apps/openssl: clean-up of unused fallback code

[openssl.git] / INSTALL.md

Build and Install
=================

This document describes installation on all supported operating
systems (the Unix/Linux family, including macOS), OpenVMS,
and Windows).

Table of Contents
=================

 - [Prerequisites](#prerequisites)
 - [Notational Conventions](#notational-conventions)
 - [Quick Installation Guide](#quick-installation-guide)
   - [Building OpenSSL](#building-openssl)
   - [Installing OpenSSL](#installing-openssl)
 - [Configuration Options](#configuration-options)
   - [API Level](#api-level)
   - [Cross Compile Prefix](#cross-compile-prefix)
   - [Build Type](#build-type)
   - [Directories](#directories)
   - [Compiler Warnings](#compiler-warnings)
   - [ZLib Flags](#zlib-flags)
   - [Seeding the Random Generator](#seeding-the-random-generator)
   - [Enable and Disable Features](#enable-and-disable-features)
   - [Displaying configuration data](#displaying-configuration-data)
 - [Installation Steps in Detail](#installation-steps-in-detail)
   - [Configure](#configure-openssl)
   - [Build](#build-openssl)
   - [Test](#test-openssl)
   - [Install](#install-openssl)
 - [Advanced Build Options](#advanced-build-options)
   - [Environment Variables](#environment-variables)
   - [Makefile Targets](#makefile-targets)
   - [Running Selected Tests](#running-selected-tests)
 - [Troubleshooting](#troubleshooting)
   - [Configuration Problems](#configuration-problems)
   - [Build Failures](#build-failures)
   - [Test Failures](#test-failures)
 - [Notes](#notes)
   - [Notes on multi-threading](#notes-on-multi-threading)
   - [Notes on shared libraries](#notes-on-shared-libraries)
   - [Notes on random number generation](#notes-on-random-number-generation)

Prerequisites
=============

To install OpenSSL, you will need:

 * A make implementation
 * Perl 5 with core modules (please read [NOTES.PERL](NOTES.PERL))
 * The Perl module Text::Template (please read [NOTES.PERL](NOTES.PERL))
 * an ANSI C compiler
 * a development environment in the form of development libraries and C
   header files
 * a supported operating system

For additional platform specific requirements, solutions to specific
issues and other details, please read one of these:

 * [NOTES.UNIX](NOTES.UNIX) - notes for Unix like systems
 * [NOTES.VMS](NOTES.VMS) - notes related to OpenVMS
 * [NOTES.WIN](NOTES.WIN) - notes related to the Windows platform
 * [NOTES.DJGPP](NOTES.DJGPP) - building for DOS with DJGPP
 * [NOTES.ANDROID](NOTES.ANDROID) - building for Android platforms (using NDK)
 * [NOTES.VALGRIND](NOTES.VALGRIND) - testing with Valgrind
 * [NOTES.PERL](NOTES.PERL) - some notes on Perl

Notational conventions
======================

Throughout this document, we use the following conventions.

Commands
--------

Any line starting with a dollar sign is a command line.

    $ command

The dollar sign indicates the shell prompt and is not to be entered as
part of the command.

Choices
-------

Several words in curly braces separated by pipe characters indicate a
**mandatory choice**, to be replaced with one of the given words.
For example, the line

    $ echo { WORD1 | WORD2 | WORD3 }

represents one of the following three commands

    $ echo WORD1
    - or -
    $ echo WORD2
    - or -
    $ echo WORD3

One or several words in square brackets separated by pipe characters
denote an **optional choice**.  It is similar to the mandatory choice,
but it can also be omitted entirely.

So the line

    $ echo [ WORD1 | WORD2 | WORD3 ]

represents one of the four commands

    $ echo WORD1
    - or -
    $ echo WORD2
    - or -
    $ echo WORD3
    - or -
    $ echo

Arguments
---------

**Mandatory arguments** are enclosed in double curly braces.
A simple example would be

    $ type {{ filename }}

which is to be understood to use the command `type` on some file name
determined by the user.

**Optional Arguments** are enclosed in double square brackets.

    [[ options ]]

Note that the notation assumes spaces around {, }, [, ], {{, }} and
[[, ]].  This is to differentiate from OpenVMS directory
specifications, which also use [ and ], but without spaces.

Quick Installation Guide
========================

If you just want to get OpenSSL installed without bothering too much
about the details, here is the short version of how to build and install
OpenSSL.  If any of the following steps fails, please consult the
[Installation in Detail](#installation-in-detail) section below.

Building OpenSSL
----------------

Use the following commands to configure, build and test OpenSSL.
The testing is optional, but recommended if you intend to install
OpenSSL for production use.

### Unix / Linux / macOS

    $ ./Configure
    $ make
    $ make test

### OpenVMS

Use the following commands to build OpenSSL:

    $ perl Configure
    $ mms
    $ mms test

### Windows

If you are using Visual Studio, open a Developer Command Prompt and
and issue the following commands to build OpenSSL.

    $ perl Configure
    $ nmake
    $ nmake test

As mentioned in the [Choices](#choices) section, you need to pick one
of the four Configure targets in the first command.

Most likely you will be using the VC-WIN64A target for 64bit Windows
binaries (AMD64) or VC-WIN32 for 32bit Windows binaries (X86).
The other two options are VC_WIN64I (Intel IA64, Itanium) and
VC-CE (Windows CE) are rather uncommon nowadays.

Installing OpenSSL
------------------

The following commands will install OpenSSL to a default system location.

**Danger Zone:** even if you are impatient, please read the following two
paragraphs carefully before you install OpenSSL.

For security reasons the default system location is by default not writable
for unprivileged users.  So for the final installation step administrative
privileges are required.  The default system location and the procedure to
obtain administrative privileges depends on the operating sytem.
It is recommended to compile and test OpenSSL with normal user privileges
and use administrative privileges only for the final installation step.

On some platforms OpenSSL is preinstalled as part of the Operating System.
In this case it is highly recommended not to overwrite the system versions,
because other applications or libraries might depend on it.
To avoid breaking other applications, install your copy of OpenSSL to a
[different location](#installing-to-a-different-location) which is not in
the global search path for system libraries.

Finally, if you plan on using the FIPS module, you need to read the
[Post-installation Notes](#post-installation-notes) further down.

### Unix / Linux / macOS

Depending on your distribution, you need to run the following command as
root user or prepend `sudo` to the command:

    $ make install

By default, OpenSSL will be installed to

    /usr/local

More precisely, the files will be installed into the  subdirectories

    /usr/local/bin
    /usr/local/lib
    /usr/local/include
    ...

depending on the file type, as it is custom on Unix-like operating systems.

