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.
357 Some build targets have a multilib postfix set in the build configuration.
358 For these targets the default libdir is `lib<multilib-postfix>`. Please use
359 `--libdir=lib` to override the libdir if adding the postfix is undesirable.
365 Directory for OpenSSL configuration files, and also the default certificate
366 and key store. Defaults are:
369 Windows: C:\Program Files\Common Files\SSL
370 OpenVMS: SYS$COMMON:[OPENSSL-COMMON]
372 For 32bit Windows applications on Windows 64bit (WOW64), always replace
373 `C:\Program Files` by `C:\Program Files (x86)`.
379 The top of the installation directory tree. Defaults are:
382 Windows: C:\Program Files\OpenSSL
383 OpenVMS: SYS$COMMON:[OPENSSL]
390 This is a developer flag that switches on various compiler options recommended
391 for OpenSSL development. It only works when using gcc or clang as the compiler.
392 If you are developing a patch for OpenSSL then it is recommended that you use
393 this option where possible.
398 ### with-zlib-include
400 --with-zlib-include=DIR
402 The directory for the location of the zlib include file. This option is only
403 necessary if [zlib](#zlib) is used and the include file is not
404 already on the system include path.
410 **On Unix**: this is the directory containing the zlib library.
411 If not provided the system library path will be used.
413 **On Windows:** this is the filename of the zlib library (with or
414 without a path). This flag must be provided if the
415 [zlib-dynamic](#zlib-dynamic) option is not also used. If `zlib-dynamic` is used
416 then this flag is optional and defaults to `ZLIB1` if not provided.
418 **On VMS:** this is the filename of the zlib library (with or without a path).
419 This flag is optional and if not provided then `GNV$LIBZSHR`, `GNV$LIBZSHR32`
420 or `GNV$LIBZSHR64` is used by default depending on the pointer size chosen.
422 Seeding the Random Generator
423 ----------------------------
425 --with-rand-seed=seed1[,seed2,...]
427 A comma separated list of seeding methods which will be tried by OpenSSL
428 in order to obtain random input (a.k.a "entropy") for seeding its
429 cryptographically secure random number generator (CSPRNG).
430 The current seeding methods are:
434 Use a trusted operating system entropy source.
435 This is the default method if such an entropy source exists.
439 Use the [getrandom(2)][man-getrandom] or equivalent system call.
441 [man-getrandom]: http://man7.org/linux/man-pages/man2/getrandom.2.html
445 Use the first device from the `DEVRANDOM` list which can be opened to read
446 random bytes. The `DEVRANDOM` preprocessor constant expands to
448 "/dev/urandom","/dev/random","/dev/srandom"
450 on most unix-ish operating systems.
454 Check for an entropy generating daemon.
455 This source is ignored by the FIPS provider.
459 Use the `RDSEED` or `RDRAND` command if provided by the CPU.
463 Use librandom (not implemented yet).
464 This source is ignored by the FIPS provider.
468 Disable automatic seeding. This is the default on some operating systems where
469 no suitable entropy source exists, or no support for it is implemented yet.
470 This option is ignored by the FIPS provider.
472 For more information, see the section [Notes on random number generation][rng]
473 at the end of this document.
475 [rng]: #notes-on-random-number-generation
477 Setting the FIPS HMAC key
478 -------------------------
482 As part of its self-test validation, the FIPS module must verify itself
483 by performing a SHA-256 HMAC computation on itself. The default key is
484 the SHA256 value of "the holy handgrenade of antioch" and is sufficient
485 for meeting the FIPS requirements.
487 To change the key to a different value, use this flag. The value should
488 be a hex string no more than 64 characters.
490 Enable and Disable Features
491 ---------------------------
493 Feature options always come in pairs, an option to enable feature
494 `xxxx`, and an option to disable it:
496 [ enable-xxxx | no-xxxx ]
498 Whether a feature is enabled or disabled by default, depends on the feature.
499 In the following list, always the non-default variant is documented: if
500 feature `xxxx` is disabled by default then `enable-xxxx` is documented and
501 if feature `xxxx` is enabled by default then `no-xxxx` is documented.
505 Don't build the AFALG engine.
507 This option will be forced on a platform that does not support AFALG.
511 Build with Kernel TLS support.
513 This option will enable the use of the Kernel TLS data-path, which can improve
514 performance and allow for the use of sendfile and splice system calls on
515 TLS sockets. The Kernel may use TLS accelerators if any are available on the
516 system. This option will be forced off on systems that do not support the
517 Kernel TLS data-path.
521 Build with the Address sanitiser.
523 This is a developer option only. It may not work on all platforms and should
524 never be used in production environments. It will only work when used with
525 gcc or clang and should be used in conjunction with the [no-shared](#no-shared)
528 ### enable-acvp-tests
530 Build support for Automated Cryptographic Validation Protocol (ACVP)
533 This is required for FIPS validation purposes. Certain ACVP tests require
534 access to algorithm internals that are not normally accessible.
535 Additional information related to ACVP can be found at
536 <https://github.com/usnistgov/ACVP>.
540 Do not use assembler code.
542 This should be viewed as debugging/troubleshooting option rather than for
543 production use. On some platforms a small amount of assembler code may still
544 be used even with this option.
