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 On platforms where the choice of 32-bit or 64-bit architecture
593 is not explicitly specified, `Configure` will print a warning
594 message and wait for a few seconds to let you interrupt the
595 configuration. Using this flag skips the wait.
599 Build only some minimal set of features.
600 This is a developer option used internally for CI build tests of the project.
604 Never cache algorithms when they are fetched from a provider. Normally, a
605 provider indicates if the algorithms it supplies can be cached or not. Using
606 this option will reduce run-time memory usage but it also introduces a
607 significant performance penalty. This option is primarily designed to help
608 with detecting incorrect reference counting.
612 Don't build the CAPI engine.
614 This option will be forced if on a platform that does not support CAPI.
618 Don't build support for Certificate Management Protocol (CMP)
619 and Certificate Request Message Format (CRMF).
623 Don't build support for Cryptographic Message Syntax (CMS).
627 Don't build support for SSL/TLS compression.
629 If this option is enabled (the default), then compression will only work if
630 the zlib or `zlib-dynamic` options are also chosen.
632 ### enable-crypto-mdebug
634 This now only enables the `failed-malloc` feature.
636 ### enable-crypto-mdebug-backtrace
638 This is a no-op; the project uses the compiler's address/leak sanitizer instead.
642 Don't build support for Certificate Transparency (CT).
646 Don't build with support for deprecated APIs up until and including the version
647 given with `--api` (or the current version, if `--api` wasn't specified).
651 Don't build support for datagram based BIOs.
653 Selecting this option will also force the disabling of DTLS.
657 Don't build support for loading Dynamic Shared Objects (DSO)
659 ### enable-devcryptoeng
661 Build the `/dev/crypto` engine.
663 This option is automatically selected on the BSD platform, in which case it can
664 be disabled with `no-devcryptoeng`.
666 ### no-dynamic-engine
668 Don't build the dynamically loaded engines.
670 This only has an effect in a shared build.
674 Don't build support for Elliptic Curves.
678 Don't build support for binary Elliptic Curves
680 ### enable-ec_nistp_64_gcc_128
682 Enable support for optimised implementations of some commonly used NIST
685 This option is only supported on platforms:
687 - with little-endian storage of non-byte types
688 - that tolerate misaligned memory references
689 - where the compiler:
690 - supports the non-standard type `__uint128_t`
691 - defines the built-in macro `__SIZEOF_INT128__`
695 Build support for gathering entropy from the Entropy Gathering Daemon (EGD).
699 Don't build support for loading engines.
703 Don't compile in any error strings.
705 ### enable-external-tests
707 Enable building of integration with external test suites.
709 This is a developer option and may not work on all platforms. The following
710 external test suites are currently supported:
712 - GOST engine test suite
713 - Python PYCA/Cryptography test suite
716 See the file [test/README-external.md](test/README-external.md)
721 Don't compile in filename and line number information (e.g. for errors and
726 Build (and install) the FIPS provider
728 ### no-fips-securitychecks
730 Don't perform FIPS module run-time checks related to enforcement of security
731 parameters such as minimum security strength of keys.
733 ### enable-fuzz-libfuzzer, enable-fuzz-afl
735 Build with support for fuzzing using either libfuzzer or AFL.
737 These are developer options only. They may not work on all platforms and
738 should never be used in production environments.
740 See the file [fuzz/README.md](fuzz/README.md) for further details.
744 Don't build support for GOST based ciphersuites.
746 Note that if this feature is enabled then GOST ciphersuites are only available
747 if the GOST algorithms are also available through loading an externally supplied
752 Don't build the legacy provider.
754 Disabling this also disables the legacy algorithms: MD2 (already disabled by default).
758 Don't generate dependencies.
762 Don't build any dynamically loadable engines.
764 This also implies `no-dynamic-engine`.
768 Don't build support for writing multiple records in one go in libssl
770 Note: this is a different capability to the pipelining functionality.
774 Don't build support for the Next Protocol Negotiation (NPN) TLS extension.
778 Don't build support for Online Certificate Status Protocol (OCSP).
782 Don't build the padlock engine.
786 As synonym for `no-padlockeng`. Deprecated and should not be used.
790 Don't build with support for Position Independent Code.
794 Don't pin the shared libraries.
796 By default OpenSSL will attempt to stay in memory until the process exits.
797 This is so that libcrypto and libssl can be properly cleaned up automatically
798 via an `atexit()` handler. The handler is registered by libcrypto and cleans
799 up both libraries. On some platforms the `atexit()` handler will run on unload of
800 libcrypto (if it has been dynamically loaded) rather than at process exit. This
801 option can be used to stop OpenSSL from attempting to stay in memory until the
802 process exits. This could lead to crashes if either libcrypto or libssl have
803 already been unloaded at the point that the atexit handler is invoked, e.g. on a
804 platform which calls `atexit()` on unload of the library, and libssl is unloaded
805 before libcrypto then a crash is likely to happen. Applications can suppress
806 running of the `atexit()` handler at run time by using the
807 `OPENSSL_INIT_NO_ATEXIT` option to `OPENSSL_init_crypto()`.
