4 This document describes installation on all supported operating
5 systems (the Unix/Linux family, including macOS), OpenVMS,
11 - [Prerequisites](#prerequisites)
12 - [Notational Conventions](#notational-conventions)
13 - [Quick Installation Guide](#quick-installation-guide)
14 - [Building OpenSSL](#building-openssl)
15 - [Installing OpenSSL](#installing-openssl)
16 - [Configuration Options](#configuration-options)
17 - [API Level](#api-level)
18 - [Cross Compile Prefix](#cross-compile-prefix)
19 - [Build Type](#build-type)
20 - [Directories](#directories)
21 - [Compiler Warnings](#compiler-warnings)
22 - [ZLib Flags](#zlib-flags)
23 - [Seeding the Random Generator](#seeding-the-random-generator)
24 - [Enable and Disable Features](#enable-and-disable-features)
25 - [Displaying configuration data](#displaying-configuration-data)
26 - [Installation Steps in Detail](#installation-steps-in-detail)
27 - [Configure](#configure-openssl)
28 - [Build](#build-openssl)
29 - [Test](#test-openssl)
30 - [Install](#install-openssl)
31 - [Advanced Build Options](#advanced-build-options)
32 - [Environment Variables](#environment-variables)
33 - [Makefile Targets](#makefile-targets)
34 - [Running Selected Tests](#running-selected-tests)
35 - [Troubleshooting](#troubleshooting)
36 - [Configuration Problems](#configuration-problems)
37 - [Build Failures](#build-failures)
38 - [Test Failures](#test-failures)
40 - [Notes on multi-threading](#notes-on-multi-threading)
41 - [Notes on shared libraries](#notes-on-shared-libraries)
42 - [Notes on random number generation](#notes-on-random-number-generation)
47 To install OpenSSL, you will need:
49 * A make implementation
50 * Perl 5 with core modules (please read [NOTES.PERL](NOTES.PERL))
51 * The Perl module Text::Template (please read [NOTES.PERL](NOTES.PERL))
53 * a development environment in the form of development libraries and C
55 * a supported operating system
57 For additional platform specific requirements, solutions to specific
58 issues and other details, please read one of these:
60 * [NOTES.UNIX](NOTES.UNIX) - notes for Unix like systems
61 * [NOTES.VMS](NOTES.VMS) - notes related to OpenVMS
62 * [NOTES.WIN](NOTES.WIN) - notes related to the Windows platform
63 * [NOTES.DJGPP](NOTES.DJGPP) - building for DOS with DJGPP
64 * [NOTES.ANDROID](NOTES.ANDROID) - building for Android platforms (using NDK)
65 * [NOTES.VALGRIND](NOTES.VALGRIND) - testing with Valgrind
66 * [NOTES.PERL](NOTES.PERL) - some notes on Perl
68 Notational conventions
69 ======================
71 Throughout this document, we use the following conventions.
76 Any line starting with a dollar sign is a command line.
80 The dollar sign indicates the shell prompt and is not to be entered as
86 Several words in curly braces separated by pipe characters indicate a
87 **mandatory choice**, to be replaced with one of the given words.
90 $ echo { WORD1 | WORD2 | WORD3 }
92 represents one of the following three commands
100 One or several words in square brackets separated by pipe characters
101 denote an **optional choice**. It is similar to the mandatory choice,
102 but it can also be omitted entirely.
106 $ echo [ WORD1 | WORD2 | WORD3 ]
108 represents one of the four commands
121 **Mandatory arguments** are enclosed in double curly braces.
122 A simple example would be
124 $ type {{ filename }}
126 which is to be understood to use the command `type` on some file name
127 determined by the user.
129 **Optional Arguments** are enclosed in double square brackets.
133 Note that the notation assumes spaces around {, }, [, ], {{, }} and
134 [[, ]]. This is to differentiate from OpenVMS directory
135 specifications, which also use [ and ], but without spaces.
137 Quick Installation Guide
138 ========================
140 If you just want to get OpenSSL installed without bothering too much
141 about the details, here is the short version of how to build and install
142 OpenSSL. If any of the following steps fails, please consult the
143 [Installation in Detail](#installation-in-detail) section below.
148 Use the following commands to configure, build and test OpenSSL.
149 The testing is optional, but recommended if you intend to install
150 OpenSSL for production use.
152 ### Unix / Linux / macOS
160 Use the following commands to build OpenSSL:
168 If you are using Visual Studio, open a Developer Command Prompt and
169 and issue the following commands to build OpenSSL.
171 $ perl Configure { VC-WIN32 | VC-WIN64A | VC-WIN64I | VC-CE }
175 As mentioned in the [Choices](#choices) section, you need to pick one
176 of the four Configure targets in the first command.
178 Most likely you will be using the VC-WIN64A target for 64bit Windows
179 binaries (AMD64) or VC-WIN32 for 32bit Windows binaries (X86).
180 The other two options are VC_WIN64I (Intel IA64, Itanium) and
181 VC-CE (Windows CE) are rather uncommon nowadays.
186 The following commands will install OpenSSL to a default system location.
188 **Danger Zone:** even if you are impatient, please read the following two
189 paragraphs carefully before you install OpenSSL.
191 For security reasons the default system location is by default not writable
192 for unprivileged users. So for the final installation step administrative
193 privileges are required. The default system location and the procedure to
194 obtain administrative privileges depends on the operating sytem.
195 It is recommended to compile and test OpenSSL with normal user privileges
196 and use administrative privileges only for the final installation step.
198 On some platforms OpenSSL is preinstalled as part of the Operating System.
199 In this case it is highly recommended not to overwrite the system versions,
200 because other applications or libraries might depend on it.
201 To avoid breaking other applications, install your copy of OpenSSL to a
202 [different location](#installing-to-a-different-location) which is not in
203 the global search path for system libraries.
205 Finally, if you plan on using the FIPS module, you need to read the
206 [Post-installation Notes](#post-installation-notes) further down.
208 ### Unix / Linux / macOS
210 Depending on your distribution, you need to run the following command as
211 root user or prepend `sudo` to the command:
215 By default, OpenSSL will be installed to
219 More precisely, the files will be installed into the subdirectories
226 depending on the file type, as it is custom on Unix-like operating systems.
230 Use the following command to install OpenSSL.
234 By default, OpenSSL will be installed to
236 SYS$COMMON:[OPENSSL-'version'...]
238 where 'version' is the OpenSSL version number with underscores instead
243 If you are using Visual Studio, open the Developer Command Prompt _elevated_
244 and issue the following command.
