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 - [Setting the FIPS HMAC key](#setting-the-FIPS-HMAC-key)
25 - [Enable and Disable Features](#enable-and-disable-features)
26 - [Displaying configuration data](#displaying-configuration-data)
27 - [Installation Steps in Detail](#installation-steps-in-detail)
28 - [Configure](#configure-openssl)
29 - [Build](#build-openssl)
30 - [Test](#test-openssl)
31 - [Install](#install-openssl)
32 - [Advanced Build Options](#advanced-build-options)
33 - [Environment Variables](#environment-variables)
34 - [Makefile Targets](#makefile-targets)
35 - [Running Selected Tests](#running-selected-tests)
36 - [Troubleshooting](#troubleshooting)
37 - [Configuration Problems](#configuration-problems)
38 - [Build Failures](#build-failures)
39 - [Test Failures](#test-failures)
41 - [Notes on multi-threading](#notes-on-multi-threading)
42 - [Notes on shared libraries](#notes-on-shared-libraries)
43 - [Notes on random number generation](#notes-on-random-number-generation)
44 - [Notes on assembler modules compilation](#notes-on-assembler-modules-compilation)
49 To install OpenSSL, you will need:
51 * A "make" implementation
52 * Perl 5 with core modules (please read [NOTES-PERL.md](NOTES-PERL.md))
53 * The Perl module `Text::Template` (please read [NOTES-PERL.md](NOTES-PERL.md))
55 * a development environment in the form of development libraries and C
57 * a supported operating system
59 For additional platform specific requirements, solutions to specific
60 issues and other details, please read one of these:
62 * [Notes for UNIX-like platforms](NOTES-UNIX.md)
63 * [Notes for Android platforms](NOTES-ANDROID.md)
64 * [Notes for Windows platforms](NOTES-WINDOWS.md)
65 * [Notes for the DOS platform with DJGPP](NOTES-DJGPP.md)
66 * [Notes for the OpenVMS platform](NOTES-VMS.md)
67 * [Notes on Perl](NOTES-PERL.md)
68 * [Notes on Valgrind](NOTES-VALGRIND.md)
70 Notational conventions
71 ======================
73 Throughout this document, we use the following conventions.
78 Any line starting with a dollar sign is a command line.
82 The dollar sign indicates the shell prompt and is not to be entered as
88 Several words in curly braces separated by pipe characters indicate a
89 **mandatory choice**, to be replaced with one of the given words.
92 $ echo { WORD1 | WORD2 | WORD3 }
94 represents one of the following three commands
102 One or several words in square brackets separated by pipe characters
103 denote an **optional choice**. It is similar to the mandatory choice,
104 but it can also be omitted entirely.
108 $ echo [ WORD1 | WORD2 | WORD3 ]
110 represents one of the four commands
123 **Mandatory arguments** are enclosed in double curly braces.
124 A simple example would be
126 $ type {{ filename }}
128 which is to be understood to use the command `type` on some file name
129 determined by the user.
131 **Optional Arguments** are enclosed in double square brackets.
135 Note that the notation assumes spaces around `{`, `}`, `[`, `]`, `{{`, `}}` and
136 `[[`, `]]`. This is to differentiate from OpenVMS directory
137 specifications, which also use [ and ], but without spaces.
139 Quick Installation Guide
140 ========================
142 If you just want to get OpenSSL installed without bothering too much
143 about the details, here is the short version of how to build and install
144 OpenSSL. If any of the following steps fails, please consult the
145 [Installation in Detail](#installation-steps-in-detail) section below.
150 Use the following commands to configure, build and test OpenSSL.
151 The testing is optional, but recommended if you intend to install
152 OpenSSL for production use.
154 ### Unix / Linux / macOS
162 Use the following commands to build OpenSSL:
170 If you are using Visual Studio, open a Developer Command Prompt and
171 issue the following commands to build OpenSSL.
177 As mentioned in the [Choices](#choices) section, you need to pick one
178 of the four Configure targets in the first command.
180 Most likely you will be using the `VC-WIN64A` target for 64bit Windows
181 binaries (AMD64) or `VC-WIN32` for 32bit Windows binaries (X86).
182 The other two options are `VC-WIN64I` (Intel IA64, Itanium) and
183 `VC-CE` (Windows CE) are rather uncommon nowadays.
188 The following commands will install OpenSSL to a default system location.
190 **Danger Zone:** even if you are impatient, please read the following two
191 paragraphs carefully before you install OpenSSL.
193 For security reasons the default system location is by default not writable
194 for unprivileged users. So for the final installation step administrative
195 privileges are required. The default system location and the procedure to
196 obtain administrative privileges depends on the operating system.
197 It is recommended to compile and test OpenSSL with normal user privileges
198 and use administrative privileges only for the final installation step.
200 On some platforms OpenSSL is preinstalled as part of the Operating System.
201 In this case it is highly recommended not to overwrite the system versions,
202 because other applications or libraries might depend on it.
203 To avoid breaking other applications, install your copy of OpenSSL to a
204 [different location](#installing-to-a-different-location) which is not in
205 the global search path for system libraries.
207 Finally, if you plan on using the FIPS module, you need to read the
208 [Post-installation Notes](#post-installation-notes) further down.
210 ### Unix / Linux / macOS
212 Depending on your distribution, you need to run the following command as
213 root user or prepend `sudo` to the command:
217 By default, OpenSSL will be installed to
221 More precisely, the files will be installed into the subdirectories
228 depending on the file type, as it is custom on Unix-like operating systems.
232 Use the following command to install OpenSSL.
236 By default, OpenSSL will be installed to
242 If you are using Visual Studio, open the Developer Command Prompt _elevated_
243 and issue the following command.
247 The easiest way to elevate the Command Prompt is to press and hold down
248 the both the `<CTRL>` and `<SHIFT>` key while clicking the menu item in the
251 The default installation location is
253 C:\Program Files\OpenSSL
255 for native binaries, or
257 C:\Program Files (x86)\OpenSSL
259 for 32bit binaries on 64bit Windows (WOW64).
261 #### Installing to a different location
263 To install OpenSSL to a different location (for example into your home
264 directory for testing purposes) run `Configure` as shown in the following
267 The options `--prefix` and `--openssldir` are explained in further detail in
268 [Directories](#directories) below, and the values used here are mere examples.
272 $ ./Configure --prefix=/opt/openssl --openssldir=/usr/local/ssl
276 $ perl Configure --prefix=PROGRAM:[INSTALLS] --openssldir=SYS$MANAGER:[OPENSSL]
278 Note: if you do add options to the configuration command, please make sure
279 you've read more than just this Quick Start, such as relevant `NOTES-*` files,
280 the options outline below, as configuration options may change the outcome
281 in otherwise unexpected ways.