548 Do not build support for async operations.
552 Don't automatically load all supported ciphers and digests.
554 Typically OpenSSL will make available all of its supported ciphers and digests.
555 For a statically linked application this may be undesirable if small executable
556 size is an objective. This only affects libcrypto. Ciphers and digests will
557 have to be loaded manually using `EVP_add_cipher()` and `EVP_add_digest()`
558 if this option is used. This option will force a non-shared build.
562 Don't automatically load all libcrypto/libssl error strings.
564 Typically OpenSSL will automatically load human readable error strings. For a
565 statically linked application this may be undesirable if small executable size
568 ### no-autoload-config
570 Don't automatically load the default `openssl.cnf` file.
572 Typically OpenSSL will automatically load a system config file which configures
575 ### enable-buildtest-c++
577 While testing, generate C++ buildtest files that simply check that the public
578 OpenSSL header files are usable standalone with C++.
580 Enabling this option demands extra care. For any compiler flag given directly
581 as configuration option, you must ensure that it's valid for both the C and
582 the C++ compiler. If not, the C++ build test will most likely break. As an
583 alternative, you can use the language specific variables, `CFLAGS` and `CXXFLAGS`.
587 Use the specified text instead of the default banner at the end of
592 Build only some minimal set of features.
593 This is a developer option used internally for CI build tests of the project.
597 Never cache algorithms when they are fetched from a provider. Normally, a
598 provider indicates if the algorithms it supplies can be cached or not. Using
599 this option will reduce run-time memory usage but it also introduces a
600 significant performance penalty. This option is primarily designed to help
601 with detecting incorrect reference counting.
605 Don't build the CAPI engine.
607 This option will be forced if on a platform that does not support CAPI.
611 Don't build support for Certificate Management Protocol (CMP)
612 and Certificate Request Message Format (CRMF).
616 Don't build support for Cryptographic Message Syntax (CMS).
620 Don't build support for SSL/TLS compression.
622 If this option is enabled (the default), then compression will only work if
623 the zlib or `zlib-dynamic` options are also chosen.
625 ### enable-crypto-mdebug
627 This now only enables the `failed-malloc` feature.
629 ### enable-crypto-mdebug-backtrace
631 This is a no-op; the project uses the compiler's address/leak sanitizer instead.
635 Don't build support for Certificate Transparency (CT).
639 Don't build with support for deprecated APIs up until and including the version
640 given with `--api` (or the current version, if `--api` wasn't specified).
644 Don't build support for datagram based BIOs.
646 Selecting this option will also force the disabling of DTLS.
650 Don't build support for loading Dynamic Shared Objects (DSO)
652 ### enable-devcryptoeng
654 Build the `/dev/crypto` engine.
656 This option is automatically selected on the BSD platform, in which case it can
657 be disabled with `no-devcryptoeng`.
659 ### no-dynamic-engine
661 Don't build the dynamically loaded engines.
663 This only has an effect in a shared build.
667 Don't build support for Elliptic Curves.
671 Don't build support for binary Elliptic Curves
673 ### enable-ec_nistp_64_gcc_128
675 Enable support for optimised implementations of some commonly used NIST
678 This option is only supported on platforms:
680 - with little-endian storage of non-byte types
681 - that tolerate misaligned memory references
682 - where the compiler:
683 - supports the non-standard type `__uint128_t`
684 - defines the built-in macro `__SIZEOF_INT128__`
688 Build support for gathering entropy from the Entropy Gathering Daemon (EGD).
692 Don't build support for loading engines.
696 Don't compile in any error strings.
698 ### enable-external-tests
700 Enable building of integration with external test suites.
702 This is a developer option and may not work on all platforms. The following
703 external test suites are currently supported:
705 - GOST engine test suite
706 - Python PYCA/Cryptography test suite
709 See the file [test/README-external.md](test/README-external.md)
714 Don't compile in filename and line number information (e.g. for errors and
719 Build (and install) the FIPS provider
721 ### no-fips-securitychecks
723 Don't perform FIPS module run-time checks related to enforcement of security
724 parameters such as minimum security strength of keys.
726 ### enable-fuzz-libfuzzer, enable-fuzz-afl
728 Build with support for fuzzing using either libfuzzer or AFL.
730 These are developer options only. They may not work on all platforms and
731 should never be used in production environments.
733 See the file [fuzz/README.md](fuzz/README.md) for further details.
737 Don't build support for GOST based ciphersuites.
739 Note that if this feature is enabled then GOST ciphersuites are only available
740 if the GOST algorithms are also available through loading an externally supplied
745 Don't build the legacy provider.
747 Disabling this also disables the legacy algorithms: MD2 (already disabled by default).
751 Don't generate dependencies.
755 Don't build any dynamically loadable engines.
757 This also implies `no-dynamic-engine`.
761 Don't build support for writing multiple records in one go in libssl
763 Note: this is a different capability to the pipelining functionality.
767 Don't build support for the Next Protocol Negotiation (NPN) TLS extension.
771 Don't build support for Online Certificate Status Protocol (OCSP).
775 Don't build the padlock engine.
779 As synonym for `no-padlockeng`. Deprecated and should not be used.
783 Don't build with support for Position Independent Code.
787 Don't pin the shared libraries.
789 By default OpenSSL will attempt to stay in memory until the process exits.
790 This is so that libcrypto and libssl can be properly cleaned up automatically
791 via an `atexit()` handler. The handler is registered by libcrypto and cleans
792 up both libraries. On some platforms the `atexit()` handler will run on unload of
793 libcrypto (if it has been dynamically loaded) rather than at process exit. This
794 option can be used to stop OpenSSL from attempting to stay in memory until the
795 process exits. This could lead to crashes if either libcrypto or libssl have
796 already been unloaded at the point that the atexit handler is invoked, e.g. on a
797 platform which calls `atexit()` on unload of the library, and libssl is unloaded
798 before libcrypto then a crash is likely to happen. Applications can suppress
799 running of the `atexit()` handler at run time by using the
800 `OPENSSL_INIT_NO_ATEXIT` option to `OPENSSL_init_crypto()`.