808 See the man page for it for further details.
812 Don't use POSIX IO capabilities.
816 Don't build support for Pre-Shared Key based ciphersuites.
820 Don't use hardware RDRAND capabilities.
824 Don't build support for RFC3779, "X.509 Extensions for IP Addresses and
829 Build support for Stream Control Transmission Protocol (SCTP).
833 Do not create shared libraries, only static ones.
835 See [Notes on shared libraries](#notes-on-shared-libraries) below.
839 Don't build support for socket BIOs.
843 Don't build support for Secure Remote Password (SRP) protocol or
844 SRP based ciphersuites.
848 Don't build Secure Real-Time Transport Protocol (SRTP) support.
852 Exclude SSE2 code paths from 32-bit x86 assembly modules.
854 Normally SSE2 extension is detected at run-time, but the decision whether or not
855 the machine code will be executed is taken solely on CPU capability vector. This
856 means that if you happen to run OS kernel which does not support SSE2 extension
857 on Intel P4 processor, then your application might be exposed to "illegal
858 instruction" exception. There might be a way to enable support in kernel, e.g.
859 FreeBSD kernel can be compiled with `CPU_ENABLE_SSE`, and there is a way to
860 disengage SSE2 code paths upon application start-up, but if you aim for wider
861 "audience" running such kernel, consider `no-sse2`. Both the `386` and `no-asm`
862 options imply `no-sse2`.
866 Don't build with SSL Trace capabilities.
868 This removes the `-trace` option from `s_client` and `s_server`, and omits the
869 `SSL_trace()` function from libssl.
871 Disabling `ssl-trace` may provide a small reduction in libssl binary size.
875 Don't build the statically linked engines.
877 This only has an impact when not built "shared".
881 Don't use anything from the C header file `stdio.h` that makes use of the `FILE`
882 type. Only libcrypto and libssl can be built in this way. Using this option will
883 suppress building the command line applications. Additionally, since the OpenSSL
884 tests also use the command line applications, the tests will also be skipped.
888 Don't build test programs or run any tests.
892 Don't build with support for multi-threaded applications.
896 Build with support for multi-threaded applications. Most platforms will enable
897 this by default. However, if on a platform where this is not the case then this
898 will usually require additional system-dependent options!
900 See [Notes on multi-threading](#notes-on-multi-threading) below.
904 Build with support for the integrated tracing api.
906 See manual pages OSSL_trace_set_channel(3) and OSSL_trace_enabled(3) for details.
910 Don't build Time Stamping (TS) Authority support.
914 Build with the Undefined Behaviour sanitiser (UBSAN).
916 This is a developer option only. It may not work on all platforms and should
917 never be used in production environments. It will only work when used with
918 gcc or clang and should be used in conjunction with the `-DPEDANTIC` option
919 (or the `--strict-warnings` option).
923 Don't build with the User Interface (UI) console method
925 The User Interface console method enables text based console prompts.
929 Enable additional unit test APIs.
931 This should not typically be used in production deployments.
935 Don't build support for UPLINK interface.
937 ### enable-weak-ssl-ciphers
939 Build support for SSL/TLS ciphers that are considered "weak"
941 Enabling this includes for example the RC4 based ciphersuites.
945 Build with support for zlib compression/decompression.
949 Like the zlib option, but has OpenSSL load the zlib library dynamically
952 This is only supported on systems where loading of shared libraries is supported.
956 In 32-bit x86 builds, use the 80386 instruction set only in assembly modules
958 The default x86 code is more efficient, but requires at least an 486 processor.
959 Note: This doesn't affect compiler generated code, so this option needs to be
960 accompanied by a corresponding compiler-specific option.
964 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}
966 Don't build support for negotiating the specified SSL/TLS protocol.
968 If `no-tls` is selected then all of `tls1`, `tls1_1`, `tls1_2` and `tls1_3`
970 Similarly `no-dtls` will disable `dtls1` and `dtls1_2`. The `no-ssl` option is
971 synonymous with `no-ssl3`. Note this only affects version negotiation.
972 OpenSSL will still provide the methods for applications to explicitly select
973 the individual protocol versions.
975 ### no-{protocol}-method
977 no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}-method
979 Analogous to `no-{protocol}` but in addition do not build the methods for
980 applications to explicitly select individual protocol versions. Note that there
981 is no `no-tls1_3-method` option because there is no application method for
984 Using individual protocol methods directly is deprecated. Applications should
985 use `TLS_method()` instead.