248 The easiest way to elevate the Command Prompt is to press and hold down
249 the both the `<CTRL>` and `<SHIFT>` key while clicking the menu item in the
252 The default installation location is
254 C:\Program Files\OpenSSL
256 for native binaries, or
258 C:\Program Files (x86)\OpenSSL
260 for 32bit binaries on 64bit Windows (WOW64).
262 #### Installing to a different location
264 To install OpenSSL to a different location (for example into your home
265 directory for testing purposes) run config like this:
269 $ ./config --prefix=/opt/openssl --openssldir=/usr/local/ssl
273 $ @config --prefix=PROGRAM:[INSTALLS] --openssldir=SYS$MANAGER:[OPENSSL]
275 Note: if you do add options to the configuration command, please make sure
276 you've read more than just this Quick Start, such as relevant `NOTES.*` files,
277 the options outline below, as configuration options may change the outcome
278 in otherwise unexpected ways.
280 Configuration Options
281 =====================
283 There are several options to ./config (or ./Configure) to customize
284 the build (note that for Windows, the defaults for `--prefix` and
285 `--openssldir` depend in what configuration is used and what Windows
286 implementation OpenSSL is built on. More notes on this in NOTES.WIN):
293 Build the OpenSSL libraries to support the API for the specified version.
294 If [no-deprecated](#no-deprecated) is also given, don't build with support
295 for deprecated APIs in or below the specified version number. For example,
298 --api=1.1.0 no-deprecated
300 will remove support for all APIs that were deprecated in OpenSSL version
301 1.1.0 or below. This is a rather specialized option for developers.
302 If you just intend to remove all deprecated APIs up to the current version
303 entirely, just specify [no-deprecated](#no-deprecated).
304 If `--api` isn't given, it defaults to the current (minor) OpenSSL version.
309 --cross-compile-prefix=PREFIX
311 The PREFIX to include in front of commands for your toolchain.
313 It is likely to have to end with dash, e.g. a-b-c- would invoke GNU compiler as
314 a-b-c-gcc, etc. Unfortunately cross-compiling is too case-specific to put
315 together one-size-fits-all instructions. You might have to pass more flags or
316 set up environment variables to actually make it work. Android and iOS cases are
317 discussed in corresponding `Configurations/15-*.conf` files. But there are cases
318 when this option alone is sufficient. For example to build the mingw64 target on
319 Linux `--cross-compile-prefix=x86_64-w64-mingw32-` works. Naturally provided
320 that mingw packages are installed. Today Debian and Ubuntu users have option to
321 install a number of prepackaged cross-compilers along with corresponding
322 run-time and development packages for "alien" hardware. To give another example
323 `--cross-compile-prefix=mipsel-linux-gnu-` suffices in such case. Needless to
324 mention that you have to invoke `./Configure`, not `./config`, and pass your target
325 name explicitly. Also, note that `--openssldir` refers to target's file system,
326 not one you are building on.
333 Build OpenSSL with debugging symbols and zero optimization level.
337 Build OpenSSL without debugging symbols. This is the default.
346 The name of the directory under the top of the installation directory tree
347 (see the `--prefix` option) where libraries will be installed. By default
348 this is "lib". Note that on Windows only static libraries (`*.lib`) will
349 be stored in this location. Shared libraries (`*.dll`) will always be
350 installed to the "bin" directory.
356 Directory for OpenSSL configuration files, and also the default certificate
357 and key store. Defaults are:
360 Windows: C:\Program Files\Common Files\SSL
361 OpenVMS: SYS$COMMON:[OPENSSL-COMMON]
363 For 32bit Windows applications on Windows 64bit (WOW64), always replace
364 `C:\Program Files` by `C:\Program Files (x86)`.
370 The top of the installation directory tree. Defaults are:
373 Windows: C:\Program Files\OpenSSL
374 OpenVMS: SYS$COMMON:[OPENSSL-'version']
381 This is a developer flag that switches on various compiler options recommended
382 for OpenSSL development. It only works when using gcc or clang as the compiler.
383 If you are developing a patch for OpenSSL then it is recommended that you use
384 this option where possible.
389 ### with-zlib-include
391 --with-zlib-include=DIR
393 The directory for the location of the zlib include file. This option is only
394 necessary if [enable-zlib](#enable-zlib) is used and the include file is not
395 already on the system include path.
401 **On Unix**: this is the directory containing the zlib library.
402 If not provided the system library path will be used.
404 **On Windows:** this is the filename of the zlib library (with or
405 without a path). This flag must be provided if the
406 [zlib-dynamic](#zlib-dynamic) option is not also used. If zlib-dynamic is used
407 then this flag is optional and defaults to "ZLIB1" if not provided.
409 **On VMS:** this is the filename of the zlib library (with or without a path).
410 This flag is optional and if not provided then "GNV$LIBZSHR", "GNV$LIBZSHR32"
411 or "GNV$LIBZSHR64" is used by default depending on the pointer size chosen.
413 Seeding the Random Generator
414 ----------------------------
416 --with-rand-seed=seed1[,seed2,...]
418 A comma separated list of seeding methods which will be tried by OpenSSL
419 in order to obtain random input (a.k.a "entropy") for seeding its
420 cryptographically secure random number generator (CSPRNG).
421 The current seeding methods are:
425 Use a trusted operating system entropy source.
426 This is the default method if such an entropy source exists.
430 Use the [getrandom(2)][man-getrandom] or equivalent system call.
432 [man-getrandom]: http://man7.org/linux/man-pages/man2/getrandom.2.html
436 Use the first device from the DEVRANDOM list which can be opened to read
437 random bytes. The DEVRANDOM preprocessor constant expands to
439 "/dev/urandom","/dev/random","/dev/srandom"
441 on most unix-ish operating systems.
445 Check for an entropy generating daemon.
449 Use the RDSEED or RDRAND command if provided by the CPU.
453 Use librandom (not implemented yet).
457 Disable automatic seeding. This is the default on some operating systems where
458 no suitable entropy source exists, or no support for it is implemented yet.
460 For more information, see the section [Notes on random number generation][rng]
461 at the end of this document.
463 [rng]: #notes-on-random-number-generation
465 Enable and Disable Features
466 ---------------------------
468 Feature options always come in pairs, an option to enable feature xxxx, and
469 and option to disable it:
471 [ enable-xxxx | no-xxxx ]
473 Whether a feature is enabled or disabled by default, depends on the feature.
474 In the following list, always the non-default variant is documented: if
475 feature xxxx is disabled by default then enable-xxxx is documented and
476 if feature xxxx is enabled by default then no-xxxx is documented.
