A local copy of OpenSSL from GitHub
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This document describes installation on all supported operating systems (the Unix/Linux family (which includes Mac OS/X), OpenVMS, and Windows).

To install OpenSSL, you will need:

  • A make implementation
  • Perl 5 with core modules (please read NOTES.PERL)
  • The perl module Text::Template (please read NOTES.PERL)
  • an ANSI C compiler
  • a development environment in the form of development libraries and C header files
  • a supported operating system

For additional platform specific requirements, solutions to specific issues and other details, please read one of these:

  • NOTES.UNIX (any supported Unix like system)
  • NOTES.WIN (any supported Windows)
  • NOTES.DJGPP (DOS platform with DJGPP)
  • NOTES.ANDROID (obviously Android [NDK])
  • NOTES.VALGRIND (testing with Valgrind)

Notational conventions in this document

Throughout this document, we use the following conventions in command examples:

$ command Any line starting with a dollar sign ($) is a command line.

{ word1 | word2 | word3 } This denotes a mandatory choice, to be replaced with one of the given words. A simple example would be this:

                            $ echo { FOO | BAR | COOKIE }

                            which is to be understood as one of

                            $ echo FOO
                            - or -
                            $ echo BAR
                            - or -
                            $ echo COOKIE

[ word1 | word2 | word3 ] Similar to { word1 | word2 | word3 } except it's optional to give any of those. In addition to the examples above, this would also be valid:

                            $ echo

{{ target }} This denotes a mandatory word or sequence of words of some sort. A simple example would be this:

                            $ type {{ filename }}

                            which is to be understood to use the
                            command 'type' on some file name
                            determined by the user.

options Similar to {{ target }}, but is optional.

Note that the notation assumes spaces around {, }, [, ], {{, }} and , . This is to differentiate from OpenVMS directory specifications, which also use [ and ], but without spaces.

Quick Start

If you want to just get on with it, do:

on Unix (again, this includes Mac OS/X):

$ ./config
$ make
$ make test
$ make install

on OpenVMS:

$ @config
$ mms
$ mms test
$ mms install

on Windows (only pick one of the targets for configuration):

$ perl Configure { VC-WIN32 | VC-WIN64A | VC-WIN64I | VC-CE }
$ nmake
$ nmake test
$ nmake install

Note that in order to perform the install step above you need to have appropriate permissions to write to the installation directory.

If any of these steps fails, see section Installation in Detail below.

This will build and install OpenSSL in the default location, which is:

Unix: normal installation directories under /usr/local OpenVMS: SYS$COMMON:[OPENSSL-'version'...], where 'version' is the OpenSSL version number with underscores instead of periods. Windows: C:\Program Files\OpenSSL or C:\Program Files (x86)\OpenSSL

The installation directory should be appropriately protected to ensure unprivileged users cannot make changes to OpenSSL binaries or files, or install engines. If you already have a pre-installed version of OpenSSL as part of your Operating System it is recommended that you do not overwrite the system version and instead install to somewhere else.

If you want to install it anywhere else, run config like this:

On Unix:

$ ./config --prefix=/opt/openssl --openssldir=/usr/local/ssl

On OpenVMS:

$ @config --prefix=PROGRAM:[INSTALLS] --openssldir=SYS$MANAGER:[OPENSSL]

(Note: if you do add options to the configuration command, please make sure you've read more than just this Quick Start, such as relevant NOTES.* files, the options outline below, as configuration options may change the outcome in otherwise unexpected ways)

Configuration Options

There are several options to ./config (or ./Configure) to customize the build (note that for Windows, the defaults for --prefix and --openssldir depend in what configuration is used and what Windows implementation OpenSSL is built on. More notes on this in NOTES.WIN):

--api=x.y[.z] Build the OpenSSL libraries to support the API for the specified version. If "no-deprecated" is also given, don't build with support for deprecated APIs in or below the specified version number. For example "--api=1.1.0" with "no-deprecated" will remove support for all APIS that were deprecated in OpenSSL version 1.1.0 or below. This is a rather specialized option for developers. If you just intend to remove all deprecated APIs entirely (up to the current version), only specify "-no-deprecated" (see below). If "--api" isn't given, it defaults to the current OpenSSL minor version.

--cross-compile-prefix=PREFIX The PREFIX to include in front of commands for your toolchain. It's likely to have to end with dash, e.g. a-b-c- would invoke GNU compiler as a-b-c-gcc, etc. Unfortunately cross-compiling is too case-specific to put together one-size-fits-all instructions. You might have to pass more flags or set up environment variables to actually make it work. Android and iOS cases are discussed in corresponding Configurations/15-*.conf files. But there are cases when this option alone is sufficient. For example to build the mingw64 target on Linux "--cross-compile-prefix=x86_64-w64-mingw32-" works. Naturally provided that mingw packages are installed. Today Debian and Ubuntu users have option to install a number of prepackaged cross-compilers along with corresponding run-time and development packages for "alien" hardware. To give another example "--cross-compile-prefix=mipsel-linux-gnu-" suffices in such case. Needless to mention that you have to invoke ./Configure, not ./config, and pass your target name explicitly. Also, note that --openssldir refers to target's file system, not one you are building on.