### OpenVMS

Use the following command to install OpenSSL.

    $ mms install

By default, OpenSSL will be installed to

    SYS$COMMON:[OPENSSL-'version'...]

where 'version' is the OpenSSL version number with underscores instead
of periods.

### Windows

If you are using Visual Studio, open the Developer Command Prompt _elevated_
and issue the following command.

    $ nmake install

The easiest way to elevate the Command Prompt is to press and hold down
the both the `<CTRL>` and `<SHIFT>` key while clicking the menu item in the
task menu.

The default installation location is

    C:\Program Files\OpenSSL

for native binaries, or

    C:\Program Files (x86)\OpenSSL

for 32bit binaries on 64bit Windows (WOW64).

#### Installing to a different location

To install OpenSSL to a different location (for example into your home
directory for testing purposes) run Configure as shown in the following
examples.

On Unix:

    $ ./Configure --prefix=/opt/openssl --openssldir=/usr/local/ssl

On OpenVMS:

    $ perl Configure --prefix=PROGRAM:[INSTALLS] --openssldir=SYS$MANAGER:[OPENSSL]

Note: if you do add options to the configuration command, please make sure
you've read more than just this Quick Start, such as relevant `NOTES.*` files,
the options outline below, as configuration options may change the outcome
in otherwise unexpected ways.

Configuration Options
=====================

There are several options to ./Configure to customize the build (note that
for Windows, the defaults for `--prefix` and `--openssldir` depend in what
configuration is used and what Windows implementation OpenSSL is built on.
More notes on this in NOTES.WIN):

API Level
---------

    --api=x.y[.z]

Build the OpenSSL libraries to support the API for the specified version.
If [no-deprecated](#no-deprecated) is also given, don't build with support
for deprecated APIs in or below the specified version number.  For example,
addding

    --api=1.1.0 no-deprecated

will remove support for all APIs that were deprecated in OpenSSL version
1.1.0 or below.  This is a rather specialized option for developers.
If you just intend to remove all deprecated APIs up to the current version
entirely, just specify [no-deprecated](#no-deprecated).
If `--api` isn't given, it defaults to the current (minor) OpenSSL version.

Cross Compile Prefix
--------------------

    --cross-compile-prefix=PREFIX

The PREFIX to include in front of commands for your toolchain.

It is likely to have to end with dash, e.g.  a-b-c- would invoke GNU compiler
as a-b-c-gcc, etc.  Unfortunately cross-compiling is too case-specific to put
together one-size-fits-all instructions.  You might have to pass more flags or
set up environment variables to actually make it work.  Android and iOS cases
are discussed in corresponding `Configurations/15-*.conf` files.  But there are
cases when this option alone is sufficient.  For example to build the mingw64
target on Linux `--cross-compile-prefix=x86_64-w64-mingw32-` works.  Naturally
provided that mingw packages are installed.  Today Debian and Ubuntu users
have option to install a number of prepackaged cross-compilers along with
corresponding run-time and development packages for "alien" hardware.  To give
another example `--cross-compile-prefix=mipsel-linux-gnu-` suffices in such
case.

For cross compilation, you must [configure manually](#manual-configuration).
Also, note that `--openssldir` refers to target's file system, not one you are
building on.

Build Type
----------

    --debug

Build OpenSSL with debugging symbols and zero optimization level.

    --release

Build OpenSSL without debugging symbols.  This is the default.

Directories
-----------

### libdir

    --libdir=DIR

The name of the directory under the top of the installation directory tree
(see the `--prefix` option) where libraries will be installed.  By default
this is "lib". Note that on Windows only static libraries (`*.lib`) will
be stored in this location. Shared libraries (`*.dll`) will always be
installed to the "bin" directory.

### openssldir

    --openssldir=DIR

Directory for OpenSSL configuration files, and also the default certificate
and key store.  Defaults are:

    Unix:           /usr/local/ssl
    Windows:        C:\Program Files\Common Files\SSL
    OpenVMS:        SYS$COMMON:[OPENSSL-COMMON]

For 32bit Windows applications on Windows 64bit (WOW64), always replace
`C:\Program Files` by `C:\Program Files (x86)`.

### prefix

    --prefix=DIR

The top of the installation directory tree.  Defaults are:

    Unix:           /usr/local
    Windows:        C:\Program Files\OpenSSL
    OpenVMS:        SYS$COMMON:[OPENSSL-'version']

Compiler Warnings
-----------------

    --strict-warnings

This is a developer flag that switches on various compiler options recommended
for OpenSSL development.  It only works when using gcc or clang as the compiler.
If you are developing a patch for OpenSSL then it is recommended that you use
this option where possible.

ZLib Flags
----------

### with-zlib-include

    --with-zlib-include=DIR

The directory for the location of the zlib include file.  This option is only
necessary if [enable-zlib](#enable-zlib) is used and the include file is not
already on the system include path.

### with-zlib-lib

    --with-zlib-lib=LIB

**On Unix**: this is the directory containing the zlib library.
If not provided the system library path will be used.

**On Windows:** this is the filename of the zlib library (with or
without a path).  This flag must be provided if the
[zlib-dynamic](#zlib-dynamic) option is not also used.  If zlib-dynamic is used
then this flag is optional and defaults to "ZLIB1" if not provided.

**On VMS:** this is the filename of the zlib library (with or without a path).
This flag is optional and if not provided then "GNV$LIBZSHR", "GNV$LIBZSHR32"
or "GNV$LIBZSHR64" is used by default depending on the pointer size chosen.

Seeding the Random Generator
----------------------------

    --with-rand-seed=seed1[,seed2,...]

A comma separated list of seeding methods which will be tried by OpenSSL
in order to obtain random input (a.k.a "entropy") for seeding its
cryptographically secure random number generator (CSPRNG).
The current seeding methods are:

### os

Use a trusted operating system entropy source.
This is the default method if such an entropy source exists.

### getrandom

Use the [getrandom(2)][man-getrandom] or equivalent system call.

[man-getrandom]: http://man7.org/linux/man-pages/man2/getrandom.2.html

### devrandom

Use the first device from the DEVRANDOM list which can be opened to read
random bytes.  The DEVRANDOM preprocessor constant expands to

    "/dev/urandom","/dev/random","/dev/srandom"

on most unix-ish operating systems.

### egd

Check for an entropy generating daemon.

### rdcpu

Use the RDSEED or RDRAND command if provided by the CPU.

### librandom

Use librandom (not implemented yet).

### none

Disable automatic seeding.  This is the default on some operating systems where
no suitable entropy source exists, or no support for it is implemented yet.