801 See the man page for it for further details.
805 Don't use POSIX IO capabilities.
809 Don't build support for Pre-Shared Key based ciphersuites.
813 Don't use hardware RDRAND capabilities.
817 Don't build support for RFC3779, "X.509 Extensions for IP Addresses and
822 Build support for Stream Control Transmission Protocol (SCTP).
826 Do not create shared libraries, only static ones.
828 See [Notes on shared libraries](#notes-on-shared-libraries) below.
832 Don't build support for socket BIOs.
836 Don't build support for Secure Remote Password (SRP) protocol or
837 SRP based ciphersuites.
841 Don't build Secure Real-Time Transport Protocol (SRTP) support.
845 Exclude SSE2 code paths from 32-bit x86 assembly modules.
847 Normally SSE2 extension is detected at run-time, but the decision whether or not
848 the machine code will be executed is taken solely on CPU capability vector. This
849 means that if you happen to run OS kernel which does not support SSE2 extension
850 on Intel P4 processor, then your application might be exposed to "illegal
851 instruction" exception. There might be a way to enable support in kernel, e.g.
852 FreeBSD kernel can be compiled with `CPU_ENABLE_SSE`, and there is a way to
853 disengage SSE2 code paths upon application start-up, but if you aim for wider
854 "audience" running such kernel, consider `no-sse2`. Both the `386` and `no-asm`
855 options imply `no-sse2`.
859 Don't build with SSL Trace capabilities.
861 This removes the `-trace` option from `s_client` and `s_server`, and omits the
862 `SSL_trace()` function from libssl.
864 Disabling `ssl-trace` may provide a small reduction in libssl binary size.
868 Don't build the statically linked engines.
870 This only has an impact when not built "shared".
874 Don't use anything from the C header file `stdio.h` that makes use of the `FILE`
875 type. Only libcrypto and libssl can be built in this way. Using this option will
876 suppress building the command line applications. Additionally, since the OpenSSL
877 tests also use the command line applications, the tests will also be skipped.
881 Don't build test programs or run any tests.
885 Don't build with support for multi-threaded applications.
889 Build with support for multi-threaded applications. Most platforms will enable
890 this by default. However, if on a platform where this is not the case then this
891 will usually require additional system-dependent options!
893 See [Notes on multi-threading](#notes-on-multi-threading) below.
897 Build with support for the integrated tracing api.
899 See manual pages OSSL_trace_set_channel(3) and OSSL_trace_enabled(3) for details.
903 Don't build Time Stamping (TS) Authority support.
907 Build with the Undefined Behaviour sanitiser (UBSAN).
909 This is a developer option only. It may not work on all platforms and should
910 never be used in production environments. It will only work when used with
911 gcc or clang and should be used in conjunction with the `-DPEDANTIC` option
912 (or the `--strict-warnings` option).
916 Don't build with the User Interface (UI) console method
918 The User Interface console method enables text based console prompts.
922 Enable additional unit test APIs.
924 This should not typically be used in production deployments.
928 Don't build support for UPLINK interface.
930 ### enable-weak-ssl-ciphers
932 Build support for SSL/TLS ciphers that are considered "weak"
934 Enabling this includes for example the RC4 based ciphersuites.
938 Build with support for zlib compression/decompression.
942 Like the zlib option, but has OpenSSL load the zlib library dynamically
945 This is only supported on systems where loading of shared libraries is supported.
949 In 32-bit x86 builds, use the 80386 instruction set only in assembly modules
951 The default x86 code is more efficient, but requires at least an 486 processor.
952 Note: This doesn't affect compiler generated code, so this option needs to be
953 accompanied by a corresponding compiler-specific option.
957 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}
959 Don't build support for negotiating the specified SSL/TLS protocol.
961 If `no-tls` is selected then all of `tls1`, `tls1_1`, `tls1_2` and `tls1_3`
963 Similarly `no-dtls` will disable `dtls1` and `dtls1_2`. The `no-ssl` option is
964 synonymous with `no-ssl3`. Note this only affects version negotiation.
965 OpenSSL will still provide the methods for applications to explicitly select
966 the individual protocol versions.
968 ### no-{protocol}-method
970 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}-method
972 Analogous to `no-{protocol}` but in addition do not build the methods for
973 applications to explicitly select individual protocol versions. Note that there
974 is no `no-tls1_3-method` option because there is no application method for
977 Using individual protocol methods directly is deprecated. Applications should
978 use `TLS_method()` instead.