--debug Build OpenSSL with debugging symbols and zero optimization level.

--libdir=DIR The name of the directory under the top of the installation directory tree (see the --prefix option) where libraries will be installed. By default this is "lib". Note that on Windows only ".lib" files will be stored in this location. dll files will always be installed to the "bin" directory.

--openssldir=DIR Directory for OpenSSL configuration files, and also the default certificate and key store. Defaults are:

               Unix:           /usr/local/ssl
               Windows:        C:\Program Files\Common Files\SSL
                            or C:\Program Files (x86)\Common Files\SSL
               OpenVMS:        SYS$COMMON:[OPENSSL-COMMON]

--prefix=DIR The top of the installation directory tree. Defaults are:

               Unix:           /usr/local
               Windows:        C:\Program Files\OpenSSL
                            or C:\Program Files (x86)\OpenSSL
               OpenVMS:        SYS$COMMON:[OPENSSL-'version']

--release Build OpenSSL without debugging symbols. This is the default.

--strict-warnings This is a developer flag that switches on various compiler options recommended for OpenSSL development. It only works when using gcc or clang as the compiler. If you are developing a patch for OpenSSL then it is recommended that you use this option where possible.

--with-zlib-include=DIR The directory for the location of the zlib include file. This option is only necessary if enable-zlib (see below) is used and the include file is not already on the system include path.

--with-zlib-lib=LIB On Unix: this is the directory containing the zlib library. If not provided the system library path will be used. On Windows: this is the filename of the zlib library (with or without a path). This flag must be provided if the zlib-dynamic option is not also used. If zlib-dynamic is used then this flag is optional and a default value ("ZLIB1") is used if not provided. On VMS: this is the filename of the zlib library (with or without a path). This flag is optional and if not provided then "GNV$LIBZSHR", "GNV$LIBZSHR32" or "GNV$LIBZSHR64" is used by default depending on the pointer size chosen.

--with-rand-seed=seed1[,seed2,...] A comma separated list of seeding methods which will be tried by OpenSSL in order to obtain random input (a.k.a "entropy") for seeding its cryptographically secure random number generator (CSPRNG). The current seeding methods are:

               os:         Use a trusted operating system entropy source.
                           This is the default method if such an entropy
                           source exists.
               getrandom:  Use the L<getrandom(2)> or equivalent system
               devrandom:  Use the first device from the DEVRANDOM list
                           which can be opened to read random bytes. The
                           DEVRANDOM preprocessor constant expands to
                           "/dev/urandom","/dev/random","/dev/srandom" on
                           most unix-ish operating systems.
               egd:        Check for an entropy generating daemon.
               rdcpu:      Use the RDSEED or RDRAND command if provided by
                           the CPU.
               librandom:  Use librandom (not implemented yet).
               none:       Disable automatic seeding. This is the default
                           on some operating systems where no suitable
                           entropy source exists, or no support for it is
                           implemented yet.

               For more information, see the section 'Note on random number
               generation' at the end of this document.

no-afalgeng Don't build the AFALG engine. This option will be forced if on a platform that does not support AFALG.

enable-ktls Build with Kernel TLS support. This option will enable the use of the Kernel TLS data-path, which can improve performance and allow for the use of sendfile and splice system calls on TLS sockets. The Kernel may use TLS accelerators if any are available on the system. This option will be forced off on systems that do not support the Kernel TLS data-path.

enable-asan Build with the Address sanitiser. This is a developer option only. It may not work on all platforms and should never be used in production environments. It will only work when used with gcc or clang and should be used in conjunction with the no-shared option.

no-asm Do not use assembler code. This should be viewed as debugging/trouble-shooting option rather than production. On some platforms a small amount of assembler code may still be used even with this option.

no-async Do not build support for async operations.

no-autoalginit Don't automatically load all supported ciphers and digests. Typically OpenSSL will make available all of its supported ciphers and digests. For a statically linked application this may be undesirable if small executable size is an objective. This only affects libcrypto. Ciphers and digests will have to be loaded manually using EVP_add_cipher() and EVP_add_digest() if this option is used. This option will force a non-shared build.

no-autoerrinit Don't automatically load all libcrypto/libssl error strings. Typically OpenSSL will automatically load human readable error strings. For a statically linked application this may be undesirable if small executable size is an objective.

no-autoload-config Don't automatically load the default openssl.cnf file. Typically OpenSSL will automatically load a system config file which configures default ssl options.

enable-buildtest-c++ While testing, generate C++ buildtest files that simply check that the public OpenSSL header files are usable standalone with C++.

