EVP_SKEYMGMT(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💖 EVP_SKEYMGMT — key mgmt routines for opaque symmetric keys 💖

okay bestie, so this is the EVP_SKEYMGMT(3ossl) page from the OpenSSL manual, and it's lowkey one of those pages where half the functions are like "you'll never call me directly but I'm still iconic." Let's get into it ✨

🌸 NAME 🌸

EVP_SKEYMGMT, EVP_SKEYMGMT_fetch, EVP_SKEYMGMT_up_ref, EVP_SKEYMGMT_free, EVP_SKEYMGMT_get0_provider, EVP_SKEYMGMT_is_a, EVP_SKEYMGMT_get0_description, EVP_SKEYMGMT_get0_name, EVP_SKEYMGMT_do_all_provided, EVP_SKEYMGMT_names_do_all, EVP_SKEYMGMT_get0_gen_settable_params, EVP_SKEYMGMT_get0_imp_settable_params — the EVP key management routines for opaque symmetric keys, fr fr 🫶

✨ SYNOPSIS ✨

#include <openssl/evp.h>

typedef struct evp_sskeymgmt_st EVP_SKEYMGMT;

EVP_SKEYMGMT *EVP_SKEYMGMT_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
                                 const char *properties);
int EVP_SKEYMGMT_up_ref(EVP_SKEYMGMT *skeymgmt);
void EVP_SKEYMGMT_free(EVP_SKEYMGMT *skeymgmt);
const OSSL_PROVIDER *EVP_SKEYMGMT_get0_provider(const EVP_SKEYMGMT *skeymgmt);
int EVP_SKEYMGMT_is_a(const EVP_SKEYMGMT *skeymgmt, const char *name);
const char *EVP_SKEYMGMT_get0_name(const EVP_SKEYMGMT *skeymgmt);
const char *EVP_SKEYMGMT_get0_description(const EVP_SKEYMGMT *skeymgmt);

void EVP_SKEYMGMT_do_all_provided(OSSL_LIB_CTX *libctx,
                                  void (*fn)(EVP_SKEYMGMT *skeymgmt, void *arg),
                                  void *arg);
int EVP_SKEYMGMT_names_do_all(const EVP_SKEYMGMT *skeymgmt,
                              void (*fn)(const char *name, void *data),
                              void *data);
const OSSL_PARAM *EVP_SKEYMGMT_get0_gen_settable_params(const EVP_SKEYMGMT *skeymgmt);
const OSSL_PARAM *EVP_SKEYMGMT_get0_imp_settable_params(const EVP_SKEYMGMT *skeymgmt);

🦋 DESCRIPTION 🦋

So EVP_SKEYMGMT is a method object — think of it as the main character that represents symmetric key management implementations for different cryptographic algorithms 💅 This method object is the one that lets providers import key material from the outside, and also export key material back out to the outside. Both directions, no cap.

Most of the functionality here can only be used internally and has no public interface at all — this opaque object is literally just passed into other functions when they need it. It's giving backstage pass, not front-row seat 🙈

  • EVP_SKEYMGMT_fetch() — looks for an algorithm within a provider that's been loaded into the OSSL_LIB_CTX given by ctx, having the name given by algorithm and the properties given by properties.
  • EVP_SKEYMGMT_up_ref() — increments the reference count for the given EVP_SKEYMGMT skeymgmt. Refcount go up 📈
  • EVP_SKEYMGMT_free() — decrements the reference count for the given EVP_SKEYMGMT skeymgmt, and when the count hits zero, it frees it. And if the argument is NULL, nothing happens — it just minds its business, we love that.
  • EVP_SKEYMGMT_get0_provider() — returns the provider that has this particular implementation. Like, which house does this algorithm belong to 👑
  • EVP_SKEYMGMT_is_a() — checks if skeymgmt is an implementation of an algorithm that's identified by name.
  • EVP_SKEYMGMT_get0_name() — returns the algorithm name from the provided implementation for the given skeymgmt. Heads up though: skeymgmt may have multiple synonyms associated with it, and in that case the first name from the algorithm definition is the one you get. Ownership of the returned string is retained by the skeymgmt object and should not be freed by the caller — so do not touch it, bestie, it's not yours 🫶
  • EVP_SKEYMGMT_names_do_all() — traverses all names for the skeymgmt, and calls fn with each name and data.
  • EVP_SKEYMGMT_get0_description() — returns a description of the skeymgmt, meant for display and human consumption. The description is totally at the discretion of the skeymgmt implementation, so it's whatever the implementation felt like writing that day 💀
  • EVP_SKEYMGMT_do_all_provided() — traverses all key skeymgmt implementations by all activated providers in the library context libctx, and for each of the implementations, calls fn with the implementation method and data as arguments.
  • EVP_SKEYMGMT_get0_gen_settable_params() and EVP_SKEYMGMT_get0_imp_settable_params() — get a constant OSSL_PARAM(3) array that describes the settable parameters that can be used with EVP_SKEY_generate() and EVP_SKEY_import() correspondingly. One's for generating, one's for importing, they're siblings, they're a matching set 🎀

⭐ NOTES ⭐

EVP_SKEYMGMT_fetch() may be called implicitly by other fetching functions, using the same library context and properties. Any other API that uses symmetric keys will typically do this — so like, you might never call it yourself and it's still out here working 24/7. Iconic behaviour, honestly 🔥

🌈 RETURN VALUES 🌈

  • EVP_SKEYMGMT_fetch() — returns a pointer to the key management implementation represented by an EVP_SKEYMGMT object, or NULL on error.
  • EVP_SKEYMGMT_up_ref() — returns 1 on success, or 0 on error.
  • EVP_SKEYMGMT_names_do_all() — returns 1 if the callback was called for all names. A return value of 0 means that the callback was not called for any names.
  • EVP_SKEYMGMT_free() — doesn't return any value. It's giving void, it's giving nothing to report 💅
  • EVP_SKEYMGMT_get0_provider() — returns a pointer to a provider object, or NULL on error.
  • EVP_SKEYMGMT_is_a() — returns 1 if skeymgmt was identifiable, otherwise 0.
  • EVP_SKEYMGMT_get0_name() — returns the algorithm name, or NULL on error.
  • EVP_SKEYMGMT_get0_description() — returns a pointer to a description, or NULL if there isn't one.

🧚 SEE ALSO 🧚

EVP_SKEY(3), EVP_MD_fetch(3), OSSL_LIB_CTX(3) — go read these next, they're the friends of this page 🦋

👑 HISTORY 👑

The EVP_SKEYMGMT structure and the functions EVP_SKEYMGMT_fetch(), EVP_SKEYMGMT_up_ref(), EVP_SKEYMGMT_free(), EVP_SKEYMGMT_get0_provider(), EVP_SKEYMGMT_is_a(), EVP_SKEYMGMT_get0_description(), EVP_SKEYMGMT_get0_name(), EVP_SKEYMGMT_do_all_provided(), EVP_SKEYMGMT_names_do_all(), EVP_SKEYMGMT_get0_gen_settable_params(), EVP_SKEYMGMT_get0_imp_settable_params() were all added in OpenSSL 3.5. New drop, fresh out the box 🍓

Copyright 2025 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>.

and that's the whole page, bestie, we ate and left zero crumbs 💅✨ this was OpenSSL 3.5.0, dated 2026-09-25 — mwah, see you in the next manpage 🎀🫶

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