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 **Optional Arguments** are enclosed in square brackets.
127 A trailing ellipsis means that more than one could be specified.
129 Quick Installation Guide
130 ========================
132 If you just want to get OpenSSL installed without bothering too much
133 about the details, here is the short version of how to build and install
134 OpenSSL. If any of the following steps fails, please consult the
135 [Installation in Detail](#installation-steps-in-detail) section below.
140 Use the following commands to configure, build and test OpenSSL.
141 The testing is optional, but recommended if you intend to install
142 OpenSSL for production use.
144 ### Unix / Linux / macOS
152 Use the following commands to build OpenSSL:
160 If you are using Visual Studio, open a Developer Command Prompt and
161 issue the following commands to build OpenSSL.
167 As mentioned in the [Choices](#choices) section, you need to pick one
168 of the four Configure targets in the first command.
170 Most likely you will be using the `VC-WIN64A` target for 64bit Windows
171 binaries (AMD64) or `VC-WIN32` for 32bit Windows binaries (X86).
172 The other two options are `VC-WIN64I` (Intel IA64, Itanium) and
173 `VC-CE` (Windows CE) are rather uncommon nowadays.
178 The following commands will install OpenSSL to a default system location.
180 **Danger Zone:** even if you are impatient, please read the following two
181 paragraphs carefully before you install OpenSSL.
183 For security reasons the default system location is by default not writable
184 for unprivileged users. So for the final installation step administrative
185 privileges are required. The default system location and the procedure to
186 obtain administrative privileges depends on the operating system.
187 It is recommended to compile and test OpenSSL with normal user privileges
188 and use administrative privileges only for the final installation step.
190 On some platforms OpenSSL is preinstalled as part of the Operating System.
191 In this case it is highly recommended not to overwrite the system versions,
192 because other applications or libraries might depend on it.
193 To avoid breaking other applications, install your copy of OpenSSL to a
194 [different location](#installing-to-a-different-location) which is not in
195 the global search path for system libraries.
197 Finally, if you plan on using the FIPS module, you need to read the
198 [Post-installation Notes](#post-installation-notes) further down.
200 ### Unix / Linux / macOS
202 Depending on your distribution, you need to run the following command as
203 root user or prepend `sudo` to the command:
207 By default, OpenSSL will be installed to
211 More precisely, the files will be installed into the subdirectories
218 depending on the file type, as it is custom on Unix-like operating systems.
222 Use the following command to install OpenSSL.
226 By default, OpenSSL will be installed to
232 If you are using Visual Studio, open the Developer Command Prompt _elevated_
233 and issue the following command.
237 The easiest way to elevate the Command Prompt is to press and hold down
238 the both the `<CTRL>` and `<SHIFT>` key while clicking the menu item in the
241 The default installation location is
243 C:\Program Files\OpenSSL
245 for native binaries, or
247 C:\Program Files (x86)\OpenSSL
249 for 32bit binaries on 64bit Windows (WOW64).
251 #### Installing to a different location
253 To install OpenSSL to a different location (for example into your home
254 directory for testing purposes) run `Configure` as shown in the following
257 The options `--prefix` and `--openssldir` are explained in further detail in
258 [Directories](#directories) below, and the values used here are mere examples.
262 $ ./Configure --prefix=/opt/openssl --openssldir=/usr/local/ssl
266 $ perl Configure --prefix=PROGRAM:[INSTALLS] --openssldir=SYS$MANAGER:[OPENSSL]
268 Note: if you do add options to the configuration command, please make sure
269 you've read more than just this Quick Start, such as relevant `NOTES-*` files,
270 the options outline below, as configuration options may change the outcome
271 in otherwise unexpected ways.
273 Configuration Options
274 =====================
276 There are several options to `./Configure` to customize the build (note that
277 for Windows, the defaults for `--prefix` and `--openssldir` depend on what
278 configuration is used and what Windows implementation OpenSSL is built on.
279 For more information, see the [Notes for Windows platforms](NOTES-WINDOWS.md).
286 Build the OpenSSL libraries to support the API for the specified version.
287 If [no-deprecated](#no-deprecated) is also given, don't build with support
288 for deprecated APIs in or below the specified version number. For example,
291 --api=1.1.0 no-deprecated
293 will remove support for all APIs that were deprecated in OpenSSL version
294 1.1.0 or below. This is a rather specialized option for developers.
295 If you just intend to remove all deprecated APIs up to the current version
296 entirely, just specify [no-deprecated](#no-deprecated).
297 If `--api` isn't given, it defaults to the current (minor) OpenSSL version.
302 --cross-compile-prefix=<PREFIX>
304 The `<PREFIX>` to include in front of commands for your toolchain.
306 It is likely to have to end with dash, e.g. `a-b-c-` would invoke GNU compiler
307 as `a-b-c-gcc`, etc. Unfortunately cross-compiling is too case-specific to put
308 together one-size-fits-all instructions. You might have to pass more flags or
309 set up environment variables to actually make it work. Android and iOS cases
310 are discussed in corresponding `Configurations/15-*.conf` files. But there are
311 cases when this option alone is sufficient. For example to build the mingw64
312 target on Linux `--cross-compile-prefix=x86_64-w64-mingw32-` works. Naturally
313 provided that mingw packages are installed. Today Debian and Ubuntu users
314 have option to install a number of prepackaged cross-compilers along with
315 corresponding run-time and development packages for "alien" hardware. To give
316 another example `--cross-compile-prefix=mipsel-linux-gnu-` suffices in such
319 For cross compilation, you must [configure manually](#manual-configuration).
320 Also, note that `--openssldir` refers to target's file system, not one you are
328 Build OpenSSL with debugging symbols and zero optimization level.
332 Build OpenSSL without debugging symbols. This is the default.
341 The name of the directory under the top of the installation directory tree
342 (see the `--prefix` option) where libraries will be installed. By default
343 this is `lib`. Note that on Windows only static libraries (`*.lib`) will
344 be stored in this location. Shared libraries (`*.dll`) will always be
345 installed to the `bin` directory.
347 Some build targets have a multilib postfix set in the build configuration.
348 For these targets the default libdir is `lib<multilib-postfix>`. Please use
349 `--libdir=lib` to override the libdir if adding the postfix is undesirable.
