OSSL_PROVIDER(3ossl)

📦

version 3.5.9 · 8 versions

3.5.9 · fedora 43, fedora 44 (latest)
3.5.9 · centos-stream 9
3.5.9 · centos-stream 10
3.5.9 · alpine 3.22
3.5.9 · alpine 3.23, alpine 3.24
3.5.8 · fedora 43
3.5.1 · fedora 43
3.5.5 · fedora 44

💖 OSSL_PROVIDER(3ossl) 💖

okay bestie, welcome to the OSSL_PROVIDER(3ossl) page — it's giving OpenSSL provider routines, and it's literally the whole backstage pass to how providers work. No cap, this one is long, so part 1 is right here, part 2 is coming. 💅

✨ NAME ✨

okay so this page is all about the provider routines: OSSL_PROVIDER_set_default_search_path, OSSL_PROVIDER_get0_default_search_path, OSSL_PROVIDER, OSSL_PROVIDER_load, OSSL_PROVIDER_try_load, OSSL_PROVIDER_unload, OSSL_PROVIDER_load_ex, OSSL_PROVIDER_try_load_ex, OSSL_PROVIDER_available, OSSL_PROVIDER_do_all, OSSL_PROVIDER_gettable_params, OSSL_PROVIDER_get_params, OSSL_PROVIDER_query_operation, OSSL_PROVIDER_unquery_operation, OSSL_PROVIDER_get0_provider_ctx, OSSL_PROVIDER_get0_dispatch, OSSL_PROVIDER_add_builtin, OSSL_PROVIDER_get0_name, OSSL_PROVIDER_get_capabilities, OSSL_PROVIDER_add_conf_parameter, OSSL_PROVIDER_get_conf_parameters, OSSL_PROVIDER_conf_get_bool, OSSL_PROVIDER_self_test — provider routines. 💖

🌸 SYNOPSIS 🌸

okay so here's the exact tea, bestie:

        #include <openssl/provider.h>

        typedef struct ossl_provider_st OSSL_PROVIDER;

        int OSSL_PROVIDER_set_default_search_path(OSSL_LIB_CTX *libctx,
                                                  const char *path);
        const char *OSSL_PROVIDER_get0_default_search_path(OSSL_LIB_CTX *libctx);

        OSSL_PROVIDER *OSSL_PROVIDER_load(OSSL_LIB_CTX *libctx, const char *name);
        OSSL_PROVIDER *OSSL_PROVIDER_load_ex(OSSL_LIB_CTX *, const char *name,
                                             OSSL_PARAM *params);
        OSSL_PROVIDER *OSSL_PROVIDER_try_load(OSSL_LIB_CTX *libctx, const char *name,
                                              int retain_fallbacks);
        OSSL_PROVIDER *OSSL_PROVIDER_try_load_ex(OSSL_LIB_CTX *, const char *name,
                                                 OSSL_PARAM *params,
                                                 int retain_fallbacks);
        int OSSL_PROVIDER_unload(OSSL_PROVIDER *prov);
        int OSSL_PROVIDER_available(OSSL_LIB_CTX *libctx, const char *name);
        int OSSL_PROVIDER_do_all(OSSL_LIB_CTX *ctx,
                                 int (*cb)(OSSL_PROVIDER *provider, void *cbdata),
                                 void *cbdata);

        const OSSL_PARAM *OSSL_PROVIDER_gettable_params(OSSL_PROVIDER *prov);
        int OSSL_PROVIDER_get_params(OSSL_PROVIDER *prov, OSSL_PARAM params[]);

        const OSSL_ALGORITHM *OSSL_PROVIDER_query_operation(const OSSL_PROVIDER *prov,
                                                            int operation_id,
                                                            int *no_cache);
        void OSSL_PROVIDER_unquery_operation(const OSSL_PROVIDER *prov,
                                             int operation_id,
                                             const OSSL_ALGORITHM *algs);
        void *OSSL_PROVIDER_get0_provider_ctx(const OSSL_PROVIDER *prov);
        const OSSL_DISPATCH *OSSL_PROVIDER_get0_dispatch(const OSSL_PROVIDER *prov);

        int OSSL_PROVIDER_add_builtin(OSSL_LIB_CTX *libctx, const char *name,
                                      ossl_provider_init_fn *init_fn);

        const char *OSSL_PROVIDER_get0_name(const OSSL_PROVIDER *prov);

        int OSSL_PROVIDER_get_capabilities(const OSSL_PROVIDER *prov,
                                           const char *capability,
                                           OSSL_CALLBACK *cb,
                                           void *arg);
        int OSSL_PROVIDER_add_conf_parameter(OSSL_PROVIDER *prov, const char *name,
                                             const char *value);
        int OSSL_PROVIDER_get_conf_parameters(OSSL_PROVIDER *prov,
                                              OSSL_PARAM params[]);
        int OSSL_PROVIDER_conf_get_bool(const OSSL_PROVIDER *prov,
                                        const char *name, int defval);
        int OSSL_PROVIDER_self_test(const OSSL_PROVIDER *prov);

💜 DESCRIPTION 💜

OSSL_PROVIDER is a type that holds internal information about implementation providers — peep provider(7) for info on what a provider even is. A provider can be built in to the application or the OpenSSL libraries, or it can be a loadable module. The functions described here handle both forms. 💖

Some of these functions operate within a library context, so please see OSSL_LIB_CTX(3) for further details.