283 Configuration Options
284 =====================
286 There are several options to `./Configure` to customize the build (note that
287 for Windows, the defaults for `--prefix` and `--openssldir` depend on what
288 configuration is used and what Windows implementation OpenSSL is built on.
289 For more information, see the [Notes for Windows platforms](NOTES-WINDOWS.md).
296 Build the OpenSSL libraries to support the API for the specified version.
297 If [no-deprecated](#no-deprecated) is also given, don't build with support
298 for deprecated APIs in or below the specified version number. For example,
301 --api=1.1.0 no-deprecated
303 will remove support for all APIs that were deprecated in OpenSSL version
304 1.1.0 or below. This is a rather specialized option for developers.
305 If you just intend to remove all deprecated APIs up to the current version
306 entirely, just specify [no-deprecated](#no-deprecated).
307 If `--api` isn't given, it defaults to the current (minor) OpenSSL version.
312 --cross-compile-prefix=<PREFIX>
314 The `<PREFIX>` to include in front of commands for your toolchain.
316 It is likely to have to end with dash, e.g. `a-b-c-` would invoke GNU compiler
317 as `a-b-c-gcc`, etc. Unfortunately cross-compiling is too case-specific to put
318 together one-size-fits-all instructions. You might have to pass more flags or
319 set up environment variables to actually make it work. Android and iOS cases
320 are discussed in corresponding `Configurations/15-*.conf` files. But there are
321 cases when this option alone is sufficient. For example to build the mingw64
322 target on Linux `--cross-compile-prefix=x86_64-w64-mingw32-` works. Naturally
323 provided that mingw packages are installed. Today Debian and Ubuntu users
324 have option to install a number of prepackaged cross-compilers along with
325 corresponding run-time and development packages for "alien" hardware. To give
326 another example `--cross-compile-prefix=mipsel-linux-gnu-` suffices in such
329 For cross compilation, you must [configure manually](#manual-configuration).
330 Also, note that `--openssldir` refers to target's file system, not one you are
338 Build OpenSSL with debugging symbols and zero optimization level.
342 Build OpenSSL without debugging symbols. This is the default.
351 The name of the directory under the top of the installation directory tree
352 (see the `--prefix` option) where libraries will be installed. By default
353 this is `lib/`. Note that on Windows only static libraries (`*.lib`) will
354 be stored in this location. Shared libraries (`*.dll`) will always be
355 installed to the `bin/` directory.
361 Directory for OpenSSL configuration files, and also the default certificate
362 and key store. Defaults are:
365 Windows: C:\Program Files\Common Files\SSL
366 OpenVMS: SYS$COMMON:[OPENSSL-COMMON]
368 For 32bit Windows applications on Windows 64bit (WOW64), always replace
369 `C:\Program Files` by `C:\Program Files (x86)`.
375 The top of the installation directory tree. Defaults are:
378 Windows: C:\Program Files\OpenSSL
379 OpenVMS: SYS$COMMON:[OPENSSL]
386 This is a developer flag that switches on various compiler options recommended
387 for OpenSSL development. It only works when using gcc or clang as the compiler.
388 If you are developing a patch for OpenSSL then it is recommended that you use
389 this option where possible.
394 ### with-zlib-include
396 --with-zlib-include=DIR
398 The directory for the location of the zlib include file. This option is only
399 necessary if [zlib](#zlib) is used and the include file is not
400 already on the system include path.
406 **On Unix**: this is the directory containing the zlib library.
407 If not provided the system library path will be used.
409 **On Windows:** this is the filename of the zlib library (with or
410 without a path). This flag must be provided if the
411 [zlib-dynamic](#zlib-dynamic) option is not also used. If `zlib-dynamic` is used
412 then this flag is optional and defaults to `ZLIB1` if not provided.
414 **On VMS:** this is the filename of the zlib library (with or without a path).
415 This flag is optional and if not provided then `GNV$LIBZSHR`, `GNV$LIBZSHR32`
416 or `GNV$LIBZSHR64` is used by default depending on the pointer size chosen.
418 Seeding the Random Generator
419 ----------------------------
421 --with-rand-seed=seed1[,seed2,...]
423 A comma separated list of seeding methods which will be tried by OpenSSL
424 in order to obtain random input (a.k.a "entropy") for seeding its
425 cryptographically secure random number generator (CSPRNG).
426 The current seeding methods are:
430 Use a trusted operating system entropy source.
431 This is the default method if such an entropy source exists.
435 Use the [getrandom(2)][man-getrandom] or equivalent system call.
437 [man-getrandom]: http://man7.org/linux/man-pages/man2/getrandom.2.html
441 Use the first device from the `DEVRANDOM` list which can be opened to read
442 random bytes. The `DEVRANDOM` preprocessor constant expands to
444 "/dev/urandom","/dev/random","/dev/srandom"
446 on most unix-ish operating systems.
450 Check for an entropy generating daemon.
451 This source is ignored by the FIPS provider.
455 Use the `RDSEED` or `RDRAND` command if provided by the CPU.
459 Use librandom (not implemented yet).
460 This source is ignored by the FIPS provider.
464 Disable automatic seeding. This is the default on some operating systems where
465 no suitable entropy source exists, or no support for it is implemented yet.
466 This option is ignored by the FIPS provider.
468 For more information, see the section [Notes on random number generation][rng]
469 at the end of this document.
471 [rng]: #notes-on-random-number-generation
473 Setting the FIPS HMAC key
474 -------------------------
478 As part of its self-test validation, the FIPS module must verify itself
479 by performing a SHA-256 HMAC computation on itself. The default key is
480 the SHA256 value of "the holy handgrenade of antioch" and is sufficient
481 for meeting the FIPS requirements.
483 To change the key to a different value, use this flag. The value should
484 be a hex string no more than 64 characters.
486 Enable and Disable Features
487 ---------------------------
489 Feature options always come in pairs, an option to enable feature
490 `xxxx`, and an option to disable it:
492 [ enable-xxxx | no-xxxx ]
494 Whether a feature is enabled or disabled by default, depends on the feature.
495 In the following list, always the non-default variant is documented: if
496 feature `xxxx` is disabled by default then `enable-xxxx` is documented and
497 if feature `xxxx` is enabled by default then `no-xxxx` is documented.
