PROVIDER-KEYMGMT(7SSL) OpenSSL PROVIDER-KEYMGMT(7SSL)
NAME
provider-keymgmt - The KEYMGMT library <-> provider functions
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 (keydata) creation and destruction */
void *OSSL_FUNC_keymgmt_new(void *provctx);
void OSSL_FUNC_keymgmt_free(void *keydata);
/* Generation, a more complex constructor */
void *OSSL_FUNC_keymgmt_gen_init(void *provctx, int selection,
const OSSL_PARAM params[]);
int OSSL_FUNC_keymgmt_gen_set_template(void *genctx, void *template);
int OSSL_FUNC_keymgmt_gen_set_params(void *genctx, const OSSL_PARAM params[]);
const OSSL_PARAM *OSSL_FUNC_keymgmt_gen_settable_params(void *genctx,
void *provctx);
void *OSSL_FUNC_keymgmt_gen(void *genctx, OSSL_CALLBACK *cb, void *cbarg);
void OSSL_FUNC_keymgmt_gen_cleanup(void *genctx);
/* Key loading by object reference, also a constructor */
void *OSSL_FUNC_keymgmt_load(const void *reference, size_t *reference_sz);
/* Key object information */
int OSSL_FUNC_keymgmt_get_params(void *keydata, OSSL_PARAM params[]);
const OSSL_PARAM *OSSL_FUNC_keymgmt_gettable_params(void *provctx);
int OSSL_FUNC_keymgmt_set_params(void *keydata, const OSSL_PARAM params[]);
const OSSL_PARAM *OSSL_FUNC_keymgmt_settable_params(void *provctx);
/* Key object content checks */
int OSSL_FUNC_keymgmt_has(const void *keydata, int selection);
int OSSL_FUNC_keymgmt_match(const void *keydata1, const void *keydata2,
int selection);
/* Discovery of supported operations */
const char *OSSL_FUNC_keymgmt_query_operation_name(int operation_id);
/* Key object import and export functions */
int OSSL_FUNC_keymgmt_import(void *keydata, int selection, const OSSL_PARAM params[]);
const OSSL_PARAM *OSSL_FUNC_keymgmt_import_types(int selection);
int OSSL_FUNC_keymgmt_export(void *keydata, int selection,
OSSL_CALLBACK *param_cb, void *cbarg);
const OSSL_PARAM *OSSL_FUNC_keymgmt_export_types(int selection);
/* Key object duplication, a constructor */
void *OSSL_FUNC_keymgmt_dup(const void *keydata_from, int selection);
/* Key object validation */
int OSSL_FUNC_keymgmt_validate(const void *keydata, int selection, int checktype);
DESCRIPTION
The KEYMGMT operation doesn't have much public visibility in OpenSSL
libraries, it's rather an internal operation that's designed to work in
tandem with operations that use private/public key pairs.
Because the KEYMGMT operation shares knowledge with the operations it
works with in tandem, they must belong to the same provider. The
OpenSSL libraries will ensure that they do.
The primary responsibility of the KEYMGMT operation is to hold the
provider side key data for the OpenSSL library EVP_PKEY structure.
All "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, and a helper function to retrieve the
function pointer from a OSSL_DISPATCH(3) element named
OSSL_FUNC_{name}. For example, the "function" OSSL_FUNC_keymgmt_new()
has these:
typedef void *(OSSL_FUNC_keymgmt_new_fn)(void *provctx);
static ossl_inline OSSL_FUNC_keymgmt_new_fn
OSSL_FUNC_keymgmt_new(const OSSL_DISPATCH *opf);
OSSL_DISPATCH(3) arrays are indexed by numbers that are provided as
macros in openssl-core_dispatch.h(7), as follows:
OSSL_FUNC_keymgmt_new OSSL_FUNC_KEYMGMT_NEW
OSSL_FUNC_keymgmt_free OSSL_FUNC_KEYMGMT_FREE
OSSL_FUNC_keymgmt_gen_init OSSL_FUNC_KEYMGMT_GEN_INIT
OSSL_FUNC_keymgmt_gen_set_template OSSL_FUNC_KEYMGMT_GEN_SET_TEMPLATE
OSSL_FUNC_keymgmt_gen_set_params OSSL_FUNC_KEYMGMT_GEN_SET_PARAMS
OSSL_FUNC_keymgmt_gen_settable_params OSSL_FUNC_KEYMGMT_GEN_SETTABLE_PARAMS
OSSL_FUNC_keymgmt_gen OSSL_FUNC_KEYMGMT_GEN
OSSL_FUNC_keymgmt_gen_cleanup OSSL_FUNC_KEYMGMT_GEN_CLEANUP
OSSL_FUNC_keymgmt_load OSSL_FUNC_KEYMGMT_LOAD
OSSL_FUNC_keymgmt_get_params OSSL_FUNC_KEYMGMT_GET_PARAMS
OSSL_FUNC_keymgmt_gettable_params OSSL_FUNC_KEYMGMT_GETTABLE_PARAMS
OSSL_FUNC_keymgmt_set_params OSSL_FUNC_KEYMGMT_SET_PARAMS