✨ Functions ✨

OSSL_PROVIDER_set_default_search_path() — specifies the default search path that is to be used for looking for providers in the specified libctx. If left unspecified, an environment variable and a fall back default value will be used instead.
OSSL_PROVIDER_get0_default_search_path() — retrieves the default search path that is to be used for looking for providers in the specified libctx. If successful, returns the path or empty string; the path is valid until the context is released or OSSL_PROVIDER_set_default_search_path() is called.
OSSL_PROVIDER_add_builtin() — adds a built in provider to the OSSL_PROVIDER store in the given library context, by associating a provider name with a provider initialization function. This name can then be used with OSSL_PROVIDER_load().
OSSL_PROVIDER_load() — loads and initializes a provider. This may simply initialize a provider that was previously added with OSSL_PROVIDER_add_builtin() and run its given initialization function, or load a provider module with the given name and run its provider entry point, "OSSL_provider_init". The name can be a path to a provider module, in that case the provider name as returned by OSSL_PROVIDER_get0_name() will be the path. Interpretation of relative paths is platform dependent and they are relative to the configured "MODULESDIR" directory or the path set in the environment variable OPENSSL_MODULES if set.
OSSL_PROVIDER_try_load() — functions like OSSL_PROVIDER_load(), except that it does not disable the fallback providers if the provider cannot be loaded and initialized or if retain_fallbacks is nonzero. If the provider loads successfully and retain_fallbacks is zero, the fallback providers are disabled.
OSSL_PROVIDER_load_ex() and OSSL_PROVIDER_try_load_ex() — are the variants of the previous functions accepting an "OSSL_PARAM" array of the parameters that are passed as the configuration of the loaded provider. The parameters of any type but "OSSL_PARAM_UTF8_STRING" are silently ignored. If the parameters are provided, they replace all the ones specified in the configuration file.
OSSL_PROVIDER_unload() — unloads the given provider. For a provider added with OSSL_PROVIDER_add_builtin(), this simply runs its teardown function.
OSSL_PROVIDER_available() — checks if a named provider is available for use.
OSSL_PROVIDER_do_all() — iterates over all loaded providers, calling cb for each one, with the current provider in provider and the cbdata that comes from the caller. If no other provider has been loaded before calling this function, the default provider is still available as fallback. See OSSL_PROVIDER-default(7) for more information on this fallback behaviour.
OSSL_PROVIDER_gettable_params() — is used to get a provider parameter descriptor set as a constant OSSL_PARAM(3) array.
OSSL_PROVIDER_get_params() — is used to get provider parameter values. The caller must prepare the OSSL_PARAM(3) array before calling this function, and the variables acting as buffers for this parameter array should be filled with data when it returns successfully.
OSSL_PROVIDER_add_conf_parameter() — sets the provider configuration parameter name to value. Provider configuration parameters are managed by the OpenSSL core and normally set in the configuration file, but can also be set early in the main program before a provider is in use by multiple threads. Parameters that only affect provider initialisation must, for now, be set in the configuration file, only parameters that are also queried later have any affect when set via this interface. Only text parameters can be given, and it's up to the provider to interpret them.
OSSL_PROVIDER_get_conf_parameters() — retrieves global configuration parameters associated with prov. These configuration parameters are stored for each provider by the OpenSSL core, not the provider itself, parameters managed by the provider are queried via OSSL_PROVIDER_get_params() described above. The parameters are returned by reference, not as copies, and so the elements of the param array must have OSSL_PARAM_UTF8_PTR as their data_type.
OSSL_PROVIDER_conf_get_bool() — parses the global configuration parameter name associated with provider prov as a boolean value, returning a default value defval when unable to retrieve or parse the parameter. Parameter values equal (case-insensitively) to 1, "on", "yes", or "true" yield a true (nonzero) result. Parameter values equal (case-insensitively) to 0, "off", "no", or "false" yield a false (zero) result.
OSSL_PROVIDER_self_test() — is used to run a provider's self tests on demand. If the self tests fail then the provider will fail to provide any further services and algorithms. OSSL_SELF_TEST_set_callback(3) may be called beforehand in order to display diagnostics for the running self tests.
OSSL_PROVIDER_query_operation() — calls the provider's query_operation function (see provider(7)), if the provider has one. It returns an array of OSSL_ALGORITHM for the given operation_id terminated by an all NULL OSSL_ALGORITHM entry. This is considered a low-level function that most applications should not need to call.
OSSL_PROVIDER_unquery_operation() — calls the provider's unquery_operation function (see provider(7)), if the provider has one. This is considered a low-level function that most applications should not need to call.
OSSL_PROVIDER_get0_provider_ctx() — returns the provider context for the given provider. The provider context is an opaque handle set by the provider itself and is passed back to the provider by libcrypto in various function calls.
OSSL_PROVIDER_get0_dispatch() — returns the provider's dispatch table as it was returned in the out parameter from the provider's init function. See provider-base(7).

