PROVIDER-SKEYMGMT(7ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💅 provider-skeymgmt — the SKEYMGMT library ↔ provider functions

Okay so bestie, welcome to PROVIDER-SKEYMGMT(7ossl) — straight out of the OpenSSL 3.5.0 manual set, and honestly? It's giving "internal baddie who does all the work behind the scenes." Let's get into it 🫶

✨ NAME ✨

provider-skeymgmt — the SKEYMGMT library ↔ provider functions. That's the whole name, no cap.

🎀 SYNOPSIS 🎀

#include <openssl/core_dispatch.h>

/*
 * None of these are actual functions, but are displayed like this for
 * the function signatures for functions that are offered as function
 * pointers in OSSL_DISPATCH arrays.
 */

/* Key object destruction */
void OSSL_FUNC_skeymgmt_free(void *keydata);

/* Key object import and export functions */
void *OSSL_FUNC_skeymgmt_import(void *provctx, int selection,
                                const OSSL_PARAM params[]);
int OSSL_FUNC_skeymgmt_export(void *keydata, int selection,
                              OSSL_CALLBACK *param_cb, void *cbarg);
void *OSSL_FUNC_skeymgmt_generate(void *provctx,
                                  const OSSL_PARAM params[]);
const OSSL_PARAM *OSSL_FUNC_skeymgmt_gen_settable_params(void *provctx);
const OSSL_PARAM *OSSL_FUNC_skeymgmt_imp_settable_params(void *provctx);
const char *OSSL_FUNC_skeymgmt_get_key_id(void *keydata);
🚨 Read the comment, bestie, it's important: none of these are actual functions. They're just displayed like this because they're the function signatures for functions that get offered as function pointers in OSSL_DISPATCH arrays. It's a vibe, not a real symbol.

🦋 DESCRIPTION 🦋

So the SKEYMGMT operation doesn't really have much public visibility in the OpenSSL libraries — it's lowkey an internal operation, designed to work with operations that use opaque symmetric keys objects. Main character energy but in the backstage way, yk?

The SKEYMGMT operation shares knowledge with the operations it works with, so the SKEYMGMT and the algorithms that use it must belong to the same provider. Don't worry though — the OpenSSL libraries will ensure that they do. ✨

The primary responsibility of the SKEYMGMT operation is to hold the provider-side key data for the OpenSSL library EVP_SKEY structure. That's literally its whole job.

All the "functions" mentioned here are passed as function pointers between libcrypto and the provider in OSSL_DISPATCH(3) arrays via OSSL_ALGORITHM(3) arrays that are returned by the provider's provider_query_operation() function (see "Provider Functions" in provider-base(7)).

All these "functions" have a corresponding function type definition named OSSL_FUNC_{name}_fn, plus a helper function to retrieve the function pointer from an OSSL_DISPATCH(3) element named OSSL_FUNC_{name}. Iconic little naming convention, honestly.

OSSL_DISPATCH(3) arrays are indexed by numbers that are provided as macros in openssl-core_dispatch.h(7), like so 👇

OSSL_FUNC_skeymgmt_free                 OSSL_FUNC_SKEYMGMT_FREE

OSSL_FUNC_skeymgmt_import               OSSL_FUNC_SKEYMGMT_IMPORT
OSSL_FUNC_skeymgmt_export               OSSL_FUNC_SKEYMGMT_EXPORT

OSSL_FUNC_skeymgmt_generate             OSSL_FUNC_SKEYMGMT_GENERATE

OSSL_FUNC_skeymgmt_get_key_id           OSSL_FUNC_SKEYMGMT_GET_KEY_ID
OSSL_FUNC_skeymgmt_imp_settable_params  OSSL_FUNC_SKEYMGMT_IMP_SETTABLE_PARAMS
OSSL_FUNC_skeymgmt_gen_settable_params  OSSL_FUNC_SKEYMGMT_GEN_SETTABLE_PARAMS

The SKEYMGMT management is inspired by KEYMGMT but is simpler. Little sibling energy fr fr 🧚

🔑 Key Objects

A key object is a collection of data for a symmetric key, and is represented as keydata in this manual.