987 ### enable-{algorithm}
991 Build with support for the specified algorithm.
995 no-{aria|bf|blake2|camellia|cast|chacha|cmac|
996 des|dh|dsa|ecdh|ecdsa|idea|md4|mdc2|ocb|
997 poly1305|rc2|rc4|rmd160|scrypt|seed|
998 siphash|siv|sm2|sm3|sm4|whirlpool}
1000 Build without support for the specified algorithm.
1002 The `ripemd` algorithm is deprecated and if used is synonymous with `rmd160`.
1004 ### Compiler-specific options
1006 -Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static
1008 These system specific options will be recognised and passed through to the
1009 compiler to allow you to define preprocessor symbols, specify additional
1010 libraries, library directories or other compiler options. It might be worth
1011 noting that some compilers generate code specifically for processor the
1012 compiler currently executes on. This is not necessarily what you might have
1013 in mind, since it might be unsuitable for execution on other, typically older,
1014 processor. Consult your compiler documentation.
1016 Take note of the [Environment Variables](#environment-variables) documentation
1017 below and how these flags interact with those variables.
1021 Additional options that are not otherwise recognised are passed through as
1022 they are to the compiler as well. Unix-style options beginning with a
1023 `-` or `+` and Windows-style options beginning with a `/` are recognized.
1024 Again, consult your compiler documentation.
1026 If the option contains arguments separated by spaces, then the URL-style
1027 notation `%20` can be used for the space character in order to avoid having
1028 to quote the option. For example, `-opt%20arg` gets expanded to `-opt arg`.
1029 In fact, any ASCII character can be encoded as %xx using its hexadecimal
1032 Take note of the [Environment Variables](#environment-variables) documentation
1033 below and how these flags interact with those variables.
1035 ### Environment Variables
1039 Assign the given value to the environment variable `VAR` for `Configure`.
1041 These work just like normal environment variable assignments, but are supported
1042 on all platforms and are confined to the configuration scripts only.
1043 These assignments override the corresponding value in the inherited environment,
1046 The following variables are used as "`make` variables" and can be used as an
1047 alternative to giving preprocessor, compiler and linker options directly as
1048 configuration. The following variables are supported:
1050 AR The static library archiver.
1051 ARFLAGS Flags for the static library archiver.
1052 AS The assembler compiler.
1053 ASFLAGS Flags for the assembler compiler.
1055 CFLAGS Flags for the C compiler.
1056 CXX The C++ compiler.
1057 CXXFLAGS Flags for the C++ compiler.
1058 CPP The C/C++ preprocessor.
1059 CPPFLAGS Flags for the C/C++ preprocessor.
1060 CPPDEFINES List of CPP macro definitions, separated
1061 by a platform specific character (':' or
1062 space for Unix, ';' for Windows, ',' for
1063 VMS). This can be used instead of using
1064 -D (or what corresponds to that on your
1065 compiler) in CPPFLAGS.
1066 CPPINCLUDES List of CPP inclusion directories, separated
1067 the same way as for CPPDEFINES. This can
1068 be used instead of -I (or what corresponds
1069 to that on your compiler) in CPPFLAGS.
1070 HASHBANGPERL Perl invocation to be inserted after '#!'
1071 in public perl scripts (only relevant on
1073 LD The program linker (not used on Unix, $(CC)
1075 LDFLAGS Flags for the shared library, DSO and
1077 LDLIBS Extra libraries to use when linking.
1078 Takes the form of a space separated list
1079 of library specifications on Unix and
1080 Windows, and as a comma separated list of
1082 RANLIB The library archive indexer.
1083 RC The Windows resource compiler.
1084 RCFLAGS Flags for the Windows resource compiler.
1085 RM The command to remove files and directories.
1087 These cannot be mixed with compiling/linking flags given on the command line.
1088 In other words, something like this isn't permitted.
1090 $ ./Configure -DFOO CPPFLAGS=-DBAR -DCOOKIE
1092 Backward compatibility note:
1094 To be compatible with older configuration scripts, the environment variables
1095 are ignored if compiling/linking flags are given on the command line, except
1098 AR, CC, CXX, CROSS_COMPILE, HASHBANGPERL, PERL, RANLIB, RC, and WINDRES
1100 For example, the following command will not see `-DBAR`:
1102 $ CPPFLAGS=-DBAR ./Configure -DCOOKIE
1104 However, the following will see both set variables:
1106 $ CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- ./Configure -DCOOKIE
1108 If `CC` is set, it is advisable to also set `CXX` to ensure both the C and C++
1109 compiler are in the same "family". This becomes relevant with
1110 `enable-external-tests` and `enable-buildtest-c++`.
