OPENSSL\_INIT\_CRYPTO(3ossl) OpenSSL OPENSSL\_INIT\_CRYPTO(3ossl) # [NAME](#NAME) OPENSSL\_INIT\_new, OPENSSL\_INIT\_set\_config\_filename, OPENSSL\_INIT\_set\_config\_appname, OPENSSL\_INIT\_set\_config\_file\_flags, OPENSSL\_INIT\_free, OPENSSL\_init\_crypto, OPENSSL\_cleanup, OPENSSL\_thread\_stop\_ex, OPENSSL\_thread\_stop - OpenSSL initialisation and deinitialisation functions # [SYNOPSIS](#SYNOPSIS) ``` #include void OPENSSL_cleanup(void); int OPENSSL_init_crypto(uint64_t opts, const OPENSSL_INIT_SETTINGS *settings); void OPENSSL_thread_stop_ex(OSSL_LIB_CTX *ctx); void OPENSSL_thread_stop(void); OPENSSL_INIT_SETTINGS *OPENSSL_INIT_new(void); int OPENSSL_INIT_set_config_filename(OPENSSL_INIT_SETTINGS *init, const char* filename); int OPENSSL_INIT_set_config_file_flags(OPENSSL_INIT_SETTINGS *init, unsigned long flags); int OPENSSL_INIT_set_config_appname(OPENSSL_INIT_SETTINGS *init, const char* name); void OPENSSL_INIT_free(OPENSSL_INIT_SETTINGS *init); ``` # [DESCRIPTION](#DESCRIPTION) During normal operation OpenSSL (libcrypto) will allocate various resources at start up that must, subsequently, be freed on close down of the library. Additionally some resources are allocated on a per thread basis (if the application is multi-threaded), and these resources must be freed prior to the thread closing. As of version 1.1.0 OpenSSL will automatically allocate all resources that it needs so no explicit initialisation is required. However, there may be situations when explicit initialisation is desirable or needed, for example when some nondefault initialisation is required. The function **OPENSSL\_init\_crypto()** can be used for this purpose for libcrypto (see also [**OPENSSL\_init\_ssl**(3)](/man/os/openssl-4.0/OPENSSL_init_ssl.3) for the libssl equivalent). Numerous internal OpenSSL functions call **OPENSSL\_init\_crypto()**. Therefore, in order to perform nondefault initialisation, **OPENSSL\_init\_crypto()** MUST be called by application code prior to any other OpenSSL function calls. The **opts** parameter specifies which aspects of libcrypto should be initialised. Valid options are: [OPENSSL\_INIT\_NO\_LOAD\_CRYPTO\_STRINGS](#OPENSSL_INIT_NO_LOAD_CRYPTO_STRINGS) Suppress automatic loading of the libcrypto error strings. This option is not a default option. Once selected subsequent calls to **OPENSSL\_init\_crypto()** with the option **OPENSSL\_INIT\_LOAD\_CRYPTO\_STRINGS** will be ignored. [OPENSSL\_INIT\_LOAD\_CRYPTO\_STRINGS](#OPENSSL_INIT_LOAD_CRYPTO_STRINGS) Automatic loading of the libcrypto error strings. With this option the library will automatically load the libcrypto error strings. This option is a default option. Once selected subsequent calls to **OPENSSL\_init\_crypto()** with the option **OPENSSL\_INIT\_NO\_LOAD\_CRYPTO\_STRINGS** will be ignored. [OPENSSL\_INIT\_ADD\_ALL\_CIPHERS](#OPENSSL_INIT_ADD_ALL_CIPHERS) With this option the library will automatically load and make available all libcrypto ciphers. This option is a default option. Once selected subsequent calls to **OPENSSL\_init\_crypto()** with the option **OPENSSL\_INIT\_NO\_ADD\_ALL\_CIPHERS** will be ignored. [OPENSSL\_INIT\_ADD\_ALL\_DIGESTS](#OPENSSL_INIT_ADD_ALL_DIGESTS) With this option the library will automatically load and make available all libcrypto digests. This option is a default option. Once selected subsequent calls to **OPENSSL\_init\_crypto()** with the option **OPENSSL\_INIT\_NO\_ADD\_ALL\_DIGESTS** will be ignored. [OPENSSL\_INIT\_NO\_ADD\_ALL\_CIPHERS](#OPENSSL_INIT_NO_ADD_ALL_CIPHERS) With this option the library will suppress automatic loading of libcrypto ciphers. This option is not a default option. Once selected subsequent calls to **OPENSSL\_init\_crypto()** with the option **OPENSSL\_INIT\_ADD\_ALL\_CIPHERS** will be ignored. [OPENSSL\_INIT\_NO\_ADD\_ALL\_DIGESTS](#OPENSSL_INIT_NO_ADD_ALL_DIGESTS) With this option the library will suppress automatic loading of libcrypto digests. This option is not a default option. Once selected subsequent calls to **OPENSSL\_init\_crypto()** with the option **OPENSSL\_INIT\_ADD\_ALL\_DIGESTS** will be ignored. [OPENSSL\_INIT\_LOAD\_CONFIG](#OPENSSL_INIT_LOAD_CONFIG) With this option