The exact contents of a key object are defined by the provider, and it is assumed that different operations in one and the same provider use the exact same structure to represent this collection of data — so that, for example, a key object that has been created using the SKEYMGMT interface can be passed as-is to other algorithms from the same provider operations, such as OSSL_FUNC_mac_init_opaque() (see provider-mac(7)). Reuse slay 💅

With the export SKEYMGMT function, it's possible to select a specific subset of data to handle, governed by the bits in a selection indicator. The bits are:

  • OSSL_SKEYMGMT_SELECT_SECRET_KEY — indicating that the secret key raw bytes in a key object should be included.
  • OSSL_SKEYMGMT_SELECT_PARAMETERS — indicating that the parameters in a key object should be included.

Combined selector bits are also defined for easier use:

  • OSSL_SKEYMGMT_SELECT_ALL — indicating that everything in a key object should be included. The whole package, no notes.

The exact interpretation of those bits, or how they combine, is left to each function where you can specify a selector. Provider's choice, bestie.

💀 Destructing Function

OSSL_FUNC_skeymgmt_free() should free the passed keydata. That's it. Clean up your mess, queen.

📥 Key Object Import and Export Functions

OSSL_FUNC_skeymgmt_import() should import data into keydata with values taken from the OSSL_PARAM(3) array params. It allocates the keydata object — and yes, there is no separate allocation function, so don't go looking for one 🙈

OSSL_FUNC_skeymgmt_imp_settable_params() returns a list of parameters that can be provided to the OSSL_FUNC_skeymgmt_import() function.

OSSL_FUNC_skeymgmt_export() should extract values indicated by selection from keydata, create an OSSL_PARAM(3) array with them, and call param_cb with that array as well as the given cbarg. Heads up: the passed OSSL_PARAM(3) array is transient and is freed upon the return from param_cb. So if you need it later, copy it yourself — no cap ⚠️

🌱 Key Object Generation Functions

OSSL_FUNC_skeymgmt_generate() creates a new key according to the values taken from the OSSL_PARAM(3) array params. It allocates the keydata object. Fresh key, fresh vibe ✨

OSSL_FUNC_skeymgmt_gen_settable_params() returns a list of parameters that can be provided to the OSSL_FUNC_skeymgmt_generate() function.

🏷️ Key Object Information Functions

OSSL_FUNC_skeymgmt_get_key_id() returns a NUL-terminated string identifying the particular key. The returned string will be freed by a call to EVP_SKEY_free() — so callers need to copy it themselves if they want to preserve the value past the key lifetime. The purpose of this function is providing a printable string that can help users access the specific key. The content of this string is provider-specific. You've been warned, bestie 😭

🧾 Common Import and Export Parameters

See OSSL_PARAM(3) for further details on the parameters structure.

Common information parameters currently recognised by built-in skeymgmt algorithms are as follows:

  • "raw-bytes" (SKEY_PARAM_RAW_BYTES) <octet string> — the value represents symmetric key as a byte array.
  • "key-length" (SKEY_PARAM_KEY_LENGTH) <integer> — the value is the byte length of the given key.

🌈 RETURN VALUES 🌈

  • OSSL_FUNC_skeymgmt_import() and OSSL_FUNC_skeymgmt_generate() return a pointer to an allocated object on success and NULL on error.
  • OSSL_FUNC_skeymgmt_export() returns 1 for success or 0 on error.
  • OSSL_FUNC_skeymgmt_get_key_id() returns a pointer to a 0-terminated string or NULL.
  • OSSL_FUNC_skeymgmt_gen_settable_params() and OSSL_FUNC_skeymgmt_imp_settable_params() return references to an array of OSSL_PARAM which can be NULL if there are no settable parameters.

👀 SEE ALSO 👀

provider(7), EVP_SKEY(3), EVP_KEYMGMT(3) — go read those next, they're the supporting cast 🫶

🕰️ HISTORY 🕰️

The SKEYMGMT interface was introduced in OpenSSL 3.5. Baby of the family, already thriving 💖

Copyright 2024-2025 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 — no crumbs left 🍓 This was PROVIDER-SKEYMGMT(7ossl) from the 3.5.0 manual set, dated 2026-09-25. Go forth and manage those symmetric keys, you absolute icon 👑💅✨

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