OSSL_FUNC_keymgmt_settable_params OSSL_FUNC_KEYMGMT_SETTABLE_PARAMS
OSSL_FUNC_keymgmt_query_operation_name OSSL_FUNC_KEYMGMT_QUERY_OPERATION_NAME
OSSL_FUNC_keymgmt_has OSSL_FUNC_KEYMGMT_HAS
OSSL_FUNC_keymgmt_validate OSSL_FUNC_KEYMGMT_VALIDATE
OSSL_FUNC_keymgmt_match OSSL_FUNC_KEYMGMT_MATCH
OSSL_FUNC_keymgmt_import OSSL_FUNC_KEYMGMT_IMPORT
OSSL_FUNC_keymgmt_import_types OSSL_FUNC_KEYMGMT_IMPORT_TYPES
OSSL_FUNC_keymgmt_export OSSL_FUNC_KEYMGMT_EXPORT
OSSL_FUNC_keymgmt_export_types OSSL_FUNC_KEYMGMT_EXPORT_TYPES
OSSL_FUNC_keymgmt_dup OSSL_FUNC_KEYMGMT_DUP
Key Objects
A key object is a collection of data for an asymmetric 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 KEYMGMT
interface that we document here can be passed as is to other provider
operations, such as OP_signature_sign_init() (see
provider-signature(7)).
With some of the KEYMGMT functions, it's possible to select a specific
subset of data to handle, governed by the bits in a selection
indicator. The bits are:
OSSL_KEYMGMT_SELECT_PRIVATE_KEY
Indicating that the private key data in a key object should be
considered.
OSSL_KEYMGMT_SELECT_PUBLIC_KEY
Indicating that the public key data in a key object should be
considered.
OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS
Indicating that the domain parameters in a key object should be
considered.
OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS
Indicating that other parameters in a key object should be
considered.
Other parameters are key parameters that don't fit any other
classification. In other words, this particular selector bit works
as a last resort bit bucket selector.
Some selector bits have also been combined for easier use:
OSSL_KEYMGMT_SELECT_ALL_PARAMETERS
Indicating that all key object parameters should be considered,
regardless of their more granular classification.
This is a combination of OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS and
OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS.
OSSL_KEYMGMT_SELECT_KEYPAIR
Indicating that both the whole key pair in a key object should be
considered, i.e. the combination of public and private key.
This is a combination of OSSL_KEYMGMT_SELECT_PRIVATE_KEY and
OSSL_KEYMGMT_SELECT_PUBLIC_KEY.
OSSL_KEYMGMT_SELECT_ALL
Indicating that everything in a key object should be considered.
The exact interpretation of those bits or how they combine is left to
each function where you can specify a selector.
It's left to the provider implementation to decide what is reasonable
to do with regards to received selector bits and how to do it. Among
others, an implementation of OSSL_FUNC_keymgmt_match() might opt to not
compare the private half if it has compared the public half, since a
match of one half implies a match of the other half.
Constructing and Destructing Functions
OSSL_FUNC_keymgmt_new() should create a provider side key object. The
provider context provctx is passed and may be incorporated in the key
object, but that is not mandatory.
OSSL_FUNC_keymgmt_free() should free the passed keydata.
OSSL_FUNC_keymgmt_gen_init(), OSSL_FUNC_keymgmt_gen_set_template(),
OSSL_FUNC_keymgmt_gen_set_params(),
OSSL_FUNC_keymgmt_gen_settable_params(), OSSL_FUNC_keymgmt_gen() and
OSSL_FUNC_keymgmt_gen_cleanup() work together as a more elaborate
context based key object constructor.
OSSL_FUNC_keymgmt_gen_init() should create the key object generation
context and initialize it with selections, which will determine what
kind of contents the key object to be generated should get. The
params, if not NULL, should be set on the context in a manner similar
to using OSSL_FUNC_keymgmt_set_params().
OSSL_FUNC_keymgmt_gen_set_template() should add template to the context
genctx. The template is assumed to be a key object constructed with
the same KEYMGMT, and from which content that the implementation
chooses can be used as a template for the key object to be generated.