For more information, see the section [Notes on random number generation][rng]
at the end of this document.

[rng]: #notes-on-random-number-generation

Enable and Disable Features
---------------------------

Feature options always come in pairs, an option to enable feature xxxx, and
and option to disable it:

    [ enable-xxxx | no-xxxx ]

Whether a feature is enabled or disabled by default, depends on the feature.
In the following list, always the non-default variant is documented: if
feature xxxx is disabled by default then enable-xxxx is documented and
if feature xxxx is enabled by default then no-xxxx is documented.

### no-afalgeng

Don't build the AFALG engine.

This option will be forced on a platform that does not support AFALG.

### enable-ktls

Build with Kernel TLS support.

This option will enable the use of the Kernel TLS data-path, which can improve
performance and allow for the use of sendfile and splice system calls on
TLS sockets.  The Kernel may use TLS accelerators if any are available on the
system.  This option will be forced off on systems that do not support the
Kernel TLS data-path.

### enable-asan

Build with the Address sanitiser.

This is a developer option only.  It may not work on all platforms and should
never be used in production environments.  It will only work when used with
gcc or clang and should be used in conjunction with the [no-shared](#no-shared)
option.

### no-acvp_tests

Do not build support for Automated Cryptographic Validation Protocol (ACVP)
tests.

This is required for FIPS validation purposes. Certain ACVP tests require
access to algorithm internals that are not normally accessible.
Additional information related to ACVP can be found at
<https://github.com/usnistgov/ACVP>.

### no-asm

Do not use assembler code.

This should be viewed as debugging/troubleshooting option rather than for
production use.  On some platforms a small amount of assembler code may still
be used even with this option.

### no-async

Do not build support for async operations.

### no-autoalginit

Don't automatically load all supported ciphers and digests.

Typically OpenSSL will make available all of its supported ciphers and digests.
For a statically linked application this may be undesirable if small executable
size is an objective.  This only affects libcrypto.  Ciphers and digests will
have to be loaded manually using EVP_add_cipher() and EVP_add_digest() if this
option is used.  This option will force a non-shared build.

### no-autoerrinit

Don't automatically load all libcrypto/libssl error strings.

Typically OpenSSL will automatically load human readable error strings.  For a
statically linked application this may be undesirable if small executable size
is an objective.

### no-autoload-config

Don't automatically load the default openssl.cnf file.

Typically OpenSSL will automatically load a system config file which configures
default SSL options.

### enable-buildtest-c++

While testing, generate C++ buildtest files that simply check that the public
OpenSSL header files are usable standalone with C++.

Enabling this option demands extra care.  For any compiler flag given directly
as configuration option, you must ensure that it's valid for both the C and
the C++ compiler.  If not, the C++ build test will most likely break.  As an
alternative, you can use the language specific variables, CFLAGS and CXXFLAGS.

### no-capieng

Don't build the CAPI engine.

This option will be forced if on a platform that does not support CAPI.

### no-cmp

Don't build support for Certificate Management Protocol (CMP).

### no-cms

Don't build support for Cryptographic Message Syntax (CMS).

### no-comp

Don't build support for SSL/TLS compression.

If this option is enabled (the default), then compression will only work if
the zlib or zlib-dynamic options are also chosen.

### enable-crypto-mdebug

This now only enables the failed-malloc feature.

### enable-crypto-mdebug-backtrace

This is a no-op; the project uses the compiler's address/leak sanitizer instead.

### no-ct

Don't build support for Certificate Transparency (CT).

### no-deprecated

Don't build with support for deprecated APIs up until and including the version
given with `--api` (or the current version, if `--api` wasn't specified).

### no-dgram

Don't build support for datagram based BIOs.

Selecting this option will also force the disabling of DTLS.

### no-dso

Don't build support for loading Dynamic Shared Objects (DSO)

### enable-devcryptoeng

Build the `/dev/crypto` engine.

This option is automatically selected on the BSD platform, in which case it can
be disabled with no-devcryptoeng.

### no-dynamic-engine

Don't build the dynamically loaded engines.

This only has an effect in a shared build.

### no-ec

Don't build support for Elliptic Curves.

### no-ec2m

Don't build support for binary Elliptic Curves

### enable-ec_nistp_64_gcc_128

Enable support for optimised implementations of some commonly used NIST
elliptic curves.

This option is only supported on platforms:

 - with little-endian storage of non-byte types
 - that tolerate misaligned memory references
 - where the compiler:
   - supports the non-standard type `__uint128_t`
   - defines the built-in macro `__SIZEOF_INT128__`

### enable-egd

Build support for gathering entropy from the Entropy Gathering Daemon (EGD).

### no-engine

Don't build support for loading engines.

### no-err

Don't compile in any error strings.

### enable-external-tests

Enable building of integration with external test suites.

This is a developer option and may not work on all platforms.  The following
external test suites are currently supported:

 - BoringSSL test suite
 - Python PYCA/Cryptography test suite
 - krb5 test suite

See the file [test/README.external](test/README.external) for further details.

### no-filenames

Don't compile in filename and line number information (e.g.  for errors and
memory allocation).

### no-fips

Don't compile the FIPS provider

### enable-fuzz-libfuzzer, enable-fuzz-afl

Build with support for fuzzing using either libfuzzer or AFL.

These are developer options only.  They may not work on all  platforms and
should never be used in production environments.

See the file [fuzz/README.md](fuzz/README.md) for further details.

### no-gost

Don't build support for GOST based ciphersuites.

Note that if this feature is enabled then GOST ciphersuites are only available
if the GOST algorithms are also available through loading an externally supplied
engine.

### no-legacy

Don't build the legacy provider.

Disabling this also disables the legacy algorithms: MD2 (already disabled by default).

### no-makedepend

Don't generate dependencies.

### no-module

Don't build any dynamically loadable engines.

This also implies 'no-dynamic-engine'.

### no-multiblock

Don't build support for writing multiple records in one go in libssl

Note: this is a different capability to the pipelining functionality.

### no-nextprotoneg

Don't build support for the Next Protocol Negotiation (NPN) TLS extension.

### no-ocsp

Don't build support for Online Certificate Status Protocol (OCSP).

### no-padlockeng

Don't build the padlock engine.

### no-hw-padlock

As synonyme for no-padlockeng.  Deprecated and should not be used.

### no-pic

Don't build with support for Position Independent Code.

### no-pinshared

Don't pin the shared libraries.