               Enabling this option demands extra care.  For any
               compiler flag given directly as configuration
               option, you must ensure that it's valid for both
               the C and the C++ compiler.  If not, the C++ build
               test will most likely break.  As an alternative,
               you can use the language specific variables, CFLAGS
               and CXXFLAGS.

no-capieng Don't build the CAPI engine. This option will be forced if on a platform that does not support CAPI.

no-cmp Don't build support for CMP features

no-cms Don't build support for CMS features

no-comp Don't build support for SSL/TLS compression. If this option is left enabled (the default), then compression will only work if the zlib or zlib-dynamic options are also chosen.

enable-crypto-mdebug This now only enables the failed-malloc feature.

enable-crypto-mdebug-backtrace This is a no-op; the project uses the compiler's address/leak sanitizer instead.

no-ct Don't build support for Certificate Transparency.

no-deprecated Don't build with support for deprecated APIs up until and including the version given with "--api" (or the current version of "--api" wasn't given).

no-dgram Don't build support for datagram based BIOs. Selecting this option will also force the disabling of DTLS.

no-dso Don't build support for loading Dynamic Shared Objects.

enable-devcryptoeng Build the /dev/crypto engine. It is automatically selected on BSD implementations, in which case it can be disabled with no-devcryptoeng.

no-dynamic-engine Don't build the dynamically loaded engines. This only has an effect in a "shared" build

no-ec Don't build support for Elliptic Curves.

no-ec2m Don't build support for binary Elliptic Curves

enable-ec_nistp_64_gcc_128 Enable support for optimised implementations of some commonly used NIST elliptic curves. This is only supported on platforms: - with little-endian storage of non-byte types - that tolerate misaligned memory references - where the compiler: - supports the non-standard type __uint128_t - defines the built-in macro SIZEOF_INT128

enable-egd Build support for gathering entropy from EGD (Entropy Gathering Daemon).

no-engine Don't build support for loading engines.

no-err Don't compile in any error strings.

enable-external-tests Enable building of integration with external test suites. This is a developer option and may not work on all platforms. The only supported external test suite at the current time is the BoringSSL test suite. See the file test/README.external for further details.

no-filenames Don't compile in filename and line number information (e.g. for errors and memory allocation).

no-fips Don't compile the FIPS module

enable-fuzz-libfuzzer, enable-fuzz-afl Build with support for fuzzing using either libfuzzer or AFL. These are developer options only. They may not work on all platforms and should never be used in production environments. See the file fuzz/README.md for further details.

no-gost Don't build support for GOST based ciphersuites. Note that if this feature is enabled then GOST ciphersuites are only available if the GOST algorithms are also available through loading an externally supplied engine.

no-legacy Don't build the legacy provider. Disabling this also disables the legacy algorithms: MD2 (already disabled by default).

no-makedepend Don't generate dependencies.

no-module Don't build any dynamically loadable engines. This also implies 'no-dynamic-engine'.

no-multiblock Don't build support for writing multiple records in one go in libssl (Note: this is a different capability to the pipelining functionality).

no-nextprotoneg Don't build support for the NPN TLS extension.

no-ocsp Don't build support for OCSP.

no-padlockeng no-hw-padlock Don't build the padlock engine. ('no-hw-padlock' is deprecated and should not be used)

no-pic Don't build with support for Position Independent Code.

no-pinshared By default OpenSSL will attempt to stay in memory until the process exits. This is so that libcrypto and libssl can be properly cleaned up automatically via an "atexit()" handler. The handler is registered by libcrypto and cleans up both libraries. On some platforms the atexit() handler will run on unload of libcrypto (if it has been dynamically loaded) rather than at process exit. This option can be used to stop OpenSSL from attempting to stay in memory until the process exits. This could lead to crashes if either libcrypto or libssl have already been unloaded at the point that the atexit handler is invoked, e.g. on a platform which calls atexit() on unload of the library, and libssl is unloaded before libcrypto then a crash is likely to happen. Applications can suppress running of the atexit() handler at run time by using the OPENSSL_INIT_NO_ATEXIT option to OPENSSL_init_crypto(). See the man page for it for further details.

no-posix-io Don't use POSIX IO capabilities.

no-psk Don't build support for Pre-Shared Key based ciphersuites.

no-rdrand Don't use hardware RDRAND capabilities.

no-rfc3779 Don't build support for RFC3779 ("X.509 Extensions for IP Addresses and AS Identifiers")

sctp Build support for SCTP

no-shared Do not create shared libraries, only static ones. See "Note on shared libraries" below.

no-sock Don't build support for socket BIOs

no-srp Don't build support for SRP or SRP based ciphersuites.

no-srtp Don't build SRTP support

no-sse2 Exclude SSE2 code paths from 32-bit x86 assembly modules. Normally SSE2 extension is detected at run-time, but the decision whether or not the machine code will be executed is taken solely on CPU capability vector. This means that if you happen to run OS kernel which does not support SSE2 extension on Intel P4 processor, then your application might be exposed to "illegal instruction" exception. There might be a way to enable support in kernel, e.g. FreeBSD kernel can be compiled with CPU_ENABLE_SSE, and there is a way to disengage SSE2 code paths upon application start-up, but if you aim for wider "audience" running such kernel, consider no-sse2. Both the 386 and no-asm options imply no-sse2.

enable-ssl-trace Build with the SSL Trace capabilities (adds the "-trace" option to s_client and s_server).

