environment-OS) 249- [What external dependencies does Mbed TLS rely on?](https://tls.mbed.org/kb/development/what-external-dependencies-does-mbedtls-rely-on) 250- [How do I configure Mbed TLS](https://tls.mbed.org/kb/compiling-and-building/how-do-i-configure-mbedtls) 251 252PSA cryptography API 253-------------------- 254 255### PSA API design 256 257Arm's [Platform Security Architecture (PSA)](https://developer.arm.com/architectures/security-architectures/platform-security-architecture) is a holistic set of threat models, security analyses, hardware and firmware architecture specifications, and an open source firmware reference implementation. PSA provides a recipe, based on industry best practice, that allows security to be consistently designed in, at both a hardware and firmware level. 258 259The [PSA cryptography API](https://armmbed.github.io/mbed-crypto/psa/#application-programming-interface) provides access to a set of cryptographic primitives. It has a dual purpose. First, it can be used in a PSA-compliant platform to build services, such as secure boot, secure storage and secure communication. Second, it can also be used independently of other PSA components on any platform. 260 261The design goals of the PSA cryptography API include: 262 263* The API distinguishes caller memory from internal memory, which allows the library to be implemented in an isolated space for additional security. Library calls can be implemented as direct function calls if isolation is not desired, and as remote procedure calls if isolation is desired. 264* The structure of internal data is hidden to the application, which allows substituting alternative implementations at build time or run time, for example, in order to take advantage of hardware accelerators. 265* All access to the keys happens through key identifiers, which allows support for external cryptoprocessors that is transparent to applications. 266* The interface to algorithms is generic, favoring algorithm agility. 267* The interface is designed to be easy to use and hard to accidentally misuse. 268 269Arm welcomes feedback on the design of the API. If you think something could be improved, please open an issue on our Github repository. Alternatively, if you prefer to provide your feedback privately, please email us at [`mbed-crypto@arm.com`](mailto:mbed-crypto@arm.com). All feedback received by email is treated confidentially. 270 271### PSA API documentation 272 273A browsable copy of the PSA Cryptography API documents is available on the [PSA cryptography interfaces documentation portal](https://armmbed.github.io/mbed-crypto/psa/#application-programming-interface) in [PDF](https://armmbed.github.io/mbed-crypto/PSA_Cryptography_API_Specification.pdf) and [HTML](https://armmbed.github.io/mbed-crypto/html/index.html) formats. 274 275### PSA implementation in Mbed TLS 276 277Mbed TLS includes a reference implementation of the PSA Cryptography API. 278This implementation is not yet as mature as the rest of the library. Some parts of the code have not been reviewed as thoroughly, and some parts of the PSA implementation are not yet well optimized for code size. 279 280The X.509 and TLS code can use PSA cryptography for a limited subset of operations. To enable this support, activate the compilation option `MBEDTLS_USE_PSA_CRYPTO` in `mbedtls_config.h`. 281 282There are currently a few deviations where the library does not yet implement the latest version of the specification. Please refer to the [compliance issues on Github](https://github.com/ARMmbed/mbed-crypto/labels/compliance) for an up-to-date list. 283 284### Upcoming features 285 286Future releases of this library will include: 287 288* A driver programming interface, which makes it possible to use hardware accelerators instead of the default software implementation for chosen algorithms. 289* Support for external keys to be stored and manipulated exclusively in a separate cryptoprocessor. 290* A configuration mechanism to compile only the algorithms you need for your application. 291* A wider set of cryptographic algorithms. 292 293License 294------- 295 296Unless specifically indicated otherwise in a file, Mbed TLS files are provided under the [Apache-2.0](https://spdx.org/licenses/Apache-2.0.html) license. See the [LICENSE](LICENSE) file for the full text of this license. Contributors must accept that their contributions are made under both the Apache-2.0 AND [GPL-2.0-or-later](https://spdx.org/licenses/GPL-2.0-or-later.html) licenses. This enables LTS (Long Term Support) branches of the software to be provided under either the Apache-2.0 OR GPL-2.0-or-later licenses. 297 298Contributing 299------------ 300 301We gratefully accept bug reports and contributions from the community. Please see the [contributing guidelines](CONTRIBUTING.md) for details on how to do this. 302 303Contact 304------- 305 306* To report a security vulnerability in Mbed TLS, please email <mbed-tls-security@lists.trustedfirmware.org>. For more information, see [`SECURITY.md`](SECURITY.md). 307* To report a bug or request a feature in Mbed TLS, please [file an issue on GitHub](https://github.com/ARMmbed/mbedtls/issues/new/choose). 308* Please see [`SUPPORT.md`](SUPPORT.md) for other channels for discussion and support about Mbed TLS. 309