355 Directory for OpenSSL configuration files, and also the default certificate
356 and key store. Defaults are:
359 Windows: C:\Program Files\Common Files\SSL
360 OpenVMS: SYS$COMMON:[OPENSSL-COMMON]
362 For 32bit Windows applications on Windows 64bit (WOW64), always replace
363 `C:\Program Files` by `C:\Program Files (x86)`.
369 The top of the installation directory tree. Defaults are:
372 Windows: C:\Program Files\OpenSSL
373 OpenVMS: SYS$COMMON:[OPENSSL]
380 This is a developer flag that switches on various compiler options recommended
381 for OpenSSL development. It only works when using gcc or clang as the compiler.
382 If you are developing a patch for OpenSSL then it is recommended that you use
383 this option where possible.
388 ### with-zlib-include
390 --with-zlib-include=DIR
392 The directory for the location of the zlib include file. This option is only
393 necessary if [zlib](#zlib) is used and the include file is not
394 already on the system include path.
400 **On Unix**: this is the directory containing the zlib library.
401 If not provided the system library path will be used.
403 **On Windows:** this is the filename of the zlib library (with or
404 without a path). This flag must be provided if the
405 [zlib-dynamic](#zlib-dynamic) option is not also used. If `zlib-dynamic` is used
406 then this flag is optional and defaults to `ZLIB1` if not provided.
408 **On VMS:** this is the filename of the zlib library (with or without a path).
409 This flag is optional and if not provided then `GNV$LIBZSHR`, `GNV$LIBZSHR32`
410 or `GNV$LIBZSHR64` is used by default depending on the pointer size chosen.
412 Seeding the Random Generator
413 ----------------------------
415 --with-rand-seed=seed1[,seed2,...]
417 A comma separated list of seeding methods which will be tried by OpenSSL
418 in order to obtain random input (a.k.a "entropy") for seeding its
419 cryptographically secure random number generator (CSPRNG).
420 The current seeding methods are:
424 Use a trusted operating system entropy source.
425 This is the default method if such an entropy source exists.
429 Use the [getrandom(2)][man-getrandom] or equivalent system call.
431 [man-getrandom]: http://man7.org/linux/man-pages/man2/getrandom.2.html
435 Use the first device from the `DEVRANDOM` list which can be opened to read
436 random bytes. The `DEVRANDOM` preprocessor constant expands to
438 "/dev/urandom","/dev/random","/dev/srandom"
440 on most unix-ish operating systems.
444 Check for an entropy generating daemon.
445 This source is ignored by the FIPS provider.
449 Use the `RDSEED` or `RDRAND` command on x86 or `RNDRRS` command on aarch64
450 if provided by the CPU.
454 Use librandom (not implemented yet).
455 This source is ignored by the FIPS provider.
459 Disable automatic seeding. This is the default on some operating systems where
460 no suitable entropy source exists, or no support for it is implemented yet.
461 This option is ignored by the FIPS provider.
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 Setting the FIPS HMAC key
469 -------------------------
473 As part of its self-test validation, the FIPS module must verify itself
474 by performing a SHA-256 HMAC computation on itself. The default key is
475 the SHA256 value of "the holy handgrenade of antioch" and is sufficient
476 for meeting the FIPS requirements.
478 To change the key to a different value, use this flag. The value should
479 be a hex string no more than 64 characters.
481 Enable and Disable Features
482 ---------------------------
484 Feature options always come in pairs, an option to enable feature
485 `xxxx`, and an option to disable it:
487 [ enable-xxxx | no-xxxx ]
489 Whether a feature is enabled or disabled by default, depends on the feature.
490 In the following list, always the non-default variant is documented: if
491 feature `xxxx` is disabled by default then `enable-xxxx` is documented and
492 if feature `xxxx` is enabled by default then `no-xxxx` is documented.
496 Don't build the AFALG engine.
498 This option will be forced on a platform that does not support AFALG.
502 Build with Kernel TLS support.
504 This option will enable the use of the Kernel TLS data-path, which can improve
505 performance and allow for the use of sendfile and splice system calls on
506 TLS sockets. The Kernel may use TLS accelerators if any are available on the
507 system. This option will be forced off on systems that do not support the
508 Kernel TLS data-path.
512 Build with the Address sanitiser.
514 This is a developer option only. It may not work on all platforms and should
515 never be used in production environments. It will only work when used with
516 gcc or clang and should be used in conjunction with the [no-shared](#no-shared)
519 ### enable-acvp-tests
521 Build support for Automated Cryptographic Validation Protocol (ACVP)
524 This is required for FIPS validation purposes. Certain ACVP tests require
525 access to algorithm internals that are not normally accessible.
526 Additional information related to ACVP can be found at
527 <https://github.com/usnistgov/ACVP>.
531 Do not use assembler code.
533 This should be viewed as debugging/troubleshooting option rather than for
534 production use. On some platforms a small amount of assembler code may still
535 be used even with this option.
539 Do not build support for async operations.
543 Don't automatically load all supported ciphers and digests.
545 Typically OpenSSL will make available all of its supported ciphers and digests.
546 For a statically linked application this may be undesirable if small executable
547 size is an objective. This only affects libcrypto. Ciphers and digests will
548 have to be loaded manually using `EVP_add_cipher()` and `EVP_add_digest()`
549 if this option is used. This option will force a non-shared build.
553 Don't automatically load all libcrypto/libssl error strings.
555 Typically OpenSSL will automatically load human readable error strings. For a
556 statically linked application this may be undesirable if small executable size
559 ### no-autoload-config
561 Don't automatically load the default `openssl.cnf` file.
563 Typically OpenSSL will automatically load a system config file which configures
566 ### enable-buildtest-c++
568 While testing, generate C++ buildtest files that simply check that the public
569 OpenSSL header files are usable standalone with C++.
571 Enabling this option demands extra care. For any compiler flag given directly
572 as configuration option, you must ensure that it's valid for both the C and
573 the C++ compiler. If not, the C++ build test will most likely break. As an
574 alternative, you can use the language specific variables, `CFLAGS` and `CXXFLAGS`.
578 Use the specified text instead of the default banner at the end of
583 On platforms where the choice of 32-bit or 64-bit architecture
584 is not explicitly specified, `Configure` will print a warning
585 message and wait for a few seconds to let you interrupt the
586 configuration. Using this flag skips the wait.