1117 Reconfigure from earlier data.
1119 This fetches the previous command line options and environment from data
1120 saved in `configdata.pm` and runs the configuration process again, using
1121 these options and environment. Note: NO other option is permitted together
1122 with `reconf`. Note: The original configuration saves away values for ALL
1123 environment variables that were used, and if they weren't defined, they are
1124 still saved away with information that they weren't originally defined.
1125 This information takes precedence over environment variables that are
1126 defined when reconfiguring.
1128 Displaying configuration data
1129 -----------------------------
1131 The configuration script itself will say very little, and finishes by
1132 creating `configdata.pm`. This perl module can be loaded by other scripts
1133 to find all the configuration data, and it can also be used as a script to
1134 display all sorts of configuration data in a human readable form.
1136 For more information, please do:
1138 $ ./configdata.pm --help # Unix
1142 $ perl configdata.pm --help # Windows and VMS
1144 Installation Steps in Detail
1145 ============================
1150 ### Automatic Configuration
1152 In previous version, the `config` script determined the platform type and
1153 compiler and then called `Configure`. Starting with this release, they are
1156 #### Unix / Linux / macOS
1158 $ ./Configure [[ options ]]
1162 $ perl Configure [[ options ]]
1166 $ perl Configure [[ options ]]
1168 ### Manual Configuration
1170 OpenSSL knows about a range of different operating system, hardware and
1171 compiler combinations. To see the ones it knows about, run
1173 $ ./Configure LIST # Unix
1177 $ perl Configure LIST # All other platforms
1179 For the remainder of this text, the Unix form will be used in all examples.
1180 Please use the appropriate form for your platform.
1182 Pick a suitable name from the list that matches your system. For most
1183 operating systems there is a choice between using cc or gcc.
1184 When you have identified your system (and if necessary compiler) use this
1185 name as the argument to `Configure`. For example, a `linux-elf` user would
1188 $ ./Configure linux-elf [[ options ]]
1190 ### Creating your own Configuration
1192 If your system isn't listed, you will have to create a configuration
1193 file named `Configurations/{{ something }}.conf` and add the correct
1194 configuration for your system. See the available configs as examples
1195 and read [Configurations/README.md](Configurations/README.md) and
1196 [Configurations/README-design.md](Configurations/README-design.md)
1197 for more information.
1199 The generic configurations `cc` or `gcc` should usually work on 32 bit
1202 `Configure` creates a build file (`Makefile` on Unix, `makefile` on Windows
1203 and `descrip.mms` on OpenVMS) from a suitable template in `Configurations/`,
1204 and defines various macros in `include/openssl/configuration.h` (generated
1205 from `include/openssl/configuration.h.in`.
1207 ### Out of Tree Builds
1209 OpenSSL can be configured to build in a build directory separate from the
1210 source code directory. It's done by placing yourself in some other
1211 directory and invoking the configuration commands from there.
1215 $ mkdir /var/tmp/openssl-build
1216 $ cd /var/tmp/openssl-build
1217 $ /PATH/TO/OPENSSL/SOURCE/Configure [[ options ]]
1219 #### OpenVMS example
1221 $ set default sys$login:
1222 $ create/dir [.tmp.openssl-build]
1223 $ set default [.tmp.openssl-build]
1224 $ perl D:[PATH.TO.OPENSSL.SOURCE]Configure [[ options ]]
1226 #### Windows example
1229 $ mkdir \temp-openssl
1231 $ perl d:\PATH\TO\OPENSSL\SOURCE\Configure [[ options ]]
1233 Paths can be relative just as well as absolute. `Configure` will do its best
1234 to translate them to relative paths whenever possible.
1239 Build OpenSSL by running:
1242 $ mms ! (or mmk) OpenVMS
1245 This will build the OpenSSL libraries (`libcrypto.a` and `libssl.a` on
1246 Unix, corresponding on other platforms) and the OpenSSL binary
1247 (`openssl`). The libraries will be built in the top-level directory,
1248 and the binary will be in the `apps/` subdirectory.
1250 If the build fails, take a look at the [Build Failures](#build-failures)
1251 subsection of the [Troubleshooting](#troubleshooting) section.
1256 After a successful build, and before installing, the libraries should
1260 $ mms test ! OpenVMS
1261 $ nmake test # Windows
1263 **Warning:** you MUST run the tests from an unprivileged account (or disable
1264 your privileges temporarily if your platform allows it).
1266 See [test/README.md](test/README.md) for further details how run tests.
1268 See [test/README-dev.md](test/README-dev.md) for guidelines on adding tests.
1273 If everything tests ok, install OpenSSL with
1275 $ make install # Unix
1276 $ mms install ! OpenVMS
1277 $ nmake install # Windows
1279 Note that in order to perform the install step above you need to have
1280 appropriate permissions to write to the installation directory.