Typically, the generation of a DSA or DH key would get the domain
parameters from this template.
OSSL_FUNC_keymgmt_gen_set_params() should set additional parameters
from params in the key object generation context genctx.
OSSL_FUNC_keymgmt_gen_settable_params() should return a constant array
of descriptor OSSL_PARAM(3), for parameters that
OSSL_FUNC_keymgmt_gen_set_params() can handle.
OSSL_FUNC_keymgmt_gen() should perform the key object generation
itself, and return the result. The callback cb should be called at
regular intervals with indications on how the key object generation
progresses.
OSSL_FUNC_keymgmt_gen_cleanup() should clean up and free the key object
generation context genctx
OSSL_FUNC_keymgmt_load() creates a provider side key object based on a
reference object with a size of reference_sz bytes, that only the
provider knows how to interpret, but that may come from other
operations. Outside the provider, this reference is simply an array of
bytes.
At least one of OSSL_FUNC_keymgmt_new(), OSSL_FUNC_keymgmt_gen() and
OSSL_FUNC_keymgmt_load() are mandatory, as well as
OSSL_FUNC_keymgmt_free() and OSSL_FUNC_keymgmt_has(). Additionally, if
OSSL_FUNC_keymgmt_gen() is present, OSSL_FUNC_keymgmt_gen_init() and
OSSL_FUNC_keymgmt_gen_cleanup() must be present as well.
Key Object Information Functions
OSSL_FUNC_keymgmt_get_params() should extract information data
associated with the given keydata, see "Common Information Parameters".
OSSL_FUNC_keymgmt_gettable_params() should return a constant array of
descriptor OSSL_PARAM(3), for parameters that
OSSL_FUNC_keymgmt_get_params() can handle.
If OSSL_FUNC_keymgmt_gettable_params() is present,
OSSL_FUNC_keymgmt_get_params() must also be present, and vice versa.
OSSL_FUNC_keymgmt_set_params() should update information data
associated with the given keydata, see "Common Information Parameters".
OSSL_FUNC_keymgmt_settable_params() should return a constant array of
descriptor OSSL_PARAM(3), for parameters that
OSSL_FUNC_keymgmt_set_params() can handle.
If OSSL_FUNC_keymgmt_settable_params() is present,
OSSL_FUNC_keymgmt_set_params() must also be present, and vice versa.
Key Object Checking Functions
OSSL_FUNC_keymgmt_query_operation_name() should return the name of the
supported algorithm for the operation operation_id. This is similar to
provider_query_operation() (see provider-base(7)), but only works as an
advisory. If this function is not present, or returns NULL, the caller
is free to assume that there's an algorithm from the same provider, of
the same name as the one used to fetch the keymgmt and try to use that.
OSSL_FUNC_keymgmt_has() should check whether the given keydata contains
the subsets of data indicated by the selector. A combination of
several selector bits must consider all those subsets, not just one.
An implementation is, however, free to consider an empty subset of data
to still be a valid subset. For algorithms where some selection is not
meaningful such as OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS for RSA keys
the function should just return 1 as the selected subset is not really
missing in the key.
OSSL_FUNC_keymgmt_validate() should check if the keydata contains valid
data subsets indicated by selection. Some combined selections of data
subsets may cause validation of the combined data. For example, the
combination of OSSL_KEYMGMT_SELECT_PRIVATE_KEY and
OSSL_KEYMGMT_SELECT_PUBLIC_KEY (or OSSL_KEYMGMT_SELECT_KEYPAIR for
short) is expected to check that the pairwise consistency of keydata is
valid. The checktype parameter controls what type of check is performed
on the subset of data. Two types of check are defined:
OSSL_KEYMGMT_VALIDATE_FULL_CHECK and OSSL_KEYMGMT_VALIDATE_QUICK_CHECK.
The interpretation of how much checking is performed in a full check
versus a quick check is key type specific. Some providers may have no
distinction between a full check and a quick check. For algorithms
where some selection is not meaningful such as
OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS for RSA keys the function should
just return 1 as there is nothing to validate for that selection.
OSSL_FUNC_keymgmt_match() should check if the data subset indicated by
selection in keydata1 and keydata2 match. It is assumed that the
caller has ensured that keydata1 and keydata2 are both owned by the
implementation of this function.
Key Object Import, Export and Duplication Functions
OSSL_FUNC_keymgmt_import() should import data indicated by selection
into keydata with values taken from the OSSL_PARAM(3) array params.
OSSL_FUNC_keymgmt_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.