no-static-engine Don't build the statically linked engines. This only has an impact when not built "shared".

no-stdio Don't use anything from the C header file "stdio.h" that makes use of the "FILE" type. Only libcrypto and libssl can be built in this way. Using this option will suppress building the command line applications. Additionally since the OpenSSL tests also use the command line applications the tests will also be skipped.

no-tests Don't build test programs or run any test.

no-threads Don't try to build with support for multi-threaded applications.

threads Build with support for multi-threaded applications. Most platforms will enable this by default. However if on a platform where this is not the case then this will usually require additional system-dependent options! See "Note on multi-threading" below.

enable-trace Build with support for the integrated tracing api. See manual pages OSSL_trace_set_channel(3) and OSSL_trace_enabled(3) for details.

no-ts Don't build Time Stamping Authority support.

enable-ubsan Build with the Undefined Behaviour sanitiser. This is a developer option only. It may not work on all platforms and should never be used in production environments. It will only work when used with gcc or clang and should be used in conjunction with the "-DPEDANTIC" option (or the --strict-warnings option).

no-ui Don't build with the "UI" capability (i.e. the set of features enabling text based prompts).

enable-unit-test Enable additional unit test APIs. This should not typically be used in production deployments.

no-uplink Don't build support for UPLINK interface.

enable-weak-ssl-ciphers Build support for SSL/TLS ciphers that are considered "weak" (e.g. RC4 based ciphersuites).

zlib Build with support for zlib compression/decompression.

zlib-dynamic Like "zlib", but has OpenSSL load the zlib library dynamically when needed. This is only supported on systems where loading of shared libraries is supported.

386 In 32-bit x86 builds, when generating assembly modules, use the 80386 instruction set only (the default x86 code is more efficient, but requires at least a 486). Note: This doesn't affect code generated by compiler, you're likely to complement configuration command line with suitable compiler-specific option.

no- Don't build support for negotiating the specified SSL/TLS protocol (one of ssl, ssl3, tls, tls1, tls1_1, tls1_2, tls1_3, dtls, dtls1 or dtls1_2). If "no-tls" is selected then all of tls1, tls1_1, tls1_2 and tls1_3 are disabled. Similarly "no-dtls" will disable dtls1 and dtls1_2. The "no-ssl" option is synonymous with "no-ssl3". Note this only affects version negotiation. OpenSSL will still provide the methods for applications to explicitly select the individual protocol versions.

no--method As for no- but in addition do not build the methods for applications to explicitly select individual protocol versions. Note that there is no "no-tls1_3-method" option because there is no application method for TLSv1.3. Using individual protocol methods directly is deprecated. Applications should use TLS_method() instead.

enable- Build with support for the specified algorithm, where is one of: md2 or rc5.

no- Build without support for the specified algorithm, where is one of: aria, bf, blake2, camellia, cast, chacha, cmac, des, dh, dsa, ecdh, ecdsa, idea, md4, mdc2, ocb, poly1305, rc2, rc4, rmd160, scrypt, seed, siphash, siv, sm2, sm3, sm4 or whirlpool. The "ripemd" algorithm is deprecated and if used is synonymous with rmd160.

-Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static These system specific options will be recognised and passed through to the compiler to allow you to define preprocessor symbols, specify additional libraries, library directories or other compiler options. It might be worth noting that some compilers generate code specifically for processor the compiler currently executes on. This is not necessarily what you might have in mind, since it might be unsuitable for execution on other, typically older, processor. Consult your compiler documentation.

               Take note of the VAR=value documentation below and how
               these flags interact with those variables.

-xxx, +xxx, /xxx Additional options that are not otherwise recognised are passed through as they are to the compiler as well. Unix-style options beginning with a '-' or '+' and Windows-style options beginning with a '/' are recognized. Again, consult your compiler documentation.

               If the option contains arguments separated by spaces,
               then the URL-style notation %20 can be used for the space
               character in order to avoid having to quote the option.
               For example, -opt%20arg gets expanded to -opt arg.
               In fact, any ASCII character can be encoded as %xx using its
               hexadecimal encoding.

               Take note of the VAR=value documentation below and how
               these flags interact with those variables.

VAR=value Assignment of environment variable for Configure. These work just like normal environment variable assignments, but are supported on all platforms and are confined to the configuration scripts only. These assignments override the corresponding value in the inherited environment, if there is one.