1282 The above commands will install all the software components in this
1283 directory tree under `<PREFIX>` (the directory given with `--prefix` or
1286 ### Unix / Linux / macOS
1288 bin/ Contains the openssl binary and a few other
1291 Contains the header files needed if you want
1292 to build your own programs that use libcrypto
1294 lib Contains the OpenSSL library files.
1295 lib/engines Contains the OpenSSL dynamically loadable engines.
1297 share/man/man1 Contains the OpenSSL command line man-pages.
1298 share/man/man3 Contains the OpenSSL library calls man-pages.
1299 share/man/man5 Contains the OpenSSL configuration format man-pages.
1300 share/man/man7 Contains the OpenSSL other misc man-pages.
1302 share/doc/openssl/html/man1
1303 share/doc/openssl/html/man3
1304 share/doc/openssl/html/man5
1305 share/doc/openssl/html/man7
1306 Contains the HTML rendition of the man-pages.
1310 'arch' is replaced with the architecture name, `ALPHA` or `IA64`,
1311 'sover' is replaced with the shared library version (`0101` for 1.1), and
1312 'pz' is replaced with the pointer size OpenSSL was built with:
1314 [.EXE.'arch'] Contains the openssl binary.
1315 [.EXE] Contains a few utility scripts.
1317 Contains the header files needed if you want
1318 to build your own programs that use libcrypto
1320 [.LIB.'arch'] Contains the OpenSSL library files.
1321 [.ENGINES'sover''pz'.'arch']
1322 Contains the OpenSSL dynamically loadable engines.
1323 [.SYS$STARTUP] Contains startup, login and shutdown scripts.
1324 These define appropriate logical names and
1326 [.SYSTEST] Contains the installation verification procedure.
1327 [.HTML] Contains the HTML rendition of the manual pages.
1329 ### Additional Directories
1331 Additionally, install will add the following directories under
1332 OPENSSLDIR (the directory given with `--openssldir` or its default)
1333 for you convenience:
1335 certs Initially empty, this is the default location
1336 for certificate files.
1337 private Initially empty, this is the default location
1338 for private key files.
1339 misc Various scripts.
1341 The installation directory should be appropriately protected to ensure
1342 unprivileged users cannot make changes to OpenSSL binaries or files, or
1343 install engines. If you already have a pre-installed version of OpenSSL as
1344 part of your Operating System it is recommended that you do not overwrite
1345 the system version and instead install to somewhere else.
1347 Package builders who want to configure the library for standard locations,
1348 but have the package installed somewhere else so that it can easily be
1351 $ make DESTDIR=/tmp/package-root install # Unix
1352 $ mms/macro="DESTDIR=TMP:[PACKAGE-ROOT]" install ! OpenVMS
1354 The specified destination directory will be prepended to all installation
1357 Compatibility issues with previous OpenSSL versions
1358 ---------------------------------------------------
1360 ### COMPILING existing applications
1362 Starting with version 1.1.0, OpenSSL hides a number of structures that were
1363 previously open. This includes all internal libssl structures and a number
1364 of EVP types. Accessor functions have been added to allow controlled access
1365 to the structures' data.
1367 This means that some software needs to be rewritten to adapt to the new ways
1368 of doing things. This often amounts to allocating an instance of a structure
1369 explicitly where you could previously allocate them on the stack as automatic
1370 variables, and using the provided accessor functions where you would previously
1371 access a structure's field directly.
1373 Some APIs have changed as well. However, older APIs have been preserved when
1376 Post-installation Notes
1377 -----------------------
1379 With the default OpenSSL installation comes a FIPS provider module, which
1380 needs some post-installation attention, without which it will not be usable.
1381 This involves using the following command:
1383 $ openssl fipsinstall
1385 See the openssl-fipsinstall(1) manual for details and examples.
1387 Advanced Build Options
1388 ======================
1390 Environment Variables
1391 ---------------------
1393 A number of environment variables can be used to provide additional control
1394 over the build process. Typically these should be defined prior to running
1395 `Configure`. Not all environment variables are relevant to all platforms.
1398 The name of the ar executable to use.
1401 Use a different build file name than the platform default
1402 ("Makefile" on Unix-like platforms, "makefile" on native Windows,
1403 "descrip.mms" on OpenVMS). This requires that there is a
1404 corresponding build file template.
1405 See [Configurations/README.md](Configurations/README.md)
1406 for further information.
1409 The compiler to use. Configure will attempt to pick a default
1410 compiler for your platform but this choice can be overridden
1411 using this variable. Set it to the compiler executable you wish
1412 to use, e.g. gcc or clang.
1415 This environment variable has the same meaning as for the
1416 "--cross-compile-prefix" Configure flag described above. If both
1417 are set then the Configure flag takes precedence.