By default OpenSSL will attempt to stay in memory until the process exits.
This is so that libcrypto and libssl can be properly cleaned up automatically
via an atexit() handler.  The handler is registered by libcrypto and cleans
up both libraries.  On some platforms the atexit() handler will run on unload of
libcrypto (if it has been dynamically loaded) rather than at process exit.  This
option can be used to stop OpenSSL from attempting to stay in memory until the
process exits.  This could lead to crashes if either libcrypto or libssl have
already been unloaded at the point that the atexit handler is invoked, e.g.  on a
platform which calls atexit() on unload of the library, and libssl is unloaded
before libcrypto then a crash is likely to happen.  Applications can suppress
running of the atexit() handler at run time by using the OPENSSL_INIT_NO_ATEXIT
option to OPENSSL_init_crypto().  See the man page for it for further details.

### no-posix-io

Don't use POSIX IO capabilities.

### no-psk

Don't build support for Pre-Shared Key based ciphersuites.

### no-rdrand

Don't use hardware RDRAND capabilities.

### no-rfc3779

Don't build support for RFC3779, "X.509 Extensions for IP Addresses and
AS Identifiers".

### sctp

Build support for Stream Control Transmission Protocol (SCTP).

### no-shared

Do not create shared libraries, only static ones.

See [Notes on shared libraries](#notes-on-shared-libraries) below.

### no-sock

Don't build support for socket BIOs.

### no-srp

Don't build support for Secure Remote Password (SRP) protocol or
SRP based ciphersuites.

### no-srtp

Don't build Secure Real-Time Transport Protocol (SRTP) support.

### no-sse2

Exclude SSE2 code paths from 32-bit x86 assembly modules.

Normally SSE2 extension is detected at run-time, but the decision whether or not
the machine code will be executed is taken solely on CPU capability vector.  This
means that if you happen to run OS kernel which does not support SSE2 extension
on Intel P4 processor, then your application might be exposed to "illegal
instruction" exception.  There might be a way to enable support in kernel, e.g.
FreeBSD kernel can be compiled with CPU_ENABLE_SSE, and there is a way to
disengage SSE2 code paths upon application start-up, but if you aim for wider
"audience" running such kernel, consider no-sse2.  Both the 386 and no-asm
options imply no-sse2.

### enable-ssl-trace

Build with the SSL Trace capabilities.

This adds the "-trace" option to s_client and s_server.

### no-static-engine

Don't build the statically linked engines.

This only has an impact when not built "shared".

### no-stdio

Don't use anything from the C header file "stdio.h" that makes use of the "FILE"
type.  Only libcrypto and libssl can be built in this way.  Using this option will
suppress building the command line applications.  Additionally, since the OpenSSL
tests also use the command line applications, the tests will also be skipped.

### no-tests

Don't build test programs or run any tests.

### no-threads

Don't build with support for multi-threaded applications.

### threads

Build with support for multi-threaded applications.  Most platforms will enable
this by default.  However if on a platform where this is not the case then this
will usually require additional system-dependent options!

See [Notes on multi-threading](#notes-on-multi-threading) below.

### enable-trace

Build with support for the integrated tracing api.

See manual pages OSSL_trace_set_channel(3) and OSSL_trace_enabled(3) for details.

### no-ts

Don't build Time Stamping (TS) Authority support.

### enable-ubsan

Build with the Undefined Behaviour sanitiser (UBSAN).

This is a developer option only.  It may not work on all platforms and should
never be used in production environments.  It will only work when used with gcc
or clang and should be used in conjunction with the `-DPEDANTIC` option
(or the `--strict-warnings` option).

### no-ui-console

Don't build with the User Interface (UI) console method

The User Interface console method enables text based console prompts.

### enable-unit-test

Enable additional unit test APIs.

This should not typically be used in production deployments.

### no-uplink

Don't build support for UPLINK interface.

### enable-weak-ssl-ciphers

Build support for SSL/TLS ciphers that are considered "weak"

Enabling this includes for example the RC4 based ciphersuites.

### zlib

Build with support for zlib compression/decompression.

### zlib-dynamic

Like the zlib option, but has OpenSSL load the zlib library dynamically
when needed.

This is only supported on systems where loading of shared libraries is supported.

### 386

In 32-bit x86 builds, use the 80386 instruction set only in assembly modules

The default x86 code is more efficient, but requires at least an 486 processor.
Note: This doesn't affect compiler generated code, so this option needs to be
accompanied by a corresponding compiler-specific option.

### no-{protocol}

    no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}

Don't build support for negotiating the specified SSL/TLS protocol.

If "no-tls" is selected then all of tls1, tls1_1, tls1_2 and tls1_3 are disabled.
Similarly "no-dtls" will disable dtls1 and dtls1_2.  The "no-ssl" option is
synonymous with "no-ssl3".  Note this only affects version negotiation.
OpenSSL will still provide the methods for applications to explicitly select
the individual protocol versions.

### no-{protocol}-method

    no-{ssl|ssl3|tls|tls1|tls1_1|tls1_2|tls1_3|dtls|dtls1|dtls1_2}-method

Analogous to no-{protocol} but in addition do not build the methods for
applications to explicitly select individual protocol versions.  Note that there
is no "no-tls1_3-method" option because there is no application method for
TLSv1.3.

Using individual protocol methods directly is deprecated.  Applications should
use TLS_method() instead.

### enable-{algorithm}

    enable-{md2|rc5}

Build with support for the specified algorithm.

### no-{algorithm}

    no-{aria|bf|blake2|camellia|cast|chacha|cmac|
        des|dh|dsa|ecdh|ecdsa|idea|md4|mdc2|ocb|
        poly1305|rc2|rc4|rmd160|scrypt|seed|
        siphash|siv|sm2|sm3|sm4|whirlpool}

Build without support for the specified algorithm.

The "ripemd" algorithm is deprecated and if used is synonymous with rmd160.

### Compiler-specific options

    -Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static

These system specific options will be recognised and passed through to the
compiler to allow you to define preprocessor symbols, specify additional
libraries, library directories or other compiler options.  It might be worth
noting that some compilers generate code specifically for processor the
compiler currently executes on.  This is not necessarily what you might have
in mind, since it might be unsuitable for execution on other, typically older,
processor.  Consult your compiler documentation.

Take note of the [Environment Variables](#environment-variables) documentation
below and how these flags interact with those variables.

    -xxx, +xxx, /xxx

Additional options that are not otherwise recognised are passed through as
they are to the compiler as well.  Unix-style options beginning with a
'-' or '+' and Windows-style options beginning with a '/' are recognized.
Again, consult your compiler documentation.