               The following variables are used as "make variables" and
               can be used as an alternative to giving preprocessor,
               compiler and linker options directly as configuration.
               The following variables are supported:

               AR              The static library archiver.
               ARFLAGS         Flags for the static library archiver.
               AS              The assembler compiler.
               ASFLAGS         Flags for the assembler compiler.
               CC              The C compiler.
               CFLAGS          Flags for the C compiler.
               CXX             The C++ compiler.
               CXXFLAGS        Flags for the C++ compiler.
               CPP             The C/C++ preprocessor.
               CPPFLAGS        Flags for the C/C++ preprocessor.
               CPPDEFINES      List of CPP macro definitions, separated
                               by a platform specific character (':' or
                               space for Unix, ';' for Windows, ',' for
                               VMS).  This can be used instead of using
                               -D (or what corresponds to that on your
                               compiler) in CPPFLAGS.
               CPPINCLUDES     List of CPP inclusion directories, separated
                               the same way as for CPPDEFINES.  This can
                               be used instead of -I (or what corresponds
                               to that on your compiler) in CPPFLAGS.
               HASHBANGPERL    Perl invocation to be inserted after '#!'
                               in public perl scripts (only relevant on
               LD              The program linker (not used on Unix, $(CC)
                               is used there).
               LDFLAGS         Flags for the shared library, DSO and
                               program linker.
               LDLIBS          Extra libraries to use when linking.
                               Takes the form of a space separated list
                               of library specifications on Unix and
                               Windows, and as a comma separated list of
                               libraries on VMS.
               RANLIB          The library archive indexer.
               RC              The Windows resource compiler.
               RCFLAGS         Flags for the Windows resource compiler.
               RM              The command to remove files and directories.

               These cannot be mixed with compiling / linking flags given
               on the command line.  In other words, something like this
               isn't permitted.

                   ./config -DFOO CPPFLAGS=-DBAR -DCOOKIE

               Backward compatibility note:

               To be compatible with older configuration scripts, the
               environment variables are ignored if compiling / linking
               flags are given on the command line, except for these:

               and WINDRES

               For example, the following command will not see -DBAR:

                    CPPFLAGS=-DBAR ./config -DCOOKIE

               However, the following will see both set variables:

                    CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- \
                    ./config -DCOOKIE

               If CC is set, it is advisable to also set CXX to ensure
               both C and C++ compilers are in the same "family".  This
               becomes relevant with 'enable-external-tests' and

reconf reconfigure Reconfigure from earlier data. This fetches the previous command line options and environment from data saved in "configdata.pm", and runs the configuration process again, using these options and environment. Note: NO other option is permitted together with "reconf". This means that you also MUST use "./Configure" (or what corresponds to that on non-Unix platforms) directly to invoke this option. Note: The original configuration saves away values for ALL environment variables that were used, and if they weren't defined, they are still saved away with information that they weren't originally defined. This information takes precedence over environment variables that are defined when reconfiguring.

Displaying configuration data

The configuration script itself will say very little, and finishes by creating "configdata.pm". This perl module can be loaded by other scripts to find all the configuration data, and it can also be used as a script to display all sorts of configuration data in a human readable form.

For more information, please do:

   $ ./configdata.pm --help                         # Unix


   $ perl configdata.pm --help                      # Windows and VMS

Installation in Detail

1a. Configure OpenSSL for your operation system automatically:

 NOTE: This is not available on Windows.

   $ ./config [[ options ]]                         # Unix


   $ @config [[ options ]]                          ! OpenVMS

 For the remainder of this text, the Unix form will be used in all
 examples, please use the appropriate form for your platform.

 This guesses at your operating system (and compiler, if necessary) and
 configures OpenSSL based on this guess. Run ./config -t to see
 if it guessed correctly. If you want to use a different compiler, you
 are cross-compiling for another platform, or the ./config guess was
 wrong for other reasons, go to step 1b. Otherwise go to step 2.

 On some systems, you can include debugging information as follows:

   $ ./config -d [[ options ]]

1b. Configure OpenSSL for your operating system manually

 OpenSSL knows about a range of different operating system, hardware and
 compiler combinations. To see the ones it knows about, run

   $ ./Configure                                    # Unix


   $ perl Configure                                 # All other platforms

 For the remainder of this text, the Unix form will be used in all
 examples, please use the appropriate form for your platform.

 Pick a suitable name from the list that matches your system. For most
 operating systems there is a choice between using "cc" or "gcc".  When
 you have identified your system (and if necessary compiler) use this name
 as the argument to Configure. For example, a "linux-elf" user would

   $ ./Configure linux-elf [[ options ]]

 If your system isn't listed, you will have to create a configuration
 file named Configurations/{{ something }}.conf and add the correct
 configuration for your system. See the available configs as examples
 and read Configurations/README and Configurations/README.design for
 more information.

 The generic configurations "cc" or "gcc" should usually work on 32 bit
 Unix-like systems.

 Configure creates a build file ("Makefile" on Unix, "makefile" on Windows
 and "descrip.mms" on OpenVMS) from a suitable template in Configurations,
 and defines various macros in include/openssl/configuration.h (generated
 from include/openssl/configuration.h.in).

1c. Configure OpenSSL for building outside of the source tree.

