EVP_SKEY(3ossl)

📦
version 15.1 · 2 versions
, in freebsd 15.1

NAME 💖

Okay bestie, this is the EVP_SKEY(3ossl) page, and it's literally all about opaque symmetric key allocation and handling functions. The whole squad is: EVP_SKEY, EVP_SKEY_generate, EVP_SKEY_import, EVP_SKEY_import_raw_key, EVP_SKEY_up_ref, EVP_SKEY_export, EVP_SKEY_get0_raw_key, EVP_SKEY_get0_key_id, EVP_SKEY_get0_skeymgmt_name, EVP_SKEY_get0_provider_name, EVP_SKEY_free, EVP_SKEY_is_a, and EVP_SKEY_to_provider. Slay. 💅

SYNOPSIS ✨

#include <openssl/evp.h>

typedef evp_skey_st EVP_SKEY;

EVP_SKEY *EVP_SKEY_generate(OSSL_LIB_CTX *libctx, const char *skeymgmtname,
                            const char *propquery, const OSSL_PARAM *params);
EVP_SKEY *EVP_SKEY_import(OSSL_LIB_CTX *libctx, const char *skeymgmtname,
                          const char *propquery,
                          int selection, const OSSL_PARAM *params);
EVP_SKEY *EVP_SKEY_import_raw_key(OSSL_LIB_CTX *libctx, const char *skeymgmtname,
                                  unsigned char *key, size_t len,
                                  const char *propquery);
int EVP_SKEY_export(const EVP_SKEY *skey, int selection,
                    OSSL_CALLBACK *export_cb, void *export_cbarg);
int EVP_SKEY_get0_raw_key(const EVP_SKEY *skey, const unsigned char **key,
                         size_t *len);
const char *EVP_SKEY_get0_key_id(const EVP_SKEY *skey);

const char *EVP_SKEY_get0_skeymgmt_name(const EVP_SKEY *skey);
const char *EVP_SKEY_get0_provider_name(const EVP_SKEY *skey);

int EVP_SKEY_up_ref(EVP_SKEY *key);
void EVP_SKEY_free(EVP_SKEY *key);
int EVP_SKEY_is_a(const EVP_SKEY *skey, const char *name);
EVP_SKEY *EVP_SKEY_to_provider(EVP_SKEY *skey, OSSL_LIB_CTX *libctx,
                               OSSL_PROVIDER *prov, const char *propquery);

DESCRIPTION 🦋

So, EVP_SKEY is a generic structure that holds symmetric keys as opaque objects. The keys themselves are often called the "internal key", and they're handled by providers using EVP_SKEYMGMT(3). Periodt.

Conceptually, an EVP_SKEY internal key may hold a symmetric key, and along with that, key parameters if the key type requires them. It's giving very organized little key container energy. 🎀

  • EVP_SKEY_generate() — creates a new EVP_SKEY object and initializes it according to the params argument. Fresh key, who dis. ✨
  • EVP_SKEY_import() — allocates an empty EVP_SKEY structure which is used by OpenSSL to store symmetric keys, assigns the EVP_SKEYMGMT object associated with the key, and initializes the object from the params argument. Very "come through, imported key" of it. 💖
  • EVP_SKEY_import_raw_key() — a helper that creates an EVP_SKEY object containing the raw byte representation of the symmetric keys from the buffer key having length len. The skeymgmtname defines the name of the target EVP_SKEYMGMT for the newly created key. Raw key bestie, no cap. 🫶
  • EVP_SKEY_export() — extracts values from a key skey using the selection. selection is described below. It uses a callback export_cb that gets passed the value of export_cbarg. See openssl-core.h(7) for more information about the callback. Note that the OSSL_PARAM(3) array that is passed to the callback is not persistent after the callback returns. Like, it does not stick around, bestie. 😭
  • EVP_SKEY_get0_raw_key() — returns a pointer to a raw key bytes to the passed address and sets the key len. The returned address is managed by the internal key management and shouldn't be freed explicitly. The operation can fail when the underlying key management doesn't support export of the secret key. Do not free it yourself, I'm begging. 🙈
  • EVP_SKEY_get0_key_id() — returns a NUL-terminated string providing some human-readable identifier of the key if provided by the underlying key management. The pointer becomes invalid after freeing the EVP_SKEY object. So don't be using it after the key is gone, okay? 💀
  • EVP_SKEY_get0_skeymgmt_name() and EVP_SKEY_get0_provider_name() — return the names of the associated EVP_SKEYMGMT object and its provider correspondingly. Name reveal, but make it cryptographic. 👑
  • EVP_SKEY_up_ref() — increments the reference count of key. Ref count go brrr. 🔥
  • EVP_SKEY_free() — decrements the reference count of key and, if the reference count is zero, frees it. If key is NULL, nothing is done. Very chill about it too. 🌈
  • EVP_SKEY_is_a() — checks if the key type of skey is name. Identity check, but for keys. ⭐
  • EVP_SKEY_to_provider() — simplifies the task of importing a skey into a different provider identified by prov. If prov is NULL, the default provider for the key type identified via skey is used. Provider glow-up, lowkey iconic. 💜

