OPENSSL INSTALLATION -------------------- This document describes installation on all supported operating systems (the Linux/Unix family, 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.VMS (OpenVMS) * NOTES.WIN (any supported Windows) * NOTES.DJGPP (DOS platform with DJGPP) 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 these: $ 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: $ ./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 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 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] 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 Don't build with support for deprecated APIs below the specified version number. For example "--api=1.1.0" will remove support for all APIS that were deprecated in OpenSSL version 1.1.0 or below. --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/10-main.cf sections. 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. --debug Build OpenSSL with debugging symbols. --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. no-afalgeng Don't build the AFALG engine. This option will be forced if on a platform that does not support AFALG. 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. On some platforms a small amount of assembler code may still be used. 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-capieng Don't build the CAPI engine. This option will be forced if on a platform that does not support CAPI. 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 Build support for debugging memory allocated via OPENSSL_malloc() or OPENSSL_zalloc(). enable-crypto-mdebug-backtrace As for crypto-mdebug, but additionally provide backtrace information for allocated memory. TO BE USED WITH CARE: this uses GNU C functionality, and is therefore not usable for non-GNU config targets. If your build complains about the use of '-rdynamic' or the lack of header file execinfo.h, this option is not for you. ALSO NOTE that even though execinfo.h is available on your system (through Gnulib), the functions might just be stubs that do nothing. no-ct Don't build support for Certificate Transparency. no-deprecated Don't build with support for any deprecated APIs. This is the same as using "--api" and supplying the latest version number. 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. 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 some platforms. 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). 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. enable-heartbeats Build support for DTLS heartbeats. no-hw-padlock Don't build the padlock engine. no-makedepend Don't generate dependencies. 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-pic Don't build with support for Position Independent Code. 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. 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 any C "stdio" features. 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-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. 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. 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 On Intel hardware, use the 80386 instruction set only (the default x86 code is more efficient, but requires at least a 486). Note: Use compiler flags for any other CPU specific configuration, e.g. "-m32" to build x86 code on an x64 system. enable-tls1_3 TODO(TLS1.3): Make this enabled by default Build support for TLS1.3. Note: This is a WIP feature and does not currently interoperate with other TLS1.3 implementations! Use with caution!! no- Don't build support for negotiating the specified SSL/TLS protocol (one of ssl, ssl3, tls, tls1, tls1_1, tls1_2, dtls, dtls1 or dtls1_2). If "no-tls" is selected then all of tls1, tls1_1 and tls1_2 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. 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: bf, blake2, camellia, cast, chacha, cmac, des, dh, dsa, ecdh, ecdsa, idea, md4, mdc2, ocb, poly1305, rc2, rc4, rmd160, scrypt, seed or whirlpool. The "ripemd" algorithm is deprecated and if used is synonymous with rmd160. -Dxxx, -lxxx, -Lxxx, -fxxx, -mXXX, -Kxxx These system specific options will be passed through to the compiler to allow you to define preprocessor symbols, specify additional libraries, library directories or other compiler options. Installation in Detail ---------------------- 1a. Configure OpenSSL for your operation system automatically: NOTE: This is not available on Windows. $ ./config [[ options ]] # Unix or $ @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 or $ 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 run: $ ./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/opensslconf.h (generated from include/openssl/opensslconf.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 there. Unix example: $ mkdir /var/tmp/openssl-build $ cd /var/tmp/openssl-build $ /PATH/TO/OPENSSL/SOURCE/config [[ options ]] or $ /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 ]] or $ @[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. 2. 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 you are 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. (If you encounter assembler error messages, try the "no-asm" configuration option as an immediate fix.) Compiling parts of OpenSSL with gcc and others with the system compiler will result in unresolved symbols on some systems. 3. 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: $ make VERBOSE=1 test # Unix $ mms /macro=(VERBOSE=1) test ! OpenVMS $ nmake VERBOSE=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 VERBOSE=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. Please send bug reports to . For more details on how the make variables TESTS can be used, see section TESTS in Detail below. 4. If everything tests ok, install OpenSSL with $ make install # Unix $ mms install ! OpenVMS $ nmake install # Windows This will install all the software components in this directory tree under PREFIX (the directory given with --prefix or its default): Unix: bin/ Contains the openssl binary and a few other utility scripts. include/openssl 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. share/doc/openssl/html/man1 share/doc/openssl/html/man3 share/doc/openssl/html/man5 share/doc/openssl/html/man7 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. [.include.openssl] 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. [.ENGINES'sover''pz'.'arch'] 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. 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 OpenSSL 1.1.0 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 Unixly 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 publically 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. WINDRES See RC. 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 default target to build all the software 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 in 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. 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" 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 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 POSIXly 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 PRNG. If not properly seeded, the internal PRNG will refuse to deliver random bytes and a "PRNG not seeded error" will occur. On systems without /dev/urandom (or similar) device, it may be necessary to install additional support software to obtain a random seed. Please check out the manual pages for RAND_add(), RAND_bytes(), RAND_egd(), and the FAQ for more information.