FindOpenSSL¶
Finds the installed OpenSSL encryption library and determines its version.
Added in version 3.20: Support for specifying version range when calling the find_package()
command. When a version is requested, it can be specified as a single value
as before, and now also a version range can be used. For a detailed
description of version range usage and capabilities, refer to the
find_package()
command.
Added in version 3.18: Support for OpenSSL 3.0.
Components¶
This module supports the following optional components:
Crypto
Added in version 3.12.
Ensures that the OpenSSL
crypto
library is found.SSL
Added in version 3.12.
Ensures that the OpenSSL
ssl
library is found.
Components can be optionally specified using a standard syntax:
find_package(OpenSSL [COMPONENTS <components>...])
If no components are requested, module by default searches for the Crypto
as required and SSL
as optional component.
Imported Targets¶
This module provides the following Imported Targets:
OpenSSL::Crypto
Added in version 3.4.
Target encapsulating the OpenSSL
crypto
library usage requirements, available only if thecrypto
library is found.OpenSSL::SSL
Added in version 3.4.
Target encapsulating the OpenSSL
ssl
library usage requirements, available only if thessl
library is found. For convenience, this target also linksOpenSSL::Crypto
, since thessl
library depends on thecrypto
library.OpenSSL::applink
Added in version 3.18.
Target encapsulating the OpenSSL application-side interface (
openssl/applink.c
) usage requirements, available only if OpenSSL is found and its version is at least 0.9.8.This interface provides a glue between OpenSSL BIO layer and the Windows compiler runtime environment and may need to be compiled into projects when using MSVC. By linking this target, the other OpenSSL imported targets can be linked even if the project uses different MSVC runtime configuration. Linking this target on platforms other than MSVC has no effect.
Note
The interface file is added using the
INTERFACE_SOURCES
target property. Due to how interface sources are propagated in CMake, it is recommended to link theOpenSSL::applink
target as PRIVATE to ensure that it is linked only once in the entire dependency graph of any library or executable:target_link_libraries(project_target PRIVATE OpenSSL::applink)
Using other scopes for this target specifically can lead to unexpected issues during the build or link process, as both the ISO C and ISO C++ standards place very few requirements on how linking should behave.
Result Variables¶
This module defines the following variables:
OpenSSL_FOUND
Boolean indicating whether the OpenSSL library has been found. For backward compatibility, the
OPENSSL_FOUND
variable is also set to the same value.OPENSSL_INCLUDE_DIR
The OpenSSL include directory.
OPENSSL_CRYPTO_LIBRARY
The OpenSSL
crypto
library.OPENSSL_CRYPTO_LIBRARIES
The OpenSSL
crypto
library and its dependencies.OPENSSL_SSL_LIBRARY
The OpenSSL
ssl
library.OPENSSL_SSL_LIBRARIES
The OpenSSL
ssl
library and its dependencies.OPENSSL_LIBRARIES
All OpenSSL libraries and their dependencies.
OPENSSL_VERSION
The OpenSSL version found. This is set to
<major>.<minor>.<revision><patch>
(e.g.0.9.8s
).OPENSSL_APPLINK_SOURCE
The sources in the target
OpenSSL::applink
mentioned above. This variable is only defined if found OpenSSL version is at least 0.9.8 and the platform is MSVC.
Hints¶
This module accepts the following variables to control the search behavior:
OPENSSL_ROOT_DIR
Set to the root directory of an OpenSSL installation to search for the OpenSSL libraries in custom locations.
OPENSSL_USE_STATIC_LIBS
Added in version 3.4.
Set to
TRUE
to prefer static OpenSSL libraries over shared ones.OPENSSL_MSVC_STATIC_RT
Added in version 3.5.
Set to
TRUE
to search for the OpenSSL libraries built with the MSVC static runtime (MT).ENV{PKG_CONFIG_PATH}
On UNIX-like systems,
pkg-config
is used to locate OpenSSL. Set thePKG_CONFIG_PATH
environment variable to specify alternate locations, which is useful on systems with multiple library installations.
Examples¶
Finding the OpenSSL crypto
library and linking it to a project target:
find_package(OpenSSL)
target_link_libraries(project_target PRIVATE OpenSSL::Crypto)
The following example shows how to find the OpenSSL crypto
and ssl
libraries and link them to a project target. The SSL
component is
explicitly specified to ensure that the find module reports an error if the
ssl
library is not found:
find_package(OpenSSL COMPONENTS SSL)
target_link_libraries(project_target PRIVATE OpenSSL::SSL)