If the option contains arguments separated by spaces, then the URL-style
notation %20 can be used for the space character in order to avoid having
to quote the option.  For example, -opt%20arg gets expanded to -opt arg.
In fact, any ASCII character can be encoded as %xx using its hexadecimal
encoding.

Take note of the [Environment Variables](#environment-variables) documentation
below and how these flags interact with those variables.

### Environment Variables

    VAR=value

Assign the given value to the environment variable VAR for Configure.

These work just like normal environment variable assignments, but are supported
on all platforms and are confined to the configuration scripts only.
These assignments override the corresponding value in the inherited environment,
if there is one.

The following variables are used as "make variables" and can be used as an
alternative to giving preprocessor, compiler and linker options directly as
configuration.  The following variables are supported:

    AR              The static library archiver.
    ARFLAGS         Flags for the static library archiver.
    AS              The assembler compiler.
    ASFLAGS         Flags for the assembler compiler.
    CC              The C compiler.
    CFLAGS          Flags for the C compiler.
    CXX             The C++ compiler.
    CXXFLAGS        Flags for the C++ compiler.
    CPP             The C/C++ preprocessor.
    CPPFLAGS        Flags for the C/C++ preprocessor.
    CPPDEFINES      List of CPP macro definitions, separated
                    by a platform specific character (':' or
                    space for Unix, ';' for Windows, ',' for
                    VMS).  This can be used instead of using
                    -D (or what corresponds to that on your
                    compiler) in CPPFLAGS.
    CPPINCLUDES     List of CPP inclusion directories, separated
                    the same way as for CPPDEFINES.  This can
                    be used instead of -I (or what corresponds
                    to that on your compiler) in CPPFLAGS.
    HASHBANGPERL    Perl invocation to be inserted after '#!'
                    in public perl scripts (only relevant on
                    Unix).
    LD              The program linker (not used on Unix, $(CC)
                    is used there).
    LDFLAGS         Flags for the shared library, DSO and
                    program linker.
    LDLIBS          Extra libraries to use when linking.
                    Takes the form of a space separated list
                    of library specifications on Unix and
                    Windows, and as a comma separated list of
                    libraries on VMS.
    RANLIB          The library archive indexer.
    RC              The Windows resource compiler.
    RCFLAGS         Flags for the Windows resource compiler.
    RM              The command to remove files and directories.

These cannot be mixed with compiling/linking flags given on the command line.
In other words, something like this isn't permitted.

    $ ./Configure -DFOO CPPFLAGS=-DBAR -DCOOKIE

Backward compatibility note:

To be compatible with older configuration scripts, the environment variables
are ignored if compiling/linking flags are given on the command line, except
for the following:

    AR, CC, CXX, CROSS_COMPILE, HASHBANGPERL, PERL, RANLIB, RC, and WINDRES

For example, the following command will not see -DBAR:

    $ CPPFLAGS=-DBAR ./Configure -DCOOKIE

However, the following will see both set variables:

    $ CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- ./Configure -DCOOKIE

If CC is set, it is advisable to also set CXX to ensure both the C and C++
compiler are in the same "family".  This becomes relevant with
'enable-external-tests' and 'enable-buildtest-c++'.

### Reconfigure

    reconf
    reconfigure

Reconfigure from earlier data.

This fetches the previous command line options and environment from data
saved in "configdata.pm" and runs the configuration process again, using
these options and environment.  Note: NO other option is permitted together
with "reconf".  Note: The original configuration saves away values for ALL
environment variables that were used, and if they weren't defined, they are
still saved away with information that they weren't originally defined.
This information takes precedence over environment variables that are
defined when reconfiguring.

Displaying configuration data
-----------------------------

The configuration script itself will say very little, and finishes by
creating "configdata.pm".  This perl module can be loaded by other scripts
to find all the configuration data, and it can also be used as a script to
display all sorts of configuration data in a human readable form.

For more information, please do:

    $ ./configdata.pm --help                         # Unix

or

    $ perl configdata.pm --help                      # Windows and VMS

Installation Steps in Detail
============================

Configure OpenSSL
-----------------

### Automatic Configuration

On some platform a `config` script is available which attempts to guess
your operating system (and compiler, if necessary) and calls the `Configure`
Perl script with appropriate target based on its guess.  Further options can
be supplied to the `config` script, which will be passed on to the `Configure`
script.

#### Unix / Linux / macOS

    $ ./Configure [[ options ]]

#### OpenVMS

    $ perl Configure [[ options ]]

#### Windows

    $ perl Configure [[ options ]]

### Manual Configuration

OpenSSL knows about a range of different operating system, hardware and
compiler combinations.  To see the ones it knows about, run

    $ ./Configure LIST                               # Unix

or

    $ perl Configure LIST                            # All other platforms

For the remainder of this text, the Unix form will be used in all examples.
Please use the appropriate form for your platform.

Pick a suitable name from the list that matches your system.  For most
operating systems there is a choice between using "cc" or "gcc".
When you have identified your system (and if necessary compiler) use this
name as the argument to Configure.  For example, a "linux-elf" user would
run:

    $ ./Configure linux-elf [[ options ]]

### Creating your own Configuration

If your system isn't listed, you will have to create a configuration
file named Configurations/{{ something }}.conf and add the correct
configuration for your system.  See the available configs as examples
and read Configurations/README and Configurations/README.design for
more information.

The generic configurations "cc" or "gcc" should usually work on 32 bit
Unix-like systems.

Configure creates a build file ("Makefile" on Unix, "makefile" on Windows
and "descrip.mms" on OpenVMS) from a suitable template in Configurations,
and defines various macros in include/openssl/configuration.h (generated
from include/openssl/configuration.h.in).

### Out of Tree Builds

OpenSSL can be configured to build in a build directory separate from the
source code directory.  It's done by placing yourself in some other
directory and invoking the configuration commands from there.

#### Unix example

    $ mkdir /var/tmp/openssl-build
    $ cd /var/tmp/openssl-build
    $ /PATH/TO/OPENSSL/SOURCE/Configure [[ options ]]

#### OpenVMS example

    $ set default sys$login:
    $ create/dir [.tmp.openssl-build]
    $ set default [.tmp.openssl-build]
    $ perl D:[PATH.TO.OPENSSL.SOURCE]Configure [[ options ]]

#### Windows example

    $ C:
    $ mkdir \temp-openssl
    $ cd \temp-openssl
    $ perl d:\PATH\TO\OPENSSL\SOURCE\Configure [[ options ]]

Paths can be relative just as well as absolute.  Configure will do its best
to translate them to relative paths whenever possible.