590 Build only some minimal set of features.
591 This is a developer option used internally for CI build tests of the project.
595 Never cache algorithms when they are fetched from a provider. Normally, a
596 provider indicates if the algorithms it supplies can be cached or not. Using
597 this option will reduce run-time memory usage but it also introduces a
598 significant performance penalty. This option is primarily designed to help
599 with detecting incorrect reference counting.
603 Don't build the CAPI engine.
605 This option will be forced if on a platform that does not support CAPI.
609 Don't build support for Certificate Management Protocol (CMP)
610 and Certificate Request Message Format (CRMF).
614 Don't build support for Cryptographic Message Syntax (CMS).
618 Don't build support for SSL/TLS compression.
620 If this option is enabled (the default), then compression will only work if
621 the zlib or `zlib-dynamic` options are also chosen.
623 ### enable-crypto-mdebug
625 This now only enables the `failed-malloc` feature.
627 ### enable-crypto-mdebug-backtrace
629 This is a no-op; the project uses the compiler's address/leak sanitizer instead.
633 Don't build support for Certificate Transparency (CT).
637 Don't build with support for deprecated APIs up until and including the version
638 given with `--api` (or the current version, if `--api` wasn't specified).
642 Don't build support for datagram based BIOs.
644 Selecting this option will also force the disabling of DTLS.
648 Don't build support for loading Dynamic Shared Objects (DSO)
650 ### enable-devcryptoeng
652 Build the `/dev/crypto` engine.
654 This option is automatically selected on the BSD platform, in which case it can
655 be disabled with `no-devcryptoeng`.
657 ### no-dynamic-engine
659 Don't build the dynamically loaded engines.
661 This only has an effect in a shared build.
665 Don't build support for Elliptic Curves.
669 Don't build support for binary Elliptic Curves
671 ### enable-ec_nistp_64_gcc_128
673 Enable support for optimised implementations of some commonly used NIST
676 This option is only supported on platforms:
678 - with little-endian storage of non-byte types
679 - that tolerate misaligned memory references
680 - where the compiler:
681 - supports the non-standard type `__uint128_t`
682 - defines the built-in macro `__SIZEOF_INT128__`
686 Build support for gathering entropy from the Entropy Gathering Daemon (EGD).
690 Don't build support for loading engines.
694 Don't compile in any error strings.
696 ### enable-external-tests
698 Enable building of integration with external test suites.
700 This is a developer option and may not work on all platforms. The following
701 external test suites are currently supported:
703 - GOST engine test suite
704 - Python PYCA/Cryptography test suite
707 See the file [test/README-external.md](test/README-external.md)
712 Don't compile in filename and line number information (e.g. for errors and
717 Build (and install) the FIPS provider
719 ### no-fips-securitychecks
721 Don't perform FIPS module run-time checks related to enforcement of security
722 parameters such as minimum security strength of keys.
724 ### enable-fuzz-libfuzzer, enable-fuzz-afl
726 Build with support for fuzzing using either libfuzzer or AFL.
728 These are developer options only. They may not work on all platforms and
729 should never be used in production environments.
731 See the file [fuzz/README.md](fuzz/README.md) for further details.
735 Don't build support for GOST based ciphersuites.
737 Note that if this feature is enabled then GOST ciphersuites are only available
738 if the GOST algorithms are also available through loading an externally supplied
743 Don't build the legacy provider.
745 Disabling this also disables the legacy algorithms: MD2 (already disabled by default).
749 Don't generate dependencies.
753 Don't build any dynamically loadable engines.
755 This also implies `no-dynamic-engine`.
759 Don't build support for writing multiple records in one go in libssl
761 Note: this is a different capability to the pipelining functionality.
765 Don't build support for the Next Protocol Negotiation (NPN) TLS extension.
769 Don't build support for Online Certificate Status Protocol (OCSP).
773 Don't build the padlock engine.
777 As synonym for `no-padlockeng`. Deprecated and should not be used.
781 Don't build with support for Position Independent Code.
785 Don't pin the shared libraries.
787 By default OpenSSL will attempt to stay in memory until the process exits.
788 This is so that libcrypto and libssl can be properly cleaned up automatically
789 via an `atexit()` handler. The handler is registered by libcrypto and cleans
790 up both libraries. On some platforms the `atexit()` handler will run on unload of
791 libcrypto (if it has been dynamically loaded) rather than at process exit. This
792 option can be used to stop OpenSSL from attempting to stay in memory until the
793 process exits. This could lead to crashes if either libcrypto or libssl have
794 already been unloaded at the point that the atexit handler is invoked, e.g. on a
795 platform which calls `atexit()` on unload of the library, and libssl is unloaded
796 before libcrypto then a crash is likely to happen. Applications can suppress
797 running of the `atexit()` handler at run time by using the
798 `OPENSSL_INIT_NO_ATEXIT` option to `OPENSSL_init_crypto()`.
799 See the man page for it for further details.
803 Don't use POSIX IO capabilities.
807 Don't build support for Pre-Shared Key based ciphersuites.
811 Don't use hardware RDRAND capabilities.
815 Don't build support for RFC3779, "X.509 Extensions for IP Addresses and
820 Build support for Stream Control Transmission Protocol (SCTP).
824 Do not create shared libraries, only static ones.
826 See [Notes on shared libraries](#notes-on-shared-libraries) below.
830 Don't build support for socket BIOs.
834 Don't build support for Secure Remote Password (SRP) protocol or
835 SRP based ciphersuites.
839 Don't build Secure Real-Time Transport Protocol (SRTP) support.
843 Exclude SSE2 code paths from 32-bit x86 assembly modules.
845 Normally SSE2 extension is detected at run-time, but the decision whether or not
846 the machine code will be executed is taken solely on CPU capability vector. This
847 means that if you happen to run OS kernel which does not support SSE2 extension
848 on Intel P4 processor, then your application might be exposed to "illegal
849 instruction" exception. There might be a way to enable support in kernel, e.g.
850 FreeBSD kernel can be compiled with `CPU_ENABLE_SSE`, and there is a way to
851 disengage SSE2 code paths upon application start-up, but if you aim for wider
852 "audience" running such kernel, consider `no-sse2`. Both the `386` and `no-asm`
853 options imply `no-sse2`.