501 Don't build the AFALG engine.
503 This option will be forced on a platform that does not support AFALG.
507 Build with Kernel TLS support.
509 This option will enable the use of the Kernel TLS data-path, which can improve
510 performance and allow for the use of sendfile and splice system calls on
511 TLS sockets. The Kernel may use TLS accelerators if any are available on the
512 system. This option will be forced off on systems that do not support the
513 Kernel TLS data-path.
517 Build with the Address sanitiser.
519 This is a developer option only. It may not work on all platforms and should
520 never be used in production environments. It will only work when used with
521 gcc or clang and should be used in conjunction with the [no-shared](#no-shared)
524 ### enable-acvp-tests
526 Build support for Automated Cryptographic Validation Protocol (ACVP)
529 This is required for FIPS validation purposes. Certain ACVP tests require
530 access to algorithm internals that are not normally accessible.
531 Additional information related to ACVP can be found at
532 <https://github.com/usnistgov/ACVP>.
536 Do not use assembler code.
538 This should be viewed as debugging/troubleshooting option rather than for
539 production use. On some platforms a small amount of assembler code may still
540 be used even with this option.
544 Do not build support for async operations.
548 Don't automatically load all supported ciphers and digests.
550 Typically OpenSSL will make available all of its supported ciphers and digests.
551 For a statically linked application this may be undesirable if small executable
552 size is an objective. This only affects libcrypto. Ciphers and digests will
553 have to be loaded manually using `EVP_add_cipher()` and `EVP_add_digest()`
554 if this option is used. This option will force a non-shared build.
558 Don't automatically load all libcrypto/libssl error strings.
560 Typically OpenSSL will automatically load human readable error strings. For a
561 statically linked application this may be undesirable if small executable size
564 ### no-autoload-config
566 Don't automatically load the default `openssl.cnf` file.
568 Typically OpenSSL will automatically load a system config file which configures
571 ### enable-buildtest-c++
573 While testing, generate C++ buildtest files that simply check that the public
574 OpenSSL header files are usable standalone with C++.
576 Enabling this option demands extra care. For any compiler flag given directly
577 as configuration option, you must ensure that it's valid for both the C and
578 the C++ compiler. If not, the C++ build test will most likely break. As an
579 alternative, you can use the language specific variables, `CFLAGS` and `CXXFLAGS`.
583 Use the specified text instead of the default banner at the end of
588 Build only some minimal set of features.
589 This is a developer option used internally for CI build tests of the project.
593 Never cache algorithms when they are fetched from a provider. Normally, a
594 provider indicates if the algorithms it supplies can be cached or not. Using
595 this option will reduce run-time memory usage but it also introduces a
596 significant performance penalty. This option is primarily designed to help
597 with detecting incorrect reference counting.
601 Don't build the CAPI engine.
603 This option will be forced if on a platform that does not support CAPI.
607 Don't build support for Certificate Management Protocol (CMP)
608 and Certificate Request Message Format (CRMF).
612 Don't build support for Cryptographic Message Syntax (CMS).
616 Don't build support for SSL/TLS compression.
618 If this option is enabled (the default), then compression will only work if
619 the zlib or `zlib-dynamic` options are also chosen.
621 ### enable-crypto-mdebug
623 This now only enables the `failed-malloc` feature.
625 ### enable-crypto-mdebug-backtrace
627 This is a no-op; the project uses the compiler's address/leak sanitizer instead.
631 Don't build support for Certificate Transparency (CT).
635 Don't build with support for deprecated APIs up until and including the version
636 given with `--api` (or the current version, if `--api` wasn't specified).
640 Don't build support for datagram based BIOs.
642 Selecting this option will also force the disabling of DTLS.
646 Don't build support for loading Dynamic Shared Objects (DSO)
648 ### enable-devcryptoeng
650 Build the `/dev/crypto` engine.
652 This option is automatically selected on the BSD platform, in which case it can
653 be disabled with `no-devcryptoeng`.
655 ### no-dynamic-engine
657 Don't build the dynamically loaded engines.
659 This only has an effect in a shared build.
663 Don't build support for Elliptic Curves.
667 Don't build support for binary Elliptic Curves
669 ### enable-ec_nistp_64_gcc_128
671 Enable support for optimised implementations of some commonly used NIST
674 This option is only supported on platforms:
676 - with little-endian storage of non-byte types
677 - that tolerate misaligned memory references
678 - where the compiler:
679 - supports the non-standard type `__uint128_t`
680 - defines the built-in macro `__SIZEOF_INT128__`
684 Build support for gathering entropy from the Entropy Gathering Daemon (EGD).
688 Don't build support for loading engines.
692 Don't compile in any error strings.
694 ### enable-external-tests
696 Enable building of integration with external test suites.
698 This is a developer option and may not work on all platforms. The following
699 external test suites are currently supported:
701 - GOST engine test suite
702 - Python PYCA/Cryptography test suite
705 See the file [test/README-external.md](test/README-external.md)
710 Don't compile in filename and line number information (e.g. for errors and
715 Build (and install) the FIPS provider
717 ### no-fips-securitychecks
719 Don't perform FIPS module run-time checks related to enforcement of security
720 parameters such as minimum security strength of keys.
722 ### enable-fuzz-libfuzzer, enable-fuzz-afl
724 Build with support for fuzzing using either libfuzzer or AFL.
726 These are developer options only. They may not work on all platforms and
727 should never be used in production environments.
729 See the file [fuzz/README.md](fuzz/README.md) for further details.
733 Don't build support for GOST based ciphersuites.
735 Note that if this feature is enabled then GOST ciphersuites are only available
736 if the GOST algorithms are also available through loading an externally supplied
741 Don't build the legacy provider.
743 Disabling this also disables the legacy algorithms: MD2 (already disabled by default).
747 Don't generate dependencies.
751 Don't build any dynamically loadable engines.
753 This also implies `no-dynamic-engine`.
757 Don't build support for writing multiple records in one go in libssl
759 Note: this is a different capability to the pipelining functionality.
763 Don't build support for the Next Protocol Negotiation (NPN) TLS extension.
767 Don't build support for Online Certificate Status Protocol (OCSP).
771 Don't build the padlock engine.
775 As synonym for `no-padlockeng`. Deprecated and should not be used.
779 Don't build with support for Position Independent Code.
783 Don't pin the shared libraries.
785 By default OpenSSL will attempt to stay in memory until the process exits.
786 This is so that libcrypto and libssl can be properly cleaned up automatically
787 via an `atexit()` handler. The handler is registered by libcrypto and cleans
788 up both libraries. On some platforms the `atexit()` handler will run on unload of
789 libcrypto (if it has been dynamically loaded) rather than at process exit. This
790 option can be used to stop OpenSSL from attempting to stay in memory until the
791 process exits. This could lead to crashes if either libcrypto or libssl have
792 already been unloaded at the point that the atexit handler is invoked, e.g. on a
793 platform which calls `atexit()` on unload of the library, and libssl is unloaded
794 before libcrypto then a crash is likely to happen. Applications can suppress
795 running of the `atexit()` handler at run time by using the
796 `OPENSSL_INIT_NO_ATEXIT` option to `OPENSSL_init_crypto()`.
