Building The Library

This document describes how to build Botan on Unix/POSIX and MS Windows systems. The POSIX oriented descriptions should apply to most common Unix systems (including MacOS X), along with POSIX-ish systems like BeOS, QNX, and Plan 9. Currently, systems other than Windows and POSIX (such as VMS, MacOS 9, OS/390, OS/400, ...) are not supported by the build system, primarily due to lack of access. Please contact the maintainer if you would like to build Botan on such a system.

Botan’s build is controlled by, which is a Python script. Python 2.6 or later is required.

For the impatient, this works for most systems:

$ ./ [--prefix=/some/directory]
$ make
$ make install

Or using nmake, if you’re compiling on Windows with Visual C++. On platforms that do not understand the ‘#!’ convention for beginning script files, or that have Python installed in an unusual spot, you might need to prefix the command with python or /path/to/python:

$ python ./ [arguments]

Configuring the Build

The first step is to run, which is a Python script that creates various directories, config files, and a Makefile for building everything. This script should run under a vanilla install of Python 2.6, 2.7, or 3.x.

The script will attempt to guess what kind of system you are trying to compile for (and will print messages telling you what it guessed). You can override this process by passing the options --cc, --os, and --cpu.

You can pass basically anything reasonable with --cpu: the script knows about a large number of different architectures, their sub-models, and common aliases for them. You should only select the 64-bit version of a CPU (such as “sparc64” or “mips64”) if your operating system knows how to handle 64-bit object code - a 32-bit kernel on a 64-bit CPU will generally not like 64-bit code.

By default the script tries to figure out what will work on your system, and use that. It will print a display at the end showing which algorithms have and have not been enabled. For instance on one system we might see lines like:

INFO: Skipping, by request only - bzip2 cvc gnump lzma openssl sqlite3 zlib
INFO: Skipping, dependency failure - sessions_sqlite
INFO: Skipping, incompatible CPU - asm_x86_32 md4_x86_32 md5_x86_32 mp_x86_32 serpent_x86_32 sha1_x86_32
INFO: Skipping, incompatible OS - beos_stats cryptoapi_rng win32_stats
INFO: Skipping, incompatible compiler - mp_x86_32_msvc

The ones that are skipped because they are ‘by request only’ have to be explicitly asked for, because they rely on third party libraries which your system might not have or that you might not want the resulting binary to depend on. For instance to enable zlib support, add --with-zlib to your invocation of

You can control which algorithms and modules are built using the options --enable-modules=MODS and --disable-modules=MODS, for instance --enable-modules=zlib and --disable-modules=rc5,idea. Modules not listed on the command line will simply be loaded if needed or if configured to load by default. If you use --no-autoload, only the most core modules will be included; you can then explicitly enable things that you want to use with --enable-modules. This is useful for creating a minimal build targeting to a specific application, especially in conjunction with the amalgamation option; see The Amalgamation Build.

For instance:

$ ./ --no-autoload --enable-modules=rsa,ecdsa,eme1,emsa1,emsa4

will set up a build that only includes RSA, ECDSA, and some padding modes, along with their dependencies. A small subset of core features, including AES, SHA-2, HMAC, and the multiple precision integer library, are always loaded.

The script tries to guess what kind of makefile to generate, and it almost always guesses correctly (basically, Visual C++ uses NMAKE with Windows commands, and everything else uses Unix make with POSIX commands). Just in case, you can override it with --make-style=X. The styles Botan currently knows about are ‘gmake’ (GNU make and possibly some other Unix makes), and ‘nmake’, the make variant commonly used by Microsoft compilers. To add a new variant (eg, a build script for VMS), you will need to create a new template file in src/build-data/makefile.

On Unix

The basic build procedure on Unix and Unix-like systems is:

$ ./ [--enable-modules=<list>] [--cc=CC]
$ make
$ ./botan test

If that fails with an error about not being able to find, you may need to set LD_LIBRARY_PATH:

$ LD_LIBRARY_PATH=. ./botan test

If the tests look OK, install:

$ make install

On Unix systems the script will default to using GCC; use --cc if you want something else. For instance use --cc=icc for Intel C++ and --cc=clang for Clang.

The make install target has a default directory in which it will install Botan (typically /usr/local). You can override this by using the --prefix argument to, like so:

./ --prefix=/opt <other arguments>

On some systems shared libraries might not be immediately visible to the runtime linker. For example, on Linux you may have to edit /etc/ and run ldconfig (as root) in order for new shared libraries to be picked up by the linker. An alternative is to set your LD_LIBRARY_PATH shell variable to include the directory that the Botan libraries were installed into.

On Mac OS X

In general the Unix instructions above should apply, however OS X does not support LD_LIBRARY_PATH. Thomas Keller suggests instead running install_name_tool between building and running the self-test program:

$ VERSION=1.11.11 # or whatever the current version is
$ install_name_tool -change $(otool -X -D libbotan-$VERSION.dylib) \
     $PWD/libbotan-$VERSION.dylib botan-test

Building Universal Binaries

To build a universal binary for OS X, you need to set some additional build flags. Do this with the –cc-abi-flags option:

$ ./ [other arguments] --cc-abi-flags="-force_cpusubtype_ALL -mmacosx-version-min=10.4 -arch i386 -arch ppc"

On MS Windows

If you don’t want to deal with building botan on Windows, check the website; commonly prebuilt Windows binaries with installers are available, especially for stable versions.

