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.
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 Configure as shown in the following
270 $ ./Configure --prefix=/opt/openssl --openssldir=/usr/local/ssl
274 $ perl Configure --prefix=PROGRAM:[INSTALLS] --openssldir=SYS$MANAGER:[OPENSSL]
276 Note: if you do add options to the configuration command, please make sure
277 you've read more than just this Quick Start, such as relevant `NOTES.*` files,
278 the options outline below, as configuration options may change the outcome
279 in otherwise unexpected ways.
281 Configuration Options
282 =====================
284 There are several options to ./Configure to customize the build (note that
285 for Windows, the defaults for `--prefix` and `--openssldir` depend in what
286 configuration is used and what Windows implementation OpenSSL is built on.
287 More notes on this in NOTES.WIN):
294 Build the OpenSSL libraries to support the API for the specified version.
295 If [no-deprecated](#no-deprecated) is also given, don't build with support
296 for deprecated APIs in or below the specified version number. For example,
299 --api=1.1.0 no-deprecated
301 will remove support for all APIs that were deprecated in OpenSSL version
302 1.1.0 or below. This is a rather specialized option for developers.
303 If you just intend to remove all deprecated APIs up to the current version
304 entirely, just specify [no-deprecated](#no-deprecated).
305 If `--api` isn't given, it defaults to the current (minor) OpenSSL version.
310 --cross-compile-prefix=PREFIX
312 The PREFIX to include in front of commands for your toolchain.
314 It is likely to have to end with dash, e.g. a-b-c- would invoke GNU compiler
315 as a-b-c-gcc, etc. Unfortunately cross-compiling is too case-specific to put
316 together one-size-fits-all instructions. You might have to pass more flags or
317 set up environment variables to actually make it work. Android and iOS cases
318 are discussed in corresponding `Configurations/15-*.conf` files. But there are
319 cases when this option alone is sufficient. For example to build the mingw64
320 target on Linux `--cross-compile-prefix=x86_64-w64-mingw32-` works. Naturally
321 provided that mingw packages are installed. Today Debian and Ubuntu users
322 have option to install a number of prepackaged cross-compilers along with
323 corresponding run-time and development packages for "alien" hardware. To give
324 another example `--cross-compile-prefix=mipsel-linux-gnu-` suffices in such
327 For cross compilation, you must [configure manually](#manual-configuration).
328 Also, note that `--openssldir` refers to target's file system, not one you are
336 Build OpenSSL with debugging symbols and zero optimization level.
340 Build OpenSSL without debugging symbols. This is the default.
349 The name of the directory under the top of the installation directory tree
350 (see the `--prefix` option) where libraries will be installed. By default
351 this is "lib". Note that on Windows only static libraries (`*.lib`) will
352 be stored in this location. Shared libraries (`*.dll`) will always be
353 installed to the "bin" directory.
359 Directory for OpenSSL configuration files, and also the default certificate
360 and key store. Defaults are:
363 Windows: C:\Program Files\Common Files\SSL
364 OpenVMS: SYS$COMMON:[OPENSSL-COMMON]
366 For 32bit Windows applications on Windows 64bit (WOW64), always replace
367 `C:\Program Files` by `C:\Program Files (x86)`.
373 The top of the installation directory tree. Defaults are:
376 Windows: C:\Program Files\OpenSSL
377 OpenVMS: SYS$COMMON:[OPENSSL-'version']
384 This is a developer flag that switches on various compiler options recommended
385 for OpenSSL development. It only works when using gcc or clang as the compiler.
386 If you are developing a patch for OpenSSL then it is recommended that you use
387 this option where possible.
392 ### with-zlib-include
394 --with-zlib-include=DIR
396 The directory for the location of the zlib include file. This option is only
397 necessary if [enable-zlib](#enable-zlib) is used and the include file is not
398 already on the system include path.
404 **On Unix**: this is the directory containing the zlib library.
405 If not provided the system library path will be used.
407 **On Windows:** this is the filename of the zlib library (with or
408 without a path). This flag must be provided if the
409 [zlib-dynamic](#zlib-dynamic) option is not also used. If zlib-dynamic is used
410 then this flag is optional and defaults to "ZLIB1" if not provided.
412 **On VMS:** this is the filename of the zlib library (with or without a path).
413 This flag is optional and if not provided then "GNV$LIBZSHR", "GNV$LIBZSHR32"
414 or "GNV$LIBZSHR64" is used by default depending on the pointer size chosen.
416 Seeding the Random Generator
417 ----------------------------
419 --with-rand-seed=seed1[,seed2,...]
421 A comma separated list of seeding methods which will be tried by OpenSSL
422 in order to obtain random input (a.k.a "entropy") for seeding its
423 cryptographically secure random number generator (CSPRNG).
424 The current seeding methods are:
428 Use a trusted operating system entropy source.
429 This is the default method if such an entropy source exists.
433 Use the [getrandom(2)][man-getrandom] or equivalent system call.
435 [man-getrandom]: http://man7.org/linux/man-pages/man2/getrandom.2.html
439 Use the first device from the DEVRANDOM list which can be opened to read
440 random bytes. The DEVRANDOM preprocessor constant expands to
442 "/dev/urandom","/dev/random","/dev/srandom"
444 on most unix-ish operating systems.
448 Check for an entropy generating daemon.
452 Use the RDSEED or RDRAND command if provided by the CPU.
456 Use librandom (not implemented yet).
460 Disable automatic seeding. This is the default on some operating systems where
461 no suitable entropy source exists, or no support for it is implemented yet.
463 For more information, see the section [Notes on random number generation][rng]
464 at the end of this document.