980 ### enable-{algorithm}
984 Build with support for the specified algorithm.
988 no-{aria|bf|blake2|camellia|cast|chacha|cmac|
989 des|dh|dsa|ecdh|ecdsa|idea|md4|mdc2|ocb|
990 poly1305|rc2|rc4|rmd160|scrypt|seed|
991 siphash|siv|sm2|sm3|sm4|whirlpool}
993 Build without support for the specified algorithm.
995 The `ripemd` algorithm is deprecated and if used is synonymous with `rmd160`.
997 ### Compiler-specific options
999 -Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static
1001 These system specific options will be recognised and passed through to the
1002 compiler to allow you to define preprocessor symbols, specify additional
1003 libraries, library directories or other compiler options. It might be worth
1004 noting that some compilers generate code specifically for processor the
1005 compiler currently executes on. This is not necessarily what you might have
1006 in mind, since it might be unsuitable for execution on other, typically older,
1007 processor. Consult your compiler documentation.
1009 Take note of the [Environment Variables](#environment-variables) documentation
1010 below and how these flags interact with those variables.
1014 Additional options that are not otherwise recognised are passed through as
1015 they are to the compiler as well. Unix-style options beginning with a
1016 `-` or `+` and Windows-style options beginning with a `/` are recognized.
1017 Again, consult your compiler documentation.
1019 If the option contains arguments separated by spaces, then the URL-style
1020 notation `%20` can be used for the space character in order to avoid having
1021 to quote the option. For example, `-opt%20arg` gets expanded to `-opt arg`.
1022 In fact, any ASCII character can be encoded as %xx using its hexadecimal
1025 Take note of the [Environment Variables](#environment-variables) documentation
1026 below and how these flags interact with those variables.
1028 ### Environment Variables
1032 Assign the given value to the environment variable `VAR` for `Configure`.
1034 These work just like normal environment variable assignments, but are supported
1035 on all platforms and are confined to the configuration scripts only.
1036 These assignments override the corresponding value in the inherited environment,
1039 The following variables are used as "`make` variables" and can be used as an
1040 alternative to giving preprocessor, compiler and linker options directly as
1041 configuration. The following variables are supported:
1043 AR The static library archiver.
1044 ARFLAGS Flags for the static library archiver.
1045 AS The assembler compiler.
1046 ASFLAGS Flags for the assembler compiler.
1048 CFLAGS Flags for the C compiler.
1049 CXX The C++ compiler.
1050 CXXFLAGS Flags for the C++ compiler.
1051 CPP The C/C++ preprocessor.
1052 CPPFLAGS Flags for the C/C++ preprocessor.
1053 CPPDEFINES List of CPP macro definitions, separated
1054 by a platform specific character (':' or
1055 space for Unix, ';' for Windows, ',' for
1056 VMS). This can be used instead of using
1057 -D (or what corresponds to that on your
1058 compiler) in CPPFLAGS.
1059 CPPINCLUDES List of CPP inclusion directories, separated
1060 the same way as for CPPDEFINES. This can
1061 be used instead of -I (or what corresponds
1062 to that on your compiler) in CPPFLAGS.
1063 HASHBANGPERL Perl invocation to be inserted after '#!'
1064 in public perl scripts (only relevant on
1066 LD The program linker (not used on Unix, $(CC)
1068 LDFLAGS Flags for the shared library, DSO and
1070 LDLIBS Extra libraries to use when linking.
1071 Takes the form of a space separated list
1072 of library specifications on Unix and
1073 Windows, and as a comma separated list of
1075 RANLIB The library archive indexer.
1076 RC The Windows resource compiler.
1077 RCFLAGS Flags for the Windows resource compiler.
1078 RM The command to remove files and directories.
1080 These cannot be mixed with compiling/linking flags given on the command line.
1081 In other words, something like this isn't permitted.
1083 $ ./Configure -DFOO CPPFLAGS=-DBAR -DCOOKIE
1085 Backward compatibility note:
1087 To be compatible with older configuration scripts, the environment variables
1088 are ignored if compiling/linking flags are given on the command line, except
1091 AR, CC, CXX, CROSS_COMPILE, HASHBANGPERL, PERL, RANLIB, RC, and WINDRES
1093 For example, the following command will not see `-DBAR`:
1095 $ CPPFLAGS=-DBAR ./Configure -DCOOKIE
1097 However, the following will see both set variables:
1099 $ CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- ./Configure -DCOOKIE
1101 If `CC` is set, it is advisable to also set `CXX` to ensure both the C and C++
1102 compiler are in the same "family". This becomes relevant with
1103 `enable-external-tests` and `enable-buildtest-c++`.
1110 Reconfigure from earlier data.
1112 This fetches the previous command line options and environment from data
1113 saved in `configdata.pm` and runs the configuration process again, using
1114 these options and environment. Note: NO other option is permitted together
1115 with `reconf`. Note: The original configuration saves away values for ALL
1116 environment variables that were used, and if they weren't defined, they are
1117 still saved away with information that they weren't originally defined.
1118 This information takes precedence over environment variables that are
1119 defined when reconfiguring.
1121 Displaying configuration data
1122 -----------------------------
1124 The configuration script itself will say very little, and finishes by
1125 creating `configdata.pm`. This perl module can be loaded by other scripts
1126 to find all the configuration data, and it can also be used as a script to
1127 display all sorts of configuration data in a human readable form.
1129 For more information, please do:
1131 $ ./configdata.pm --help # Unix
1135 $ perl configdata.pm --help # Windows and VMS
1137 Installation Steps in Detail
1138 ============================
1143 ### Automatic Configuration
1145 On some platform a `config` script is available which attempts to guess
1146 your operating system (and compiler, if necessary) and calls the `Configure`
1147 Perl script with appropriate target based on its guess. Further options can
1148 be supplied to the `config` script, which will be passed on to the `Configure`
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/{{ something }}.conf` and add the correct
1189 configuration for your system. See the available configs as examples
1190 and read [Configurations/README.md](Configurations/README.md) and
1191 [Configurations/README-design.md](Configurations/README-design.md)
1192 for more information.