797 See the man page for it for further details.
801 Don't use POSIX IO capabilities.
805 Don't build support for Pre-Shared Key based ciphersuites.
809 Don't use hardware RDRAND capabilities.
813 Don't build support for RFC3779, "X.509 Extensions for IP Addresses and
818 Build support for Stream Control Transmission Protocol (SCTP).
822 Do not create shared libraries, only static ones.
824 See [Notes on shared libraries](#notes-on-shared-libraries) below.
828 Don't build support for socket BIOs.
832 Don't build support for Secure Remote Password (SRP) protocol or
833 SRP based ciphersuites.
837 Don't build Secure Real-Time Transport Protocol (SRTP) support.
841 Exclude SSE2 code paths from 32-bit x86 assembly modules.
843 Normally SSE2 extension is detected at run-time, but the decision whether or not
844 the machine code will be executed is taken solely on CPU capability vector. This
845 means that if you happen to run OS kernel which does not support SSE2 extension
846 on Intel P4 processor, then your application might be exposed to "illegal
847 instruction" exception. There might be a way to enable support in kernel, e.g.
848 FreeBSD kernel can be compiled with `CPU_ENABLE_SSE`, and there is a way to
849 disengage SSE2 code paths upon application start-up, but if you aim for wider
850 "audience" running such kernel, consider `no-sse2`. Both the `386` and `no-asm`
851 options imply `no-sse2`.
855 Don't build with SSL Trace capabilities.
857 This removes the `-trace` option from `s_client` and `s_server`, and omits the
858 `SSL_trace()` function from libssl.
860 Disabling `ssl-trace` may provide a small reduction in libssl binary size.
864 Don't build the statically linked engines.
866 This only has an impact when not built "shared".
870 Don't use anything from the C header file `stdio.h` that makes use of the `FILE`
871 type. Only libcrypto and libssl can be built in this way. Using this option will
872 suppress building the command line applications. Additionally, since the OpenSSL
873 tests also use the command line applications, the tests will also be skipped.
877 Don't build test programs or run any tests.
881 Don't build with support for multi-threaded applications.
885 Build with support for multi-threaded applications. Most platforms will enable
886 this by default. However, if on a platform where this is not the case then this
887 will usually require additional system-dependent options!
889 See [Notes on multi-threading](#notes-on-multi-threading) below.
893 Build with support for the integrated tracing api.
895 See manual pages OSSL_trace_set_channel(3) and OSSL_trace_enabled(3) for details.
899 Don't build Time Stamping (TS) Authority support.
903 Build with the Undefined Behaviour sanitiser (UBSAN).
905 This is a developer option only. It may not work on all platforms and should
906 never be used in production environments. It will only work when used with
907 gcc or clang and should be used in conjunction with the `-DPEDANTIC` option
908 (or the `--strict-warnings` option).
912 Don't build with the User Interface (UI) console method
914 The User Interface console method enables text based console prompts.
918 Enable additional unit test APIs.
920 This should not typically be used in production deployments.
924 Don't build support for UPLINK interface.
926 ### enable-weak-ssl-ciphers
928 Build support for SSL/TLS ciphers that are considered "weak"
930 Enabling this includes for example the RC4 based ciphersuites.
934 Build with support for zlib compression/decompression.
938 Like the zlib option, but has OpenSSL load the zlib library dynamically
941 This is only supported on systems where loading of shared libraries is supported.
945 In 32-bit x86 builds, use the 80386 instruction set only in assembly modules
947 The default x86 code is more efficient, but requires at least an 486 processor.
948 Note: This doesn't affect compiler generated code, so this option needs to be
949 accompanied by a corresponding compiler-specific option.
953 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}
955 Don't build support for negotiating the specified SSL/TLS protocol.
957 If `no-tls` is selected then all of `tls1`, `tls1_1`, `tls1_2` and `tls1_3`
959 Similarly `no-dtls` will disable `dtls1` and `dtls1_2`. The `no-ssl` option is
960 synonymous with `no-ssl3`. Note this only affects version negotiation.
961 OpenSSL will still provide the methods for applications to explicitly select
962 the individual protocol versions.
964 ### no-{protocol}-method
966 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}-method
968 Analogous to `no-{protocol}` but in addition do not build the methods for
969 applications to explicitly select individual protocol versions. Note that there
970 is no `no-tls1_3-method` option because there is no application method for
973 Using individual protocol methods directly is deprecated. Applications should
974 use `TLS_method()` instead.
976 ### enable-{algorithm}
980 Build with support for the specified algorithm.
984 no-{aria|bf|blake2|camellia|cast|chacha|cmac|
985 des|dh|dsa|ecdh|ecdsa|idea|md4|mdc2|ocb|
986 poly1305|rc2|rc4|rmd160|scrypt|seed|
987 siphash|siv|sm2|sm3|sm4|whirlpool}
989 Build without support for the specified algorithm.
991 The `ripemd` algorithm is deprecated and if used is synonymous with `rmd160`.
993 ### Compiler-specific options
995 -Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static
997 These system specific options will be recognised and passed through to the
998 compiler to allow you to define preprocessor symbols, specify additional
999 libraries, library directories or other compiler options. It might be worth
1000 noting that some compilers generate code specifically for processor the
1001 compiler currently executes on. This is not necessarily what you might have
1002 in mind, since it might be unsuitable for execution on other, typically older,
1003 processor. Consult your compiler documentation.
1005 Take note of the [Environment Variables](#environment-variables) documentation
1006 below and how these flags interact with those variables.
1010 Additional options that are not otherwise recognised are passed through as
1011 they are to the compiler as well. Unix-style options beginning with a
1012 `-` or `+` and Windows-style options beginning with a `/` are recognized.
1013 Again, consult your compiler documentation.
1015 If the option contains arguments separated by spaces, then the URL-style
1016 notation `%20` can be used for the space character in order to avoid having
1017 to quote the option. For example, `-opt%20arg` gets expanded to `-opt arg`.
1018 In fact, any ASCII character can be encoded as %xx using its hexadecimal
1021 Take note of the [Environment Variables](#environment-variables) documentation
1022 below and how these flags interact with those variables.