1420 The command string for the Perl executable to insert in the
1421 #! line of perl scripts that will be publicly installed.
1422 Default: /usr/bin/env perl
1423 Note: the value of this variable is added to the same scripts
1424 on all platforms, but it's only relevant on Unix-like platforms.
1427 This can be the value `32` or `64` to specify the architecture
1428 when it is not "obvious" to the configuration. It should generally
1429 not be necessary to specify this environment variable.
1432 The name of the nm executable to use.
1434 OPENSSL_LOCAL_CONFIG_DIR
1435 OpenSSL comes with a database of information about how it
1436 should be built on different platforms as well as build file
1437 templates for those platforms. The database is comprised of
1438 ".conf" files in the Configurations directory. The build
1439 file templates reside there as well as ".tmpl" files. See the
1440 file [Configurations/README.md](Configurations/README.md)
1441 for further information about the format of ".conf" files
1442 as well as information on the ".tmpl" files.
1443 In addition to the standard ".conf" and ".tmpl" files, it is
1444 possible to create your own ".conf" and ".tmpl" files and
1445 store them locally, outside the OpenSSL source tree.
1446 This environment variable can be set to the directory where
1447 these files are held and will be considered by Configure
1448 before it looks in the standard directories.
1451 The name of the Perl executable to use when building OpenSSL.
1452 Only needed if builing should use a different Perl executable
1453 than what is used to run the Configure script.
1456 The name of the ranlib executable to use.
1459 The name of the rc executable to use. The default will be as
1460 defined for the target platform in the ".conf" file. If not
1461 defined then "windres" will be used. The WINDRES environment
1462 variable is synonymous to this. If both are defined then RC
1471 The `Configure` script generates a Makefile in a format relevant to the specific
1472 platform. The Makefiles provide a number of targets that can be used. Not all
1473 targets may be available on all platforms. Only the most common targets are
1474 described here. Examine the Makefiles themselves for the full list.
1477 The target to build all the software components and
1481 Build all the software components.
1482 THIS IS THE DEFAULT TARGET.
1485 Build all documentation components.
1488 Remove all build artefacts and return the directory to a "clean"
1492 Rebuild the dependencies in the Makefiles. This is a legacy
1493 option that no longer needs to be used since OpenSSL 1.1.0.
1496 Install all OpenSSL components.
1499 Only install the OpenSSL software components.
1502 Only install the OpenSSL documentation components.
1505 Only install the OpenSSL man pages (Unix only).
1508 Only install the OpenSSL HTML documentation.
1511 Install the FIPS provider module configuration file.
1514 Prints a list of all the self test names.
1517 Build and run the OpenSSL self tests.
1520 Uninstall all OpenSSL components.
1524 Re-run the configuration process, as exactly as the last time
1528 This is a developer option. If you are developing a patch for
1529 OpenSSL you may need to use this if you want to update
1530 automatically generated files; add new error codes or add new
1531 (or change the visibility of) public API functions. (Unix only).
1533 Running Selected Tests
1534 ----------------------
1536 You can specify a set of tests to be performed
1537 using the `make` variable `TESTS`.
1539 See the section [Running Selected Tests of
1540 test/README.md](test/README.md#running-selected-tests).
1545 Configuration Problems
1546 ----------------------
1548 ### Selecting the correct target
1550 The `./Configure` script tries hard to guess your operating system, but in some
1551 cases it does not succeed. You will see a message like the following:
1554 Operating system: x86-whatever-minix
1555 This system (minix) is not supported. See file INSTALL.md for details.
1557 Even if the automatic target selection by the `./Configure` script fails,
1558 chances are that you still might find a suitable target in the `Configurations`
1559 directory, which you can supply to the `./Configure` command,
1560 possibly after some adjustment.
1562 The `Configurations/` directory contains a lot of examples of such targets.
1563 The main configuration file is [10-main.conf], which contains all targets that
1564 are officially supported by the OpenSSL team. Other configuration files contain
1565 targets contributed by other OpenSSL users. The list of targets can be found in
1566 a Perl list `my %targets = ( ... )`.
1571 inherit_from => [ "base-target" ],
1573 cflags => add("..."),
1575 perlasm_scheme => "...",
1580 If you call `./Configure` without arguments, it will give you a list of all
1581 known targets. Using `grep`, you can lookup the target definition in the
1582 `Configurations/` directory. For example the `android-x86_64` can be found in
1583 [Configurations/15-android.conf](Configurations/15-android.conf).
1585 The directory contains two README files, which explain the general syntax and
1586 design of the configuration files.