857 Don't build with SSL Trace capabilities.
859 This removes the `-trace` option from `s_client` and `s_server`, and omits the
860 `SSL_trace()` function from libssl.
862 Disabling `ssl-trace` may provide a small reduction in libssl binary size.
866 Don't build the statically linked engines.
868 This only has an impact when not built "shared".
872 Don't use anything from the C header file `stdio.h` that makes use of the `FILE`
873 type. Only libcrypto and libssl can be built in this way. Using this option will
874 suppress building the command line applications. Additionally, since the OpenSSL
875 tests also use the command line applications, the tests will also be skipped.
879 Don't build test programs or run any tests.
883 Build with support for TCP Fast Open (RFC7413). Supported on Linux, macOS and FreeBSD.
887 Don't build with support for multi-threaded applications.
891 Build with support for multi-threaded applications. Most platforms will enable
892 this by default. However, if on a platform where this is not the case then this
893 will usually require additional system-dependent options!
895 See [Notes on multi-threading](#notes-on-multi-threading) below.
899 Build with support for the integrated tracing api.
901 See manual pages OSSL_trace_set_channel(3) and OSSL_trace_enabled(3) for details.
905 Don't build Time Stamping (TS) Authority support.
909 Build with the Undefined Behaviour sanitiser (UBSAN).
911 This is a developer option only. It may not work on all platforms and should
912 never be used in production environments. It will only work when used with
913 gcc or clang and should be used in conjunction with the `-DPEDANTIC` option
914 (or the `--strict-warnings` option).
918 Don't build with the User Interface (UI) console method
920 The User Interface console method enables text based console prompts.
924 Enable additional unit test APIs.
926 This should not typically be used in production deployments.
930 Don't build support for UPLINK interface.
932 ### enable-weak-ssl-ciphers
934 Build support for SSL/TLS ciphers that are considered "weak"
936 Enabling this includes for example the RC4 based ciphersuites.
940 Build with support for zlib compression/decompression.
944 Like the zlib option, but has OpenSSL load the zlib library dynamically
947 This is only supported on systems where loading of shared libraries is supported.
951 In 32-bit x86 builds, use the 80386 instruction set only in assembly modules
953 The default x86 code is more efficient, but requires at least an 486 processor.
954 Note: This doesn't affect compiler generated code, so this option needs to be
955 accompanied by a corresponding compiler-specific option.
959 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}
961 Don't build support for negotiating the specified SSL/TLS protocol.
963 If `no-tls` is selected then all of `tls1`, `tls1_1`, `tls1_2` and `tls1_3`
965 Similarly `no-dtls` will disable `dtls1` and `dtls1_2`. The `no-ssl` option is
966 synonymous with `no-ssl3`. Note this only affects version negotiation.
967 OpenSSL will still provide the methods for applications to explicitly select
968 the individual protocol versions.
970 ### no-{protocol}-method
972 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}-method
974 Analogous to `no-{protocol}` but in addition do not build the methods for
975 applications to explicitly select individual protocol versions. Note that there
976 is no `no-tls1_3-method` option because there is no application method for
979 Using individual protocol methods directly is deprecated. Applications should
980 use `TLS_method()` instead.
982 ### enable-{algorithm}
986 Build with support for the specified algorithm.
990 no-{aria|bf|blake2|camellia|cast|chacha|cmac|
991 des|dh|dsa|ecdh|ecdsa|idea|md4|mdc2|ocb|
992 poly1305|rc2|rc4|rmd160|scrypt|seed|
993 siphash|siv|sm2|sm3|sm4|whirlpool}
995 Build without support for the specified algorithm.
997 The `ripemd` algorithm is deprecated and if used is synonymous with `rmd160`.
999 ### Compiler-specific options
1001 -Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static
1003 These system specific options will be recognised and passed through to the
1004 compiler to allow you to define preprocessor symbols, specify additional
1005 libraries, library directories or other compiler options. It might be worth
1006 noting that some compilers generate code specifically for processor the
1007 compiler currently executes on. This is not necessarily what you might have
1008 in mind, since it might be unsuitable for execution on other, typically older,
1009 processor. Consult your compiler documentation.
1011 Take note of the [Environment Variables](#environment-variables) documentation
1012 below and how these flags interact with those variables.
1016 Additional options that are not otherwise recognised are passed through as
1017 they are to the compiler as well. Unix-style options beginning with a
1018 `-` or `+` and Windows-style options beginning with a `/` are recognized.
1019 Again, consult your compiler documentation.
1021 If the option contains arguments separated by spaces, then the URL-style
1022 notation `%20` can be used for the space character in order to avoid having
1023 to quote the option. For example, `-opt%20arg` gets expanded to `-opt arg`.
1024 In fact, any ASCII character can be encoded as %xx using its hexadecimal
1027 Take note of the [Environment Variables](#environment-variables) documentation
1028 below and how these flags interact with those variables.
1030 ### Environment Variables
1034 Assign the given value to the environment variable `VAR` for `Configure`.
1036 These work just like normal environment variable assignments, but are supported
1037 on all platforms and are confined to the configuration scripts only.
1038 These assignments override the corresponding value in the inherited environment,
1041 The following variables are used as "`make` variables" and can be used as an
1042 alternative to giving preprocessor, compiler and linker options directly as
1043 configuration. The following variables are supported:
1045 AR The static library archiver.
1046 ARFLAGS Flags for the static library archiver.
1047 AS The assembler compiler.
1048 ASFLAGS Flags for the assembler compiler.
1050 CFLAGS Flags for the C compiler.
1051 CXX The C++ compiler.
1052 CXXFLAGS Flags for the C++ compiler.
1053 CPP The C/C++ preprocessor.
1054 CPPFLAGS Flags for the C/C++ preprocessor.
1055 CPPDEFINES List of CPP macro definitions, separated
1056 by a platform specific character (':' or
1057 space for Unix, ';' for Windows, ',' for
1058 VMS). This can be used instead of using
1059 -D (or what corresponds to that on your
1060 compiler) in CPPFLAGS.
1061 CPPINCLUDES List of CPP inclusion directories, separated
1062 the same way as for CPPDEFINES. This can
1063 be used instead of -I (or what corresponds
1064 to that on your compiler) in CPPFLAGS.