an OpenSSL configuration file will be automatically loaded and used by calling **OPENSSL\_config()**. This is a default option. Note that in OpenSSL 1.1.1 this was the default for libssl but not for libcrypto (see [**OPENSSL\_init\_ssl**(3)](/man/os/openssl-4.0/OPENSSL_init_ssl.3) for further details about libssl initialisation). In OpenSSL 1.1.0 this was a nondefault option for both libssl and libcrypto. See the description of **OPENSSL\_INIT\_new()**, below. [OPENSSL\_INIT\_NO\_LOAD\_CONFIG](#OPENSSL_INIT_NO_LOAD_CONFIG) With this option the loading of OpenSSL configuration files will be suppressed. It is the equivalent of calling **OPENSSL\_no\_config()**. This is not a default option. [OPENSSL\_INIT\_ASYNC](#OPENSSL_INIT_ASYNC) With this option the library with automatically initialise the libcrypto async sub-library (see [**ASYNC\_start\_job**(3)](/man/os/openssl-4.0/ASYNC_start_job.3)). This is a default option. [OPENSSL\_INIT\_ATFORK](#OPENSSL_INIT_ATFORK) With this option the library will register its fork handlers. See [**OPENSSL\_fork\_prepare**(3)](/man/os/openssl-4.0/OPENSSL_fork_prepare.3) for details. [OPENSSL\_INIT\_NO\_ATEXIT](#OPENSSL_INIT_NO_ATEXIT) The option has no effect in 4.0 and later. Multiple options may be combined together in a single call to **OPENSSL\_init\_crypto()**. For example: ``` OPENSSL_init_crypto(OPENSSL_INIT_NO_ADD_ALL_CIPHERS | OPENSSL_INIT_NO_ADD_ALL_DIGESTS, NULL); ``` The **OPENSSL\_cleanup()** function requests deinitialization of OpenSSL (both libcrypto and libssl). OpenSSL installs a global destructor function at initialization time if the toolchain supports this. This destructor is run after exit and after subordinate library destructors have run. By default the destructor does nothing. If deinitialization has been requested by a call to **OPENSSL\_cleanup()**, then the destructor frees all global resources allocated by OpenSSL. If the toolchain building OpenSSL does not support a global destructor, by default OPENSSL\_cleanup will do nothing, as this is the safest option, allowing the operating system to then reap all library resources on process exit. Note, this may, on some leak detection tools (like valgrind) result in reports that indicate reachable memory remains on exit in certain configurations. As these are not formally leaks, it is recommended that reachable memory reports be suppressed when running such tools. If OpenSSL is compiled with the compile time option of DO\_NOT\_SKIP\_OPENSSL\_CLEANUP **OPENSSL\_cleanup()** will deinitialize the library immediately when called. This is not normally recommended unless you are certain that the global resources will not be used by something after the point at which **OPENSSL\_cleanup()** is called. Once **OPENSSL\_cleanup()** has been called the library cannot be reinitialised. Attempts to call **OPENSSL\_init\_crypto()** will fail and an ERR\_R\_INIT\_FAIL error will be added to the error stack. Note that because initialisation has failed OpenSSL error strings will not be available, only an error code. This code can be put through the openssl errstr command line application to produce a human readable error (see [**openssl-errstr**(1)](/man/os/openssl-4.0/openssl-errstr.1)). The **OPENSSL\_thread\_stop\_ex()** function deallocates resources associated with the current thread for the given OSSL\_LIB\_CTX **ctx**. The **ctx** parameter can be NULL in which case the default OSSL\_LIB\_CTX is used. Typically, this function will be called automatically by the library when the thread exits as long as the OSSL\_LIB\_CTX has not been freed before the thread exits. If **OSSL\_LIB\_CTX\_free()** is called OPENSSL\_thread\_stop\_ex will be called automatically for the current thread (but not any other threads that may have used this OSSL\_LIB\_CTX). OPENSSL\_thread\_stop\_ex should be called on all threads that will exit after the OSSL\_LIB\_CTX is freed. Typically this is not necessary for the default OSSL\_LIB\_CTX (because all resources are cleaned up on library exit) except if thread local resources should be freed before library exit, or under the circumstances described in the NOTES section below. **OPENSSL\_thread\_stop()** is