480 Don't build the AFALG engine.
482 This option will be forced on a platform that does not support AFALG.
486 Build with Kernel TLS support.
488 This option will enable the use of the Kernel TLS data-path, which can improve
489 performance and allow for the use of sendfile and splice system calls on
490 TLS sockets. The Kernel may use TLS accelerators if any are available on the
491 system. This option will be forced off on systems that do not support the
492 Kernel TLS data-path.
496 Build with the Address sanitiser.
498 This is a developer option only. It may not work on all platforms and should
499 never be used in production environments. It will only work when used with
500 gcc or clang and should be used in conjunction with the [no-shared](#no-shared)
505 Do not use assembler code.
507 This should be viewed as debugging/troubleshooting option rather than for
508 production use. On some platforms a small amount of assembler code may still
509 be used even with this option.
513 Do not build support for async operations.
517 Don't automatically load all supported ciphers and digests.
519 Typically OpenSSL will make available all of its supported ciphers and digests.
520 For a statically linked application this may be undesirable if small executable
521 size is an objective. This only affects libcrypto. Ciphers and digests will
522 have to be loaded manually using EVP_add_cipher() and EVP_add_digest() if this
523 option is used. This option will force a non-shared build.
527 Don't automatically load all libcrypto/libssl error strings.
529 Typically OpenSSL will automatically load human readable error strings. For a
530 statically linked application this may be undesirable if small executable size
533 ### no-autoload-config
535 Don't automatically load the default openssl.cnf file.
537 Typically OpenSSL will automatically load a system config file which configures
540 ### enable-buildtest-c++
542 While testing, generate C++ buildtest files that simply check that the public
543 OpenSSL header files are usable standalone with C++.
545 Enabling this option demands extra care. For any compiler flag given directly
546 as configuration option, you must ensure that it's valid for both the C and
547 the C++ compiler. If not, the C++ build test will most likely break. As an
548 alternative, you can use the language specific variables, CFLAGS and CXXFLAGS.
552 Don't build the CAPI engine.
554 This option will be forced if on a platform that does not support CAPI.
558 Don't build support for Certificate Management Protocol (CMP).
562 Don't build support for Cryptographic Message Syntax (CMS).
566 Don't build support for SSL/TLS compression.
568 If this option is enabled (the default), then compression will only work if
569 the zlib or zlib-dynamic options are also chosen.
571 ### enable-crypto-mdebug
573 This now only enables the failed-malloc feature.
575 ### enable-crypto-mdebug-backtrace
577 This is a no-op; the project uses the compiler's address/leak sanitizer instead.
581 Don't build support for Certificate Transparency (CT).
585 Don't build with support for deprecated APIs up until and including the version
586 given with `--api` (or the current version, if `--api` wasn't specified).
590 Don't build support for datagram based BIOs.
592 Selecting this option will also force the disabling of DTLS.
596 Don't build support for loading Dynamic Shared Objects (DSO)
598 ### enable-devcryptoeng
600 Build the `/dev/crypto` engine.
602 This option is automatically selected on the BSD platform, in which case it can
603 be disabled with no-devcryptoeng.
605 ### no-dynamic-engine
607 Don't build the dynamically loaded engines.
609 This only has an effect in a shared build.
613 Don't build support for Elliptic Curves.
617 Don't build support for binary Elliptic Curves
619 ### enable-ec_nistp_64_gcc_128
621 Enable support for optimised implementations of some commonly used NIST
624 This option is only supported on platforms:
626 - with little-endian storage of non-byte types
627 - that tolerate misaligned memory references
628 - where the compiler:
629 - supports the non-standard type `__uint128_t`
630 - defines the built-in macro `__SIZEOF_INT128__`
634 Build support for gathering entropy from the Entropy Gathering Daemon (EGD).
638 Don't build support for loading engines.
642 Don't compile in any error strings.
644 ### enable-external-tests
646 Enable building of integration with external test suites.
648 This is a developer option and may not work on all platforms. The following
649 external test suites are currently supported:
651 - BoringSSL test suite
652 - Python PYCA/Cryptography test suite
655 See the file [test/README.external]/(test/README.external) for further details.
659 Don't compile in filename and line number information (e.g. for errors and
664 Don't compile the FIPS provider
666 ### enable-fuzz-libfuzzer, enable-fuzz-afl
668 Build with support for fuzzing using either libfuzzer or AFL.
670 These are developer options only. They may not work on all platforms and
671 should never be used in production environments.
673 See the file [fuzz/README.md](fuzz/README.md) for further details.
677 Don't build support for GOST based ciphersuites.
679 Note that if this feature is enabled then GOST ciphersuites are only available
680 if the GOST algorithms are also available through loading an externally supplied
685 Don't build the legacy provider.
687 Disabling this also disables the legacy algorithms: MD2 (already disabled by default).
691 Don't generate dependencies.
695 Don't build any dynamically loadable engines.
697 This also implies 'no-dynamic-engine'.
701 Don't build support for writing multiple records in one go in libssl
703 Note: this is a different capability to the pipelining functionality.
707 Don't build support for the Next Protocol Negotiation (NPN) TLS extension.
711 Don't build support for Online Certificate Status Protocol (OCSP).
715 Don't build the padlock engine.
719 As synonyme for no-padlockeng. Deprecated and should not be used.
723 Don't build with support for Position Independent Code.
727 Don't pin the shared libraries.
729 By default OpenSSL will attempt to stay in memory until the process exits.
730 This is so that libcrypto and libssl can be properly cleaned up automatically
731 via an atexit() handler. The handler is registered by libcrypto and cleans
732 up both libraries. On some platforms the atexit() handler will run on unload of
733 libcrypto (if it has been dynamically loaded) rather than at process exit. This
734 option can be used to stop OpenSSL from attempting to stay in memory until the
735 process exits. This could lead to crashes if either libcrypto or libssl have
736 already been unloaded at the point that the atexit handler is invoked, e.g. on a
737 platform which calls atexit() on unload of the library, and libssl is unloaded
738 before libcrypto then a crash is likely to happen. Applications can suppress
739 running of the atexit() handler at run time by using the OPENSSL_INIT_NO_ATEXIT
740 option to OPENSSL_init_crypto(). See the man page for it for further details.
