OSSL_PROVIDER(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

okay bestie, this is OSSL_PROVIDER(3ossl) — the OpenSSL manual page for provider routines, and we’re keeping every single detail because that’s the whole vibe 💅✨

🎀 NAME 🎀

the whole squad, aka 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

OSSL_PROVIDER is the type, and the rest are functions — all provider routines, periodt 🫶

🌸 SYNOPSIS 🌸

the literal signatures, no edits, no vibes-based renaming:

#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 the type that holds the internal info about implementation providers — peep provider(7) if you need the whole “what even is a provider” lore. A provider can be built in to the application or the OpenSSL libraries, or it can be a loadable module. The functions here handle both forms, no cap.

Some of these functions operate inside a library context, so check OSSL_LIB_CTX(3) for the details, bestie.

🦋 Functions 🦋

OSSL_PROVIDER_set_default_search_path() — sets the default search path used when looking for providers in the specified libctx. If you leave it 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 used for looking for providers in the specified libctx. If successful it returns the path or an empty string; the path is valid until the context is released or OSSL_PROVIDER_set_default_search_path() is called.
OSSL_PROVIDER_add_builtin() — used to add a built in provider to the OSSL_PROVIDER store in the given library context by associating a provider name with a provider initialization function. That 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() — the variants of the previous functions accepting an OSSL_PARAM array of the parameters that are passed as the configuration of the loaded provider. 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() — used to get a provider parameter descriptor set as a constant OSSL_PARAM(3) array.
OSSL_PROVIDER_get_params() — 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() — 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).
tiny cache note 🫶 — 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 "CAPABILTIIES" in provider-base(7).

💖 RETURN VALUES 💖

okay bestie, here's the vibe check on what everything 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() — return 1 on success, or 0 on error. slay or flop, no in-between 💅
OSSL_PROVIDER_get0_default_search_path() — returns a pointer to a path on success, or NULL on error or if the path has not previously been set. (yes, NULL can mean "oops" or "nobody set this yet", iconic ambiguity honestly)
OSSL_PROVIDER_load() and OSSL_PROVIDER_try_load() — return a pointer to a provider object on success, or NULL on error.
OSSL_PROVIDER_do_all() — returns 1 if the callback cb returns 1 for every provider it is called with, or 0 if any provider callback invocation returns 0. and listen: callback processing stops at the first callback invocation on a provider that returns 0 — like, it does not keep going, bestie 🛑
OSSL_PROVIDER_available() — returns 1 if the named provider is available, otherwise 0.
OSSL_PROVIDER_gettable_params() — returns a pointer to an array of constant OSSL_PARAM(3), or NULL if none is provided.
OSSL_PROVIDER_get_params() and returns 1 on success, or 0 on error.
OSSL_PROVIDER_query_operation() — returns an array of OSSL_ALGORITHM or NULL on error.
OSSL_PROVIDER_self_test() — returns 1 if the self tests pass, or 0 on error. 🧚

✨ EXAMPLES ✨

okay this one's actually so cute, it shows how to load the provider module "foo" and ask for its build information 🫶

#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);

like, load it, ask it stuff, print the tea — and if anything goes sideways, ERR_print_errors_fp(stderr) spills the receipts to stderr 😭

go read those for the full lore, iykyk 📚

🦋 HISTORY 🦋

The type and functions described here were added in OpenSSL 3.0. 🌱
The OSSL_PROVIDER_load_ex and OSSL_PROVIDER_try_load_ex functions were added in OpenSSL 3.2.
The OSSL_PROVIDER_add_conf_parameter, OSSL_PROVIDER_get_conf_parameters, and OSSL_PROVIDER_conf_get_bool functions were 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>.

and that's the whole page, bestie, you ate that 💅✨ this iconic little writeup is from OpenSSL 3.5.0, dated 2026-09-25, and it lives at OSSL_PROVIDER(3ossl) — go forth and load some providers, periodt 🌈💖

📦 where this page comes from

opensuse-leap 16.0: openssl-3-doc 3.5.0-160000.11.1 · Apache-2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-04: a language model's rewrite of the original, under its terms