1588 - [Configurations/README.md](Configurations/README.md)
1589 - [Configurations/README-design.md](Configurations/README-design.md)
1591 If you need further help, try to search the [openssl-users] mailing list
1592 or the [GitHub Issues] for existing solutions. If you don't find anything,
1593 you can [raise an issue] to ask a question yourself.
1595 More about our support resources can be found in the [SUPPORT] file.
1597 ### Configuration Errors
1599 If the `./Configure` or `./Configure` command fails with an error message,
1600 read the error message carefully and try to figure out whether you made
1601 a mistake (e.g., by providing a wrong option), or whether the script is
1602 working incorrectly. If you think you encountered a bug, please
1603 [raise an issue] on GitHub to file a bug report.
1605 Along with a short description of the bug, please provide the complete
1606 configure command line and the relevant output including the error message.
1608 Note: To make the output readable, pleace add a 'code fence' (three backquotes
1609 ` ``` ` on a separate line) before and after your output:
1612 ./Configure [your arguments...]
1621 If the build fails, look carefully at the output. Try to locate and understand
1622 the error message. It might be that the compiler is already telling you
1623 exactly what you need to do to fix your problem.
1625 There may be reasons for the failure that aren't problems in OpenSSL itself,
1626 for example if the compiler reports missing standard or third party headers.
1628 If the build succeeded previously, but fails after a source or configuration
1629 change, it might be helpful to clean the build tree before attempting another
1630 build. Use this command:
1633 $ mms clean ! (or mmk) OpenVMS
1634 $ nmake clean # Windows
1636 Assembler error messages can sometimes be sidestepped by using the `no-asm`
1637 configuration option. See also [notes](#notes-on-assembler-modules-compilation).
1639 Compiling parts of OpenSSL with gcc and others with the system compiler will
1640 result in unresolved symbols on some systems.
1642 If you are still having problems, try to search the [openssl-users] mailing
1643 list or the [GitHub Issues] for existing solutions. If you think you
1644 encountered an OpenSSL bug, please [raise an issue] to file a bug report.
1645 Please take the time to review the existing issues first; maybe the bug was
1646 already reported or has already been fixed.
1651 If some tests fail, look at the output. There may be reasons for the failure
1652 that isn't a problem in OpenSSL itself (like an OS malfunction or a Perl issue).
1654 You may want increased verbosity, that can be accomplished as described in
1655 section [Test Failures of test/README.md](test/README.md#test-failures).
1657 You may also want to selectively specify which test(s) to perform. This can be
1658 done using the `make` variable `TESTS` as described in section [Running
1659 Selected Tests of test/README.md](test/README.md#running-selected-tests).
1661 If you find a problem with OpenSSL itself, try removing any
1662 compiler optimization flags from the `CFLAGS` line in the Makefile and
1663 run `make clean; make` or corresponding.
1665 To report a bug please open an issue on GitHub, at
1666 <https://github.com/openssl/openssl/issues>.
1671 Notes on multi-threading
1672 ------------------------
1674 For some systems, the OpenSSL `Configure` script knows what compiler options
1675 are needed to generate a library that is suitable for multi-threaded
1676 applications. On these systems, support for multi-threading is enabled
1677 by default; use the `no-threads` option to disable (this should never be
1680 On other systems, to enable support for multi-threading, you will have
1681 to specify at least two options: `threads`, and a system-dependent option.
1682 (The latter is `-D_REENTRANT` on various systems.) The default in this
1683 case, obviously, is not to include support for multi-threading (but
1684 you can still use `no-threads` to suppress an annoying warning message
1685 from the `Configure` script.)
1687 OpenSSL provides built-in support for two threading models: pthreads (found on
1688 most UNIX/Linux systems), and Windows threads. No other threading models are
1689 supported. If your platform does not provide pthreads or Windows threads then
1690 you should use `Configure` with the `no-threads` option.
1692 For pthreads, all locks are non-recursive. In addition, in a debug build,
1693 the mutex attribute `PTHREAD_MUTEX_ERRORCHECK` is used. If this is not
1694 available on your platform, you might have to add
1695 `-DOPENSSL_NO_MUTEX_ERRORCHECK` to your `Configure` invocation.
1696 (On Linux `PTHREAD_MUTEX_ERRORCHECK` is an enum value, so a built-in
1697 ifdef test cannot be used.)
1699 Notes on shared libraries
1700 -------------------------
1702 For most systems the OpenSSL `Configure` script knows what is needed to
1703 build shared libraries for libcrypto and libssl. On these systems
1704 the shared libraries will be created by default. This can be suppressed and
1705 only static libraries created by using the `no-shared` option. On systems
1706 where OpenSSL does not know how to build shared libraries the `no-shared`
1707 option will be forced and only static libraries will be created.