466 [rng]: #notes-on-random-number-generation
468 Enable and Disable Features
469 ---------------------------
471 Feature options always come in pairs, an option to enable feature xxxx, and
472 and option to disable it:
474 [ enable-xxxx | no-xxxx ]
476 Whether a feature is enabled or disabled by default, depends on the feature.
477 In the following list, always the non-default variant is documented: if
478 feature xxxx is disabled by default then enable-xxxx is documented and
479 if feature xxxx is enabled by default then no-xxxx is documented.
483 Don't build the AFALG engine.
485 This option will be forced on a platform that does not support AFALG.
489 Build with Kernel TLS support.
491 This option will enable the use of the Kernel TLS data-path, which can improve
492 performance and allow for the use of sendfile and splice system calls on
493 TLS sockets. The Kernel may use TLS accelerators if any are available on the
494 system. This option will be forced off on systems that do not support the
495 Kernel TLS data-path.
499 Build with the Address sanitiser.
501 This is a developer option only. It may not work on all platforms and should
502 never be used in production environments. It will only work when used with
503 gcc or clang and should be used in conjunction with the [no-shared](#no-shared)
508 Do not build support for Automated Cryptographic Validation Protocol (ACVP)
511 This is required for FIPS validation purposes. Certain ACVP tests require
512 access to algorithm internals that are not normally accessible.
513 Additional information related to ACVP can be found at
514 <https://github.com/usnistgov/ACVP>.
518 Do not use assembler code.
520 This should be viewed as debugging/troubleshooting option rather than for
521 production use. On some platforms a small amount of assembler code may still
522 be used even with this option.
526 Do not build support for async operations.
530 Don't automatically load all supported ciphers and digests.
532 Typically OpenSSL will make available all of its supported ciphers and digests.
533 For a statically linked application this may be undesirable if small executable
534 size is an objective. This only affects libcrypto. Ciphers and digests will
535 have to be loaded manually using EVP_add_cipher() and EVP_add_digest() if this
536 option is used. This option will force a non-shared build.
540 Don't automatically load all libcrypto/libssl error strings.
542 Typically OpenSSL will automatically load human readable error strings. For a
543 statically linked application this may be undesirable if small executable size
546 ### no-autoload-config
548 Don't automatically load the default openssl.cnf file.
550 Typically OpenSSL will automatically load a system config file which configures
553 ### enable-buildtest-c++
555 While testing, generate C++ buildtest files that simply check that the public
556 OpenSSL header files are usable standalone with C++.
558 Enabling this option demands extra care. For any compiler flag given directly
559 as configuration option, you must ensure that it's valid for both the C and
560 the C++ compiler. If not, the C++ build test will most likely break. As an
561 alternative, you can use the language specific variables, CFLAGS and CXXFLAGS.
565 Don't build the CAPI engine.
567 This option will be forced if on a platform that does not support CAPI.
571 Don't build support for Certificate Management Protocol (CMP).
575 Don't build support for Cryptographic Message Syntax (CMS).
579 Don't build support for SSL/TLS compression.
581 If this option is enabled (the default), then compression will only work if
582 the zlib or zlib-dynamic options are also chosen.
584 ### enable-crypto-mdebug
586 This now only enables the failed-malloc feature.
588 ### enable-crypto-mdebug-backtrace
590 This is a no-op; the project uses the compiler's address/leak sanitizer instead.
594 Don't build support for Certificate Transparency (CT).
598 Don't build with support for deprecated APIs up until and including the version
599 given with `--api` (or the current version, if `--api` wasn't specified).
603 Don't build support for datagram based BIOs.
605 Selecting this option will also force the disabling of DTLS.
609 Don't build support for loading Dynamic Shared Objects (DSO)
611 ### enable-devcryptoeng
613 Build the `/dev/crypto` engine.
615 This option is automatically selected on the BSD platform, in which case it can
616 be disabled with no-devcryptoeng.
618 ### no-dynamic-engine
620 Don't build the dynamically loaded engines.
622 This only has an effect in a shared build.
626 Don't build support for Elliptic Curves.
630 Don't build support for binary Elliptic Curves
632 ### enable-ec_nistp_64_gcc_128
634 Enable support for optimised implementations of some commonly used NIST
637 This option is only supported on platforms:
639 - with little-endian storage of non-byte types
640 - that tolerate misaligned memory references
641 - where the compiler:
642 - supports the non-standard type `__uint128_t`
643 - defines the built-in macro `__SIZEOF_INT128__`
647 Build support for gathering entropy from the Entropy Gathering Daemon (EGD).
651 Don't build support for loading engines.
655 Don't compile in any error strings.
657 ### enable-external-tests
659 Enable building of integration with external test suites.
661 This is a developer option and may not work on all platforms. The following
662 external test suites are currently supported:
664 - BoringSSL test suite
665 - Python PYCA/Cryptography test suite
668 See the file [test/README.external](test/README.external) for further details.
672 Don't compile in filename and line number information (e.g. for errors and
677 Don't compile the FIPS provider
679 ### enable-fuzz-libfuzzer, enable-fuzz-afl
681 Build with support for fuzzing using either libfuzzer or AFL.
683 These are developer options only. They may not work on all platforms and
684 should never be used in production environments.