 OpenSSL can be configured to build in a build directory separate from
 the directory with the source code.  It's done by placing yourself in
 some other directory and invoking the configuration commands from

 Unix example:

   $ mkdir /var/tmp/openssl-build
   $ cd /var/tmp/openssl-build
   $ /PATH/TO/OPENSSL/SOURCE/config [[ options ]]


   $ /PATH/TO/OPENSSL/SOURCE/Configure {{ target }} [[ options ]]

 OpenVMS example:

   $ set default sys$login:
   $ create/dir [.tmp.openssl-build]
   $ set default [.tmp.openssl-build]
   $ @[PATH.TO.OPENSSL.SOURCE]config [[ options ]]


   $ @[PATH.TO.OPENSSL.SOURCE]Configure {{ target }} [[ options ]]

 Windows example:

   $ C:
   $ mkdir \temp-openssl
   $ cd \temp-openssl
   $ perl d:\PATH\TO\OPENSSL\SOURCE\Configure {{ target }} [[ options ]]

 Paths can be relative just as well as absolute.  Configure will
 do its best to translate them to relative paths whenever possible.
  1. Build OpenSSL by running:

    $ make # Unix $ mms ! (or mmk) OpenVMS $ nmake # Windows

    This will build the OpenSSL libraries (libcrypto.a and libssl.a on Unix, corresponding on other platforms) and the OpenSSL binary ("openssl"). The libraries will be built in the top-level directory, and the binary will be in the "apps" subdirectory.


    If the build fails, look at the output. There may be reasons for the failure that aren't problems in OpenSSL itself (like missing standard headers).

    If the build succeeded previously, but fails after a source or configuration change, it might be helpful to clean the build tree before attempting another build. Use this command:

    $ make clean # Unix $ mms clean ! (or mmk) OpenVMS $ nmake clean # Windows

    Assembler error messages can sometimes be sidestepped by using the "no-asm" configuration option.

    Compiling parts of OpenSSL with gcc and others with the system compiler will result in unresolved symbols on some systems.

    If you are still having problems you can get help by sending an email to the openssl-users email list (see https://www.openssl.org/community/mailinglists.html for details). If it is a bug with OpenSSL itself, please open an issue on GitHub, at https://github.com/openssl/openssl/issues. Please review the existing ones first; maybe the bug was already reported or has already been fixed.

  2. After a successful build, the libraries should be tested. Run:

    $ make test # Unix $ mms test ! OpenVMS $ nmake test # Windows

    NOTE: you MUST run the tests from an unprivileged account (or disable your privileges temporarily if your platform allows it).

    If some tests fail, look at the output. There may be reasons for the failure that isn't a problem in OpenSSL itself (like a malfunction with Perl). You may want increased verbosity, that can be accomplished like this:

    Verbosity on failure only (make macro VERBOSE_FAILURE or VF):

    $ make VF=1 test # Unix $ mms /macro=(VF=1) test ! OpenVMS $ nmake VF=1 test # Windows

    Full verbosity (make macro VERBOSE or V):

    $ make V=1 test # Unix $ mms /macro=(V=1) test ! OpenVMS $ nmake V=1 test # Windows

    If you want to run just one or a few specific tests, you can use the make variable TESTS to specify them, like this:

    $ make TESTS='test_rsa test_dsa' test # Unix $ mms/macro="TESTS=test_rsa test_dsa" test ! OpenVMS $ nmake TESTS='test_rsa test_dsa' test # Windows

    And of course, you can combine (Unix example shown):

    $ make VF=1 TESTS='test_rsa test_dsa' test

    You can find the list of available tests like this:

    $ make list-tests # Unix $ mms list-tests ! OpenVMS $ nmake list-tests # Windows

    Have a look at the manual for the perl module Test::Harness to see what other HARNESS_* variables there are.

    If you find a problem with OpenSSL itself, try removing any compiler optimization flags from the CFLAGS line in Makefile and run "make clean; make" or corresponding.

    To report a bug please open an issue on GitHub, at https://github.com/openssl/openssl/issues.

    For more details on how the make variables TESTS can be used, see section TESTS in Detail below.

  3. If everything tests ok, install OpenSSL with

    $ make install # Unix $ mms install ! OpenVMS $ nmake install # Windows

    Note that in order to perform the install step above you need to have appropriate permissions to write to the installation directory.

    The above commands will install all the software components in this directory tree under PREFIX (the directory given with --prefix or its default):


    bin/           Contains the openssl binary and a few other
                   utility scripts.
                   Contains the header files needed if you want
                   to build your own programs that use libcrypto
                   or libssl.
    lib            Contains the OpenSSL library files.
    lib/engines    Contains the OpenSSL dynamically loadable engines.
    share/man/man1 Contains the OpenSSL command line man-pages.
    share/man/man3 Contains the OpenSSL library calls man-pages.
    share/man/man5 Contains the OpenSSL configuration format man-pages.
    share/man/man7 Contains the OpenSSL other misc man-pages.
                   Contains the HTML rendition of the man-pages.

    OpenVMS ('arch' is replaced with the architecture name, "Alpha" or "ia64", 'sover' is replaced with the shared library version (0101 for 1.1), and 'pz' is replaced with the pointer size OpenSSL was built with):

    [.EXE.'arch']  Contains the openssl binary.
    [.EXE]         Contains a few utility scripts.
                   Contains the header files needed if you want
                   to build your own programs that use libcrypto
                   or libssl.
    [.LIB.'arch']  Contains the OpenSSL library files.
                   Contains the OpenSSL dynamically loadable engines.
    [.SYS$STARTUP] Contains startup, login and shutdown scripts.
                   These define appropriate logical names and
                   command symbols.
    [.SYSTEST]     Contains the installation verification procedure.
    [.HTML]        Contains the HTML rendition of the manual pages.