1194 The generic configurations `cc` or `gcc` should usually work on 32 bit
1197 `Configure` creates a build file (`Makefile` on Unix, `makefile` on Windows
1198 and `descrip.mms` on OpenVMS) from a suitable template in `Configurations/`,
1199 and defines various macros in `include/openssl/configuration.h` (generated
1200 from `include/openssl/configuration.h.in`.
1202 ### Out of Tree Builds
1204 OpenSSL can be configured to build in a build directory separate from the
1205 source code directory. It's done by placing yourself in some other
1206 directory and invoking the configuration commands from there.
1210 $ mkdir /var/tmp/openssl-build
1211 $ cd /var/tmp/openssl-build
1212 $ /PATH/TO/OPENSSL/SOURCE/Configure [[ options ]]
1214 #### OpenVMS example
1216 $ set default sys$login:
1217 $ create/dir [.tmp.openssl-build]
1218 $ set default [.tmp.openssl-build]
1219 $ perl D:[PATH.TO.OPENSSL.SOURCE]Configure [[ options ]]
1221 #### Windows example
1224 $ mkdir \temp-openssl
1226 $ perl d:\PATH\TO\OPENSSL\SOURCE\Configure [[ options ]]
1228 Paths can be relative just as well as absolute. `Configure` will do its best
1229 to translate them to relative paths whenever possible.
1234 Build OpenSSL by running:
1237 $ mms ! (or mmk) OpenVMS
1240 This will build the OpenSSL libraries (`libcrypto.a` and `libssl.a` on
1241 Unix, corresponding on other platforms) and the OpenSSL binary
1242 (`openssl`). The libraries will be built in the top-level directory,
1243 and the binary will be in the `apps/` subdirectory.
1245 If the build fails, take a look at the [Build Failures](#build-failures)
1246 subsection of the [Troubleshooting](#troubleshooting) section.
1251 After a successful build, and before installing, the libraries should
1255 $ mms test ! OpenVMS
1256 $ nmake test # Windows
1258 **Warning:** you MUST run the tests from an unprivileged account (or disable
1259 your privileges temporarily if your platform allows it).
1261 See [test/README.md](test/README.md) for further details how run tests.
1263 See [test/README-dev.md](test/README-dev.md) for guidelines on adding tests.
1268 If everything tests ok, install OpenSSL with
1270 $ make install # Unix
1271 $ mms install ! OpenVMS
1272 $ nmake install # Windows
1274 Note that in order to perform the install step above you need to have
1275 appropriate permissions to write to the installation directory.
1277 The above commands will install all the software components in this
1278 directory tree under `<PREFIX>` (the directory given with `--prefix` or
1281 ### Unix / Linux / macOS
1283 bin/ Contains the openssl binary and a few other
1286 Contains the header files needed if you want
1287 to build your own programs that use libcrypto
1289 lib Contains the OpenSSL library files.
1290 lib/engines Contains the OpenSSL dynamically loadable engines.
1292 share/man/man1 Contains the OpenSSL command line man-pages.
1293 share/man/man3 Contains the OpenSSL library calls man-pages.
1294 share/man/man5 Contains the OpenSSL configuration format man-pages.
1295 share/man/man7 Contains the OpenSSL other misc man-pages.
1297 share/doc/openssl/html/man1
1298 share/doc/openssl/html/man3
1299 share/doc/openssl/html/man5
1300 share/doc/openssl/html/man7
1301 Contains the HTML rendition of the man-pages.
1305 'arch' is replaced with the architecture name, `ALPHA` or `IA64`,
1306 'sover' is replaced with the shared library version (`0101` for 1.1), and
1307 'pz' is replaced with the pointer size OpenSSL was built with:
1309 [.EXE.'arch'] Contains the openssl binary.
1310 [.EXE] Contains a few utility scripts.
1312 Contains the header files needed if you want
1313 to build your own programs that use libcrypto
1315 [.LIB.'arch'] Contains the OpenSSL library files.
1316 [.ENGINES'sover''pz'.'arch']
1317 Contains the OpenSSL dynamically loadable engines.
1318 [.SYS$STARTUP] Contains startup, login and shutdown scripts.
1319 These define appropriate logical names and
1321 [.SYSTEST] Contains the installation verification procedure.
1322 [.HTML] Contains the HTML rendition of the manual pages.
1324 ### Additional Directories
1326 Additionally, install will add the following directories under
1327 OPENSSLDIR (the directory given with `--openssldir` or its default)
1328 for you convenience:
1330 certs Initially empty, this is the default location
1331 for certificate files.
1332 private Initially empty, this is the default location
1333 for private key files.
1334 misc Various scripts.
1336 The installation directory should be appropriately protected to ensure
1337 unprivileged users cannot make changes to OpenSSL binaries or files, or
1338 install engines. If you already have a pre-installed version of OpenSSL as
1339 part of your Operating System it is recommended that you do not overwrite
1340 the system version and instead install to somewhere else.