686 See the file [fuzz/README.md](fuzz/README.md) for further details.
690 Don't build support for GOST based ciphersuites.
692 Note that if this feature is enabled then GOST ciphersuites are only available
693 if the GOST algorithms are also available through loading an externally supplied
698 Don't build the legacy provider.
700 Disabling this also disables the legacy algorithms: MD2 (already disabled by default).
704 Don't generate dependencies.
708 Don't build any dynamically loadable engines.
710 This also implies 'no-dynamic-engine'.
714 Don't build support for writing multiple records in one go in libssl
716 Note: this is a different capability to the pipelining functionality.
720 Don't build support for the Next Protocol Negotiation (NPN) TLS extension.
724 Don't build support for Online Certificate Status Protocol (OCSP).
728 Don't build the padlock engine.
732 As synonyme for no-padlockeng. Deprecated and should not be used.
736 Don't build with support for Position Independent Code.
740 Don't pin the shared libraries.
742 By default OpenSSL will attempt to stay in memory until the process exits.
743 This is so that libcrypto and libssl can be properly cleaned up automatically
744 via an atexit() handler. The handler is registered by libcrypto and cleans
745 up both libraries. On some platforms the atexit() handler will run on unload of
746 libcrypto (if it has been dynamically loaded) rather than at process exit. This
747 option can be used to stop OpenSSL from attempting to stay in memory until the
748 process exits. This could lead to crashes if either libcrypto or libssl have
749 already been unloaded at the point that the atexit handler is invoked, e.g. on a
750 platform which calls atexit() on unload of the library, and libssl is unloaded
751 before libcrypto then a crash is likely to happen. Applications can suppress
752 running of the atexit() handler at run time by using the OPENSSL_INIT_NO_ATEXIT
753 option to OPENSSL_init_crypto(). See the man page for it for further details.
757 Don't use POSIX IO capabilities.
761 Don't build support for Pre-Shared Key based ciphersuites.
765 Don't use hardware RDRAND capabilities.
769 Don't build support for RFC3779, "X.509 Extensions for IP Addresses and
774 Build support for Stream Control Transmission Protocol (SCTP).
778 Do not create shared libraries, only static ones.
780 See [Notes on shared libraries](#notes-on-shared-libraries) below.
784 Don't build support for socket BIOs.
788 Don't build support for Secure Remote Password (SRP) protocol or
789 SRP based ciphersuites.
793 Don't build Secure Real-Time Transport Protocol (SRTP) support.
797 Exclude SSE2 code paths from 32-bit x86 assembly modules.
799 Normally SSE2 extension is detected at run-time, but the decision whether or not
800 the machine code will be executed is taken solely on CPU capability vector. This
801 means that if you happen to run OS kernel which does not support SSE2 extension
802 on Intel P4 processor, then your application might be exposed to "illegal
803 instruction" exception. There might be a way to enable support in kernel, e.g.
804 FreeBSD kernel can be compiled with CPU_ENABLE_SSE, and there is a way to
805 disengage SSE2 code paths upon application start-up, but if you aim for wider
806 "audience" running such kernel, consider no-sse2. Both the 386 and no-asm
807 options imply no-sse2.
811 Build with the SSL Trace capabilities.
813 This adds the "-trace" option to s_client and s_server.
817 Don't build the statically linked engines.
819 This only has an impact when not built "shared".
823 Don't use anything from the C header file "stdio.h" that makes use of the "FILE"
824 type. Only libcrypto and libssl can be built in this way. Using this option will
825 suppress building the command line applications. Additionally, since the OpenSSL
826 tests also use the command line applications, the tests will also be skipped.
830 Don't build test programs or run any tests.
834 Don't build with support for multi-threaded applications.
838 Build with support for multi-threaded applications. Most platforms will enable
839 this by default. However if on a platform where this is not the case then this
840 will usually require additional system-dependent options!
842 See [Notes on multi-threading](#notes-on-multi-threading) below.
846 Build with support for the integrated tracing api.
848 See manual pages OSSL_trace_set_channel(3) and OSSL_trace_enabled(3) for details.
852 Don't build Time Stamping (TS) Authority support.
856 Build with the Undefined Behaviour sanitiser (UBSAN).
858 This is a developer option only. It may not work on all platforms and should
859 never be used in production environments. It will only work when used with gcc
860 or clang and should be used in conjunction with the `-DPEDANTIC` option
861 (or the `--strict-warnings` option).
865 Don't build with the User Interface (UI) console method
867 The User Interface console method enables text based console prompts.
871 Enable additional unit test APIs.
873 This should not typically be used in production deployments.
877 Don't build support for UPLINK interface.
879 ### enable-weak-ssl-ciphers
881 Build support for SSL/TLS ciphers that are considered "weak"
883 Enabling this includes for example the RC4 based ciphersuites.
887 Build with support for zlib compression/decompression.
891 Like the zlib option, but has OpenSSL load the zlib library dynamically
894 This is only supported on systems where loading of shared libraries is supported.
898 In 32-bit x86 builds, use the 80386 instruction set only in assembly modules
900 The default x86 code is more efficient, but requires at least an 486 processor.
901 Note: This doesn't affect compiler generated code, so this option needs to be
902 accompanied by a corresponding compiler-specific option.
906 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}
908 Don't build support for negotiating the specified SSL/TLS protocol.
910 If "no-tls" is selected then all of tls1, tls1_1, tls1_2 and tls1_3 are disabled.
911 Similarly "no-dtls" will disable dtls1 and dtls1_2. The "no-ssl" option is
912 synonymous with "no-ssl3". Note this only affects version negotiation.
913 OpenSSL will still provide the methods for applications to explicitly select
914 the individual protocol versions.
916 ### no-{protocol}-method
918 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}-method
920 Analogous to no-{protocol} but in addition do not build the methods for
921 applications to explicitly select individual protocol versions. Note that there
922 is no "no-tls1_3-method" option because there is no application method for
925 Using individual protocol methods directly is deprecated. Applications should
926 use TLS_method() instead.