1709 Shared libraries are named a little differently on different platforms.
1710 One way or another, they all have the major OpenSSL version number as
1711 part of the file name, i.e. for OpenSSL 1.1.x, `1.1` is somehow part of
1714 On most POSIX platforms, shared libraries are named `libcrypto.so.1.1`
1715 and `libssl.so.1.1`.
1717 on Cygwin, shared libraries are named `cygcrypto-1.1.dll` and `cygssl-1.1.dll`
1718 with import libraries `libcrypto.dll.a` and `libssl.dll.a`.
1720 On Windows build with MSVC or using MingW, shared libraries are named
1721 `libcrypto-1_1.dll` and `libssl-1_1.dll` for 32-bit Windows,
1722 `libcrypto-1_1-x64.dll` and `libssl-1_1-x64.dll` for 64-bit x86_64 Windows,
1723 and `libcrypto-1_1-ia64.dll` and `libssl-1_1-ia64.dll` for IA64 Windows.
1724 With MSVC, the import libraries are named `libcrypto.lib` and `libssl.lib`,
1725 while with MingW, they are named `libcrypto.dll.a` and `libssl.dll.a`.
1727 On VMS, shareable images (VMS speak for shared libraries) are named
1728 `ossl$libcrypto0101_shr.exe` and `ossl$libssl0101_shr.exe`. However, when
1729 OpenSSL is specifically built for 32-bit pointers, the shareable images
1730 are named `ossl$libcrypto0101_shr32.exe` and `ossl$libssl0101_shr32.exe`
1731 instead, and when built for 64-bit pointers, they are named
1732 `ossl$libcrypto0101_shr64.exe` and `ossl$libssl0101_shr64.exe`.
1734 Notes on random number generation
1735 ---------------------------------
1737 Availability of cryptographically secure random numbers is required for
1738 secret key generation. OpenSSL provides several options to seed the
1739 internal CSPRNG. If not properly seeded, the internal CSPRNG will refuse
1740 to deliver random bytes and a "PRNG not seeded error" will occur.
1742 The seeding method can be configured using the `--with-rand-seed` option,
1743 which can be used to specify a comma separated list of seed methods.
1744 However, in most cases OpenSSL will choose a suitable default method,
1745 so it is not necessary to explicitly provide this option. Note also
1746 that not all methods are available on all platforms. The FIPS provider will
1747 silently ignore seed sources that were not validated.
1749 I) On operating systems which provide a suitable randomness source (in
1750 form of a system call or system device), OpenSSL will use the optimal
1751 available method to seed the CSPRNG from the operating system's
1752 randomness sources. This corresponds to the option `--with-rand-seed=os`.
1754 II) On systems without such a suitable randomness source, automatic seeding
1755 and reseeding is disabled (`--with-rand-seed=none`) and it may be necessary
1756 to install additional support software to obtain a random seed and reseed
1757 the CSPRNG manually. Please check out the manual pages for `RAND_add()`,
1758 `RAND_bytes()`, `RAND_egd()`, and the FAQ for more information.
1760 Notes on assembler modules compilation
1761 --------------------------------------
1763 Compilation of some code paths in assembler modules might depend on whether the
1764 current assembler version supports certain ISA extensions or not. Code paths
1765 that use the AES-NI, PCLMULQDQ, SSSE3, and SHA extensions are always assembled.
1766 Apart from that, the minimum requirements for the assembler versions are shown
1769 | ISA extension | GNU as | nasm | llvm |
1770 |---------------|--------|--------|---------|
1771 | AVX | 2.19 | 2.09 | 3.0 |
1772 | AVX2 | 2.22 | 2.10 | 3.1 |
1773 | ADCX/ADOX | 2.23 | 2.10 | 3.3 |
1774 | AVX512 | 2.25 | 2.11.8 | 3.6 (*) |
1775 | AVX512IFMA | 2.26 | 2.11.8 | 6.0 (*) |
1776 | VAES | 2.30 | 2.13.3 | 6.0 (*) |
1780 (*) Even though AVX512 support was implemented in llvm 3.6, prior to version 7.0
1781 an explicit -march flag was apparently required to compile assembly modules. But
1782 then the compiler generates processor-specific code, which in turn contradicts
1783 the idea of performing dispatch at run-time, which is facilitated by the special
1784 variable `OPENSSL_ia32cap`. For versions older than 7.0, it is possible to work
1785 around the problem by forcing the build procedure to use the following script:
1788 exec clang -no-integrated-as "$@"
1790 instead of the real clang. In which case it doesn't matter what clang version
1791 is used, as it is the version of the GNU assembler that will be checked.
1798 <https://mta.openssl.org/mailman/listinfo/openssl-users>
1804 <https://github.com/openssl/openssl/issues>
1807 <https://github.com/openssl/openssl/issues/new/choose>
1810 Configurations/10-main.conf