744 Don't use POSIX IO capabilities.
748 Don't build support for Pre-Shared Key based ciphersuites.
752 Don't use hardware RDRAND capabilities.
756 Don't build support for RFC3779, "X.509 Extensions for IP Addresses and
761 Build support for Stream Control Transmission Protocol (SCTP).
765 Do not create shared libraries, only static ones.
767 See [Notes on shared libraries](#notes-on-shared-libraries) below.
771 Don't build support for socket BIOs.
775 Don't build support for Secure Remote Password (SRP) protocol or
776 SRP based ciphersuites.
780 Don't build Secure Real-Time Transport Protocol (SRTP) support.
784 Exclude SSE2 code paths from 32-bit x86 assembly modules.
786 Normally SSE2 extension is detected at run-time, but the decision whether or not
787 the machine code will be executed is taken solely on CPU capability vector. This
788 means that if you happen to run OS kernel which does not support SSE2 extension
789 on Intel P4 processor, then your application might be exposed to "illegal
790 instruction" exception. There might be a way to enable support in kernel, e.g.
791 FreeBSD kernel can be compiled with CPU_ENABLE_SSE, and there is a way to
792 disengage SSE2 code paths upon application start-up, but if you aim for wider
793 "audience" running such kernel, consider no-sse2. Both the 386 and no-asm
794 options imply no-sse2.
798 Build with the SSL Trace capabilities.
800 This adds the "-trace" option to s_client and s_server.
804 Don't build the statically linked engines.
806 This only has an impact when not built "shared".
810 Don't use anything from the C header file "stdio.h" that makes use of the "FILE"
811 type. Only libcrypto and libssl can be built in this way. Using this option will
812 suppress building the command line applications. Additionally, since the OpenSSL
813 tests also use the command line applications, the tests will also be skipped.
817 Don't build test programs or run any tests.
821 Don't build with support for multi-threaded applications.
825 Build with support for multi-threaded applications. Most platforms will enable
826 this by default. However if on a platform where this is not the case then this
827 will usually require additional system-dependent options!
829 See [Notes on multi-threading](#notes-on-multi-threading) below.
833 Build with support for the integrated tracing api.
835 See manual pages OSSL_trace_set_channel(3) and OSSL_trace_enabled(3) for details.
839 Don't build Time Stamping (TS) Authority support.
843 Build with the Undefined Behaviour sanitiser (UBSAN).
845 This is a developer option only. It may not work on all platforms and should
846 never be used in production environments. It will only work when used with gcc
847 or clang and should be used in conjunction with the `-DPEDANTIC` option
848 (or the `--strict-warnings` option).
852 Don't build with the User Interface (UI) console method
854 The User Interface console method enables text based console prompts.
858 Enable additional unit test APIs.
860 This should not typically be used in production deployments.
864 Don't build support for UPLINK interface.
866 ### enable-weak-ssl-ciphers
868 Build support for SSL/TLS ciphers that are considered "weak"
870 Enabling this includes for example the RC4 based ciphersuites.
874 Build with support for zlib compression/decompression.
878 Like the zlib option, but has OpenSSL load the zlib library dynamically
881 This is only supported on systems where loading of shared libraries is supported.
885 In 32-bit x86 builds, use the 80386 instruction set only in assembly modules
887 The default x86 code is more efficient, but requires at least an 486 processor.
888 Note: This doesn't affect compiler generated code, so this option needs to be
889 accompanied by a corresponding compiler-specific option.
893 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}
895 Don't build support for negotiating the specified SSL/TLS protocol.
897 If "no-tls" is selected then all of tls1, tls1_1, tls1_2 and tls1_3 are disabled.
898 Similarly "no-dtls" will disable dtls1 and dtls1_2. The "no-ssl" option is
899 synonymous with "no-ssl3". Note this only affects version negotiation.
900 OpenSSL will still provide the methods for applications to explicitly select
901 the individual protocol versions.
903 ### no-{protocol}-method
905 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}-method
907 Analogous to no-{protocol} but in addition do not build the methods for
908 applications to explicitly select individual protocol versions. Note that there
909 is no "no-tls1_3-method" option because there is no application method for
912 Using individual protocol methods directly is deprecated. Applications should
913 use TLS_method() instead.
915 ### enable-{algorithm}
919 Build with support for the specified algorithm.
923 no-{aria|bf|blake2|camellia|cast|chacha|cmac|
924 des|dh|dsa|ecdh|ecdsa|idea|md4|mdc2|ocb|
925 poly1305|rc2|rc4|rmd160|scrypt|seed|
926 siphash|siv|sm2|sm3|sm4|whirlpool}
928 Build without support for the specified algorithm.
930 The "ripemd" algorithm is deprecated and if used is synonymous with rmd160.
932 ### Compiler-specific options
934 -Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static
936 These system specific options will be recognised and passed through to the
937 compiler to allow you to define preprocessor symbols, specify additional
938 libraries, library directories or other compiler options. It might be worth
939 noting that some compilers generate code specifically for processor the
940 compiler currently executes on. This is not necessarily what you might have
941 in mind, since it might be unsuitable for execution on other, typically older,
942 processor. Consult your compiler documentation.
944 Take note of the [Environment Variables](#environment-variables) documentation
945 below and how these flags interact with those variables.
949 Additional options that are not otherwise recognised are passed through as
950 they are to the compiler as well. Unix-style options beginning with a
951 '-' or '+' and Windows-style options beginning with a '/' are recognized.
952 Again, consult your compiler documentation.
954 If the option contains arguments separated by spaces, then the URL-style
955 notation %20 can be used for the space character in order to avoid having
956 to quote the option. For example, -opt%20arg gets expanded to -opt arg.
957 In fact, any ASCII character can be encoded as %xx using its hexadecimal
960 Take note of the [Environment Variables](#environment-variables) documentation
961 below and how these flags interact with those variables.
963 ### Environment Variables
967 Assign the given value to the environment variable VAR for Configure.
969 These work just like normal environment variable assignments, but are supported
970 on all platforms and are confined to the configuration scripts only.
971 These assignments override the corresponding value in the inherited environment,
974 The following variables are used as "make variables" and can be used as an
975 alternative to giving preprocessor, compiler and linker options directly as
976 configuration. The following variables are supported:
978 AR The static library archiver.
979 ARFLAGS Flags for the static library archiver.
980 AS The assembler compiler.
981 ASFLAGS Flags for the assembler compiler.
983 CFLAGS Flags for the C compiler.
984 CXX The C++ compiler.
985 CXXFLAGS Flags for the C++ compiler.
986 CPP The C/C++ preprocessor.
987 CPPFLAGS Flags for the C/C++ preprocessor.
988 CPPDEFINES List of CPP macro definitions, separated
989 by a platform specific character (':' or
990 space for Unix, ';' for Windows, ',' for
991 VMS). This can be used instead of using
992 -D (or what corresponds to that on your
993 compiler) in CPPFLAGS.