928 ### enable-{algorithm}
932 Build with support for the specified algorithm.
936 no-{aria|bf|blake2|camellia|cast|chacha|cmac|
937 des|dh|dsa|ecdh|ecdsa|idea|md4|mdc2|ocb|
938 poly1305|rc2|rc4|rmd160|scrypt|seed|
939 siphash|siv|sm2|sm3|sm4|whirlpool}
941 Build without support for the specified algorithm.
943 The "ripemd" algorithm is deprecated and if used is synonymous with rmd160.
945 ### Compiler-specific options
947 -Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static
949 These system specific options will be recognised and passed through to the
950 compiler to allow you to define preprocessor symbols, specify additional
951 libraries, library directories or other compiler options. It might be worth
952 noting that some compilers generate code specifically for processor the
953 compiler currently executes on. This is not necessarily what you might have
954 in mind, since it might be unsuitable for execution on other, typically older,
955 processor. Consult your compiler documentation.
957 Take note of the [Environment Variables](#environment-variables) documentation
958 below and how these flags interact with those variables.
962 Additional options that are not otherwise recognised are passed through as
963 they are to the compiler as well. Unix-style options beginning with a
964 '-' or '+' and Windows-style options beginning with a '/' are recognized.
965 Again, consult your compiler documentation.
967 If the option contains arguments separated by spaces, then the URL-style
968 notation %20 can be used for the space character in order to avoid having
969 to quote the option. For example, -opt%20arg gets expanded to -opt arg.
970 In fact, any ASCII character can be encoded as %xx using its hexadecimal
973 Take note of the [Environment Variables](#environment-variables) documentation
974 below and how these flags interact with those variables.
976 ### Environment Variables
980 Assign the given value to the environment variable VAR for Configure.
982 These work just like normal environment variable assignments, but are supported
983 on all platforms and are confined to the configuration scripts only.
984 These assignments override the corresponding value in the inherited environment,
987 The following variables are used as "make variables" and can be used as an
988 alternative to giving preprocessor, compiler and linker options directly as
989 configuration. The following variables are supported:
991 AR The static library archiver.
992 ARFLAGS Flags for the static library archiver.
993 AS The assembler compiler.
994 ASFLAGS Flags for the assembler compiler.
996 CFLAGS Flags for the C compiler.
997 CXX The C++ compiler.
998 CXXFLAGS Flags for the C++ compiler.
999 CPP The C/C++ preprocessor.
1000 CPPFLAGS Flags for the C/C++ preprocessor.
1001 CPPDEFINES List of CPP macro definitions, separated
1002 by a platform specific character (':' or
1003 space for Unix, ';' for Windows, ',' for
1004 VMS). This can be used instead of using
1005 -D (or what corresponds to that on your
1006 compiler) in CPPFLAGS.
1007 CPPINCLUDES List of CPP inclusion directories, separated
1008 the same way as for CPPDEFINES. This can
1009 be used instead of -I (or what corresponds
1010 to that on your compiler) in CPPFLAGS.
1011 HASHBANGPERL Perl invocation to be inserted after '#!'
1012 in public perl scripts (only relevant on
1014 LD The program linker (not used on Unix, $(CC)
1016 LDFLAGS Flags for the shared library, DSO and
1018 LDLIBS Extra libraries to use when linking.
1019 Takes the form of a space separated list
1020 of library specifications on Unix and
1021 Windows, and as a comma separated list of
1023 RANLIB The library archive indexer.
1024 RC The Windows resource compiler.
1025 RCFLAGS Flags for the Windows resource compiler.
1026 RM The command to remove files and directories.
1028 These cannot be mixed with compiling/linking flags given on the command line.
1029 In other words, something like this isn't permitted.
1031 $ ./Configure -DFOO CPPFLAGS=-DBAR -DCOOKIE
1033 Backward compatibility note:
1035 To be compatible with older configuration scripts, the environment variables
1036 are ignored if compiling/linking flags are given on the command line, except
1039 AR, CC, CXX, CROSS_COMPILE, HASHBANGPERL, PERL, RANLIB, RC, and WINDRES
1041 For example, the following command will not see -DBAR:
1043 $ CPPFLAGS=-DBAR ./Configure -DCOOKIE
1045 However, the following will see both set variables:
1047 $ CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- ./Configure -DCOOKIE
1049 If CC is set, it is advisable to also set CXX to ensure both the C and C++
1050 compiler are in the same "family". This becomes relevant with
1051 'enable-external-tests' and 'enable-buildtest-c++'.
1058 Reconfigure from earlier data.
1060 This fetches the previous command line options and environment from data
1061 saved in "configdata.pm" and runs the configuration process again, using
1062 these options and environment. Note: NO other option is permitted together
1063 with "reconf". Note: The original configuration saves away values for ALL
1064 environment variables that were used, and if they weren't defined, they are
1065 still saved away with information that they weren't originally defined.
1066 This information takes precedence over environment variables that are
1067 defined when reconfiguring.
1069 Displaying configuration data
1070 -----------------------------
1072 The configuration script itself will say very little, and finishes by
1073 creating "configdata.pm". This perl module can be loaded by other scripts
1074 to find all the configuration data, and it can also be used as a script to
1075 display all sorts of configuration data in a human readable form.