1024 ### Environment Variables
1028 Assign the given value to the environment variable `VAR` for `Configure`.
1030 These work just like normal environment variable assignments, but are supported
1031 on all platforms and are confined to the configuration scripts only.
1032 These assignments override the corresponding value in the inherited environment,
1035 The following variables are used as "`make` variables" and can be used as an
1036 alternative to giving preprocessor, compiler and linker options directly as
1037 configuration. The following variables are supported:
1039 AR The static library archiver.
1040 ARFLAGS Flags for the static library archiver.
1041 AS The assembler compiler.
1042 ASFLAGS Flags for the assembler compiler.
1044 CFLAGS Flags for the C compiler.
1045 CXX The C++ compiler.
1046 CXXFLAGS Flags for the C++ compiler.
1047 CPP The C/C++ preprocessor.
1048 CPPFLAGS Flags for the C/C++ preprocessor.
1049 CPPDEFINES List of CPP macro definitions, separated
1050 by a platform specific character (':' or
1051 space for Unix, ';' for Windows, ',' for
1052 VMS). This can be used instead of using
1053 -D (or what corresponds to that on your
1054 compiler) in CPPFLAGS.
1055 CPPINCLUDES List of CPP inclusion directories, separated
1056 the same way as for CPPDEFINES. This can
1057 be used instead of -I (or what corresponds
1058 to that on your compiler) in CPPFLAGS.
1059 HASHBANGPERL Perl invocation to be inserted after '#!'
1060 in public perl scripts (only relevant on
1062 LD The program linker (not used on Unix, $(CC)
1064 LDFLAGS Flags for the shared library, DSO and
1066 LDLIBS Extra libraries to use when linking.
1067 Takes the form of a space separated list
1068 of library specifications on Unix and
1069 Windows, and as a comma separated list of
1071 RANLIB The library archive indexer.
1072 RC The Windows resource compiler.
1073 RCFLAGS Flags for the Windows resource compiler.
1074 RM The command to remove files and directories.
1076 These cannot be mixed with compiling/linking flags given on the command line.
1077 In other words, something like this isn't permitted.
1079 $ ./Configure -DFOO CPPFLAGS=-DBAR -DCOOKIE
1081 Backward compatibility note:
1083 To be compatible with older configuration scripts, the environment variables
1084 are ignored if compiling/linking flags are given on the command line, except
1087 AR, CC, CXX, CROSS_COMPILE, HASHBANGPERL, PERL, RANLIB, RC, and WINDRES
1089 For example, the following command will not see `-DBAR`:
1091 $ CPPFLAGS=-DBAR ./Configure -DCOOKIE
1093 However, the following will see both set variables:
1095 $ CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- ./Configure -DCOOKIE
1097 If `CC` is set, it is advisable to also set `CXX` to ensure both the C and C++
1098 compiler are in the same "family". This becomes relevant with
1099 `enable-external-tests` and `enable-buildtest-c++`.
1106 Reconfigure from earlier data.
1108 This fetches the previous command line options and environment from data
1109 saved in `configdata.pm` and runs the configuration process again, using
1110 these options and environment. Note: NO other option is permitted together
1111 with `reconf`. Note: The original configuration saves away values for ALL
1112 environment variables that were used, and if they weren't defined, they are
1113 still saved away with information that they weren't originally defined.
1114 This information takes precedence over environment variables that are
1115 defined when reconfiguring.
1117 Displaying configuration data
1118 -----------------------------
1120 The configuration script itself will say very little, and finishes by
1121 creating `configdata.pm`. This perl module can be loaded by other scripts
1122 to find all the configuration data, and it can also be used as a script to
1123 display all sorts of configuration data in a human readable form.
1125 For more information, please do:
1127 $ ./configdata.pm --help # Unix
1131 $ perl configdata.pm --help # Windows and VMS
1133 Installation Steps in Detail
1134 ============================
1139 ### Automatic Configuration
1141 On some platform a `config` script is available which attempts to guess
1142 your operating system (and compiler, if necessary) and calls the `Configure`
1143 Perl script with appropriate target based on its guess. Further options can
1144 be supplied to the `config` script, which will be passed on to the `Configure`
1147 #### Unix / Linux / macOS
1149 $ ./Configure [[ options ]]
1153 $ perl Configure [[ options ]]
1157 $ perl Configure [[ options ]]
1159 ### Manual Configuration
1161 OpenSSL knows about a range of different operating system, hardware and
1162 compiler combinations. To see the ones it knows about, run
1164 $ ./Configure LIST # Unix
1168 $ perl Configure LIST # All other platforms
1170 For the remainder of this text, the Unix form will be used in all examples.
1171 Please use the appropriate form for your platform.
1173 Pick a suitable name from the list that matches your system. For most
1174 operating systems there is a choice between using cc or gcc.
1175 When you have identified your system (and if necessary compiler) use this
1176 name as the argument to `Configure`. For example, a `linux-elf` user would
1179 $ ./Configure linux-elf [[ options ]]
1181 ### Creating your own Configuration
1183 If your system isn't listed, you will have to create a configuration
1184 file named `Configurations/{{ something }}.conf` and add the correct
1185 configuration for your system. See the available configs as examples
1186 and read [Configurations/README.md](Configurations/README.md) and
1187 [Configurations/README-design.md](Configurations/README-design.md)
1188 for more information.
1190 The generic configurations `cc` or `gcc` should usually work on 32 bit
1193 `Configure` creates a build file (`Makefile` on Unix, `makefile` on Windows
1194 and `descrip.mms` on OpenVMS) from a suitable template in `Configurations/`,
1195 and defines various macros in `include/openssl/configuration.h` (generated
1196 from `include/openssl/configuration.h.in`.
1198 ### Out of Tree Builds
1200 OpenSSL can be configured to build in a build directory separate from the
1201 source code directory. It's done by placing yourself in some other
1202 directory and invoking the configuration commands from there.
1206 $ mkdir /var/tmp/openssl-build
1207 $ cd /var/tmp/openssl-build
1208 $ /PATH/TO/OPENSSL/SOURCE/Configure [[ options ]]
1210 #### OpenVMS example
1212 $ set default sys$login:
1213 $ create/dir [.tmp.openssl-build]
1214 $ set default [.tmp.openssl-build]
1215 $ perl D:[PATH.TO.OPENSSL.SOURCE]Configure [[ options ]]
1217 #### Windows example
1220 $ mkdir \temp-openssl
1222 $ perl d:\PATH\TO\OPENSSL\SOURCE\Configure [[ options ]]
1224 Paths can be relative just as well as absolute. `Configure` will do its best
1225 to translate them to relative paths whenever possible.