994 CPPINCLUDES List of CPP inclusion directories, separated
995 the same way as for CPPDEFINES. This can
996 be used instead of -I (or what corresponds
997 to that on your compiler) in CPPFLAGS.
998 HASHBANGPERL Perl invocation to be inserted after '#!'
999 in public perl scripts (only relevant on
1001 LD The program linker (not used on Unix, $(CC)
1003 LDFLAGS Flags for the shared library, DSO and
1005 LDLIBS Extra libraries to use when linking.
1006 Takes the form of a space separated list
1007 of library specifications on Unix and
1008 Windows, and as a comma separated list of
1010 RANLIB The library archive indexer.
1011 RC The Windows resource compiler.
1012 RCFLAGS Flags for the Windows resource compiler.
1013 RM The command to remove files and directories.
1015 These cannot be mixed with compiling/linking flags given on the command line.
1016 In other words, something like this isn't permitted.
1018 ./config -DFOO CPPFLAGS=-DBAR -DCOOKIE
1020 Backward compatibility note:
1022 To be compatible with older configuration scripts, the environment variables
1023 are ignored if compiling/linking flags are given on the command line, except
1026 AR, CC, CXX, CROSS_COMPILE, HASHBANGPERL, PERL, RANLIB, RC, and WINDRES
1028 For example, the following command will not see -DBAR:
1030 CPPFLAGS=-DBAR ./config -DCOOKIE
1032 However, the following will see both set variables:
1034 CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- ./config -DCOOKIE
1036 If CC is set, it is advisable to also set CXX to ensure both the C and C++
1037 compiler are in the same "family". This becomes relevant with
1038 'enable-external-tests' and 'enable-buildtest-c++'.
1045 Reconfigure from earlier data.
1047 This fetches the previous command line options and environment from data saved
1048 in "configdata.pm" and runs the configuration process again, using these
1049 options and environment. Note: NO other option is permitted together with
1050 "reconf". This means that you also MUST use "./Configure" (or what corresponds
1051 to that on non-Unix platforms) directly to invoke this option. Note: The
1052 original configuration saves away values for ALL environment variables that were
1053 used, and if they weren't defined, they are still saved away with information
1054 that they weren't originally defined. This information takes precedence over
1055 environment variables that are defined when reconfiguring.
1057 Displaying configuration data
1058 -----------------------------
1060 The configuration script itself will say very little, and finishes by
1061 creating "configdata.pm". This perl module can be loaded by other scripts
1062 to find all the configuration data, and it can also be used as a script to
1063 display all sorts of configuration data in a human readable form.
1065 For more information, please do:
1067 $ ./configdata.pm --help # Unix
1071 $ perl configdata.pm --help # Windows and VMS
1073 Installation Steps in Detail
1074 ============================
1079 ### Automatic Configuration
1081 On some platform a `config` script is available which attempts to guess
1082 your operating system (and compiler, if necessary) and calls the `Configure`
1083 Perl script with appropriate target based on its guess. Further options can
1084 be supplied to the `config` script, which will be passed on to the `Configure`
1087 #### Unix / Linux / macOS
1089 $ ./config [[ options ]]
1093 $ @config [[ options ]]
1097 Automatic configuration is not available on Windows.
1099 For the remainder of this text, the Unix form will be used in all examples,
1100 please use the appropriate form for your platform.
1106 to see whether your target is guessed correctly. If you want to use a different
1107 compiler, you are cross-compiling for another platform, or the ./config guess
1108 was wrong for other reasons, see the [Manual Configuration](#manual-configuration)
1109 section. Oherwise continue with the [Build OpenSSL](#build-openssl) section below.
1111 On some systems, you can include debugging information as follows:
1113 $ ./config -d [[ options ]]
1115 ### Manual Configuration
1117 OpenSSL knows about a range of different operating system, hardware and
1118 compiler combinations. To see the ones it knows about, run
1120 $ ./Configure # Unix
1124 $ perl Configure # All other platforms
1126 For the remainder of this text, the Unix form will be used in all examples.
1127 Please use the appropriate form for your platform.
1129 Pick a suitable name from the list that matches your system. For most
1130 operating systems there is a choice between using "cc" or "gcc".
1131 When you have identified your system (and if necessary compiler) use this
1132 name as the argument to Configure. For example, a "linux-elf" user would
1135 $ ./Configure linux-elf [[ options ]]
1137 ### Creating your own Configuration
1139 If your system isn't listed, you will have to create a configuration
1140 file named Configurations/{{ something }}.conf and add the correct
1141 configuration for your system. See the available configs as examples
1142 and read Configurations/README and Configurations/README.design for
1145 The generic configurations "cc" or "gcc" should usually work on 32 bit
1148 Configure creates a build file ("Makefile" on Unix, "makefile" on Windows
1149 and "descrip.mms" on OpenVMS) from a suitable template in Configurations,
1150 and defines various macros in include/openssl/configuration.h (generated
1151 from include/openssl/configuration.h.in).
1153 ### Out of Tree Builds
1155 OpenSSL can be configured to build in a build directory separate from the
1156 source code directory. It's done by placing yourself in some other
1157 directory and invoking the configuration commands from there.
1161 $ mkdir /var/tmp/openssl-build
1162 $ cd /var/tmp/openssl-build
1163 $ /PATH/TO/OPENSSL/SOURCE/config [[ options ]]
1167 $ /PATH/TO/OPENSSL/SOURCE/Configure {{ target }} [[ options ]]
1169 #### OpenVMS example
1171 $ set default sys$login:
1172 $ create/dir [.tmp.openssl-build]
1173 $ set default [.tmp.openssl-build]
1174 $ @[PATH.TO.OPENSSL.SOURCE]config [[ options ]]
1178 $ @[PATH.TO.OPENSSL.SOURCE]Configure {{ target }} [[ options ]]
1180 #### Windows example
1183 $ mkdir \temp-openssl
1185 $ perl d:\PATH\TO\OPENSSL\SOURCE\Configure {{ target }} [[ options ]]
1187 Paths can be relative just as well as absolute. Configure will do its best
1188 to translate them to relative paths whenever possible.
1193 Build OpenSSL by running:
1196 $ mms ! (or mmk) OpenVMS
1199 This will build the OpenSSL libraries (libcrypto.a and libssl.a on
1200 Unix, corresponding on other platforms) and the OpenSSL binary
1201 ("openssl"). The libraries will be built in the top-level directory,
1202 and the binary will be in the "apps" subdirectory.