1065 HASHBANGPERL Perl invocation to be inserted after '#!'
1066 in public perl scripts (only relevant on
1068 LD The program linker (not used on Unix, $(CC)
1070 LDFLAGS Flags for the shared library, DSO and
1072 LDLIBS Extra libraries to use when linking.
1073 Takes the form of a space separated list
1074 of library specifications on Unix and
1075 Windows, and as a comma separated list of
1077 RANLIB The library archive indexer.
1078 RC The Windows resource compiler.
1079 RCFLAGS Flags for the Windows resource compiler.
1080 RM The command to remove files and directories.
1082 These cannot be mixed with compiling/linking flags given on the command line.
1083 In other words, something like this isn't permitted.
1085 $ ./Configure -DFOO CPPFLAGS=-DBAR -DCOOKIE
1087 Backward compatibility note:
1089 To be compatible with older configuration scripts, the environment variables
1090 are ignored if compiling/linking flags are given on the command line, except
1093 AR, CC, CXX, CROSS_COMPILE, HASHBANGPERL, PERL, RANLIB, RC, and WINDRES
1095 For example, the following command will not see `-DBAR`:
1097 $ CPPFLAGS=-DBAR ./Configure -DCOOKIE
1099 However, the following will see both set variables:
1101 $ CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- ./Configure -DCOOKIE
1103 If `CC` is set, it is advisable to also set `CXX` to ensure both the C and C++
1104 compiler are in the same "family". This becomes relevant with
1105 `enable-external-tests` and `enable-buildtest-c++`.
1112 Reconfigure from earlier data.
1114 This fetches the previous command line options and environment from data
1115 saved in `configdata.pm` and runs the configuration process again, using
1116 these options and environment. Note: NO other option is permitted together
1117 with `reconf`. Note: The original configuration saves away values for ALL
1118 environment variables that were used, and if they weren't defined, they are
1119 still saved away with information that they weren't originally defined.
1120 This information takes precedence over environment variables that are
1121 defined when reconfiguring.
1123 Displaying configuration data
1124 -----------------------------
1126 The configuration script itself will say very little, and finishes by
1127 creating `configdata.pm`. This perl module can be loaded by other scripts
1128 to find all the configuration data, and it can also be used as a script to
1129 display all sorts of configuration data in a human readable form.
1131 For more information, please do:
1133 $ ./configdata.pm --help # Unix
1137 $ perl configdata.pm --help # Windows and VMS
1139 Installation Steps in Detail
1140 ============================
1145 ### Automatic Configuration
1147 In previous version, the `config` script determined the platform type and
1148 compiler and then called `Configure`. Starting with this release, they are
1151 #### Unix / Linux / macOS
1153 $ ./Configure [options...]
1157 $ perl Configure [options...]
1161 $ perl Configure [options...]
1163 ### Manual Configuration
1165 OpenSSL knows about a range of different operating system, hardware and
1166 compiler combinations. To see the ones it knows about, run
1168 $ ./Configure LIST # Unix
1172 $ perl Configure LIST # All other platforms
1174 For the remainder of this text, the Unix form will be used in all examples.
1175 Please use the appropriate form for your platform.
1177 Pick a suitable name from the list that matches your system. For most
1178 operating systems there is a choice between using cc or gcc.
1179 When you have identified your system (and if necessary compiler) use this
1180 name as the argument to `Configure`. For example, a `linux-elf` user would
1183 $ ./Configure linux-elf [options...]
1185 ### Creating your own Configuration
1187 If your system isn't listed, you will have to create a configuration
1188 file named `Configurations/YOURFILENAME.conf` (replace `YOURFILENAME`
1189 with a filename of your choosing) and add the correct
1190 configuration for your system. See the available configs as examples
1191 and read [Configurations/README.md](Configurations/README.md) and
1192 [Configurations/README-design.md](Configurations/README-design.md)
1193 for more information.
1195 The generic configurations `cc` or `gcc` should usually work on 32 bit
1198 `Configure` creates a build file (`Makefile` on Unix, `makefile` on Windows
1199 and `descrip.mms` on OpenVMS) from a suitable template in `Configurations/`,
1200 and defines various macros in `include/openssl/configuration.h` (generated
1201 from `include/openssl/configuration.h.in`.
1203 ### Out of Tree Builds
1205 OpenSSL can be configured to build in a build directory separate from the
1206 source code directory. It's done by placing yourself in some other
1207 directory and invoking the configuration commands from there.
1211 $ mkdir /var/tmp/openssl-build
1212 $ cd /var/tmp/openssl-build
1213 $ /PATH/TO/OPENSSL/SOURCE/Configure [options...]
1215 #### OpenVMS example
1217 $ set default sys$login:
1218 $ create/dir [.tmp.openssl-build]
1219 $ set default [.tmp.openssl-build]
1220 $ perl D:[PATH.TO.OPENSSL.SOURCE]Configure [options...]
1222 #### Windows example
1225 $ mkdir \temp-openssl
1227 $ perl d:\PATH\TO\OPENSSL\SOURCE\Configure [options...]
1229 Paths can be relative just as well as absolute. `Configure` will do its best
1230 to translate them to relative paths whenever possible.
1235 Build OpenSSL by running:
1238 $ mms ! (or mmk) OpenVMS
1241 This will build the OpenSSL libraries (`libcrypto.a` and `libssl.a` on
1242 Unix, corresponding on other platforms) and the OpenSSL binary
1243 (`openssl`). The libraries will be built in the top-level directory,
1244 and the binary will be in the `apps/` subdirectory.
1246 If the build fails, take a look at the [Build Failures](#build-failures)
1247 subsection of the [Troubleshooting](#troubleshooting) section.
1252 After a successful build, and before installing, the libraries should
1256 $ mms test ! OpenVMS
1257 $ nmake test # Windows
1259 **Warning:** you MUST run the tests from an unprivileged account (or disable
1260 your privileges temporarily if your platform allows it).
1262 See [test/README.md](test/README.md) for further details how run tests.
1264 See [test/README-dev.md](test/README-dev.md) for guidelines on adding tests.
1269 If everything tests ok, install OpenSSL with
1271 $ make install # Unix
1272 $ mms install ! OpenVMS
1273 $ nmake install # Windows
1275 Note that in order to perform the install step above you need to have
1276 appropriate permissions to write to the installation directory.
