NAME

       provider-object - A specification for a provider-native object abstraction

SYNOPSIS

        #include <openssl/core_object.h>
        #include <openssl/core_names.h>

DESCRIPTION

       The provider-native object abstraction is a set of OSSL_PARAM(3) keys and values that can
       be used to pass provider-native objects to OpenSSL library code or between different
       provider operation implementations with the help of OpenSSL library code.

       The intention is that certain provider-native operations can pass any sort of object that
       belong with other operations, or with OpenSSL library code.

       An object may be passed in the following manners:

       1.  By value

           This means that the object data is passed as an octet string or an UTF8 string, which
           can be handled in diverse ways by other provided implementations.  The encoding of the
           object depends on the context it's used in; for example, OSSL_DECODER(3) allows
           multiple encodings, depending on existing decoders.  If central OpenSSL library
           functionality is to handle the data directly, it must be encoded in DER for all object
           types except for OSSL_OBJECT_NAME (see "Parameter reference" below), where it's
           assumed to a plain UTF8 string.

       2.  By reference

           This means that the object data isn't passed directly, an object reference is passed
           instead.  It's an octet string that only the correct provider understands correctly.

       Objects by value can be used by anything that handles DER encoded objects.

       Objects by reference need a higher level of cooperation from the implementation where the
       object originated (let's call it X) and its target implementation (let's call it Y):

       1.  An object loading function in the target implementation

           The target implementation (Y) may have a function that can take an object reference.
           This can only be used if the target implementation is from the same provider as the
           one originating the object abstraction in question (X).

           The exact target implementation to use is determined from the object type and possibly
           the object data type.  For example, when the OpenSSL library receives an object
           abstraction with the object type OSSL_OBJECT_PKEY, it will fetch a provider-keymgmt(7)
           using the object data type as its key type (the second argument in
           EVP_KEYMGMT_fetch(3)).

       2.  An object exporter in the originating implementation

           The originating implementation (X) may have an exporter function.  This exporter
           function can be used to export the object in OSSL_PARAM(3) form, that can then be
           imported by the target implementation's imported function.

           This can be used when it's not possible to fetch the target implementation (Y) from
           the same provider.

   Parameter reference
       A provider-native object abstraction is an OSSL_PARAM(3) with a selection of the following
       parameters:

       "data" (OSSL_OBJECT_PARAM_DATA) <octet string> or <UTF8 string>
           The object data passed by value.

       "reference" (OSSL_OBJECT_PARAM_REFERENCE) <octet string>
           The object data passed by reference.

       "type" (OSSL_OBJECT_PARAM_TYPE) <integer>
           The object type, a number that may have any of the following values (all defined in
           <openssl/core_object.h>):

           OSSL_OBJECT_NAME
               The object data may only be passed by value, and should be a UTF8 string.

               This is useful for provider-storemgmt(7) when a URI load results in new URIs.

           OSSL_OBJECT_PKEY
               The object data is suitable as provider-native EVP_PKEY key data.  The object data
               may be passed by value or passed by reference.

           OSSL_OBJECT_CERT
               The object data is suitable as X509 data.  The object data for this object type
               can only be passed by value, and should be an octet string.

               Since there's no provider-native X.509 object, OpenSSL libraries that receive this
               object abstraction are expected to convert the data to a X509 object with
               d2i_X509().

           OSSL_OBJECT_CRL
               The object data is suitable as X509_CRL data.  The object data can only be passed
               by value, and should be an octet string.

               Since there's no provider-native X.509 CRL object, OpenSSL libraries that receive
               this object abstraction are expected to convert the data to a X509_CRL object with
               d2i_X509_CRL().

       "data-type" (OSSL_OBJECT_PARAM_DATA_TYPE) <UTF8 string>
           The specific type of the object content.  Legitimate values depend on the object type;
           if it is OSSL_OBJECT_PKEY, the data type is expected to be a key type suitable for
           fetching a provider-keymgmt(7) that can handle the data.

       "data-structure" (OSSL_OBJECT_PARAM_DATA_STRUCTURE) <UTF8 string>
           The outermost structure of the object content.  Legitimate values depend on the object
           type.

       "desc" (OSSL_OBJECT_PARAM_DESC) <UTF8 string>
           A human readable text that describes extra details on the object.

       When a provider-native object abtraction is used, it must contain object data in at least
       one form (object data passed by value, i.e. the "data" item, or object data passed by
       reference, i.e. the "reference" item).  Both may be present at once, in which case the
       OpenSSL library code that receives this will use the most optimal variant.

       For objects with the object type OSSL_OBJECT_NAME, that object type must be given.

SEE ALSO

       provider(7), OSSL_DECODER(3)

HISTORY

       The concept of providers and everything surrounding them was introduced in OpenSSL 3.0.

COPYRIGHT

       Copyright 2020-2021 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>.