1230 Build OpenSSL by running:
1233 $ mms ! (or mmk) OpenVMS
1236 This will build the OpenSSL libraries (`libcrypto.a` and `libssl.a` on
1237 Unix, corresponding on other platforms) and the OpenSSL binary
1238 (`openssl`). The libraries will be built in the top-level directory,
1239 and the binary will be in the `apps/` subdirectory.
1241 If the build fails, take a look at the [Build Failures](#build-failures)
1242 subsection of the [Troubleshooting](#troubleshooting) section.
1247 After a successful build, and before installing, the libraries should
1251 $ mms test ! OpenVMS
1252 $ nmake test # Windows
1254 **Warning:** you MUST run the tests from an unprivileged account (or disable
1255 your privileges temporarily if your platform allows it).
1257 See [test/README.md](test/README.md) for further details how run tests.
1259 See [test/README-dev.md](test/README-dev.md) for guidelines on adding tests.
1264 If everything tests ok, install OpenSSL with
1266 $ make install # Unix
1267 $ mms install ! OpenVMS
1268 $ nmake install # Windows
1270 Note that in order to perform the install step above you need to have
1271 appropriate permissions to write to the installation directory.
1273 The above commands will install all the software components in this
1274 directory tree under `<PREFIX>` (the directory given with `--prefix` or
1277 ### Unix / Linux / macOS
1279 bin/ Contains the openssl binary and a few other
1282 Contains the header files needed if you want
1283 to build your own programs that use libcrypto
1285 lib Contains the OpenSSL library files.
1286 lib/engines Contains the OpenSSL dynamically loadable engines.
1288 share/man/man1 Contains the OpenSSL command line man-pages.
1289 share/man/man3 Contains the OpenSSL library calls man-pages.
1290 share/man/man5 Contains the OpenSSL configuration format man-pages.
1291 share/man/man7 Contains the OpenSSL other misc man-pages.
1293 share/doc/openssl/html/man1
1294 share/doc/openssl/html/man3
1295 share/doc/openssl/html/man5
1296 share/doc/openssl/html/man7
1297 Contains the HTML rendition of the man-pages.
1301 'arch' is replaced with the architecture name, `ALPHA` or `IA64`,
1302 'sover' is replaced with the shared library version (`0101` for 1.1), and
1303 'pz' is replaced with the pointer size OpenSSL was built with:
1305 [.EXE.'arch'] Contains the openssl binary.
1306 [.EXE] Contains a few utility scripts.
1308 Contains the header files needed if you want
1309 to build your own programs that use libcrypto
1311 [.LIB.'arch'] Contains the OpenSSL library files.
1312 [.ENGINES'sover''pz'.'arch']
1313 Contains the OpenSSL dynamically loadable engines.
1314 [.SYS$STARTUP] Contains startup, login and shutdown scripts.
1315 These define appropriate logical names and
1317 [.SYSTEST] Contains the installation verification procedure.
1318 [.HTML] Contains the HTML rendition of the manual pages.
1320 ### Additional Directories
1322 Additionally, install will add the following directories under
1323 OPENSSLDIR (the directory given with `--openssldir` or its default)
1324 for you convenience:
1326 certs Initially empty, this is the default location
1327 for certificate files.
1328 private Initially empty, this is the default location
1329 for private key files.
1330 misc Various scripts.
1332 The installation directory should be appropriately protected to ensure
1333 unprivileged users cannot make changes to OpenSSL binaries or files, or
1334 install engines. If you already have a pre-installed version of OpenSSL as
1335 part of your Operating System it is recommended that you do not overwrite
1336 the system version and instead install to somewhere else.
1338 Package builders who want to configure the library for standard locations,
1339 but have the package installed somewhere else so that it can easily be
1342 $ make DESTDIR=/tmp/package-root install # Unix
1343 $ mms/macro="DESTDIR=TMP:[PACKAGE-ROOT]" install ! OpenVMS
1345 The specified destination directory will be prepended to all installation
1348 Compatibility issues with previous OpenSSL versions
1349 ---------------------------------------------------
1351 ### COMPILING existing applications
1353 Starting with version 1.1.0, OpenSSL hides a number of structures that were
1354 previously open. This includes all internal libssl structures and a number
1355 of EVP types. Accessor functions have been added to allow controlled access
1356 to the structures' data.
1358 This means that some software needs to be rewritten to adapt to the new ways
1359 of doing things. This often amounts to allocating an instance of a structure
1360 explicitly where you could previously allocate them on the stack as automatic
1361 variables, and using the provided accessor functions where you would previously
1362 access a structure's field directly.
1364 Some APIs have changed as well. However, older APIs have been preserved when
1367 Post-installation Notes
1368 -----------------------
1370 With the default OpenSSL installation comes a FIPS provider module, which
1371 needs some post-installation attention, without which it will not be usable.
1372 This involves using the following command:
1374 $ openssl fipsinstall
1376 See the openssl-fipsinstall(1) manual for details and examples.
1378 Advanced Build Options
1379 ======================
1381 Environment Variables
1382 ---------------------
1384 A number of environment variables can be used to provide additional control
1385 over the build process. Typically these should be defined prior to running
1386 `Configure`. Not all environment variables are relevant to all platforms.
1389 The name of the ar executable to use.
1392 Use a different build file name than the platform default
1393 ("Makefile" on Unix-like platforms, "makefile" on native Windows,
1394 "descrip.mms" on OpenVMS). This requires that there is a
1395 corresponding build file template.
1396 See [Configurations/README.md](Configurations/README.md)
1397 for further information.
1400 The compiler to use. Configure will attempt to pick a default
1401 compiler for your platform but this choice can be overridden
1402 using this variable. Set it to the compiler executable you wish
1403 to use, e.g. gcc or clang.
1406 This environment variable has the same meaning as for the
1407 "--cross-compile-prefix" Configure flag described above. If both
1408 are set then the Configure flag takes precedence.
1411 The name of the nm executable to use.
1413 OPENSSL_LOCAL_CONFIG_DIR
1414 OpenSSL comes with a database of information about how it
1415 should be built on different platforms as well as build file
1416 templates for those platforms. The database is comprised of
1417 ".conf" files in the Configurations directory. The build
1418 file templates reside there as well as ".tmpl" files. See the
1419 file [Configurations/README.md](Configurations/README.md)
1420 for further information about the format of ".conf" files
1421 as well as information on the ".tmpl" files.
1422 In addition to the standard ".conf" and ".tmpl" files, it is
1423 possible to create your own ".conf" and ".tmpl" files and
1424 store them locally, outside the OpenSSL source tree.