1278 The above commands will install all the software components in this
1279 directory tree under `<PREFIX>` (the directory given with `--prefix` or
1282 ### Unix / Linux / macOS
1284 bin/ Contains the openssl binary and a few other
1287 Contains the header files needed if you want
1288 to build your own programs that use libcrypto
1290 lib Contains the OpenSSL library files.
1291 lib/engines Contains the OpenSSL dynamically loadable engines.
1293 share/man/man1 Contains the OpenSSL command line man-pages.
1294 share/man/man3 Contains the OpenSSL library calls man-pages.
1295 share/man/man5 Contains the OpenSSL configuration format man-pages.
1296 share/man/man7 Contains the OpenSSL other misc man-pages.
1298 share/doc/openssl/html/man1
1299 share/doc/openssl/html/man3
1300 share/doc/openssl/html/man5
1301 share/doc/openssl/html/man7
1302 Contains the HTML rendition of the man-pages.
1306 'arch' is replaced with the architecture name, `ALPHA` or `IA64`,
1307 'sover' is replaced with the shared library version (`0101` for 1.1), and
1308 'pz' is replaced with the pointer size OpenSSL was built with:
1310 [.EXE.'arch'] Contains the openssl binary.
1311 [.EXE] Contains a few utility scripts.
1313 Contains the header files needed if you want
1314 to build your own programs that use libcrypto
1316 [.LIB.'arch'] Contains the OpenSSL library files.
1317 [.ENGINES'sover''pz'.'arch']
1318 Contains the OpenSSL dynamically loadable engines.
1319 [.SYS$STARTUP] Contains startup, login and shutdown scripts.
1320 These define appropriate logical names and
1322 [.SYSTEST] Contains the installation verification procedure.
1323 [.HTML] Contains the HTML rendition of the manual pages.
1325 ### Additional Directories
1327 Additionally, install will add the following directories under
1328 OPENSSLDIR (the directory given with `--openssldir` or its default)
1329 for you convenience:
1331 certs Initially empty, this is the default location
1332 for certificate files.
1333 private Initially empty, this is the default location
1334 for private key files.
1335 misc Various scripts.
1337 The installation directory should be appropriately protected to ensure
1338 unprivileged users cannot make changes to OpenSSL binaries or files, or
1339 install engines. If you already have a pre-installed version of OpenSSL as
1340 part of your Operating System it is recommended that you do not overwrite
1341 the system version and instead install to somewhere else.
1343 Package builders who want to configure the library for standard locations,
1344 but have the package installed somewhere else so that it can easily be
1347 $ make DESTDIR=/tmp/package-root install # Unix
1348 $ mms/macro="DESTDIR=TMP:[PACKAGE-ROOT]" install ! OpenVMS
1350 The specified destination directory will be prepended to all installation
1353 Compatibility issues with previous OpenSSL versions
1354 ---------------------------------------------------
1356 ### COMPILING existing applications
1358 Starting with version 1.1.0, OpenSSL hides a number of structures that were
1359 previously open. This includes all internal libssl structures and a number
1360 of EVP types. Accessor functions have been added to allow controlled access
1361 to the structures' data.
1363 This means that some software needs to be rewritten to adapt to the new ways
1364 of doing things. This often amounts to allocating an instance of a structure
1365 explicitly where you could previously allocate them on the stack as automatic
1366 variables, and using the provided accessor functions where you would previously
1367 access a structure's field directly.
1369 Some APIs have changed as well. However, older APIs have been preserved when
1372 Post-installation Notes
1373 -----------------------
1375 With the default OpenSSL installation comes a FIPS provider module, which
1376 needs some post-installation attention, without which it will not be usable.
1377 This involves using the following command:
1379 $ openssl fipsinstall
1381 See the openssl-fipsinstall(1) manual for details and examples.
1383 Advanced Build Options
1384 ======================
1386 Environment Variables
1387 ---------------------
1389 A number of environment variables can be used to provide additional control
1390 over the build process. Typically these should be defined prior to running
1391 `Configure`. Not all environment variables are relevant to all platforms.
1394 The name of the ar executable to use.
1397 Use a different build file name than the platform default
1398 ("Makefile" on Unix-like platforms, "makefile" on native Windows,
1399 "descrip.mms" on OpenVMS). This requires that there is a
1400 corresponding build file template.
1401 See [Configurations/README.md](Configurations/README.md)
1402 for further information.
1405 The compiler to use. Configure will attempt to pick a default
1406 compiler for your platform but this choice can be overridden
1407 using this variable. Set it to the compiler executable you wish
1408 to use, e.g. gcc or clang.
1411 This environment variable has the same meaning as for the
1412 "--cross-compile-prefix" Configure flag described above. If both
1413 are set then the Configure flag takes precedence.
1416 The command string for the Perl executable to insert in the
1417 #! line of perl scripts that will be publicly installed.
1418 Default: /usr/bin/env perl
1419 Note: the value of this variable is added to the same scripts
1420 on all platforms, but it's only relevant on Unix-like platforms.
1423 This can be the value `32` or `64` to specify the architecture
1424 when it is not "obvious" to the configuration. It should generally
1425 not be necessary to specify this environment variable.
1428 The name of the nm executable to use.
1430 OPENSSL_LOCAL_CONFIG_DIR
1431 OpenSSL comes with a database of information about how it
1432 should be built on different platforms as well as build file
1433 templates for those platforms. The database is comprised of
1434 ".conf" files in the Configurations directory. The build
1435 file templates reside there as well as ".tmpl" files. See the
1436 file [Configurations/README.md](Configurations/README.md)
1437 for further information about the format of ".conf" files
1438 as well as information on the ".tmpl" files.
1439 In addition to the standard ".conf" and ".tmpl" files, it is
1440 possible to create your own ".conf" and ".tmpl" files and
1441 store them locally, outside the OpenSSL source tree.
1442 This environment variable can be set to the directory where
1443 these files are held and will be considered by Configure
1444 before it looks in the standard directories.
1447 The name of the Perl executable to use when building OpenSSL.
1448 Only needed if builing should use a different Perl executable
1449 than what is used to run the Configure script.