If it is permissible to cache references to this array then *no_store is set to 0 or 1 otherwise. If the array is not cacheable then it is assumed to have a short lifetime.

OSSL_PROVIDER_get0_name() — returns the name of the given provider.
OSSL_PROVIDER_get_capabilities() — provides information about the capabilities supported by the provider specified in prov with the capability name capability. For each capability of that name supported by the provider it will call the callback cb and supply a set of OSSL_PARAM(3)s describing the capability. It will also pass back the argument arg. For more details about capabilities and what they can be used for please see "CAPABILITIES" in provider-base(7).

💖 RETURN VALUES 💖

okay bestie, here's the receipts on what each function hands back to you ✨

OSSL_PROVIDER_set_default_search_path(), OSSL_PROVIDER_add(), OSSL_PROVIDER_unload(), OSSL_PROVIDER_get_params(), OSSL_PROVIDER_add_conf_parameter(), OSSL_PROVIDER_get_conf_parameters() and OSSL_PROVIDER_get_capabilities() — these all give you 1 when it works and 0 when it doesn't. that's it, that's the whole personality 🎀
OSSL_PROVIDER_get0_default_search_path() — hands you a pointer to a path if it goes well, or NULL if something errored or if that path was never set in the first place. no path, no pointer, periodt 💅
OSSL_PROVIDER_load() and OSSL_PROVIDER_try_load() — you get a pointer to a provider object when it works, NULL when it doesn't. iconic when it works, devastating when it's NULL 😭
OSSL_PROVIDER_do_all() — returns 1 if your callback cb returns 1 for every provider it gets called with. returns 0 if any single provider callback invocation returns 0. and listen, the callback processing stops right at that first invocation that returns 0 — no second chances, no encore, it's done 🌸
OSSL_PROVIDER_available() — 1 if the named provider is available, otherwise 0. vibe check: passed or not passed, no in-between ✨
OSSL_PROVIDER_gettable_params() — gives you a pointer to an array of constant OSSL_PARAM(3), or NULL if there isn't one provided. if it's not there, it's just not there, we don't make things up 🦋
OSSL_PROVIDER_get_params() — 1 on success, 0 on error. lowkey the most reliable girl in the friend group 💖
OSSL_PROVIDER_query_operation() — returns an array of OSSL_ALGORITHM, or NULL on error. arrays are giving main character energy fr fr 👑
OSSL_PROVIDER_self_test() — 1 if the self tests pass, or 0 on error. it either aced the quiz or it didn't, no partial credit 🙈

🌈 EXAMPLES 🌈

okay so this lil demo shows you how to load the provider module "foo" and then ask it for its build information. we love a nosy queen asking questions 💅

#include <openssl/params.h>
#include <openssl/provider.h>
#include <openssl/err.h>

OSSL_PROVIDER *prov = NULL;
const char *build = NULL;
OSSL_PARAM request[] = {
    { "buildinfo", OSSL_PARAM_UTF8_PTR, &build, 0, 0 },
    { NULL, 0, NULL, 0, 0 }
};

if ((prov = OSSL_PROVIDER_load(NULL, "foo")) != NULL
    && OSSL_PROVIDER_get_params(prov, request))
    printf("Provider 'foo' buildinfo: %s\n", build);
else
    ERR_print_errors_fp(stderr);

so real talk: if the load works and OSSL_PROVIDER_get_params() works, you print the buildinfo like a boss ✨ otherwise you dump the errors to stderr and we all have a little cry about it 😭

👀 SEE ALSO 👀

go read those too bestie, the lore is deep 🫶

🎀 HISTORY 🎀

the type and functions described here? added in OpenSSL 3.0. so they're not new new, they're established 💖

OSSL_PROVIDER_load_ex and OSSL_PROVIDER_try_load_ex showed up later, in OpenSSL 3.2 — a lil glow-up moment ✨

and OSSL_PROVIDER_add_conf_parameter, OSSL_PROVIDER_get_conf_parameters, and OSSL_PROVIDER_conf_get_bool are the freshest of the fresh, added in OpenSSL 3.5 🌸

💜 COPYRIGHT 💜

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>.

ngl bestie, "you may not use this file except in compliance with the License" is the legal version of "read the group chat rules before you post" 🙈

and that's a wrap on OSSL_PROVIDER(3ossl) 💖 this whole page is from OpenSSL 3.5.9, dated 2026-09-29 — screenshot it, bookmark it, send it to the group chat, because that's the version that ate and left no crumbs ✨💅👑

📦 where this page comes from

fedora 43: openssl-devel 1:3.5.9-1.fc43 · Apache-2.0
fedora 43: openssl-devel 1:3.5.9-1.fc43 · Apache-2.0
fedora 44: openssl-devel 1:3.5.9-1.fc44 · Apache-2.0
fedora 44: openssl-devel 1:3.5.9-1.fc44 · Apache-2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-14: a language model's rewrite of the original, under its terms