Selections 🎀

The following constants can be used for selection:

  • OSSL_SKEYMGMT_SELECT_SECRET_KEY — Only the raw key representation will be selected. Secret key only, bestie. 💅
  • OSSL_SKEYMGMT_SELECT_PARAMETERS — Only the key parameters will be selected. This includes optional key parameters. Parameter girlies, this is your moment. 🌸
  • OSSL_SKEYMGMT_SELECT_ALL — All parameters will be selected. The whole menu, not just the appetizer. ✨

NOTES 🧚

The EVP_SKEY structure is used by various OpenSSL functions which require a general symmetric key without reference to any particular algorithm. It's the general-purpose bestie of symmetric keys. 🦋

The EVP_SKEY_to_provider() function will fail and return NULL if the origin key skey cannot be exported from its provider. Like, if it can't leave the provider, it can't leave. Periodt. 💀

RETURN VALUES 🌈

  • EVP_SKEY_generate(), EVP_SKEY_import() and EVP_SKEY_import_raw_key() return either the newly allocated EVP_SKEY structure or NULL if an error occurred. New key or no key, no in-between. 💖
  • EVP_SKEY_get0_key_id() returns either a valid pointer or NULL. Simple as that. 🎀
  • EVP_SKEY_up_ref() returns 1 for success and 0 on failure. Ref count success slay. ✨
  • EVP_SKEY_export() and EVP_SKEY_get0_raw_key() return 1 for success and 0 on failure. Honestly? Fair. 💅
  • EVP_SKEY_get0_skeymgmt_name() and EVP_SKEY_get0_provider_name() return the names of the associated EVP_SKEYMGMT object and its provider correspondingly. Names, delivered. 👑
  • EVP_SKEY_is_a() returns 1 if skey has the key type name, otherwise 0. Identity confirmed or denied. ⭐
  • EVP_SKEY_to_provider() returns a new EVP_SKEY suitable for operations with the prov provider or NULL in case of failure. Provider-ready key or absolutely nothing. 🫶

SEE ALSO 🔍

EVP_SKEYMGMT(3), provider(7), OSSL_PARAM(3)

HISTORY 🕰️

The EVP_SKEY API and functions EVP_SKEY_export(), EVP_SKEY_free(), EVP_SKEY_get0_raw_key(), EVP_SKEY_import(), EVP_SKEY_import_raw_key(), EVP_SKEY_up_ref(), EVP_SKEY_generate(), EVP_SKEY_get0_key_id(), EVP_SKEY_get0_provider_name(), EVP_SKEY_get0_skeymgmt_name(), EVP_SKEY_is_a(), EVP_SKEY_to_provider() were introduced in OpenSSL 3.5. Historic. Iconic. New in 3.5. 💅

Copyright 2025-2026 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>. Legal bestie has entered the chat. 🫶

And that's the whole vibe check, bestie: this page is from OpenSSL 3.5.6, dated 2026-04-07, and it's the EVP_SKEY(3ossl) manual page signing off. Stay opaque, stay symmetric, and don't free stuff you don't own. 💖✨🎀

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