1204 If the build fails, take a look at the [Build Failures](#build-failures)
1205 subsection of the [Troubleshooting](#troubleshooting) section.
1210 After a successful build, and before installing, the libraries should
1214 $ mms test ! OpenVMS
1215 $ nmake test # Windows
1217 **Warning:** you MUST run the tests from an unprivileged account (or disable
1218 your privileges temporarily if your platform allows it).
1220 If some tests fail, take a look at the [Test Failures](#test-failures)
1221 subsection of the [Troubleshooting](#troubleshooting) section.
1226 If everything tests ok, install OpenSSL with
1228 $ make install # Unix
1229 $ mms install ! OpenVMS
1230 $ nmake install # Windows
1232 Note that in order to perform the install step above you need to have
1233 appropriate permissions to write to the installation directory.
1235 The above commands will install all the software components in this
1236 directory tree under PREFIX (the directory given with `--prefix` or
1239 ### Unix / Linux / macOS
1241 bin/ Contains the openssl binary and a few other
1244 Contains the header files needed if you want
1245 to build your own programs that use libcrypto
1247 lib Contains the OpenSSL library files.
1248 lib/engines Contains the OpenSSL dynamically loadable engines.
1250 share/man/man1 Contains the OpenSSL command line man-pages.
1251 share/man/man3 Contains the OpenSSL library calls man-pages.
1252 share/man/man5 Contains the OpenSSL configuration format man-pages.
1253 share/man/man7 Contains the OpenSSL other misc man-pages.
1255 share/doc/openssl/html/man1
1256 share/doc/openssl/html/man3
1257 share/doc/openssl/html/man5
1258 share/doc/openssl/html/man7
1259 Contains the HTML rendition of the man-pages.
1263 'arch' is replaced with the architecture name, "Alpha" or "ia64",
1264 'sover' is replaced with the shared library version (0101 for 1.1), and
1265 'pz' is replaced with the pointer size OpenSSL was built with:
1267 [.EXE.'arch'] Contains the openssl binary.
1268 [.EXE] Contains a few utility scripts.
1270 Contains the header files needed if you want
1271 to build your own programs that use libcrypto
1273 [.LIB.'arch'] Contains the OpenSSL library files.
1274 [.ENGINES'sover''pz'.'arch']
1275 Contains the OpenSSL dynamically loadable engines.
1276 [.SYS$STARTUP] Contains startup, login and shutdown scripts.
1277 These define appropriate logical names and
1279 [.SYSTEST] Contains the installation verification procedure.
1280 [.HTML] Contains the HTML rendition of the manual pages.
1282 ### Additional Directories
1284 Additionally, install will add the following directories under
1285 OPENSSLDIR (the directory given with `--openssldir` or its default)
1286 for you convenience:
1288 certs Initially empty, this is the default location
1289 for certificate files.
1290 private Initially empty, this is the default location
1291 for private key files.
1292 misc Various scripts.
1294 The installation directory should be appropriately protected to ensure
1295 unprivileged users cannot make changes to OpenSSL binaries or files, or
1296 install engines. If you already have a pre-installed version of OpenSSL as
1297 part of your Operating System it is recommended that you do not overwrite
1298 the system version and instead install to somewhere else.
1300 Package builders who want to configure the library for standard locations,
1301 but have the package installed somewhere else so that it can easily be
1304 $ make DESTDIR=/tmp/package-root install # Unix
1305 $ mms/macro="DESTDIR=TMP:[PACKAGE-ROOT]" install ! OpenVMS
1307 The specified destination directory will be prepended to all installation
1310 Compatibility issues with previous OpenSSL versions
1311 ---------------------------------------------------
1313 ### COMPILING existing applications
1315 Starting with version 1.1.0, OpenSSL hides a number of structures that were
1316 previously open. This includes all internal libssl structures and a number
1317 of EVP types. Accessor functions have been added to allow controlled access
1318 to the structures' data.
1320 This means that some software needs to be rewritten to adapt to the new ways
1321 of doing things. This often amounts to allocating an instance of a structure
1322 explicitly where you could previously allocate them on the stack as automatic
1323 variables, and using the provided accessor functions where you would previously
1324 access a structure's field directly.
1326 Some APIs have changed as well. However, older APIs have been preserved when
1329 Post-installation Notes
1330 -----------------------
1332 With the default OpenSSL installation comes a FIPS provider module, which
1333 needs some post-installation attention, without which it will not be usable.
1334 This involves using the following command:
1338 See the openssl-fipsinstall(1) manual for details and examples.
1340 Advanced Build Options
1341 ======================
1343 Environment Variables
1344 ---------------------
1346 A number of environment variables can be used to provide additional control
1347 over the build process. Typically these should be defined prior to running
1348 config or Configure. Not all environment variables are relevant to all
1352 The name of the ar executable to use.
1355 Use a different build file name than the platform default
1356 ("Makefile" on Unix-like platforms, "makefile" on native Windows,
1357 "descrip.mms" on OpenVMS). This requires that there is a
1358 corresponding build file template. See Configurations/README
1359 for further information.
1362 The compiler to use. Configure will attempt to pick a default
1363 compiler for your platform but this choice can be overridden
1364 using this variable. Set it to the compiler executable you wish
1365 to use, e.g. "gcc" or "clang".
1368 This environment variable has the same meaning as for the
1369 "--cross-compile-prefix" Configure flag described above. If both
1370 are set then the Configure flag takes precedence.
1373 The name of the nm executable to use.
1375 OPENSSL_LOCAL_CONFIG_DIR
1376 OpenSSL comes with a database of information about how it
1377 should be built on different platforms as well as build file
1378 templates for those platforms. The database is comprised of
1379 ".conf" files in the Configurations directory. The build
1380 file templates reside there as well as ".tmpl" files. See the
1381 file Configurations/README for further information about the
1382 format of ".conf" files as well as information on the ".tmpl"
1384 In addition to the standard ".conf" and ".tmpl" files, it is
1385 possible to create your own ".conf" and ".tmpl" files and store
1386 them locally, outside the OpenSSL source tree. This environment
1387 variable can be set to the directory where these files are held
1388 and will be considered by Configure before it looks in the
1389 standard directories.
1392 The name of the Perl executable to use when building OpenSSL.
1393 This variable is used in config script only. Configure on the
1394 other hand imposes the interpreter by which it itself was
1395 executed on the whole build procedure.
1398 The command string for the Perl executable to insert in the
1399 #! line of perl scripts that will be publicly installed.