1077 For more information, please do:
1079 $ ./configdata.pm --help # Unix
1083 $ perl configdata.pm --help # Windows and VMS
1085 Installation Steps in Detail
1086 ============================
1091 ### Automatic Configuration
1093 On some platform a `config` script is available which attempts to guess
1094 your operating system (and compiler, if necessary) and calls the `Configure`
1095 Perl script with appropriate target based on its guess. Further options can
1096 be supplied to the `config` script, which will be passed on to the `Configure`
1099 #### Unix / Linux / macOS
1101 $ ./Configure [[ options ]]
1105 $ perl Configure [[ options ]]
1109 $ perl Configure [[ options ]]
1111 ### Manual Configuration
1113 OpenSSL knows about a range of different operating system, hardware and
1114 compiler combinations. To see the ones it knows about, run
1116 $ ./Configure LIST # Unix
1120 $ perl Configure LIST # All other platforms
1122 For the remainder of this text, the Unix form will be used in all examples.
1123 Please use the appropriate form for your platform.
1125 Pick a suitable name from the list that matches your system. For most
1126 operating systems there is a choice between using "cc" or "gcc".
1127 When you have identified your system (and if necessary compiler) use this
1128 name as the argument to Configure. For example, a "linux-elf" user would
1131 $ ./Configure linux-elf [[ options ]]
1133 ### Creating your own Configuration
1135 If your system isn't listed, you will have to create a configuration
1136 file named Configurations/{{ something }}.conf and add the correct
1137 configuration for your system. See the available configs as examples
1138 and read Configurations/README and Configurations/README.design for
1141 The generic configurations "cc" or "gcc" should usually work on 32 bit
1144 Configure creates a build file ("Makefile" on Unix, "makefile" on Windows
1145 and "descrip.mms" on OpenVMS) from a suitable template in Configurations,
1146 and defines various macros in include/openssl/configuration.h (generated
1147 from include/openssl/configuration.h.in).
1149 ### Out of Tree Builds
1151 OpenSSL can be configured to build in a build directory separate from the
1152 source code directory. It's done by placing yourself in some other
1153 directory and invoking the configuration commands from there.
1157 $ mkdir /var/tmp/openssl-build
1158 $ cd /var/tmp/openssl-build
1159 $ /PATH/TO/OPENSSL/SOURCE/Configure [[ options ]]
1161 #### OpenVMS example
1163 $ set default sys$login:
1164 $ create/dir [.tmp.openssl-build]
1165 $ set default [.tmp.openssl-build]
1166 $ perl D:[PATH.TO.OPENSSL.SOURCE]Configure [[ options ]]
1168 #### Windows example
1171 $ mkdir \temp-openssl
1173 $ perl d:\PATH\TO\OPENSSL\SOURCE\Configure [[ options ]]
1175 Paths can be relative just as well as absolute. Configure will do its best
1176 to translate them to relative paths whenever possible.
1181 Build OpenSSL by running:
1184 $ mms ! (or mmk) OpenVMS
1187 This will build the OpenSSL libraries (libcrypto.a and libssl.a on
1188 Unix, corresponding on other platforms) and the OpenSSL binary
1189 ("openssl"). The libraries will be built in the top-level directory,
1190 and the binary will be in the "apps" subdirectory.
1192 If the build fails, take a look at the [Build Failures](#build-failures)
1193 subsection of the [Troubleshooting](#troubleshooting) section.
1198 After a successful build, and before installing, the libraries should
1202 $ mms test ! OpenVMS
1203 $ nmake test # Windows
1205 **Warning:** you MUST run the tests from an unprivileged account (or disable
1206 your privileges temporarily if your platform allows it).
1208 If some tests fail, take a look at the [Test Failures](#test-failures)
1209 subsection of the [Troubleshooting](#troubleshooting) section.
1214 If everything tests ok, install OpenSSL with
1216 $ make install # Unix
1217 $ mms install ! OpenVMS
1218 $ nmake install # Windows
1220 Note that in order to perform the install step above you need to have
1221 appropriate permissions to write to the installation directory.
1223 The above commands will install all the software components in this
1224 directory tree under PREFIX (the directory given with `--prefix` or
1227 ### Unix / Linux / macOS
1229 bin/ Contains the openssl binary and a few other
1232 Contains the header files needed if you want
1233 to build your own programs that use libcrypto
1235 lib Contains the OpenSSL library files.
1236 lib/engines Contains the OpenSSL dynamically loadable engines.
1238 share/man/man1 Contains the OpenSSL command line man-pages.
1239 share/man/man3 Contains the OpenSSL library calls man-pages.
1240 share/man/man5 Contains the OpenSSL configuration format man-pages.
1241 share/man/man7 Contains the OpenSSL other misc man-pages.
1243 share/doc/openssl/html/man1
1244 share/doc/openssl/html/man3
1245 share/doc/openssl/html/man5
1246 share/doc/openssl/html/man7
1247 Contains the HTML rendition of the man-pages.
1251 'arch' is replaced with the architecture name, "Alpha" or "ia64",
1252 'sover' is replaced with the shared library version (0101 for 1.1), and
1253 'pz' is replaced with the pointer size OpenSSL was built with:
1255 [.EXE.'arch'] Contains the openssl binary.
1256 [.EXE] Contains a few utility scripts.
1258 Contains the header files needed if you want
1259 to build your own programs that use libcrypto
1261 [.LIB.'arch'] Contains the OpenSSL library files.
1262 [.ENGINES'sover''pz'.'arch']
1263 Contains the OpenSSL dynamically loadable engines.
1264 [.SYS$STARTUP] Contains startup, login and shutdown scripts.
1265 These define appropriate logical names and
1267 [.SYSTEST] Contains the installation verification procedure.
1268 [.HTML] Contains the HTML rendition of the manual pages.
1270 ### Additional Directories
1272 Additionally, install will add the following directories under
1273 OPENSSLDIR (the directory given with `--openssldir` or its default)
1274 for you convenience:
1276 certs Initially empty, this is the default location
1277 for certificate files.
1278 private Initially empty, this is the default location
1279 for private key files.
1280 misc Various scripts.