You need to have a copy of Python installed, and have both Python and your chosen compiler in your path. Open a command shell (or the SDK shell), and run:

> python --cc=msvc (or --cc=gcc for MinGW) [--cpu=CPU]
> nmake
> botan.exe test
> nmake install

For Win95 pre OSR2, the cryptoapi_rng module will not work, because CryptoAPI didn’t exist. And all versions of NT4 lack the ToolHelp32 interface, which is how win32_stats does its slow polls, so a version of the library built with that module will not load under NT4. Later versions of Windows support both methods, so this shouldn’t be much of an issue anymore.

By default the install target will be C:\botan; you can modify this with the --prefix option.

When building your applications, all you have to do is tell the compiler to look for both include files and library files in C:\botan, and it will find both. Or you can move them to a place where they will be in the default compiler search paths (consult your documentation and/or local expert for details).

For iOS using XCode

To cross compile for iOS, configure with:

$ ./ --cpu=armv7 --cc=clang --cc-abi-flags="-arch armv7 -arch armv7s --sysroot=$(IOS_SYSROOT)"

Along with any additional configuration arguments. Using --no-autoload might be helpful as can substantially reduce code size.

Edit the makefile and change AR (around line 30) to:

AR = libtool -static -o

You may also want to edit LIB_OPT to use -Os to optimize for size.

Now build as normal with make. Confirm the binaries are compiled for both architectures with:

$ xcrun -sdk iphoneos lipo -info botan
Architectures in the fat file: botan are: armv7 armv7s

Now sign the test application with:

$ codesign -fs "Your Name" botan-test

which should allow you to run the library self tests on a jailbroken device.

For Android

Instructions for building the library on Android can be found here.

Building Applications


Botan usually links in several different system libraries (such as librt and libz), depending on which modules are configured at compile time. In many environments, particularly ones using static libraries, an application has to link against the same libraries as Botan for the linking step to succeed. But how does it figure out what libraries it is linked against?

The answer is to ask the botan-config script. This basically solves the same problem all the other *-config scripts solve, and in basically the same manner.

There are 4 options:

--prefix[=DIR]: If no argument, print the prefix where Botan is installed (such as /opt or /usr/local). If an argument is specified, other options given with the same command will execute as if Botan as actually installed at DIR and not where it really is; or at least where botan-config thinks it really is. I should mention that it

--version: Print the Botan version number.

--cflags: Print options that should be passed to the compiler whenever a C++ file is compiled. Typically this is used for setting include paths.

--libs: Print options for which libraries to link to (this includes -lbotan).

Your Makefile can run botan-config and get the options necessary for getting your application to compile and link, regardless of whatever crazy libraries Botan might be linked against.

Botan also by default installs a file for pkg-config, namespaced by the major and minor versions. So it can be used, for instance, as:

$ pkg-config botan-1.11 --modversion
$ pkg-config botan-1.11 --cflags
$ pkg-config botan-1.11 --libs
-L/usr/local/lib -lbotan -lm -lbz2 -lpthread -lrt

MS Windows

No special help exists for building applications on Windows. However, given that typically Windows software is distributed as binaries, this is less of a problem - only the developer needs to worry about it. As long as they can remember where they installed Botan, they just have to set the appropriate flags in their Makefile/project file.

Language Wrappers

Building the Python wrappers

The Python wrappers for Botan use Boost.Python, so you must have Boost installed. To build the wrappers, pass the flag --with-boost-python to and build the python target with make.

To install the module, use the install_python target.

See Python Bindings for more information about the binding.

Building the Perl XS wrappers

To build the Perl XS wrappers, change your directory to src/wrap/perl-xs and run perl Makefile.PL, then run make to build the module and make test to run the test suite:

$ perl Makefile.PL
Checking if your kit is complete...
Looks good
Writing Makefile for Botan
$ make
cp blib/lib/
AutoSplitting blib/lib/ (blib/lib/auto/Botan)
/usr/bin/perl5.8.8 /usr/lib64/perl5/5.8.8/ExtUtils/xsubpp  [...]
g++ -c   -Wno-write-strings -fexceptions  -g   [...]
Running Mkbootstrap for Botan ()
chmod 644
rm -f blib/arch/auto/Botan/
g++  -shared Botan.o  -o blib/arch/auto/Botan/  \
           -lbotan -lbz2 -lpthread -lrt -lz     \

chmod 755 blib/arch/auto/Botan/
cp blib/arch/auto/Botan/
chmod 644 blib/arch/auto/Botan/
Manifying blib/man3/Botan.3pm
$ make test
PERL_DL_NONLAZY=1 /usr/bin/perl5.8.8 [...]
All tests successful.
Files=6, Tests=83,  0 wallclock secs ( 0.08 cusr +  0.02 csys =  0.10 CPU)