man > provider-keymgmt(7ssl)

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                                       2026-07-29                       PROVIDER-KEYMGMT(7SSL)