Build OpenSSL
-------------

Build OpenSSL by running:

    $ make                                           # Unix
    $ mms                                            ! (or mmk) OpenVMS
    $ nmake                                          # Windows

This will build the OpenSSL libraries (libcrypto.a and libssl.a on
Unix, corresponding on other platforms) and the OpenSSL binary
("openssl").  The libraries will be built in the top-level directory,
and the binary will be in the "apps" subdirectory.

If the build fails, take a look at the [Build Failures](#build-failures)
subsection of the [Troubleshooting](#troubleshooting) section.

Test OpenSSL
------------

After a successful build, and before installing, the libraries should
be tested.  Run:

    $ make test                                      # Unix
    $ mms test                                       ! OpenVMS
    $ nmake test                                     # Windows

**Warning:** you MUST run the tests from an unprivileged account (or disable
your privileges temporarily if your platform allows it).

If some tests fail, take a look at the [Test Failures](#test-failures)
subsection of the [Troubleshooting](#troubleshooting) section.

Install OpenSSL
---------------

If everything tests ok, install OpenSSL with

    $ make install                                   # Unix
    $ mms install                                    ! OpenVMS
    $ nmake install                                  # Windows

Note that in order to perform the install step above you need to have
appropriate permissions to write to the installation directory.

The above commands will install all the software components in this
directory tree under PREFIX (the directory given with `--prefix` or
its default):

### Unix / Linux / macOS

    bin/           Contains the openssl binary and a few other
                   utility scripts.
    include/openssl
                   Contains the header files needed if you want
                   to build your own programs that use libcrypto
                   or libssl.
    lib            Contains the OpenSSL library files.
    lib/engines    Contains the OpenSSL dynamically loadable engines.

    share/man/man1 Contains the OpenSSL command line man-pages.
    share/man/man3 Contains the OpenSSL library calls man-pages.
    share/man/man5 Contains the OpenSSL configuration format man-pages.
    share/man/man7 Contains the OpenSSL other misc man-pages.

    share/doc/openssl/html/man1
    share/doc/openssl/html/man3
    share/doc/openssl/html/man5
    share/doc/openssl/html/man7
                   Contains the HTML rendition of the man-pages.

### OpenVMS

'arch' is replaced with the architecture name, "Alpha" or "ia64",
'sover' is replaced with the shared library version (0101 for 1.1), and
'pz' is replaced with the pointer size OpenSSL was built with:

    [.EXE.'arch']  Contains the openssl binary.
    [.EXE]         Contains a few utility scripts.
    [.include.openssl]
                   Contains the header files needed if you want
                   to build your own programs that use libcrypto
                   or libssl.
    [.LIB.'arch']  Contains the OpenSSL library files.
    [.ENGINES'sover''pz'.'arch']
                   Contains the OpenSSL dynamically loadable engines.
    [.SYS$STARTUP] Contains startup, login and shutdown scripts.
                   These define appropriate logical names and
                   command symbols.
    [.SYSTEST]     Contains the installation verification procedure.
    [.HTML]        Contains the HTML rendition of the manual pages.

### Additional Directories

Additionally, install will add the following directories under
OPENSSLDIR (the directory given with `--openssldir` or its default)
for you convenience:

    certs          Initially empty, this is the default location
                   for certificate files.
    private        Initially empty, this is the default location
                   for private key files.
    misc           Various scripts.

The installation directory should be appropriately protected to ensure
unprivileged users cannot make changes to OpenSSL binaries or files, or
install engines.  If you already have a pre-installed version of OpenSSL as
part of your Operating System it is recommended that you do not overwrite
the system version and instead install to somewhere else.

Package builders who want to configure the library for standard locations,
but have the package installed somewhere else so that it can easily be
packaged, can use

  $ make DESTDIR=/tmp/package-root install         # Unix
  $ mms/macro="DESTDIR=TMP:[PACKAGE-ROOT]" install ! OpenVMS

The specified destination directory will be prepended to all installation
target paths.

Compatibility issues with previous OpenSSL versions
---------------------------------------------------

### COMPILING existing applications

Starting with version 1.1.0, OpenSSL hides a number of structures that were
previously open.  This includes all internal libssl structures and a number
of EVP types.  Accessor functions have been added to allow controlled access
to the structures' data.

This means that some software needs to be rewritten to adapt to the new ways
of doing things.  This often amounts to allocating an instance of a structure
explicitly where you could previously allocate them on the stack as automatic
variables, and using the provided accessor functions where you would previously
access a structure's field directly.

Some APIs have changed as well.  However, older APIs have been preserved when
possible.

Post-installation Notes
-----------------------

With the default OpenSSL installation comes a FIPS provider module, which
needs some post-installation attention, without which it will not be usable.
This involves using the following command:

    $ openssl fipsinstall

See the openssl-fipsinstall(1) manual for details and examples.

Advanced Build Options
======================

Environment Variables
---------------------

A number of environment variables can be used to provide additional control
over the build process.  Typically these should be defined prior to running
Configure.  Not all environment variables are relevant to all platforms.

    AR
                   The name of the ar executable to use.

    BUILDFILE
                   Use a different build file name than the platform default
                   ("Makefile" on Unix-like platforms, "makefile" on native Windows,
                   "descrip.mms" on OpenVMS).  This requires that there is a
                   corresponding build file template.  See Configurations/README
                   for further information.

    CC
                   The compiler to use. Configure will attempt to pick a default
                   compiler for your platform but this choice can be overridden
                   using this variable. Set it to the compiler executable you wish
                   to use, e.g. "gcc" or "clang".

    CROSS_COMPILE
                   This environment variable has the same meaning as for the
                   "--cross-compile-prefix" Configure flag described above. If both
                   are set then the Configure flag takes precedence.

    NM
                   The name of the nm executable to use.

    OPENSSL_LOCAL_CONFIG_DIR
                   OpenSSL comes with a database of information about how it
                   should be built on different platforms as well as build file
                   templates for those platforms. The database is comprised of
                   ".conf" files in the Configurations directory.  The build
                   file templates reside there as well as ".tmpl" files. See the
                   file Configurations/README for further information about the
                   format of ".conf" files as well as information on the ".tmpl"
                   files.
                   In addition to the standard ".conf" and ".tmpl" files, it is
                   possible to create your own ".conf" and ".tmpl" files and store
                   them locally, outside the OpenSSL source tree. This environment
                   variable can be set to the directory where these files are held
                   and will be considered by Configure before it looks in the
                   standard directories.

    PERL
                   The name of the Perl executable to use when building OpenSSL.
                   Only needed if builing should use a different Perl executable
                   than what is used to run the Configure script.