1425 This environment variable can be set to the directory where
1426 these files are held and will be considered by Configure
1427 before it looks in the standard directories.
1430 The name of the Perl executable to use when building OpenSSL.
1431 Only needed if builing should use a different Perl executable
1432 than what is used to run the Configure script.
1435 The command string for the Perl executable to insert in the
1436 #! line of perl scripts that will be publicly installed.
1437 Default: /usr/bin/env perl
1438 Note: the value of this variable is added to the same scripts
1439 on all platforms, but it's only relevant on Unix-like platforms.
1442 The name of the rc executable to use. The default will be as
1443 defined for the target platform in the ".conf" file. If not
1444 defined then "windres" will be used. The WINDRES environment
1445 variable is synonymous to this. If both are defined then RC
1449 The name of the ranlib executable to use.
1457 The `Configure` script generates a Makefile in a format relevant to the specific
1458 platform. The Makefiles provide a number of targets that can be used. Not all
1459 targets may be available on all platforms. Only the most common targets are
1460 described here. Examine the Makefiles themselves for the full list.
1463 The target to build all the software components and
1467 Build all the software components.
1468 THIS IS THE DEFAULT TARGET.
1471 Build all documentation components.
1474 Remove all build artefacts and return the directory to a "clean"
1478 Rebuild the dependencies in the Makefiles. This is a legacy
1479 option that no longer needs to be used since OpenSSL 1.1.0.
1482 Install all OpenSSL components.
1485 Only install the OpenSSL software components.
1488 Only install the OpenSSL documentation components.
1491 Only install the OpenSSL man pages (Unix only).
1494 Only install the OpenSSL HTML documentation.
1497 Install the FIPS provider module configuration file.
1500 Prints a list of all the self test names.
1503 Build and run the OpenSSL self tests.
1506 Uninstall all OpenSSL components.
1510 Re-run the configuration process, as exactly as the last time
1514 This is a developer option. If you are developing a patch for
1515 OpenSSL you may need to use this if you want to update
1516 automatically generated files; add new error codes or add new
1517 (or change the visibility of) public API functions. (Unix only).
1519 Running Selected Tests
1520 ----------------------
1522 You can specify a set of tests to be performed
1523 using the `make` variable `TESTS`.
1525 See the section [Running Selected Tests of
1526 test/README.md](test/README.md#running-selected-tests).
1531 Configuration Problems
1532 ----------------------
1534 ### Selecting the correct target
1536 The `./Configure` script tries hard to guess your operating system, but in some
1537 cases it does not succeed. You will see a message like the following:
1540 Operating system: x86-whatever-minix
1541 This system (minix) is not supported. See file INSTALL.md for details.
1543 Even if the automatic target selection by the `./Configure` script fails,
1544 chances are that you still might find a suitable target in the `Configurations`
1545 directory, which you can supply to the `./Configure` command,
1546 possibly after some adjustment.
1548 The `Configurations/` directory contains a lot of examples of such targets.
1549 The main configuration file is [10-main.conf], which contains all targets that
1550 are officially supported by the OpenSSL team. Other configuration files contain
1551 targets contributed by other OpenSSL users. The list of targets can be found in
1552 a Perl list `my %targets = ( ... )`.
1557 inherit_from => [ "base-target" ],
1559 cflags => add("..."),
1561 perlasm_scheme => "...",
1566 If you call `./Configure` without arguments, it will give you a list of all
1567 known targets. Using `grep`, you can lookup the target definition in the
1568 `Configurations/` directory. For example the `android-x86_64` can be found in
1569 [Configurations/15-android.conf](Configurations/15-android.conf).
1571 The directory contains two README files, which explain the general syntax and
1572 design of the configuration files.
1574 - [Configurations/README.md](Configurations/README.md)
1575 - [Configurations/README-design.md](Configurations/README-design.md)
1577 If you need further help, try to search the [openssl-users] mailing list
1578 or the [GitHub Issues] for existing solutions. If you don't find anything,
1579 you can [raise an issue] to ask a question yourself.
1581 More about our support resources can be found in the [SUPPORT] file.
1583 ### Configuration Errors
1585 If the `./Configure` or `./Configure` command fails with an error message,
1586 read the error message carefully and try to figure out whether you made
1587 a mistake (e.g., by providing a wrong option), or whether the script is
1588 working incorrectly. If you think you encountered a bug, please
1589 [raise an issue] on GitHub to file a bug report.
1591 Along with a short description of the bug, please provide the complete
1592 configure command line and the relevant output including the error message.
1594 Note: To make the output readable, pleace add a 'code fence' (three backquotes
1595 ` ``` ` on a separate line) before and after your output:
1598 ./Configure [your arguments...]
1607 If the build fails, look carefully at the output. Try to locate and understand
1608 the error message. It might be that the compiler is already telling you
1609 exactly what you need to do to fix your problem.
1611 There may be reasons for the failure that aren't problems in OpenSSL itself,
1612 for example if the compiler reports missing standard or third party headers.
1614 If the build succeeded previously, but fails after a source or configuration
1615 change, it might be helpful to clean the build tree before attempting another
1616 build. Use this command:
1619 $ mms clean ! (or mmk) OpenVMS
1620 $ nmake clean # Windows
1622 Assembler error messages can sometimes be sidestepped by using the `no-asm`
1623 configuration option. See also [notes](#notes-on-assembler-modules-compilation).
1625 Compiling parts of OpenSSL with gcc and others with the system compiler will
1626 result in unresolved symbols on some systems.
1628 If you are still having problems, try to search the [openssl-users] mailing
1629 list or the [GitHub Issues] for existing solutions. If you think you
1630 encountered an OpenSSL bug, please [raise an issue] to file a bug report.
1631 Please take the time to review the existing issues first; maybe the bug was
1632 already reported or has already been fixed.
1637 If some tests fail, look at the output. There may be reasons for the failure
1638 that isn't a problem in OpenSSL itself (like an OS malfunction or a Perl issue).
1640 You may want increased verbosity, that can be accomplished as described in
1641 section [Test Failures of test/README.md](test/README.md#test-failures).
1643 You may also want to selectively specify which test(s) to perform. This can be
1644 done using the `make` variable `TESTS` as described in section [Running
1645 Selected Tests of test/README.md](test/README.md#running-selected-tests).
1647 If you find a problem with OpenSSL itself, try removing any
1648 compiler optimization flags from the `CFLAGS` line in the Makefile and
1649 run `make clean; make` or corresponding.
1651 To report a bug please open an issue on GitHub, at
1652 <https://github.com/openssl/openssl/issues>.
