EVP_SKEYMGMT(3SSL)

📦
version 4.0.3 · 6 versions
, in ubuntu stonking

💖 EVP_SKEYMGMT — the OpenSSL glow-up for opaque symmetric key management 💖

okay so bestie, pull up a chair, because this is the 3SSL girlies' guide to EVP_SKEYMGMT and friends. it's giving "keys but make them ✨opaque✨" and honestly? obsessed. 🦋

✨ 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 💅

🌸 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 👑

okay so EVP_SKEYMGMT is a method object — like, a whole vibe — and what it represents is the symmetric key management implementations for all the different cryptographic algorithms. no cap. what it does is let providers import key material from the outside, and also export key material back out to the outside. bidirectional slay. 🔥

most of the functionality here can only be used internally and has no public interface, so this opaque object is literally just passed into other functions when somebody needs it. it's the quiet main character. 🎀

  • EVP_SKEYMGMT_fetch() — goes looking for an algorithm inside a provider that's been loaded into the OSSL_LIB_CTX you hand it as ctx, with the name given by algorithm and the properties given by properties. it's the "hey do you have this" text message of functions. 💌
  • EVP_SKEYMGMT_up_ref() — bumps the reference count up on the given EVP_SKEYMGMT skeymgmt. more refs, more love. 💖
  • EVP_SKEYMGMT_free() — decrements the reference count on the given EVP_SKEYMGMT skeymgmt, and when that count hits zero, it frees it. and if the argument is NULL? nothing happens. no drama, nothing done. 🫶
  • EVP_SKEYMGMT_get0_provider() — returns the provider that has this particular implementation. like, whose child is this. 🧚
  • EVP_SKEYMGMT_is_a() — checks whether skeymgmt is an implementation of an algorithm identified by name. vibe check: is it her? 💅
  • EVP_SKEYMGMT_get0_name() — returns the algorithm name from the provided implementation for the given skeymgmt. IMPORTANT though: the skeymgmt may have multiple synonyms attached to it, and in that case the first name from the algorithm definition is the one that comes back. ownership of the returned string stays with the skeymgmt object, so do not free it, bestie. that's not your keychain. 🔑
  • EVP_SKEYMGMT_names_do_all() — traverses every name for the skeymgmt and calls fn with each name and data. a whole name tour. ✨
  • EVP_SKEYMGMT_get0_description() — returns a description of the skeymgmt, meant for display and human consumption. the description is entirely at the discretion of the skeymgmt implementation, so it writes its own bio. 💜
  • EVP_SKEYMGMT_do_all_provided() — traverses all key skeymgmt implementations across all activated providers in the library context libctx, and for each implementation calls fn with the implementation method and data as arguments. a full scroll through the roster. 📜
  • EVP_SKEYMGMT_get0_gen_settable_params() and EVP_SKEYMGMT_get0_imp_settable_params() — these two get a constant OSSL_PARAM(3) array that describes the settable parameters you can use with EVP_SKEY_generate() and EVP_SKEY_import() correspondingly. matching set, obviously. 🎀

🦋 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, if you didn't call it and it still got called… don't be shocked. it's not doing too much, it's just doing its job. 🙈

⭐ 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 the callback was not called for any names. 💀
  • EVP_SKEYMGMT_free() — doesn't return any value. it simply does not. 🌸
  • 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. sometimes she has no bio. it happens. 🎀

🌈 SEE ALSO 🌈

EVP_SKEY(3), EVP_MD_fetch(3), OSSL_LIB_CTX(3)

💜 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(), and EVP_SKEYMGMT_get0_imp_settable_params() were all added in OpenSSL 3.5. new era, new keys, periodt. 👑

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>.

okay that's the whole page bestie, go forth and manage those opaque symmetric keys responsibly 💖✨

this has been your girl signing off from the OpenSSL manual, page EVP_SKEYMGMT(3SSL), version 4.0.3, dated 2026-09-29 — stay iconic, stay referenced, and don't forget to free your refs 🫶💅🌸

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