phpman > man > openssl-core.h(7)

OPENSSL-CORE.H(7SSL)                           OpenSSL                          OPENSSL-CORE.H(7SSL)



NAME
       openssl/core.h - OpenSSL Core types

SYNOPSIS
        #include <openssl/core.h>

DESCRIPTION
       The <openssl/core.h> header defines a number of public types that are used to communicate
       between the OpenSSL libraries and implementation providers.  These types are designed to
       minimise the need for intimate knowledge of internal structures between the OpenSSL libraries
       and the providers.

       The types are:

       OSSL_DISPATCH
           This type is a tuple of function identity and function pointer.  Arrays of this type are
           passed between the OpenSSL libraries and the providers to describe what functionality one
           side provides to the other.  Arrays of this type must be terminated with a tuple having
           function identity zero and function pointer NULL.

           The available function identities and corresponding function signatures are defined in
           openssl-core_dispatch.h(7).

           Any function identity not recognised by the recipient of this type will be ignored.  This
           ensures that providers built with one OpenSSL version in mind will work together with any
           other OpenSSL version that supports this mechanism.

       OSSL_ITEM
           This type is a tuple of integer and pointer.  It's a generic type used as a generic
           descriptor, its exact meaning being defined by how it's used.  Arrays of this type are
           passed between the OpenSSL libraries and the providers, and must be terminated with a
           tuple where the integer is zero and the pointer NULL.

       OSSL_ALGORITHM
           This type is a tuple of an algorithm name (string), a property definition (string) and a
           dispatch table (array of OSSL_DISPATCH).  Arrays of this type are passed on demand from
           the providers to the OpenSSL libraries to describe what algorithms the providers provide
           implementations of, and with what properties.  Arrays of this type must be terminated
           with a tuple having function identity zero and function pointer NULL.

           The algorithm names and property definitions are defined by the providers.

           The OpenSSL libraries use the first of the algorithm names as the main or canonical name,
           on a per algorithm implementation basis.

       OSSL_PARAM
           This type is a structure that allows passing arbitrary object data between two parties
           that have no or very little shared knowledge about their respective internal structures
           for that object.  It's normally passed in arrays, where the array is terminated with an
           element where all fields are zero (for non-pointers) or NULL (for pointers).

           These arrays can be used to set parameters for some object, to request parameters, and to
           describe parameters.

           OSSL_PARAM is further described in OSSL_PARAM(3)

       OSSL_CALLBACK
           This is a function type for a generic feedback callback function:

               typedef int (OSSL_CALLBACK)(const OSSL_PARAM params[], void *arg);

           A function that takes a pointer of this type should also take a pointer to caller data.
           When calling this callback, the function is expected to build an OSSL_PARAM array of data
           it wants or is expected to pass back, and pass that as params, as well as the caller data
           pointer it received, as arg.

       OSSL_PASSPHRASE_CALLBACK
           This is a function type for a generic pass phrase callback function:

               typedef int (OSSL_PASSPHRASE_CALLBACK)(char *pass, size_t pass_size,
                                                      size_t *pass_len,
                                                      const OSSL_PARAM params[],
                                                      void *arg);

           This callback can be used to prompt the user for a passphrase.  When calling it, a buffer
           to store the pass phrase needs to be given with pass, and its size with pass_size.  The
           length of the prompted pass phrase will be given back in *pass_len.

           Additional parameters can be passed with the OSSL_PARAM array params.

           A function that takes a pointer of this type should also take a pointer to caller data,
           which should be passed as arg to this callback.

SEE ALSO
       openssl-core_dispatch.h(7)

HISTORY
       The types described here were added in OpenSSL 3.0.

COPYRIGHT
       Copyright 2019-2021 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>.



3.0.2                                        2026-04-07                         OPENSSL-CORE.H(7SSL)