1657 Notes on multi-threading
1658 ------------------------
1660 For some systems, the OpenSSL `Configure` script knows what compiler options
1661 are needed to generate a library that is suitable for multi-threaded
1662 applications. On these systems, support for multi-threading is enabled
1663 by default; use the `no-threads` option to disable (this should never be
1666 On other systems, to enable support for multi-threading, you will have
1667 to specify at least two options: `threads`, and a system-dependent option.
1668 (The latter is `-D_REENTRANT` on various systems.) The default in this
1669 case, obviously, is not to include support for multi-threading (but
1670 you can still use `no-threads` to suppress an annoying warning message
1671 from the `Configure` script.)
1673 OpenSSL provides built-in support for two threading models: pthreads (found on
1674 most UNIX/Linux systems), and Windows threads. No other threading models are
1675 supported. If your platform does not provide pthreads or Windows threads then
1676 you should use `Configure` with the `no-threads` option.
1678 For pthreads, all locks are non-recursive. In addition, in a debug build,
1679 the mutex attribute `PTHREAD_MUTEX_ERRORCHECK` is used. If this is not
1680 available on your platform, you might have to add
1681 `-DOPENSSL_NO_MUTEX_ERRORCHECK` to your `Configure` invocation.
1682 (On Linux `PTHREAD_MUTEX_ERRORCHECK` is an enum value, so a built-in
1683 ifdef test cannot be used.)
1685 Notes on shared libraries
1686 -------------------------
1688 For most systems the OpenSSL `Configure` script knows what is needed to
1689 build shared libraries for libcrypto and libssl. On these systems
1690 the shared libraries will be created by default. This can be suppressed and
1691 only static libraries created by using the `no-shared` option. On systems
1692 where OpenSSL does not know how to build shared libraries the `no-shared`
1693 option will be forced and only static libraries will be created.
1695 Shared libraries are named a little differently on different platforms.
1696 One way or another, they all have the major OpenSSL version number as
1697 part of the file name, i.e. for OpenSSL 1.1.x, `1.1` is somehow part of
1700 On most POSIX platforms, shared libraries are named `libcrypto.so.1.1`
1701 and `libssl.so.1.1`.
1703 on Cygwin, shared libraries are named `cygcrypto-1.1.dll` and `cygssl-1.1.dll`
1704 with import libraries `libcrypto.dll.a` and `libssl.dll.a`.
1706 On Windows build with MSVC or using MingW, shared libraries are named
1707 `libcrypto-1_1.dll` and `libssl-1_1.dll` for 32-bit Windows,
1708 `libcrypto-1_1-x64.dll` and `libssl-1_1-x64.dll` for 64-bit x86_64 Windows,
1709 and `libcrypto-1_1-ia64.dll` and `libssl-1_1-ia64.dll` for IA64 Windows.
1710 With MSVC, the import libraries are named `libcrypto.lib` and `libssl.lib`,
1711 while with MingW, they are named `libcrypto.dll.a` and `libssl.dll.a`.
1713 On VMS, shareable images (VMS speak for shared libraries) are named
1714 `ossl$libcrypto0101_shr.exe` and `ossl$libssl0101_shr.exe`. However, when
1715 OpenSSL is specifically built for 32-bit pointers, the shareable images
1716 are named `ossl$libcrypto0101_shr32.exe` and `ossl$libssl0101_shr32.exe`
1717 instead, and when built for 64-bit pointers, they are named
1718 `ossl$libcrypto0101_shr64.exe` and `ossl$libssl0101_shr64.exe`.
1720 Notes on random number generation
1721 ---------------------------------
1723 Availability of cryptographically secure random numbers is required for
1724 secret key generation. OpenSSL provides several options to seed the
1725 internal CSPRNG. If not properly seeded, the internal CSPRNG will refuse
1726 to deliver random bytes and a "PRNG not seeded error" will occur.
1728 The seeding method can be configured using the `--with-rand-seed` option,
1729 which can be used to specify a comma separated list of seed methods.
1730 However, in most cases OpenSSL will choose a suitable default method,
1731 so it is not necessary to explicitly provide this option. Note also
1732 that not all methods are available on all platforms. The FIPS provider will
1733 silently ignore seed sources that were not validated.
1735 I) On operating systems which provide a suitable randomness source (in
1736 form of a system call or system device), OpenSSL will use the optimal
1737 available method to seed the CSPRNG from the operating system's
1738 randomness sources. This corresponds to the option `--with-rand-seed=os`.
1740 II) On systems without such a suitable randomness source, automatic seeding
1741 and reseeding is disabled (`--with-rand-seed=none`) and it may be necessary
1742 to install additional support software to obtain a random seed and reseed
1743 the CSPRNG manually. Please check out the manual pages for `RAND_add()`,
1744 `RAND_bytes()`, `RAND_egd()`, and the FAQ for more information.
1746 Notes on assembler modules compilation
1747 --------------------------------------
1749 Compilation of some code paths in assembler modules might depend on whether the
1750 current assembler version supports certain ISA extensions or not. Code paths
1751 that use the AES-NI, PCLMULQDQ, SSSE3, and SHA extensions are always assembled.
1752 Apart from that, the minimum requirements for the assembler versions are shown
1755 | ISA extension | GNU as | nasm | llvm |
1756 |---------------|--------|--------|---------|
1757 | AVX | 2.19 | 2.09 | 3.0 |
1758 | AVX2 | 2.22 | 2.10 | 3.1 |
1759 | ADCX/ADOX | 2.23 | 2.10 | 3.3 |
1760 | AVX512 | 2.25 | 2.11.8 | 3.6 (*) |
1761 | AVX512IFMA | 2.26 | 2.11.8 | 6.0 (*) |
1762 | VAES | 2.30 | 2.13.3 | 6.0 (*) |
1766 (*) Even though AVX512 support was implemented in llvm 3.6, prior to version 7.0
1767 an explicit -march flag was apparently required to compile assembly modules. But
1768 then the compiler generates processor-specific code, which in turn contradicts
1769 the idea of performing dispatch at run-time, which is facilitated by the special
1770 variable `OPENSSL_ia32cap`. For versions older than 7.0, it is possible to work
1771 around the problem by forcing the build procedure to use the following script:
1774 exec clang -no-integrated-as "$@"
1776 instead of the real clang. In which case it doesn't matter what clang version
1777 is used, as it is the version of the GNU assembler that will be checked.
1784 <https://mta.openssl.org/mailman/listinfo/openssl-users>
1790 <https://github.com/openssl/openssl/issues>
1793 <https://github.com/openssl/openssl/issues/new/choose>
1796 Configurations/10-main.conf