    HASHBANGPERL
                   The command string for the Perl executable to insert in the
                   #! line of perl scripts that will be publicly installed.
                   Default: /usr/bin/env perl
                   Note: the value of this variable is added to the same scripts
                   on all platforms, but it's only relevant on Unix-like platforms.

    RC
                   The name of the rc executable to use. The default will be as
                   defined for the target platform in the ".conf" file. If not
                   defined then "windres" will be used. The WINDRES environment
                   variable is synonymous to this. If both are defined then RC
                   takes precedence.

    RANLIB
                   The name of the ranlib executable to use.

    WINDRES
                   See RC.

Makefile Targets
----------------

The Configure script generates a Makefile in a format relevant to the specific
platform.  The Makefiles provide a number of targets that can be used.  Not all
targets may be available on all platforms.  Only the most common targets are
described here.  Examine the Makefiles themselves for the full list.

    all
                   The target to build all the software components and
                   documentation.

    build_sw
                   Build all the software components.
                   THIS IS THE DEFAULT TARGET.

    build_docs
                   Build all documentation components.

    clean
                   Remove all build artefacts and return the directory to a "clean"
                   state.

    depend
                   Rebuild the dependencies in the Makefiles. This is a legacy
                   option that no longer needs to be used since OpenSSL 1.1.0.

    install
                   Install all OpenSSL components.

    install_sw
                   Only install the OpenSSL software components.

    install_docs
                   Only install the OpenSSL documentation components.

    install_man_docs
                   Only install the OpenSSL man pages (Unix only).

    install_html_docs
                   Only install the OpenSSL html documentation.

    list-tests
                   Prints a list of all the self test names.

    test
                   Build and run the OpenSSL self tests.

    uninstall
                   Uninstall all OpenSSL components.

    reconfigure
    reconf
                   Re-run the configuration process, as exactly as the last time
                   as possible.

    update
                   This is a developer option. If you are developing a patch for
                   OpenSSL you may need to use this if you want to update
                   automatically generated files; add new error codes or add new
                   (or change the visibility of) public API functions. (Unix only).

Running Selected Tests
----------------------

The make variable TESTS supports a versatile set of space separated tokens
with which you can specify a set of tests to be performed.  With a "current
set of tests" in mind, initially being empty, here are the possible tokens:

     alltests      The current set of tests becomes the whole set of available
                   tests (as listed when you do 'make list-tests' or similar).

     xxx           Adds the test 'xxx' to the current set of tests.

    -xxx           Removes 'xxx' from the current set of tests.  If this is the
                   first token in the list, the current set of tests is first
                   assigned the whole set of available tests, effectively making
                   this token equivalent to TESTS="alltests -xxx".

     nn            Adds the test group 'nn' (which is a number) to the current
                   set of tests.

    -nn            Removes the test group 'nn' from the current set of tests.
                   If this is the first token in the list, the current set of
                   tests is first assigned the whole set of available tests,
                   effectively making this token equivalent to
                   TESTS="alltests -xxx".

Also, all tokens except for "alltests" may have wildcards, such as *.
(on Unix and Windows, BSD style wildcards are supported, while on VMS,
it's VMS style wildcards)

### Examples

Run all tests except for the fuzz tests:

    $ make TESTS=-test_fuzz test

or, if you want to be explicit:

    $ make TESTS='alltests -test_fuzz' test

Run all tests that have a name starting with "test_ssl" but not those
starting with "test_ssl_":

    $ make TESTS='test_ssl* -test_ssl_*' test

Run only test group 10:

    $ make TESTS='10'

Run all tests except the slow group (group 99):

    $ make TESTS='-99'

Run all tests in test groups 80 to 99 except for tests in group 90:

    $ make TESTS='[89]? -90'

To stochastically verify that the algorithm that produces uniformly distributed
random numbers is operating correctly (with a false positive rate of 0.01%):

    $ ./util/wrap.sh test/bntest -stochastic

Troubleshooting
===============

Configuration Problems
----------------------

### Selecting the correct target

The `./Configure` script tries hard to guess your operating system, but in some
cases it does not succeed. You will see a message like the following:

    $ ./Configure
    Operating system: x86-whatever-minix
    This system (minix) is not supported. See file INSTALL for details.

Even if the automatic target selection by the `./Configure` script fails, chances
are that you still might find a suitable target in the Configurations directory,
which you can supply to the `./Configure` command, possibly after some adjustment.

The Configurations directory contains a lot of examples of such targets.
The main configuration file is [10-main.conf][], which contains all targets that
are officially supported by the OpenSSL team. Other configuration files contain
targets contributed by other OpenSSL users. The list of targets can be found in
a Perl list `my %targets = ( ... )`.

    my %targets = (
    ...
    "target-name" => {
        inherit_from     => [ "base-target" ],
        CC               => "...",
        cflags           => add("..."),
        asm_arch         => '...',
        perlasm_scheme   => "...",
    },
    ...
    )

If you call `./Configure` without arguments, it will give you a list of all
known targets. Using `grep`, you can lookup the target definition in the
Configurations directory. For example the "android-x86_64" can be found in
Configurations/15-android.conf.

The directory contains two README files, which explain the general syntax and
design of the configurations files.

 - [Configurations/README](Configurations/README)
 - [Configurations/README.design](Configurations/README.design)

If you need further help, try to search the [openssl-users][] mailing list
or the [GitHub Issues][] for existing solutions. If you don't find anything,
you can [raise an issue][] to ask a question yourself.

More about our support resources can be found in the [SUPPORT][] file.

### Configuration Errors

If the `./Configure` or `./Configure` command fails with an error message,
read the error message carefully and try to figure out whether you made
a mistake (e.g., by providing a wrong option), or whether the script is
working incorrectly. If you think you encountered a bug, please
[raise an issue][] on GitHub to file a bug report.

Along with a short description of the bug, please provide the complete
configure command line and the relevant output including the error message.

Note: To make the output readable, pleace add a 'code fence' (three backquotes
` ``` ` on a separate line) before and after your output:

     ```
     ./Configure [your arguments...]

     [output...]

     ```

Build Failures
--------------

If the build fails, look carefully at the output. Try to locate and understand
the error message. It might be that the compiler is already telling you
exactly what you need to do to fix your problem.

There may be reasons for the failure that aren't problems in OpenSSL itself,
for example if the compiler reports missing standard or third party headers.

If the build succeeded previously, but fails after a source or configuration
change, it might be helpful to clean the build tree before attempting another
build.  Use this command:

    $ make clean                                     # Unix
    $ mms clean                                      ! (or mmk) OpenVMS
    $ nmake clean                                    # Windows

Assembler error messages can sometimes be sidestepped by using the
"no-asm" configuration option.