1282 The installation directory should be appropriately protected to ensure
1283 unprivileged users cannot make changes to OpenSSL binaries or files, or
1284 install engines. If you already have a pre-installed version of OpenSSL as
1285 part of your Operating System it is recommended that you do not overwrite
1286 the system version and instead install to somewhere else.
1288 Package builders who want to configure the library for standard locations,
1289 but have the package installed somewhere else so that it can easily be
1292 $ make DESTDIR=/tmp/package-root install # Unix
1293 $ mms/macro="DESTDIR=TMP:[PACKAGE-ROOT]" install ! OpenVMS
1295 The specified destination directory will be prepended to all installation
1298 Compatibility issues with previous OpenSSL versions
1299 ---------------------------------------------------
1301 ### COMPILING existing applications
1303 Starting with version 1.1.0, OpenSSL hides a number of structures that were
1304 previously open. This includes all internal libssl structures and a number
1305 of EVP types. Accessor functions have been added to allow controlled access
1306 to the structures' data.
1308 This means that some software needs to be rewritten to adapt to the new ways
1309 of doing things. This often amounts to allocating an instance of a structure
1310 explicitly where you could previously allocate them on the stack as automatic
1311 variables, and using the provided accessor functions where you would previously
1312 access a structure's field directly.
1314 Some APIs have changed as well. However, older APIs have been preserved when
1317 Post-installation Notes
1318 -----------------------
1320 With the default OpenSSL installation comes a FIPS provider module, which
1321 needs some post-installation attention, without which it will not be usable.
1322 This involves using the following command:
1324 $ openssl fipsinstall
1326 See the openssl-fipsinstall(1) manual for details and examples.
1328 Advanced Build Options
1329 ======================
1331 Environment Variables
1332 ---------------------
1334 A number of environment variables can be used to provide additional control
1335 over the build process. Typically these should be defined prior to running
1336 Configure. Not all environment variables are relevant to all platforms.
1339 The name of the ar executable to use.
1342 Use a different build file name than the platform default
1343 ("Makefile" on Unix-like platforms, "makefile" on native Windows,
1344 "descrip.mms" on OpenVMS). This requires that there is a
1345 corresponding build file template. See Configurations/README
1346 for further information.
1349 The compiler to use. Configure will attempt to pick a default
1350 compiler for your platform but this choice can be overridden
1351 using this variable. Set it to the compiler executable you wish
1352 to use, e.g. "gcc" or "clang".
1355 This environment variable has the same meaning as for the
1356 "--cross-compile-prefix" Configure flag described above. If both
1357 are set then the Configure flag takes precedence.
1360 The name of the nm executable to use.
1362 OPENSSL_LOCAL_CONFIG_DIR
1363 OpenSSL comes with a database of information about how it
1364 should be built on different platforms as well as build file
1365 templates for those platforms. The database is comprised of
1366 ".conf" files in the Configurations directory. The build
1367 file templates reside there as well as ".tmpl" files. See the
1368 file Configurations/README for further information about the
1369 format of ".conf" files as well as information on the ".tmpl"
1371 In addition to the standard ".conf" and ".tmpl" files, it is
1372 possible to create your own ".conf" and ".tmpl" files and store
1373 them locally, outside the OpenSSL source tree. This environment
1374 variable can be set to the directory where these files are held
1375 and will be considered by Configure before it looks in the
1376 standard directories.
1379 The name of the Perl executable to use when building OpenSSL.
1380 Only needed if builing should use a different Perl executable
1381 than what is used to run the Configure script.
1384 The command string for the Perl executable to insert in the
1385 #! line of perl scripts that will be publicly installed.
1386 Default: /usr/bin/env perl
1387 Note: the value of this variable is added to the same scripts
1388 on all platforms, but it's only relevant on Unix-like platforms.
1391 The name of the rc executable to use. The default will be as
1392 defined for the target platform in the ".conf" file. If not
1393 defined then "windres" will be used. The WINDRES environment
1394 variable is synonymous to this. If both are defined then RC
1398 The name of the ranlib executable to use.
1406 The Configure script generates a Makefile in a format relevant to the specific
1407 platform. The Makefiles provide a number of targets that can be used. Not all
1408 targets may be available on all platforms. Only the most common targets are
1409 described here. Examine the Makefiles themselves for the full list.
1412 The target to build all the software components and
1416 Build all the software components.
1417 THIS IS THE DEFAULT TARGET.
1420 Build all documentation components.
1423 Remove all build artefacts and return the directory to a "clean"
1427 Rebuild the dependencies in the Makefiles. This is a legacy
1428 option that no longer needs to be used since OpenSSL 1.1.0.
1431 Install all OpenSSL components.
1434 Only install the OpenSSL software components.
1437 Only install the OpenSSL documentation components.
1440 Only install the OpenSSL man pages (Unix only).
1443 Only install the OpenSSL html documentation.
1446 Prints a list of all the self test names.
1449 Build and run the OpenSSL self tests.
1452 Uninstall all OpenSSL components.
1456 Re-run the configuration process, as exactly as the last time
1460 This is a developer option. If you are developing a patch for
1461 OpenSSL you may need to use this if you want to update
1462 automatically generated files; add new error codes or add new
1463 (or change the visibility of) public API functions. (Unix only).
1465 Running Selected Tests
1466 ----------------------
1468 The make variable TESTS supports a versatile set of space separated tokens
1469 with which you can specify a set of tests to be performed. With a "current
1470 set of tests" in mind, initially being empty, here are the possible tokens:
1472 alltests The current set of tests becomes the whole set of available
1473 tests (as listed when you do 'make list-tests' or similar).