1452 The name of the ranlib executable to use.
1455 The name of the rc executable to use. The default will be as
1456 defined for the target platform in the ".conf" file. If not
1457 defined then "windres" will be used. The WINDRES environment
1458 variable is synonymous to this. If both are defined then RC
1467 The `Configure` script generates a Makefile in a format relevant to the specific
1468 platform. The Makefiles provide a number of targets that can be used. Not all
1469 targets may be available on all platforms. Only the most common targets are
1470 described here. Examine the Makefiles themselves for the full list.
1473 The target to build all the software components and
1477 Build all the software components.
1478 THIS IS THE DEFAULT TARGET.
1481 Build all documentation components.
1484 Remove all build artefacts and return the directory to a "clean"
1488 Rebuild the dependencies in the Makefiles. This is a legacy
1489 option that no longer needs to be used since OpenSSL 1.1.0.
1492 Install all OpenSSL components.
1495 Only install the OpenSSL software components.
1498 Only install the OpenSSL documentation components.
1501 Only install the OpenSSL man pages (Unix only).
1504 Only install the OpenSSL HTML documentation.
1507 Install the FIPS provider module configuration file.
1510 Prints a list of all the self test names.
1513 Build and run the OpenSSL self tests.
1516 Uninstall all OpenSSL components.
1520 Re-run the configuration process, as exactly as the last time
1524 This is a developer option. If you are developing a patch for
1525 OpenSSL you may need to use this if you want to update
1526 automatically generated files; add new error codes or add new
1527 (or change the visibility of) public API functions. (Unix only).
1529 Running Selected Tests
1530 ----------------------
1532 You can specify a set of tests to be performed
1533 using the `make` variable `TESTS`.
1535 See the section [Running Selected Tests of
1536 test/README.md](test/README.md#running-selected-tests).
1541 Configuration Problems
1542 ----------------------
1544 ### Selecting the correct target
1546 The `./Configure` script tries hard to guess your operating system, but in some
1547 cases it does not succeed. You will see a message like the following:
1550 Operating system: x86-whatever-minix
1551 This system (minix) is not supported. See file INSTALL.md for details.
1553 Even if the automatic target selection by the `./Configure` script fails,
1554 chances are that you still might find a suitable target in the `Configurations`
1555 directory, which you can supply to the `./Configure` command,
1556 possibly after some adjustment.
1558 The `Configurations/` directory contains a lot of examples of such targets.
1559 The main configuration file is [10-main.conf], which contains all targets that
1560 are officially supported by the OpenSSL team. Other configuration files contain
1561 targets contributed by other OpenSSL users. The list of targets can be found in
1562 a Perl list `my %targets = ( ... )`.
1567 inherit_from => [ "base-target" ],
1569 cflags => add("..."),
1571 perlasm_scheme => "...",
1576 If you call `./Configure` without arguments, it will give you a list of all
1577 known targets. Using `grep`, you can lookup the target definition in the
1578 `Configurations/` directory. For example the `android-x86_64` can be found in
1579 [Configurations/15-android.conf](Configurations/15-android.conf).
1581 The directory contains two README files, which explain the general syntax and
1582 design of the configuration files.
1584 - [Configurations/README.md](Configurations/README.md)
1585 - [Configurations/README-design.md](Configurations/README-design.md)
1587 If you need further help, try to search the [openssl-users] mailing list
1588 or the [GitHub Issues] for existing solutions. If you don't find anything,
1589 you can [raise an issue] to ask a question yourself.
1591 More about our support resources can be found in the [SUPPORT] file.
1593 ### Configuration Errors
1595 If the `./Configure` or `./Configure` command fails with an error message,
1596 read the error message carefully and try to figure out whether you made
1597 a mistake (e.g., by providing a wrong option), or whether the script is
1598 working incorrectly. If you think you encountered a bug, please
1599 [raise an issue] on GitHub to file a bug report.
1601 Along with a short description of the bug, please provide the complete
1602 configure command line and the relevant output including the error message.
1604 Note: To make the output readable, please add a 'code fence' (three backquotes
1605 ` ``` ` on a separate line) before and after your output:
1608 ./Configure [your arguments...]
1617 If the build fails, look carefully at the output. Try to locate and understand
1618 the error message. It might be that the compiler is already telling you
1619 exactly what you need to do to fix your problem.
1621 There may be reasons for the failure that aren't problems in OpenSSL itself,
1622 for example if the compiler reports missing standard or third party headers.
1624 If the build succeeded previously, but fails after a source or configuration
1625 change, it might be helpful to clean the build tree before attempting another
1626 build. Use this command:
1629 $ mms clean ! (or mmk) OpenVMS
1630 $ nmake clean # Windows
1632 Assembler error messages can sometimes be sidestepped by using the `no-asm`
1633 configuration option. See also [notes](#notes-on-assembler-modules-compilation).
1635 Compiling parts of OpenSSL with gcc and others with the system compiler will
1636 result in unresolved symbols on some systems.
1638 If you are still having problems, try to search the [openssl-users] mailing
1639 list or the [GitHub Issues] for existing solutions. If you think you
1640 encountered an OpenSSL bug, please [raise an issue] to file a bug report.
1641 Please take the time to review the existing issues first; maybe the bug was
1642 already reported or has already been fixed.
1647 If some tests fail, look at the output. There may be reasons for the failure
1648 that isn't a problem in OpenSSL itself (like an OS malfunction or a Perl issue).
1650 You may want increased verbosity, that can be accomplished as described in
1651 section [Test Failures of test/README.md](test/README.md#test-failures).
1653 You may also want to selectively specify which test(s) to perform. This can be
1654 done using the `make` variable `TESTS` as described in section [Running
1655 Selected Tests of test/README.md](test/README.md#running-selected-tests).
1657 If you find a problem with OpenSSL itself, try removing any
1658 compiler optimization flags from the `CFLAGS` line in the Makefile and
1659 run `make clean; make` or corresponding.
1661 To report a bug please open an issue on GitHub, at
1662 <https://github.com/openssl/openssl/issues>.
1667 Notes on multi-threading
1668 ------------------------
1670 For some systems, the OpenSSL `Configure` script knows what compiler options
1671 are needed to generate a library that is suitable for multi-threaded
1672 applications. On these systems, support for multi-threading is enabled
1673 by default; use the `no-threads` option to disable (this should never be
1676 On other systems, to enable support for multi-threading, you will have
1677 to specify at least two options: `threads`, and a system-dependent option.