1342 Package builders who want to configure the library for standard locations,
1343 but have the package installed somewhere else so that it can easily be
1346 $ make DESTDIR=/tmp/package-root install # Unix
1347 $ mms/macro="DESTDIR=TMP:[PACKAGE-ROOT]" install ! OpenVMS
1349 The specified destination directory will be prepended to all installation
1352 Compatibility issues with previous OpenSSL versions
1353 ---------------------------------------------------
1355 ### COMPILING existing applications
1357 Starting with version 1.1.0, OpenSSL hides a number of structures that were
1358 previously open. This includes all internal libssl structures and a number
1359 of EVP types. Accessor functions have been added to allow controlled access
1360 to the structures' data.
1362 This means that some software needs to be rewritten to adapt to the new ways
1363 of doing things. This often amounts to allocating an instance of a structure
1364 explicitly where you could previously allocate them on the stack as automatic
1365 variables, and using the provided accessor functions where you would previously
1366 access a structure's field directly.
1368 Some APIs have changed as well. However, older APIs have been preserved when
1371 Post-installation Notes
1372 -----------------------
1374 With the default OpenSSL installation comes a FIPS provider module, which
1375 needs some post-installation attention, without which it will not be usable.
1376 This involves using the following command:
1378 $ openssl fipsinstall
1380 See the openssl-fipsinstall(1) manual for details and examples.
1382 Advanced Build Options
1383 ======================
1385 Environment Variables
1386 ---------------------
1388 A number of environment variables can be used to provide additional control
1389 over the build process. Typically these should be defined prior to running
1390 `Configure`. Not all environment variables are relevant to all platforms.
1393 The name of the ar executable to use.
1396 Use a different build file name than the platform default
1397 ("Makefile" on Unix-like platforms, "makefile" on native Windows,
1398 "descrip.mms" on OpenVMS). This requires that there is a
1399 corresponding build file template.
1400 See [Configurations/README.md](Configurations/README.md)
1401 for further information.
1404 The compiler to use. Configure will attempt to pick a default
1405 compiler for your platform but this choice can be overridden
1406 using this variable. Set it to the compiler executable you wish
1407 to use, e.g. gcc or clang.
1410 This environment variable has the same meaning as for the
1411 "--cross-compile-prefix" Configure flag described above. If both
1412 are set then the Configure flag takes precedence.
1415 The name of the nm executable to use.
1417 OPENSSL_LOCAL_CONFIG_DIR
1418 OpenSSL comes with a database of information about how it
1419 should be built on different platforms as well as build file
1420 templates for those platforms. The database is comprised of
1421 ".conf" files in the Configurations directory. The build
1422 file templates reside there as well as ".tmpl" files. See the
1423 file [Configurations/README.md](Configurations/README.md)
1424 for further information about the format of ".conf" files
1425 as well as information on the ".tmpl" files.
1426 In addition to the standard ".conf" and ".tmpl" files, it is
1427 possible to create your own ".conf" and ".tmpl" files and
1428 store them locally, outside the OpenSSL source tree.
1429 This environment variable can be set to the directory where
1430 these files are held and will be considered by Configure
1431 before it looks in the standard directories.
1434 The name of the Perl executable to use when building OpenSSL.
1435 Only needed if builing should use a different Perl executable
1436 than what is used to run the Configure script.
1439 The command string for the Perl executable to insert in the
1440 #! line of perl scripts that will be publicly installed.
1441 Default: /usr/bin/env perl
1442 Note: the value of this variable is added to the same scripts
1443 on all platforms, but it's only relevant on Unix-like platforms.
1446 The name of the rc executable to use. The default will be as
1447 defined for the target platform in the ".conf" file. If not
1448 defined then "windres" will be used. The WINDRES environment
1449 variable is synonymous to this. If both are defined then RC
1453 The name of the ranlib executable to use.
1461 The `Configure` script generates a Makefile in a format relevant to the specific
1462 platform. The Makefiles provide a number of targets that can be used. Not all
1463 targets may be available on all platforms. Only the most common targets are
1464 described here. Examine the Makefiles themselves for the full list.
1467 The target to build all the software components and
1471 Build all the software components.
1472 THIS IS THE DEFAULT TARGET.
1475 Build all documentation components.
1478 Remove all build artefacts and return the directory to a "clean"
1482 Rebuild the dependencies in the Makefiles. This is a legacy
1483 option that no longer needs to be used since OpenSSL 1.1.0.
1486 Install all OpenSSL components.
1489 Only install the OpenSSL software components.
1492 Only install the OpenSSL documentation components.
1495 Only install the OpenSSL man pages (Unix only).
1498 Only install the OpenSSL HTML documentation.
1501 Install the FIPS provider module configuration file.
1504 Prints a list of all the self test names.
1507 Build and run the OpenSSL self tests.
1510 Uninstall all OpenSSL components.
1514 Re-run the configuration process, as exactly as the last time
1518 This is a developer option. If you are developing a patch for
1519 OpenSSL you may need to use this if you want to update
1520 automatically generated files; add new error codes or add new
1521 (or change the visibility of) public API functions. (Unix only).
1523 Running Selected Tests
1524 ----------------------
1526 You can specify a set of tests to be performed
1527 using the `make` variable `TESTS`.
1529 See the section [Running Selected Tests of
1530 test/README.md](test/README.md#running-selected-tests).