1475 xxx Adds the test 'xxx' to the current set of tests.
1477 -xxx Removes 'xxx' from the current set of tests. If this is the
1478 first token in the list, the current set of tests is first
1479 assigned the whole set of available tests, effectively making
1480 this token equivalent to TESTS="alltests -xxx".
1482 nn Adds the test group 'nn' (which is a number) to the current
1485 -nn Removes the test group 'nn' from the current set of tests.
1486 If this is the first token in the list, the current set of
1487 tests is first assigned the whole set of available tests,
1488 effectively making this token equivalent to
1489 TESTS="alltests -xxx".
1491 Also, all tokens except for "alltests" may have wildcards, such as *.
1492 (on Unix and Windows, BSD style wildcards are supported, while on VMS,
1493 it's VMS style wildcards)
1497 Run all tests except for the fuzz tests:
1499 $ make TESTS=-test_fuzz test
1501 or, if you want to be explicit:
1503 $ make TESTS='alltests -test_fuzz' test
1505 Run all tests that have a name starting with "test_ssl" but not those
1506 starting with "test_ssl_":
1508 $ make TESTS='test_ssl* -test_ssl_*' test
1510 Run only test group 10:
1514 Run all tests except the slow group (group 99):
1518 Run all tests in test groups 80 to 99 except for tests in group 90:
1520 $ make TESTS='[89]? -90'
1522 To stochastically verify that the algorithm that produces uniformly distributed
1523 random numbers is operating correctly (with a false positive rate of 0.01%):
1525 $ ./util/wrap.sh test/bntest -stochastic
1530 Configuration Problems
1531 ----------------------
1533 ### Selecting the correct target
1535 The `./Configure` script tries hard to guess your operating system, but in some
1536 cases it does not succeed. You will see a message like the following:
1539 Operating system: x86-whatever-minix
1540 This system (minix) is not supported. See file INSTALL for details.
1542 Even if the automatic target selection by the `./Configure` script fails, chances
1543 are that you still might find a suitable target in the Configurations directory,
1544 which you can supply to the `./Configure` command, possibly after some adjustment.
1546 The Configurations directory contains a lot of examples of such targets.
1547 The main configuration file is [10-main.conf][], which contains all targets that
1548 are officially supported by the OpenSSL team. Other configuration files contain
1549 targets contributed by other OpenSSL users. The list of targets can be found in
1550 a Perl list `my %targets = ( ... )`.
1555 inherit_from => [ "base-target" ],
1557 cflags => add("..."),
1559 perlasm_scheme => "...",
1564 If you call `./Configure` without arguments, it will give you a list of all
1565 known targets. Using `grep`, you can lookup the target definition in the
1566 Configurations directory. For example the "android-x86_64" can be found in
1567 Configurations/15-android.conf.
1569 The directory contains two README files, which explain the general syntax and
1570 design of the configurations files.
1572 - [Configurations/README](Configurations/README)
1573 - [Configurations/README.design](Configurations/README.design)
1575 If you need further help, try to search the [openssl-users][] mailing list
1576 or the [GitHub Issues][] for existing solutions. If you don't find anything,
1577 you can [raise an issue][] to ask a question yourself.
1579 More about our support resources can be found in the [SUPPORT][] file.
1581 ### Configuration Errors
1583 If the `./Configure` or `./Configure` command fails with an error message,
1584 read the error message carefully and try to figure out whether you made
1585 a mistake (e.g., by providing a wrong option), or whether the script is
1586 working incorrectly. If you think you encountered a bug, please
1587 [raise an issue][] on GitHub to file a bug report.
1589 Along with a short description of the bug, please provide the complete
1590 configure command line and the relevant output including the error message.
1592 Note: To make the output readable, pleace add a 'code fence' (three backquotes
1593 ` ``` ` on a separate line) before and after your output:
1596 ./Configure [your arguments...]
1605 If the build fails, look carefully at the output. Try to locate and understand
1606 the error message. It might be that the compiler is already telling you
1607 exactly what you need to do to fix your problem.
1609 There may be reasons for the failure that aren't problems in OpenSSL itself,
1610 for example if the compiler reports missing standard or third party headers.
1612 If the build succeeded previously, but fails after a source or configuration
1613 change, it might be helpful to clean the build tree before attempting another
1614 build. Use this command:
1617 $ mms clean ! (or mmk) OpenVMS
1618 $ nmake clean # Windows
1620 Assembler error messages can sometimes be sidestepped by using the
1621 "no-asm" configuration option.
1623 Compiling parts of OpenSSL with gcc and others with the system compiler will
1624 result in unresolved symbols on some systems.
1626 If you are still having problems, try to search the [openssl-users][] mailing
1627 list or the [GitHub Issues][] for existing solutions. If you think you
1628 encountered an OpenSSL bug, please [raise an issue][] to file a bug report.
1629 Please take the time to review the existing issues first; maybe the bug was
1630 already reported or has already been fixed.
1635 If some tests fail, look at the output. There may be reasons for the failure
1636 that isn't a problem in OpenSSL itself (like an OS malfunction or a Perl issue).