1678 (The latter is `-D_REENTRANT` on various systems.) The default in this
1679 case, obviously, is not to include support for multi-threading (but
1680 you can still use `no-threads` to suppress an annoying warning message
1681 from the `Configure` script.)
1683 OpenSSL provides built-in support for two threading models: pthreads (found on
1684 most UNIX/Linux systems), and Windows threads. No other threading models are
1685 supported. If your platform does not provide pthreads or Windows threads then
1686 you should use `Configure` with the `no-threads` option.
1688 For pthreads, all locks are non-recursive. In addition, in a debug build,
1689 the mutex attribute `PTHREAD_MUTEX_ERRORCHECK` is used. If this is not
1690 available on your platform, you might have to add
1691 `-DOPENSSL_NO_MUTEX_ERRORCHECK` to your `Configure` invocation.
1692 (On Linux `PTHREAD_MUTEX_ERRORCHECK` is an enum value, so a built-in
1693 ifdef test cannot be used.)
1695 Notes on shared libraries
1696 -------------------------
1698 For most systems the OpenSSL `Configure` script knows what is needed to
1699 build shared libraries for libcrypto and libssl. On these systems
1700 the shared libraries will be created by default. This can be suppressed and
1701 only static libraries created by using the `no-shared` option. On systems
1702 where OpenSSL does not know how to build shared libraries the `no-shared`
1703 option will be forced and only static libraries will be created.
1705 Shared libraries are named a little differently on different platforms.
1706 One way or another, they all have the major OpenSSL version number as
1707 part of the file name, i.e. for OpenSSL 1.1.x, `1.1` is somehow part of
1710 On most POSIX platforms, shared libraries are named `libcrypto.so.1.1`
1711 and `libssl.so.1.1`.
1713 on Cygwin, shared libraries are named `cygcrypto-1.1.dll` and `cygssl-1.1.dll`
1714 with import libraries `libcrypto.dll.a` and `libssl.dll.a`.
1716 On Windows build with MSVC or using MingW, shared libraries are named
1717 `libcrypto-1_1.dll` and `libssl-1_1.dll` for 32-bit Windows,
1718 `libcrypto-1_1-x64.dll` and `libssl-1_1-x64.dll` for 64-bit x86_64 Windows,
1719 and `libcrypto-1_1-ia64.dll` and `libssl-1_1-ia64.dll` for IA64 Windows.
1720 With MSVC, the import libraries are named `libcrypto.lib` and `libssl.lib`,
1721 while with MingW, they are named `libcrypto.dll.a` and `libssl.dll.a`.
1723 On VMS, shareable images (VMS speak for shared libraries) are named
1724 `ossl$libcrypto0101_shr.exe` and `ossl$libssl0101_shr.exe`. However, when
1725 OpenSSL is specifically built for 32-bit pointers, the shareable images
1726 are named `ossl$libcrypto0101_shr32.exe` and `ossl$libssl0101_shr32.exe`
1727 instead, and when built for 64-bit pointers, they are named
1728 `ossl$libcrypto0101_shr64.exe` and `ossl$libssl0101_shr64.exe`.
1730 Notes on random number generation
1731 ---------------------------------
1733 Availability of cryptographically secure random numbers is required for
1734 secret key generation. OpenSSL provides several options to seed the
1735 internal CSPRNG. If not properly seeded, the internal CSPRNG will refuse
1736 to deliver random bytes and a "PRNG not seeded error" will occur.
1738 The seeding method can be configured using the `--with-rand-seed` option,
1739 which can be used to specify a comma separated list of seed methods.
1740 However, in most cases OpenSSL will choose a suitable default method,
1741 so it is not necessary to explicitly provide this option. Note also
1742 that not all methods are available on all platforms. The FIPS provider will
1743 silently ignore seed sources that were not validated.
1745 I) On operating systems which provide a suitable randomness source (in
1746 form of a system call or system device), OpenSSL will use the optimal
1747 available method to seed the CSPRNG from the operating system's
1748 randomness sources. This corresponds to the option `--with-rand-seed=os`.
1750 II) On systems without such a suitable randomness source, automatic seeding
1751 and reseeding is disabled (`--with-rand-seed=none`) and it may be necessary
1752 to install additional support software to obtain a random seed and reseed
1753 the CSPRNG manually. Please check out the manual pages for `RAND_add()`,
1754 `RAND_bytes()`, `RAND_egd()`, and the FAQ for more information.
1756 Notes on assembler modules compilation
1757 --------------------------------------
1759 Compilation of some code paths in assembler modules might depend on whether the
1760 current assembler version supports certain ISA extensions or not. Code paths
1761 that use the AES-NI, PCLMULQDQ, SSSE3, and SHA extensions are always assembled.
1762 Apart from that, the minimum requirements for the assembler versions are shown
1765 | ISA extension | GNU as | nasm | llvm |
1766 |---------------|--------|--------|---------|
1767 | AVX | 2.19 | 2.09 | 3.0 |
1768 | AVX2 | 2.22 | 2.10 | 3.1 |
1769 | ADCX/ADOX | 2.23 | 2.10 | 3.3 |
1770 | AVX512 | 2.25 | 2.11.8 | 3.6 (*) |
1771 | AVX512IFMA | 2.26 | 2.11.8 | 6.0 (*) |
1772 | VAES | 2.30 | 2.13.3 | 6.0 (*) |
1776 (*) Even though AVX512 support was implemented in llvm 3.6, prior to version 7.0
1777 an explicit -march flag was apparently required to compile assembly modules. But
1778 then the compiler generates processor-specific code, which in turn contradicts
1779 the idea of performing dispatch at run-time, which is facilitated by the special
1780 variable `OPENSSL_ia32cap`. For versions older than 7.0, it is possible to work
1781 around the problem by forcing the build procedure to use the following script:
1784 exec clang -no-integrated-as "$@"
1786 instead of the real clang. In which case it doesn't matter what clang version
1787 is used, as it is the version of the GNU assembler that will be checked.
1794 <https://mta.openssl.org/mailman/listinfo/openssl-users>
1800 <https://github.com/openssl/openssl/issues>
1803 <https://github.com/openssl/openssl/issues/new/choose>
1806 Configurations/10-main.conf