1535 Configuration Problems
1536 ----------------------
1538 ### Selecting the correct target
1540 The `./Configure` script tries hard to guess your operating system, but in some
1541 cases it does not succeed. You will see a message like the following:
1544 Operating system: x86-whatever-minix
1545 This system (minix) is not supported. See file INSTALL.md for details.
1547 Even if the automatic target selection by the `./Configure` script fails,
1548 chances are that you still might find a suitable target in the `Configurations`
1549 directory, which you can supply to the `./Configure` command,
1550 possibly after some adjustment.
1552 The `Configurations/` directory contains a lot of examples of such targets.
1553 The main configuration file is [10-main.conf], which contains all targets that
1554 are officially supported by the OpenSSL team. Other configuration files contain
1555 targets contributed by other OpenSSL users. The list of targets can be found in
1556 a Perl list `my %targets = ( ... )`.
1561 inherit_from => [ "base-target" ],
1563 cflags => add("..."),
1565 perlasm_scheme => "...",
1570 If you call `./Configure` without arguments, it will give you a list of all
1571 known targets. Using `grep`, you can lookup the target definition in the
1572 `Configurations/` directory. For example the `android-x86_64` can be found in
1573 [Configurations/15-android.conf](Configurations/15-android.conf).
1575 The directory contains two README files, which explain the general syntax and
1576 design of the configuration files.
1578 - [Configurations/README.md](Configurations/README.md)
1579 - [Configurations/README-design.md](Configurations/README-design.md)
1581 If you need further help, try to search the [openssl-users] mailing list
1582 or the [GitHub Issues] for existing solutions. If you don't find anything,
1583 you can [raise an issue] to ask a question yourself.
1585 More about our support resources can be found in the [SUPPORT] file.
1587 ### Configuration Errors
1589 If the `./Configure` or `./Configure` command fails with an error message,
1590 read the error message carefully and try to figure out whether you made
1591 a mistake (e.g., by providing a wrong option), or whether the script is
1592 working incorrectly. If you think you encountered a bug, please
1593 [raise an issue] on GitHub to file a bug report.
1595 Along with a short description of the bug, please provide the complete
1596 configure command line and the relevant output including the error message.
1598 Note: To make the output readable, pleace add a 'code fence' (three backquotes
1599 ` ``` ` on a separate line) before and after your output:
1602 ./Configure [your arguments...]
1611 If the build fails, look carefully at the output. Try to locate and understand
1612 the error message. It might be that the compiler is already telling you
1613 exactly what you need to do to fix your problem.
1615 There may be reasons for the failure that aren't problems in OpenSSL itself,
1616 for example if the compiler reports missing standard or third party headers.
1618 If the build succeeded previously, but fails after a source or configuration
1619 change, it might be helpful to clean the build tree before attempting another
1620 build. Use this command:
1623 $ mms clean ! (or mmk) OpenVMS
1624 $ nmake clean # Windows
1626 Assembler error messages can sometimes be sidestepped by using the `no-asm`
1627 configuration option. See also [notes](#notes-on-assembler-modules-compilation).
1629 Compiling parts of OpenSSL with gcc and others with the system compiler will
1630 result in unresolved symbols on some systems.
1632 If you are still having problems, try to search the [openssl-users] mailing
1633 list or the [GitHub Issues] for existing solutions. If you think you
1634 encountered an OpenSSL bug, please [raise an issue] to file a bug report.
1635 Please take the time to review the existing issues first; maybe the bug was
1636 already reported or has already been fixed.
1641 If some tests fail, look at the output. There may be reasons for the failure
1642 that isn't a problem in OpenSSL itself (like an OS malfunction or a Perl issue).
1644 You may want increased verbosity, that can be accomplished as described in
1645 section [Test Failures of test/README.md](test/README.md#test-failures).
1647 You may also want to selectively specify which test(s) to perform. This can be
1648 done using the `make` variable `TESTS` as described in section [Running
1649 Selected Tests of test/README.md](test/README.md#running-selected-tests).
1651 If you find a problem with OpenSSL itself, try removing any
1652 compiler optimization flags from the `CFLAGS` line in the Makefile and
1653 run `make clean; make` or corresponding.
1655 To report a bug please open an issue on GitHub, at
1656 <https://github.com/openssl/openssl/issues>.
1661 Notes on multi-threading
1662 ------------------------
1664 For some systems, the OpenSSL `Configure` script knows what compiler options
1665 are needed to generate a library that is suitable for multi-threaded
1666 applications. On these systems, support for multi-threading is enabled
1667 by default; use the `no-threads` option to disable (this should never be
1670 On other systems, to enable support for multi-threading, you will have
1671 to specify at least two options: `threads`, and a system-dependent option.
1672 (The latter is `-D_REENTRANT` on various systems.) The default in this
1673 case, obviously, is not to include support for multi-threading (but
1674 you can still use `no-threads` to suppress an annoying warning message
1675 from the `Configure` script.)
1677 OpenSSL provides built-in support for two threading models: pthreads (found on
1678 most UNIX/Linux systems), and Windows threads. No other threading models are
1679 supported. If your platform does not provide pthreads or Windows threads then
1680 you should use `Configure` with the `no-threads` option.
1682 For pthreads, all locks are non-recursive. In addition, in a debug build,
1683 the mutex attribute `PTHREAD_MUTEX_ERRORCHECK` is used. If this is not
1684 available on your platform, you might have to add
1685 `-DOPENSSL_NO_MUTEX_ERRORCHECK` to your `Configure` invocation.