1400 Default: /usr/bin/env perl
1401 Note: the value of this variable is added to the same scripts
1402 on all platforms, but it's only relevant on Unix-like platforms.
1405 The name of the rc executable to use. The default will be as
1406 defined for the target platform in the ".conf" file. If not
1407 defined then "windres" will be used. The WINDRES environment
1408 variable is synonymous to this. If both are defined then RC
1412 The name of the ranlib executable to use.
1420 The Configure script generates a Makefile in a format relevant to the specific
1421 platform. The Makefiles provide a number of targets that can be used. Not all
1422 targets may be available on all platforms. Only the most common targets are
1423 described here. Examine the Makefiles themselves for the full list.
1426 The target to build all the software components and
1430 Build all the software components.
1431 THIS IS THE DEFAULT TARGET.
1434 Build all documentation components.
1437 Remove all build artefacts and return the directory to a "clean"
1441 Rebuild the dependencies in the Makefiles. This is a legacy
1442 option that no longer needs to be used since OpenSSL 1.1.0.
1445 Install all OpenSSL components.
1448 Only install the OpenSSL software components.
1451 Only install the OpenSSL documentation components.
1454 Only install the OpenSSL man pages (Unix only).
1457 Only install the OpenSSL html documentation.
1460 Prints a list of all the self test names.
1463 Build and run the OpenSSL self tests.
1466 Uninstall all OpenSSL components.
1470 Re-run the configuration process, as exactly as the last time
1474 This is a developer option. If you are developing a patch for
1475 OpenSSL you may need to use this if you want to update
1476 automatically generated files; add new error codes or add new
1477 (or change the visibility of) public API functions. (Unix only).
1479 Running Selected Tests
1480 ----------------------
1482 The make variable TESTS supports a versatile set of space separated tokens
1483 with which you can specify a set of tests to be performed. With a "current
1484 set of tests" in mind, initially being empty, here are the possible tokens:
1486 alltests The current set of tests becomes the whole set of available
1487 tests (as listed when you do 'make list-tests' or similar).
1489 xxx Adds the test 'xxx' to the current set of tests.
1491 -xxx Removes 'xxx' from the current set of tests. If this is the
1492 first token in the list, the current set of tests is first
1493 assigned the whole set of available tests, effectively making
1494 this token equivalent to TESTS="alltests -xxx".
1496 nn Adds the test group 'nn' (which is a number) to the current
1499 -nn Removes the test group 'nn' from the current set of tests.
1500 If this is the first token in the list, the current set of
1501 tests is first assigned the whole set of available tests,
1502 effectively making this token equivalent to
1503 TESTS="alltests -xxx".
1505 Also, all tokens except for "alltests" may have wildcards, such as *.
1506 (on Unix and Windows, BSD style wildcards are supported, while on VMS,
1507 it's VMS style wildcards)
1511 Run all tests except for the fuzz tests:
1513 $ make TESTS=-test_fuzz test
1515 or, if you want to be explicit:
1517 $ make TESTS='alltests -test_fuzz' test
1519 Run all tests that have a name starting with "test_ssl" but not those
1520 starting with "test_ssl_":
1522 $ make TESTS='test_ssl* -test_ssl_*' test
1524 Run only test group 10:
1528 Run all tests except the slow group (group 99):
1532 Run all tests in test groups 80 to 99 except for tests in group 90:
1534 $ make TESTS='[89]? -90'
1536 To stochastically verify that the algorithm that produces uniformly distributed
1537 random numbers is operating correctly (with a false positive rate of 0.01%):
1539 $ ./util/wrap.sh test/bntest -stochastic
1544 Configuration Problems
1545 ----------------------
1547 ### Selecting the correct target
1549 The `./config` script tries hard to guess your operating system, but in some
1550 cases it does not succeed. You will see a message like the following:
1553 Operating system: x86-whatever-minix
1554 This system (minix) is not supported. See file INSTALL for details.
1556 Even if the automatic target selection by the `./config` script fails, chances
1557 are that you still might find a suitable target in the Configurations directory,
1558 which you can supply to the `./Configure` command, possibly after some adjustment.
1560 The Configurations directory contains a lot of examples of such targets.
1561 The main configuration file is [10-main.conf][], which contains all targets that
1562 are officially supported by the OpenSSL team. Other configuration files contain
1563 targets contributed by other OpenSSL users. The list of targets can be found in
1564 a Perl list `my %targets = ( ... )`.
1569 inherit_from => [ "base-target" ],
1571 cflags => add("..."),
1573 perlasm_scheme => "...",
1578 If you call `.\Configure` without arguments, it will give you a list of all
1579 known targets. Using `grep`, you can lookup the target definition in the
1580 Configurations directory. For example the "android-x86_64" can be found in
1581 Configurations/15-android.conf.
1583 The directory contains two README files, which explain the general syntax and
1584 design of the configurations files.
1586 - [Configurations/README](Configurations/README)
1587 - [Configurations/README.design](Configurations/README.design)
1589 If you need further help, try to search the [openssl-users][] mailing list
1590 or the [GitHub Issues][] for existing solutions. If you don't find anything,
1591 you can [raise an issue][] to ask a question yourself.
1593 More about our support resources can be found in the [SUPPORT][] file.
1595 ### Configuration Errors
1597 If the `./config` or `./Configure` command fails with an error message,
1598 read the error message carefully and try to figure out whether you made
1599 a mistake (e.g., by providing a wrong option), or whether the script is
1600 working incorrectly. If you think you encountered a bug, please
1601 [raise an issue][] on GitHub to file a bug report.
1603 Along with a short description of the bug, please provide the complete
1604 configure command line and the relevant output including the error message.
1606 Note: To make the output readable, pleace add a 'code fence' (three backquotes
1607 ` ``` ` on a separate line) before and after your output:
1610 $ ./Configure [your arguments...]
1619 If the build fails, look carefully at the output. Try to locate and understand
1620 the error message. It might be that the compiler is already telling you
1621 exactly what you need to do to fix your problem.
1623 There may be reasons for the failure that aren't problems in OpenSSL itself,
1624 for example if the compiler reports missing standard or third party headers.
1626 If the build succeeded previously, but fails after a source or configuration
1627 change, it might be helpful to clean the build tree before attempting another
1628 build. Use this command:
1631 $ mms clean ! (or mmk) OpenVMS
1632 $ nmake clean # Windows
1634 Assembler error messages can sometimes be sidestepped by using the
1635 "no-asm" configuration option.