1637 You may want increased verbosity, that can be accomplished like this:
1639 Full verbosity (`make` macro `VERBOSE` or `V`):
1641 $ make V=1 test # Unix
1642 $ mms /macro=(V=1) test ! OpenVMS
1643 $ nmake V=1 test # Windows
1645 Verbosity on test failure (`VERBOSE_FAILURE` or `VF´, Unix example shown):
1649 Verbosity on failed (sub-)tests only (`VERBOSE_FAILURES_ONLY` or `VFO`):
1653 Verbosity on failed (sub-)tests, in addition progress on succeeded (sub-)tests
1654 (`VERBOSE_FAILURES_PROGRESS` or `VFP`):
1658 If you want to run just one or a few specific tests, you can use
1659 the make variable TESTS to specify them, like this:
1661 $ make TESTS='test_rsa test_dsa' test # Unix
1662 $ mms/macro="TESTS=test_rsa test_dsa" test ! OpenVMS
1663 $ nmake TESTS='test_rsa test_dsa' test # Windows
1665 And of course, you can combine (Unix examples shown):
1667 $ make test TESTS='test_rsa test_dsa' VF=1
1668 $ make test TESTS="test_cmp_*" VFO=1
1670 You can find the list of available tests like this:
1672 $ make list-tests # Unix
1673 $ mms list-tests ! OpenVMS
1674 $ nmake list-tests # Windows
1676 Have a look at the manual for the perl module Test::Harness to
1677 see what other HARNESS_* variables there are.
1679 If you find a problem with OpenSSL itself, try removing any
1680 compiler optimization flags from the CFLAGS line in Makefile and
1681 run "make clean; make" or corresponding.
1683 To report a bug please open an issue on GitHub, at
1684 <https://github.com/openssl/openssl/issues>.
1686 For more details on how the make variables TESTS can be used,
1687 see section [Running Selected Tests](#running-selected-tests) below.
1692 Notes on multi-threading
1693 ------------------------
1695 For some systems, the OpenSSL Configure script knows what compiler options
1696 are needed to generate a library that is suitable for multi-threaded
1697 applications. On these systems, support for multi-threading is enabled
1698 by default; use the "no-threads" option to disable (this should never be
1701 On other systems, to enable support for multi-threading, you will have
1702 to specify at least two options: "threads", and a system-dependent option.
1703 (The latter is "-D_REENTRANT" on various systems.) The default in this
1704 case, obviously, is not to include support for multi-threading (but
1705 you can still use "no-threads" to suppress an annoying warning message
1706 from the Configure script.)
1708 OpenSSL provides built-in support for two threading models: pthreads (found on
1709 most UNIX/Linux systems), and Windows threads. No other threading models are
1710 supported. If your platform does not provide pthreads or Windows threads then
1711 you should Configure with the "no-threads" option.
1713 Notes on shared libraries
1714 -------------------------
1716 For most systems the OpenSSL Configure script knows what is needed to
1717 build shared libraries for libcrypto and libssl. On these systems
1718 the shared libraries will be created by default. This can be suppressed and
1719 only static libraries created by using the "no-shared" option. On systems
1720 where OpenSSL does not know how to build shared libraries the "no-shared"
1721 option will be forced and only static libraries will be created.
1723 Shared libraries are named a little differently on different platforms.
1724 One way or another, they all have the major OpenSSL version number as
1725 part of the file name, i.e. for OpenSSL 1.1.x, 1.1 is somehow part of
1728 On most POSIX platforms, shared libraries are named libcrypto.so.1.1
1731 on Cygwin, shared libraries are named cygcrypto-1.1.dll and cygssl-1.1.dll
1732 with import libraries libcrypto.dll.a and libssl.dll.a.
1734 On Windows build with MSVC or using MingW, shared libraries are named
1735 libcrypto-1_1.dll and libssl-1_1.dll for 32-bit Windows, libcrypto-1_1-x64.dll
1736 and libssl-1_1-x64.dll for 64-bit x86_64 Windows, and libcrypto-1_1-ia64.dll
1737 and libssl-1_1-ia64.dll for IA64 Windows. With MSVC, the import libraries
1738 are named libcrypto.lib and libssl.lib, while with MingW, they are named
1739 libcrypto.dll.a and libssl.dll.a.
1741 On VMS, shareable images (VMS speak for shared libraries) are named
1742 ossl$libcrypto0101_shr.exe and ossl$libssl0101_shr.exe. However, when
1743 OpenSSL is specifically built for 32-bit pointers, the shareable images
1744 are named ossl$libcrypto0101_shr32.exe and ossl$libssl0101_shr32.exe
1745 instead, and when built for 64-bit pointers, they are named
1746 ossl$libcrypto0101_shr64.exe and ossl$libssl0101_shr64.exe.
1748 Notes on random number generation
1749 ---------------------------------
1751 Availability of cryptographically secure random numbers is required for
1752 secret key generation. OpenSSL provides several options to seed the
1753 internal CSPRNG. If not properly seeded, the internal CSPRNG will refuse
1754 to deliver random bytes and a "PRNG not seeded error" will occur.
1756 The seeding method can be configured using the `--with-rand-seed` option,
1757 which can be used to specify a comma separated list of seed methods.
1758 However in most cases OpenSSL will choose a suitable default method,
1759 so it is not necessary to explicitly provide this option. Note also
1760 that not all methods are available on all platforms.
1762 I) On operating systems which provide a suitable randomness source (in
1763 form of a system call or system device), OpenSSL will use the optimal
1764 available method to seed the CSPRNG from the operating system's
1765 randomness sources. This corresponds to the option `--with-rand-seed=os`.
1767 II) On systems without such a suitable randomness source, automatic seeding
1768 and reseeding is disabled (--with-rand-seed=none) and it may be necessary
1769 to install additional support software to obtain a random seed and reseed
1770 the CSPRNG manually. Please check out the manual pages for RAND_add(),
1771 RAND_bytes(), RAND_egd(), and the FAQ for more information.
1776 <https://mta.openssl.org/mailman/listinfo/openssl-users>
1782 <https://github.com/openssl/openssl/issues>
1785 <https://github.com/openssl/openssl/issues/new/choose>
1788 Configurations/10-main.conf