OSSL_FUNC_keymgmt_import_types() should return a constant array of
descriptor OSSL_PARAM(3) for data indicated by selection, for
parameters that OSSL_FUNC_keymgmt_import() can handle.
OSSL_FUNC_keymgmt_export_types() should return a constant array of
descriptor OSSL_PARAM(3) for data indicated by selection, that the
OSSL_FUNC_keymgmt_export() callback can expect to receive.
OSSL_FUNC_keymgmt_dup() should duplicate data subsets indicated by
selection or the whole key data keydata_from and create a new provider
side key object with the data.
Common Information Parameters
See OSSL_PARAM(3) for further details on the parameters structure.
Common information parameters currently recognised by all built-in
keymgmt algorithms are as follows:
"bits" (OSSL_PKEY_PARAM_BITS) <integer>
The value should be the cryptographic length of the cryptosystem to
which the key belongs, in bits. The definition of cryptographic
length is specific to the key cryptosystem.
"max-size" (OSSL_PKEY_PARAM_MAX_SIZE) <integer>
The value should be the maximum size that a caller should allocate
to safely store a signature (called sig in provider-signature(7)),
the result of asymmetric encryption / decryption (out in
provider-asym_cipher(7), a derived secret (secret in
provider-keyexch(7), and similar data).
Because an EVP_KEYMGMT method is always tightly bound to another
method (signature, asymmetric cipher, key exchange, ...) and must
be of the same provider, this number only needs to be synchronised
with the dimensions handled in the rest of the same provider.
"security-bits" (OSSL_PKEY_PARAM_SECURITY_BITS) <integer>
The value should be the number of security bits of the given key.
Bits of security is defined in SP800-57.
"mandatory-digest" (OSSL_PKEY_PARAM_MANDATORY_DIGEST) <UTF8 string>
If there is a mandatory digest for performing a signature operation
with keys from this keymgmt, this parameter should get its name as
value.
When EVP_PKEY_get_default_digest_name() queries this parameter and
it's filled in by the implementation, its return value will be 2.
If the keymgmt implementation fills in the value "" or "UNDEF",
EVP_PKEY_get_default_digest_name(3) will place the string "UNDEF"
into its argument mdname. This signifies that no digest should be
specified with the corresponding signature operation.
"default-digest" (OSSL_PKEY_PARAM_DEFAULT_DIGEST) <UTF8 string>
If there is a default digest for performing a signature operation
with keys from this keymgmt, this parameter should get its name as
value.
When EVP_PKEY_get_default_digest_name(3) queries this parameter and
it's filled in by the implementation, its return value will be 1.
Note that if OSSL_PKEY_PARAM_MANDATORY_DIGEST is responded to as
well, EVP_PKEY_get_default_digest_name(3) ignores the response to
this parameter.
If the keymgmt implementation fills in the value "" or "UNDEF",
EVP_PKEY_get_default_digest_name(3) will place the string "UNDEF"
into its argument mdname. This signifies that no digest has to be
specified with the corresponding signature operation, but may be
specified as an option.
RETURN VALUES
OSSL_FUNC_keymgmt_new() and OSSL_FUNC_keymgmt_dup() should return a
valid reference to the newly created provider side key object, or NULL
on failure.
OSSL_FUNC_keymgmt_import(), OSSL_FUNC_keymgmt_export(),
OSSL_FUNC_keymgmt_get_params() and OSSL_FUNC_keymgmt_set_params()
should return 1 for success or 0 on error.
OSSL_FUNC_keymgmt_validate() should return 1 on successful validation,
or 0 on failure.
OSSL_FUNC_keymgmt_has() should return 1 if all the selected data
subsets are contained in the given keydata or 0 otherwise.
OSSL_FUNC_keymgmt_query_operation_name() should return a pointer to a
string matching the requested operation, or NULL if the same name used
to fetch the keymgmt applies.
OSSL_FUNC_keymgmt_gettable_params() and
OSSL_FUNC_keymgmt_settable_params() OSSL_FUNC_keymgmt_import_types(),
OSSL_FUNC_keymgmt_export_types() should always return a constant
OSSL_PARAM(3) array.
SEE ALSO
provider(7), EVP_PKEY-X25519(7), EVP_PKEY-X448(7), EVP_PKEY-ED25519(7),
EVP_PKEY-ED448(7), EVP_PKEY-EC(7), EVP_PKEY-RSA(7), EVP_PKEY-DSA(7),
EVP_PKEY-DH(7)
HISTORY
The KEYMGMT interface was introduced in OpenSSL 3.0.
COPYRIGHT
Copyright 2019-2024 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>.
3.0.13 2025-09-18 PROVIDER-KEYMGMT(7SSL)
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