0957b409a9
Disabled by default, used by loader and sbin/veriexec Reviewed by: emaste Sponsored by: Juniper Networks Differential Revision: D16334
137 lines
6.2 KiB
Plaintext
137 lines
6.2 KiB
Plaintext
# Documentation
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The most up-to-date documentation is supposed to be available on the
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[BearSSL Web site](https://www.bearssl.org/).
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# Disclaimer
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BearSSL is considered beta-level software. Most planned functionalities
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are implemented; new evolution may still break both source and binary
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compatibility.
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Using BearSSL for production purposes would be a relatively bold but not
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utterly crazy move. BearSSL is free, open-source software, provided
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without any guarantee of fitness or reliability. That being said, it
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appears to behave properly, and only minor issues have been found (and
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fixed) so far. You are encourage to inspect its API and code for
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learning, testing and possibly contributing.
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The usage license is explicited in the `LICENSE.txt` file. This is the
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"MIT license". It can be summarised in the following way:
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- You can use and reuse the library as you wish, and modify it, and
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integrate it in your own code, and distribute it as is or in any
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modified form, and so on.
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- The only obligation that the license terms put upon you is that you
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acknowledge and make it clear that if anything breaks, it is not my
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fault, and I am not liable for anything, regardless of the type and
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amount of collateral damage. The license terms say that the copyright
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notice "shall be included in all copies or substantial portions of
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the Software": this is how the disclaimer is "made explicit".
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Basically, I have put it in every source file, so just keep it there.
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# Installation
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Right now, BearSSL is a simple library, along with a few test and debug
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command-line tools. There is no installer yet. The library _can_ be
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compiled as a shared library on some systems, but since the binary API
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is not fully stabilised, this is not a very good idea to do that right
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now.
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To compile the code, just type `make`. This will try to use sane
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"default" values. On a Windows system with Visual Studio, run a console
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with the environment initialised for a specific version of the C compiler,
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and type `nmake`.
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To override the default settings, create a custom configuration file in
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the `conf` directory, and invoke `make` (or `nmake`) with an explicit
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`CONF=` parameter. For instance, to use the provided `samd20.mk`
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configuration file (that targets cross-compilation for an Atmel board
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that features a Cortex-M0+ CPU), type:
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make CONF=samd20
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The `conf/samd20.mk` file includes the `Unix.mk` file and then overrides
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some of the parameters, including the destination directory. Any custom
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configuration can be made the same way.
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Some compile-time options can be set through macros, either on the
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compiler command-line, or in the `src/config.h` file. See the comments
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in that file. Some settings are autodetected but they can still be
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explicitly overridden.
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When compilation is done, the library (static and DLL, when appropriate)
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and the command-line tools can be found in the designated build
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directory (by default named `build`). The public headers (to be used
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by applications linked against BearSSL) are in the `inc/` directory.
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To run the tests:
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- `testcrypto all` runs the cryptographic tests (test vectors on all
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implemented cryptogaphic functions). It can be slow. You can also
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run a selection of the tests by providing their names (run
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`testcrypto` without any parameter to see the available names).
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- `testspeed all` runs a number of performance benchmarks, there again
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on cryptographic functions. It gives a taste of how things go on the
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current platform. As for `testcrypto`, specific named benchmarks can
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be executed.
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- `testx509` runs X.509 validation tests. The test certificates are
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all in `test/x509/`.
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The `brssl` command-line tool produced in the build directory is a
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stand-alone binary. It can exercise some of the functionalities of
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BearSSL, in particular running a test SSL client or server. It is not
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meant for production purposes (e.g. the SSL client has a mode where it
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disregards the inability to validate the server's certificate, which is
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inherently unsafe, but convenient for debug).
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**Using the library** means writing some application code that invokes
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it, and linking with the static library. The header files are all in the
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`inc` directory; copy them wherever makes sense (e.g. in the
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`/usr/local/include` directory). The library itself (`libbearssl.a`) is
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what you link against.
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Alternatively, you may want to copy the source files directly into your
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own application code. This will make integrating ulterior versions of
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BearSSL more difficult. If you still want to go down that road, then
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simply copy all the `*.h` and `*.c` files from the `src` and `inc`
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directories into your application source code. In the BearSSL source
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archive, the source files are segregated into various sub-directories,
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but this is for my convenience only. There is no technical requirement
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for that, and all files can be dumped together in a simple directory.
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Dependencies are simple and systematic:
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- Each `*.c` file includes `inner.h`
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- `inner.h` includes `config.h` and `bearssl.h`
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- `bearssl.h` includes the other `bearssl_*.h`
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# Versioning
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I follow this simple version numbering scheme:
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- Version numbers are `x.y` or `x.y.z` where `x`, `y` and `z` are
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decimal integers (possibly greater than 10). When the `.z` part is
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missing, it is equivalent to `.0`.
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- Backward compatibility is maintained, at both source and binary levels,
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for each major version: this means that if some application code was
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designed for version `x.y`, then it should compile, link and run
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properly with any version `x.y'` for any `y'` greater than `y`.
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The major version `0` is an exception. You shall not expect that any
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version that starts with `0.` offers any kind of compatibility,
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either source or binary, with any other `0.` version. (Of course I
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will try to maintain some decent level of source compatibility, but I
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make no promise in that respect. Since the API uses caller-allocated
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context structures, I already know that binary compatibility _will_
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be broken.)
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- Sub-versions (the `y` part) are about added functionality. That is,
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it can be expected that `1.3` will contain some extra functions when
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compared to `1.2`. The next version level (the `z` part) is for
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bugfixes that do not add any functionality.
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