    Additionally, install will add the following directories under OPENSSLDIR (the directory given with --openssldir or its default) for you convenience:

    certs          Initially empty, this is the default location
                   for certificate files.
    private        Initially empty, this is the default location
                   for private key files.
    misc           Various scripts.

    The installation directory should be appropriately protected to ensure unprivileged users cannot make changes to OpenSSL binaries or files, or install engines. If you already have a pre-installed version of OpenSSL as part of your Operating System it is recommended that you do not overwrite the system version and instead install to somewhere else.

    Package builders who want to configure the library for standard locations, but have the package installed somewhere else so that it can easily be packaged, can use

    $ make DESTDIR=/tmp/package-root install # Unix $ mms/macro="DESTDIR=TMP:[PACKAGE-ROOT]" install ! OpenVMS

    The specified destination directory will be prepended to all installation target paths.

Compatibility issues with previous OpenSSL versions:

  • COMPILING existing applications

    Starting with version 1.1.0, OpenSSL hides a number of structures that were previously open. This includes all internal libssl structures and a number of EVP types. Accessor functions have been added to allow controlled access to the structures' data.

    This means that some software needs to be rewritten to adapt to the new ways of doing things. This often amounts to allocating an instance of a structure explicitly where you could previously allocate them on the stack as automatic variables, and using the provided accessor functions where you would previously access a structure's field directly.

    Some APIs have changed as well. However, older APIs have been preserved when possible.

Environment Variables

A number of environment variables can be used to provide additional control over the build process. Typically these should be defined prior to running config or Configure. Not all environment variables are relevant to all platforms.

AR The name of the ar executable to use.

BUILDFILE Use a different build file name than the platform default ("Makefile" on Unix-like platforms, "makefile" on native Windows, "descrip.mms" on OpenVMS). This requires that there is a corresponding build file template. See Configurations/README for further information.

CC The compiler to use. Configure will attempt to pick a default compiler for your platform but this choice can be overridden using this variable. Set it to the compiler executable you wish to use, e.g. "gcc" or "clang".

CROSS_COMPILE This environment variable has the same meaning as for the "--cross-compile-prefix" Configure flag described above. If both are set then the Configure flag takes precedence.

NM The name of the nm executable to use.

OPENSSL_LOCAL_CONFIG_DIR OpenSSL comes with a database of information about how it should be built on different platforms as well as build file templates for those platforms. The database is comprised of ".conf" files in the Configurations directory. The build file templates reside there as well as ".tmpl" files. See the file Configurations/README for further information about the format of ".conf" files as well as information on the ".tmpl" files. In addition to the standard ".conf" and ".tmpl" files, it is possible to create your own ".conf" and ".tmpl" files and store them locally, outside the OpenSSL source tree. This environment variable can be set to the directory where these files are held and will be considered by Configure before it looks in the standard directories.

PERL The name of the Perl executable to use when building OpenSSL. This variable is used in config script only. Configure on the other hand imposes the interpreter by which it itself was executed on the whole build procedure.

HASHBANGPERL The command string for the Perl executable to insert in the #! line of perl scripts that will be publicly installed. Default: /usr/bin/env perl Note: the value of this variable is added to the same scripts on all platforms, but it's only relevant on Unix-like platforms.

RC The name of the rc executable to use. The default will be as defined for the target platform in the ".conf" file. If not defined then "windres" will be used. The WINDRES environment variable is synonymous to this. If both are defined then RC takes precedence.

RANLIB The name of the ranlib executable to use.


Makefile targets

The Configure script generates a Makefile in a format relevant to the specific platform. The Makefiles provide a number of targets that can be used. Not all targets may be available on all platforms. Only the most common targets are described here. Examine the Makefiles themselves for the full list.

all The target to build all the software components and documentation.

build_sw Build all the software components. THIS IS THE DEFAULT TARGET.

build_docs Build all documentation components.

clean Remove all build artefacts and return the directory to a "clean" state.

depend Rebuild the dependencies in the Makefiles. This is a legacy option that no longer needs to be used since OpenSSL 1.1.0.

install Install all OpenSSL components.

install_sw Only install the OpenSSL software components.

install_docs Only install the OpenSSL documentation components.

install_man_docs Only install the OpenSSL man pages (Unix only).

install_html_docs Only install the OpenSSL html documentation.

list-tests Prints a list of all the self test names.

test Build and run the OpenSSL self tests.

uninstall Uninstall all OpenSSL components.

reconfigure reconf Re-run the configuration process, as exactly as the last time as possible.

update This is a developer option. If you are developing a patch for OpenSSL you may need to use this if you want to update automatically generated files; add new error codes or add new (or change the visibility of) public API functions. (Unix only).