1686 (On Linux `PTHREAD_MUTEX_ERRORCHECK` is an enum value, so a built-in
1687 ifdef test cannot be used.)
1689 Notes on shared libraries
1690 -------------------------
1692 For most systems the OpenSSL `Configure` script knows what is needed to
1693 build shared libraries for libcrypto and libssl. On these systems
1694 the shared libraries will be created by default. This can be suppressed and
1695 only static libraries created by using the `no-shared` option. On systems
1696 where OpenSSL does not know how to build shared libraries the `no-shared`
1697 option will be forced and only static libraries will be created.
1699 Shared libraries are named a little differently on different platforms.
1700 One way or another, they all have the major OpenSSL version number as
1701 part of the file name, i.e. for OpenSSL 1.1.x, `1.1` is somehow part of
1704 On most POSIX platforms, shared libraries are named `libcrypto.so.1.1`
1705 and `libssl.so.1.1`.
1707 on Cygwin, shared libraries are named `cygcrypto-1.1.dll` and `cygssl-1.1.dll`
1708 with import libraries `libcrypto.dll.a` and `libssl.dll.a`.
1710 On Windows build with MSVC or using MingW, shared libraries are named
1711 `libcrypto-1_1.dll` and `libssl-1_1.dll` for 32-bit Windows,
1712 `libcrypto-1_1-x64.dll` and `libssl-1_1-x64.dll` for 64-bit x86_64 Windows,
1713 and `libcrypto-1_1-ia64.dll` and `libssl-1_1-ia64.dll` for IA64 Windows.
1714 With MSVC, the import libraries are named `libcrypto.lib` and `libssl.lib`,
1715 while with MingW, they are named `libcrypto.dll.a` and `libssl.dll.a`.
1717 On VMS, shareable images (VMS speak for shared libraries) are named
1718 `ossl$libcrypto0101_shr.exe` and `ossl$libssl0101_shr.exe`. However, when
1719 OpenSSL is specifically built for 32-bit pointers, the shareable images
1720 are named `ossl$libcrypto0101_shr32.exe` and `ossl$libssl0101_shr32.exe`
1721 instead, and when built for 64-bit pointers, they are named
1722 `ossl$libcrypto0101_shr64.exe` and `ossl$libssl0101_shr64.exe`.
1724 Notes on random number generation
1725 ---------------------------------
1727 Availability of cryptographically secure random numbers is required for
1728 secret key generation. OpenSSL provides several options to seed the
1729 internal CSPRNG. If not properly seeded, the internal CSPRNG will refuse
1730 to deliver random bytes and a "PRNG not seeded error" will occur.
1732 The seeding method can be configured using the `--with-rand-seed` option,
1733 which can be used to specify a comma separated list of seed methods.
1734 However, in most cases OpenSSL will choose a suitable default method,
1735 so it is not necessary to explicitly provide this option. Note also
1736 that not all methods are available on all platforms. The FIPS provider will
1737 silently ignore seed sources that were not validated.
1739 I) On operating systems which provide a suitable randomness source (in
1740 form of a system call or system device), OpenSSL will use the optimal
1741 available method to seed the CSPRNG from the operating system's
1742 randomness sources. This corresponds to the option `--with-rand-seed=os`.
1744 II) On systems without such a suitable randomness source, automatic seeding
1745 and reseeding is disabled (`--with-rand-seed=none`) and it may be necessary
1746 to install additional support software to obtain a random seed and reseed
1747 the CSPRNG manually. Please check out the manual pages for `RAND_add()`,
1748 `RAND_bytes()`, `RAND_egd()`, and the FAQ for more information.
1750 Notes on assembler modules compilation
1751 --------------------------------------
1753 Compilation of some code paths in assembler modules might depend on whether the
1754 current assembler version supports certain ISA extensions or not. Code paths
1755 that use the AES-NI, PCLMULQDQ, SSSE3, and SHA extensions are always assembled.
1756 Apart from that, the minimum requirements for the assembler versions are shown
1759 | ISA extension | GNU as | nasm | llvm |
1760 |---------------|--------|--------|---------|
1761 | AVX | 2.19 | 2.09 | 3.0 |
1762 | AVX2 | 2.22 | 2.10 | 3.1 |
1763 | ADCX/ADOX | 2.23 | 2.10 | 3.3 |
1764 | AVX512 | 2.25 | 2.11.8 | 3.6 (*) |
1765 | AVX512IFMA | 2.26 | 2.11.8 | 6.0 (*) |
1766 | VAES | 2.30 | 2.13.3 | 6.0 (*) |
1770 (*) Even though AVX512 support was implemented in llvm 3.6, prior to version 7.0
1771 an explicit -march flag was apparently required to compile assembly modules. But
1772 then the compiler generates processor-specific code, which in turn contradicts
1773 the idea of performing dispatch at run-time, which is facilitated by the special
1774 variable `OPENSSL_ia32cap`. For versions older than 7.0, it is possible to work
1775 around the problem by forcing the build procedure to use the following script:
1778 exec clang -no-integrated-as "$@"
1780 instead of the real clang. In which case it doesn't matter what clang version
1781 is used, as it is the version of the GNU assembler that will be checked.
1788 <https://mta.openssl.org/mailman/listinfo/openssl-users>
1794 <https://github.com/openssl/openssl/issues>
1797 <https://github.com/openssl/openssl/issues/new/choose>
1800 Configurations/10-main.conf