1637 Compiling parts of OpenSSL with gcc and others with the system compiler will
1638 result in unresolved symbols on some systems.
1640 If you are still having problems, try to search the [openssl-users][] mailing
1641 list or the [GitHub Issues][] for existing solutions. If you think you
1642 encountered an OpenSSL bug, please [raise an issue][] to file a bug report.
1643 Please take the time to review the existing issues first; maybe the bug was
1644 already reported or has already been fixed.
1649 If some tests fail, look at the output. There may be reasons for the failure
1650 that isn't a problem in OpenSSL itself (like a malfunction with Perl).
1651 You may want increased verbosity, that can be accomplished like this:
1653 Verbosity on failure only (make macro VERBOSE_FAILURE or VF):
1655 $ make VF=1 test # Unix
1656 $ mms /macro=(VF=1) test ! OpenVMS
1657 $ nmake VF=1 test # Windows
1659 Full verbosity (make macro VERBOSE or V):
1661 $ make V=1 test # Unix
1662 $ mms /macro=(V=1) test ! OpenVMS
1663 $ nmake V=1 test # Windows
1665 If you want to run just one or a few specific tests, you can use
1666 the make variable TESTS to specify them, like this:
1668 $ make TESTS='test_rsa test_dsa' test # Unix
1669 $ mms/macro="TESTS=test_rsa test_dsa" test ! OpenVMS
1670 $ nmake TESTS='test_rsa test_dsa' test # Windows
1672 And of course, you can combine (Unix example shown):
1674 $ make VF=1 TESTS='test_rsa test_dsa' test
1676 You can find the list of available tests like this:
1678 $ make list-tests # Unix
1679 $ mms list-tests ! OpenVMS
1680 $ nmake list-tests # Windows
1682 Have a look at the manual for the perl module Test::Harness to
1683 see what other HARNESS_* variables there are.
1685 If you find a problem with OpenSSL itself, try removing any
1686 compiler optimization flags from the CFLAGS line in Makefile and
1687 run "make clean; make" or corresponding.
1689 To report a bug please open an issue on GitHub, at
1690 <https://github.com/openssl/openssl/issues>.
1692 For more details on how the make variables TESTS can be used,
1693 see section [Running Selected Tests](#running-selected-tests) below.
1698 Notes on multi-threading
1699 ------------------------
1701 For some systems, the OpenSSL Configure script knows what compiler options
1702 are needed to generate a library that is suitable for multi-threaded
1703 applications. On these systems, support for multi-threading is enabled
1704 by default; use the "no-threads" option to disable (this should never be
1707 On other systems, to enable support for multi-threading, you will have
1708 to specify at least two options: "threads", and a system-dependent option.
1709 (The latter is "-D_REENTRANT" on various systems.) The default in this
1710 case, obviously, is not to include support for multi-threading (but
1711 you can still use "no-threads" to suppress an annoying warning message
1712 from the Configure script.)
1714 OpenSSL provides built-in support for two threading models: pthreads (found on
1715 most UNIX/Linux systems), and Windows threads. No other threading models are
1716 supported. If your platform does not provide pthreads or Windows threads then
1717 you should Configure with the "no-threads" option.
1719 Notes on shared libraries
1720 -------------------------
1722 For most systems the OpenSSL Configure script knows what is needed to
1723 build shared libraries for libcrypto and libssl. On these systems
1724 the shared libraries will be created by default. This can be suppressed and
1725 only static libraries created by using the "no-shared" option. On systems
1726 where OpenSSL does not know how to build shared libraries the "no-shared"
1727 option will be forced and only static libraries will be created.
1729 Shared libraries are named a little differently on different platforms.
1730 One way or another, they all have the major OpenSSL version number as
1731 part of the file name, i.e. for OpenSSL 1.1.x, 1.1 is somehow part of
1734 On most POSIX platforms, shared libraries are named libcrypto.so.1.1
1737 on Cygwin, shared libraries are named cygcrypto-1.1.dll and cygssl-1.1.dll
1738 with import libraries libcrypto.dll.a and libssl.dll.a.
1740 On Windows build with MSVC or using MingW, shared libraries are named
1741 libcrypto-1_1.dll and libssl-1_1.dll for 32-bit Windows, libcrypto-1_1-x64.dll
1742 and libssl-1_1-x64.dll for 64-bit x86_64 Windows, and libcrypto-1_1-ia64.dll
1743 and libssl-1_1-ia64.dll for IA64 Windows. With MSVC, the import libraries
1744 are named libcrypto.lib and libssl.lib, while with MingW, they are named
1745 libcrypto.dll.a and libssl.dll.a.
1747 On VMS, shareable images (VMS speak for shared libraries) are named
1748 ossl$libcrypto0101_shr.exe and ossl$libssl0101_shr.exe. However, when
1749 OpenSSL is specifically built for 32-bit pointers, the shareable images
1750 are named ossl$libcrypto0101_shr32.exe and ossl$libssl0101_shr32.exe
1751 instead, and when built for 64-bit pointers, they are named
1752 ossl$libcrypto0101_shr64.exe and ossl$libssl0101_shr64.exe.
1754 Notes on random number generation
1755 ---------------------------------
1757 Availability of cryptographically secure random numbers is required for
1758 secret key generation. OpenSSL provides several options to seed the
1759 internal CSPRNG. If not properly seeded, the internal CSPRNG will refuse
1760 to deliver random bytes and a "PRNG not seeded error" will occur.
1762 The seeding method can be configured using the `--with-rand-seed` option,
1763 which can be used to specify a comma separated list of seed methods.
1764 However in most cases OpenSSL will choose a suitable default method,
1765 so it is not necessary to explicitly provide this option. Note also
1766 that not all methods are available on all platforms.
1768 I) On operating systems which provide a suitable randomness source (in
1769 form of a system call or system device), OpenSSL will use the optimal
1770 available method to seed the CSPRNG from the operating system's
1771 randomness sources. This corresponds to the option `--with-rand-seed=os`.
1773 II) On systems without such a suitable randomness source, automatic seeding
1774 and reseeding is disabled (--with-rand-seed=none) and it may be necessary
1775 to install additional support software to obtain a random seed and reseed
1776 the CSPRNG manually. Please check out the manual pages for RAND_add(),
1777 RAND_bytes(), RAND_egd(), and the FAQ for more information.
1782 <https://mta.openssl.org/mailman/listinfo/openssl-users>
1788 <https://github.com/openssl/openssl/issues>
1791 <https://github.com/openssl/openssl/issues/new/choose>
1794 Configurations/10-main.conf