TESTS in Detail

The make variable TESTS supports a versatile set of space separated tokens with which you can specify a set of tests to be performed. With a "current set of tests" in mind, initially being empty, here are the possible tokens:

alltests The current set of tests becomes the whole set of available tests (as listed when you do 'make list-tests' or similar). xxx Adds the test 'xxx' to the current set of tests. -xxx Removes 'xxx' from the current set of tests. If this is the first token in the list, the current set of tests is first assigned the whole set of available tests, effectively making this token equivalent to TESTS="alltests -xxx". nn Adds the test group 'nn' (which is a number) to the current set of tests. -nn Removes the test group 'nn' from the current set of tests. If this is the first token in the list, the current set of tests is first assigned the whole set of available tests, effectively making this token equivalent to TESTS="alltests -xxx".

Also, all tokens except for "alltests" may have wildcards, such as *. (on Unix and Windows, BSD style wildcards are supported, while on VMS, it's VMS style wildcards)

Example: All tests except for the fuzz tests:

$ make TESTS=-test_fuzz test

or (if you want to be explicit)

$ make TESTS='alltests -test_fuzz' test

Example: All tests that have a name starting with "test_ssl" but not those starting with "test_ssl_":

$ make TESTS='test_ssl* -test_ssl_*' test

Example: Only test group 10:

$ make TESTS='10'

Example: All tests except the slow group (group 99):

$ make TESTS='-99'

Example: All tests in test groups 80 to 99 except for tests in group 90:

$ make TESTS='[89]? -90'

To stochastically verify that the algorithm that produces uniformly distributed random numbers is operating correctly (with a false positive rate of 0.01%):

$ ./util/shlib_wrap.sh test/bntest -stochastic

Note on multi-threading

For some systems, the OpenSSL Configure script knows what compiler options are needed to generate a library that is suitable for multi-threaded applications. On these systems, support for multi-threading is enabled by default; use the "no-threads" option to disable (this should never be necessary).

On other systems, to enable support for multi-threading, you will have to specify at least two options: "threads", and a system-dependent option. (The latter is "-D_REENTRANT" on various systems.) The default in this case, obviously, is not to include support for multi-threading (but you can still use "no-threads" to suppress an annoying warning message from the Configure script.)

OpenSSL provides built-in support for two threading models: pthreads (found on most UNIX/Linux systems), and Windows threads. No other threading models are supported. If your platform does not provide pthreads or Windows threads then you should Configure with the "no-threads" option.

Notes on shared libraries

For most systems the OpenSSL Configure script knows what is needed to build shared libraries for libcrypto and libssl. On these systems the shared libraries will be created by default. This can be suppressed and only static libraries created by using the "no-shared" option. On systems where OpenSSL does not know how to build shared libraries the "no-shared" option will be forced and only static libraries will be created.

Shared libraries are named a little differently on different platforms. One way or another, they all have the major OpenSSL version number as part of the file name, i.e. for OpenSSL 1.1.x, 1.1 is somehow part of the name.

On most POSIX platforms, shared libraries are named libcrypto.so.1.1 and libssl.so.1.1.

on Cygwin, shared libraries are named cygcrypto-1.1.dll and cygssl-1.1.dll with import libraries libcrypto.dll.a and libssl.dll.a.

On Windows build with MSVC or using MingW, shared libraries are named libcrypto-1_1.dll and libssl-1_1.dll for 32-bit Windows, libcrypto-1_1-x64.dll and libssl-1_1-x64.dll for 64-bit x86_64 Windows, and libcrypto-1_1-ia64.dll and libssl-1_1-ia64.dll for IA64 Windows. With MSVC, the import libraries are named libcrypto.lib and libssl.lib, while with MingW, they are named libcrypto.dll.a and libssl.dll.a.

On VMS, shareable images (VMS speak for shared libraries) are named ossl$libcrypto0101_shr.exe and ossl$libssl0101_shr.exe. However, when OpenSSL is specifically built for 32-bit pointers, the shareable images are named ossl$libcrypto0101_shr32.exe and ossl$libssl0101_shr32.exe instead, and when built for 64-bit pointers, they are named ossl$libcrypto0101_shr64.exe and ossl$libssl0101_shr64.exe.

Note on random number generation

Availability of cryptographically secure random numbers is required for secret key generation. OpenSSL provides several options to seed the internal CSPRNG. If not properly seeded, the internal CSPRNG will refuse to deliver random bytes and a "PRNG not seeded error" will occur.

The seeding method can be configured using the --with-rand-seed option, which can be used to specify a comma separated list of seed methods. However in most cases OpenSSL will choose a suitable default method, so it is not necessary to explicitly provide this option. Note also that not all methods are available on all platforms.

I) On operating systems which provide a suitable randomness source (in form of a system call or system device), OpenSSL will use the optimal available method to seed the CSPRNG from the operating system's randomness sources. This corresponds to the option --with-rand-seed=os.

II) On systems without such a suitable randomness source, automatic seeding and reseeding is disabled (--with-rand-seed=none) and it may be necessary to install additional support software to obtain a random seed and reseed the CSPRNG manually. Please check out the manual pages for RAND_add(), RAND_bytes(), RAND_egd(), and the FAQ for more information.