Compiling parts of OpenSSL with gcc and others with the system compiler will
result in unresolved symbols on some systems.

If you are still having problems, try to search the [openssl-users][] mailing
list or the [GitHub Issues][] for existing solutions. If you think you
encountered an OpenSSL bug, please [raise an issue][] to file a bug report.
Please take the time to review the existing issues first; maybe the bug was
already reported or has already been fixed.

Test Failures
-------------

If some tests fail, look at the output.  There may be reasons for the failure
that isn't a problem in OpenSSL itself (like an OS malfunction or a Perl issue).
You may want increased verbosity, that can be accomplished like this:

Full verbosity (`make` macro `VERBOSE` or `V`):

    $ make V=1 test                                  # Unix
    $ mms /macro=(V=1) test                          ! OpenVMS
    $ nmake V=1 test                                 # Windows

Verbosity on test failure (`VERBOSE_FAILURE` or `VF´, Unix example shown):

    $ make test VF=1

Verbosity on failed (sub-)tests only (`VERBOSE_FAILURES_ONLY` or `VFO`):

    $ make test VFO=1

Verbosity on failed (sub-)tests, in addition progress on succeeded (sub-)tests
(`VERBOSE_FAILURES_PROGRESS` or `VFP`):

    $ make test VFP=1

If you want to run just one or a few specific tests, you can use
the make variable TESTS to specify them, like this:

    $ make TESTS='test_rsa test_dsa' test            # Unix
    $ mms/macro="TESTS=test_rsa test_dsa" test       ! OpenVMS
    $ nmake TESTS='test_rsa test_dsa' test           # Windows

And of course, you can combine (Unix examples shown):

    $ make test TESTS='test_rsa test_dsa' VF=1
    $ make test TESTS="test_cmp_*" VFO=1

You can find the list of available tests like this:

    $ make list-tests                                # Unix
    $ mms list-tests                                 ! OpenVMS
    $ nmake list-tests                               # Windows

Have a look at the manual for the perl module Test::Harness to
see what other HARNESS_* variables there are.

If you find a problem with OpenSSL itself, try removing any
compiler optimization flags from the CFLAGS line in Makefile and
run "make clean; make" or corresponding.

To report a bug please open an issue on GitHub, at
<https://github.com/openssl/openssl/issues>.

For more details on how the make variables TESTS can be used,
see section [Running Selected Tests](#running-selected-tests) below.

Notes
=====

Notes on multi-threading
------------------------

For some systems, the OpenSSL Configure script knows what compiler options
are needed to generate a library that is suitable for multi-threaded
applications.  On these systems, support for multi-threading is enabled
by default; use the "no-threads" option to disable (this should never be
necessary).

On other systems, to enable support for multi-threading, you will have
to specify at least two options: "threads", and a system-dependent option.
(The latter is "-D_REENTRANT" on various systems.)  The default in this
case, obviously, is not to include support for multi-threading (but
you can still use "no-threads" to suppress an annoying warning message
from the Configure script.)

OpenSSL provides built-in support for two threading models: pthreads (found on
most UNIX/Linux systems), and Windows threads.  No other threading models are
supported.  If your platform does not provide pthreads or Windows threads then
you should Configure with the "no-threads" option.

Notes on shared libraries
-------------------------

For most systems the OpenSSL Configure script knows what is needed to
build shared libraries for libcrypto and libssl.  On these systems
the shared libraries will be created by default.  This can be suppressed and
only static libraries created by using the "no-shared" option.  On systems
where OpenSSL does not know how to build shared libraries the "no-shared"
option will be forced and only static libraries will be created.

Shared libraries are named a little differently on different platforms.
One way or another, they all have the major OpenSSL version number as
part of the file name, i.e.  for OpenSSL 1.1.x, 1.1 is somehow part of
the name.

On most POSIX platforms, shared libraries are named libcrypto.so.1.1
and libssl.so.1.1.

on Cygwin, shared libraries are named cygcrypto-1.1.dll and cygssl-1.1.dll
with import libraries libcrypto.dll.a and libssl.dll.a.

On Windows build with MSVC or using MingW, shared libraries are named
libcrypto-1_1.dll and libssl-1_1.dll for 32-bit Windows, libcrypto-1_1-x64.dll
and libssl-1_1-x64.dll for 64-bit x86_64 Windows, and libcrypto-1_1-ia64.dll
and libssl-1_1-ia64.dll for IA64 Windows.  With MSVC, the import libraries
are named libcrypto.lib and libssl.lib, while with MingW, they are named
libcrypto.dll.a and libssl.dll.a.

On VMS, shareable images (VMS speak for shared libraries) are named
ossl$libcrypto0101_shr.exe and ossl$libssl0101_shr.exe.  However, when
OpenSSL is specifically built for 32-bit pointers, the shareable images
are named ossl$libcrypto0101_shr32.exe and ossl$libssl0101_shr32.exe
instead, and when built for 64-bit pointers, they are named
ossl$libcrypto0101_shr64.exe and ossl$libssl0101_shr64.exe.

Notes on random number generation
---------------------------------

Availability of cryptographically secure random numbers is required for
secret key generation.  OpenSSL provides several options to seed the
internal CSPRNG.  If not properly seeded, the internal CSPRNG will refuse
to deliver random bytes and a "PRNG not seeded error" will occur.

The seeding method can be configured using the `--with-rand-seed` option,
which can be used to specify a comma separated list of seed methods.
However in most cases OpenSSL will choose a suitable default method,
so it is not necessary to explicitly provide this option.  Note also
that not all methods are available on all platforms.

I) On operating systems which provide a suitable randomness source (in
form  of a system call or system device), OpenSSL will use the optimal
available  method to seed the CSPRNG from the operating system's
randomness sources.  This corresponds to the option `--with-rand-seed=os`.

II) On systems without such a suitable randomness source, automatic seeding
and reseeding is disabled (--with-rand-seed=none) and it may be necessary
to install additional support software to obtain a random seed and reseed
the CSPRNG manually.  Please check out the manual pages for RAND_add(),
RAND_bytes(), RAND_egd(), and the FAQ for more information.

<!-- Links  -->

[openssl-users]:
    <https://mta.openssl.org/mailman/listinfo/openssl-users>

[SUPPORT]:
    ./SUPPORT.md

[GitHub Issues]:
    <https://github.com/openssl/openssl/issues>

[raise an issue]:
    <https://github.com/openssl/openssl/issues/new/choose>

[10-main.conf]:
    Configurations/10-main.conf