the same as **OPENSSL\_thread\_stop\_ex()** except that the default OSSL\_LIB\_CTX is always used. The **OPENSSL\_INIT\_LOAD\_CONFIG** flag will load a configuration file, as with [**CONF\_modules\_load\_file**(3)](/man/os/openssl-4.0/CONF_modules_load_file.3) with, by default, NULL filename and application name and the **CONF\_MFLAGS\_IGNORE\_MISSING\_FILE**, **CONF\_MFLAGS\_IGNORE\_RETURN\_CODES** and **CONF\_MFLAGS\_DEFAULT\_SECTION** flags. The filename, application name, and flags can be customized by providing a non-null **OPENSSL\_INIT\_SETTINGS** object. The object can be allocated via **OPENSSL\_INIT\_new()**. The **OPENSSL\_INIT\_set\_config\_filename()** function can be used to specify a nondefault filename, which is copied and need not refer to persistent storage. Similarly, **OPENSSL\_INIT\_set\_config\_appname()** can be used to specify a nondefault application name. Finally, OPENSSL\_INIT\_set\_file\_flags can be used to specify nondefault flags. If the **CONF\_MFLAGS\_IGNORE\_RETURN\_CODES** flag is not included, any errors in the configuration file will cause an error return from **OPENSSL\_init\_crypto** or indirectly [**OPENSSL\_init\_ssl**(3)](/man/os/openssl-4.0/OPENSSL_init_ssl.3). The object can be released with **OPENSSL\_INIT\_free()** when done. If the argument to **OPENSSL\_INIT\_free()** is NULL, nothing is done. # [NOTES](#NOTES) Resources local to a thread are deallocated automatically when the thread exits (e.g. in a pthreads environment, when **pthread\_exit()** is called). On Windows platforms this is done in response to a DLL\_THREAD\_DETACH message being sent to the libcrypto32.dll entry point. Some windows functions may cause threads to exit without sending this message (for example **ExitProcess()**). If the application uses such functions, then the application must free up OpenSSL resources directly via a call to **OPENSSL\_thread\_stop()** on each thread. Similarly this message will also not be sent if OpenSSL is linked statically, and therefore applications using static linking should also call **OPENSSL\_thread\_stop()** on each thread. Additionally if OpenSSL is loaded dynamically via **LoadLibrary()** and the threads are not destroyed until after **FreeLibrary()** is called then each thread should call **OPENSSL\_thread\_stop()** prior to the **FreeLibrary()** call. On Linux/Unix where OpenSSL has been loaded via **dlopen()** and the application is multi-threaded and if **dlclose()** is subsequently called prior to the threads being destroyed then OpenSSL will not be able to deallocate resources associated with those threads. The application should either call **OPENSSL\_thread\_stop()** on each thread prior to the **dlclose()** call, or alternatively the original **dlopen()** call should use the RTLD\_NODELETE flag (where available on the platform). Thread cleanup does not unwind an OpenSSL function interrupted by cancellation or thread exit; see [**openssl-threads**(7)](/man/os/openssl-4.0/openssl-threads.7). # [RETURN VALUES](#RETURN_VALUES) The functions OPENSSL\_init\_crypto, and **OPENSSL\_INIT\_set\_config\_appname()** return 1 on success or 0 on error. # [SEE ALSO](#SEE_ALSO) [**OPENSSL\_init\_ssl**(3)](/man/os/openssl-4.0/OPENSSL_init_ssl.3), [**openssl-threads**(7)](/man/os/openssl-4.0/openssl-threads.7) # [HISTORY](#HISTORY) The **OPENSSL\_init\_crypto()**, **OPENSSL\_cleanup()** **OPENSSL\_thread\_stop()**, **OPENSSL\_INIT\_new()**, **OPENSSL\_INIT\_set\_config\_appname()** and **OPENSSL\_INIT\_free()** functions were added in OpenSSL 1.1.0. **OPENSSL\_INIT\_ENGINE\_RDRAND**, **OPENSSL\_INIT\_ENGINE\_DYNAMIC**, **OPENSSL\_INIT\_ENGINE\_OPENSSL**, **OPENSSL\_INIT\_ENGINE\_CRYPTODEV**, **OPENSSL\_INIT\_ENGINE\_CAPI**, **OPENSSL\_INIT\_ENGINE\_PADLOCK**, **OPENSSL\_INIT\_ENGINE\_AFALG** **OPENSSL\_init\_crypto()** *opts* were removed in OpenSSL 4.0. **OPENSSL\_INIT\_ENGINE\_ALL\_BUILTIN** is defined to 0 since OpenSSL 4.0. # [COPYRIGHT](#COPYRIGHT) Copyright 2016-2026 The OpenSSL Project Authors. All Rights Reserved. Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>. 2026-09-29 4.0.3 --- Document: OPENSSL_INIT_new(3ossl) from openssl-4.0 4.0.3-r6 (Chainguard OS)